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Aerial grounding and QRM pick-up: theory & practice
Hi group,
I'm a SWL and am specially interested in Navtex DX-reception.My problem is (was) the heavy QRM from about every TV-set, monitor, PC in the neighbourhood. I'm currently using a T-aerial: horizontal wire 20 meters long, ca. 10 meter above ground, vertical part ca. 10 meter down from the middle, = 1:9 "magnetic" balun = 25 meter RG58 to receiver. Receiver is located on the first floor, and is grounded via a thick wire to the earth pin of the house. Typical reception sounds like this: http://users.pandora.be/dirk.claessens2/div/not_grounded.wav ....humming, hissing, hard to decode, nightmare. In despair - and against all advise in antenna textbooks (ground loops!) - I decided to make an additional earth point at the balun. I drove two 1 meter 1/2 inch copperpipes into the ground, and connected these to the shield of the RG58 at the balun. Grounding at the receiver was unchanged. The result was stunning: http://users.pandora.be/dirk.claessens2/div/grounded.wav QRM totally gone! Can anyone explain this? Thanks for any insight - Dirk |
Aerial grounding and QRM pick-up: theory & practice
On Fri, 21 Sep 2007 14:28:47 GMT, Navtex-Fan wrote:
I'm a SWL and am specially interested in Navtex DX-reception.My problem is (was) the heavy QRM from about every TV-set, monitor, PC in the neighbourhood. .... In despair - and against all advise in antenna textbooks (ground loops!) - I decided to make an additional earth point at the balun. .... QRM totally gone! Can anyone explain this? Hi Dirk, The coax to your antenna was suffering common mode currents. These currents came from noise sources in your home (by coupling directly through conduction, or over-the-air). Those currents traveled towards the antenna along the outer surface of the coax's braided shield. When those currents got to the antenna feed point, they reversed direction and entered INTO the transmission line and went back to your receiver. When you grounded the far end, those currents went to ground the easy way instead of through your receiver's front end. A "magnetic" BalUn is not an effective choke. Chokes are used to decouple the transmission line from the feed point. The W2DU choke BalUn (1:1) would also reduce noise. You were LUCKY with ground loops. When the weather changes, you may see your luck change. 73's Richard Clark, KB7QHC |
Aerial grounding and QRM pick-up: theory & practice
On 2007-09-21, Richard Clark (67.168.144.41) wrote in
message On Fri, 21 Sep 2007 14:28:47 GMT, Navtex-Fan wrote: I'm a SWL and am specially interested in Navtex DX-reception.My problem is (was) the heavy QRM from about every TV-set, monitor, PC in the neighbourhood. ... In despair - and against all advise in antenna textbooks (ground loops!) - I decided to make an additional earth point at the balun. ... QRM totally gone! Can anyone explain this? Hi Dirk, The coax to your antenna was suffering common mode currents. These currents came from noise sources in your home (by coupling directly through conduction, or over-the-air). Those currents traveled towards the antenna along the outer surface of the coax's braided shield. When those currents got to the antenna feed point, they reversed direction and entered INTO the transmission line and went back to your receiver. Thanks for the clarification Richard. So in fact the coax shield was part of the antenna? When you grounded the far end, those currents went to ground the easy way instead of through your receiver's front end. A "magnetic" BalUn is not an effective choke. Chokes are used to decouple the transmission line from the feed point. The W2DU choke BalUn (1:1) would also reduce noise. Google gives many hits on this, thanks for the tip. You were LUCKY with ground loops. When the weather changes, you may see your luck change. I'll keep my fingers crossed... :-) The soil here is partly clay/ partly sand. In winter it becomes quite moist. Would that adversely affect the situation? |
Aerial grounding and QRM pick-up: theory & practice
On Fri, 21 Sep 2007 14:28:47 GMT, Navtex-Fan wrote:
Hi group, I'm a SWL and am specially interested in Navtex DX-reception.My problem is (was) the heavy QRM from about every TV-set, monitor, PC in the neighbourhood. I'm currently using a T-aerial: horizontal wire 20 meters long, ca. 10 meter above ground, vertical part ca. 10 meter down from the middle, = 1:9 "magnetic" balun = 25 meter RG58 to receiver. Receiver is located on the first floor, and is grounded via a thick wire to the earth pin of the house. Typical reception sounds like this: http://users.pandora.be/dirk.claessens2/div/not_grounded.wav ...humming, hissing, hard to decode, nightmare. In despair - and against all advise in antenna textbooks (ground loops!) - I have never seen "ground loops" mentioned in an antenna book. Ground loops are a main problem in audio frequency equipment, not in HF. In high frequency equipment GROUND EVERY POINT YOU CAN to create a quasi-reference potential area as large as possible. The usual way to overcome stray noise from nearby sources a 1.) Electrostatic shielding of the antenna. Use coax for the horizontal dipoles, and ground the coax shield at the ends but do not create short circuited loops. (do not confuse with "ground loops") 2. Use a noise eliminator which feeds a phase shifted signal from a small local antenna into a combining network. 3. Improve grounding as you did. To me it is not quite clear what happened in your case, but antennas are and have always been much try-and-error. w. I decided to make an additional earth point at the balun. I drove two 1 meter 1/2 inch copperpipes into the ground, and connected these to the shield of the RG58 at the balun. Grounding at the receiver was unchanged. The result was stunning: http://users.pandora.be/dirk.claessens2/div/grounded.wav QRM totally gone! Can anyone explain this? Thanks for any insight - Dirk |
Aerial grounding and QRM pick-up: theory & practice
On Fri, 21 Sep 2007 18:40:00 GMT, Navtex-Fan wrote:
Thanks for the clarification Richard. So in fact the coax shield was part of the antenna? Hi Dirk, Yes. And that "part" of the antenna was inside your home. Please keep in mind that the same coax shield can support TWO currents: one on the outside and one on the inside. Even though it is the same metallic conductor, the shape creates two circuits because RF currents on the outside cannot penetrate to the inside (that is how it shields). Instead, those currents on the outside travel to a common point such as the feed and gain entrance. Also, the reverse is true as well (when we are thinking in terms of transmission). Put a choke somewhere along that outside circuit, and you cut off that current. In your case, you grounded it at both ends. The soil here is partly clay/ partly sand. In winter it becomes quite moist. Would that adversely affect the situation? It has happened to me (Seattle = Rain City). The "earth" connection you use at the AC plug is NOT a shield, instead it is a safety ground. It is in close proximity to a lot of noisy circuits. Another noise solution is to move your plug to a different room's socket (on a different circuit breaker). You don't have to move the radio to experiment with this, use an extension cord. Better yet, run off battery and unplug everything but the antenna. Remember these last suggestions if the noise returns with rain (or after a rain). 73's Richard Clark, KB7QHC |
Aerial grounding and QRM pick-up: theory & practice
On 21 Sep, 12:14, Helmut Wabnig .... .-- .- -... -. .. --.
@ .- --- -. dot .- - wrote: On Fri, 21 Sep 2007 14:28:47 GMT, Navtex-Fan wrote: Hi group, I'm a SWL and am specially interested in Navtex DX-reception.My problem is (was) the heavy QRM from about every TV-set, monitor, PC in the neighbourhood. I'm currently using a T-aerial: horizontal wire 20 meters long, ca. 10 meter above ground, vertical part ca. 10 meter down from the middle, = 1:9 "magnetic" balun = 25 meter RG58 to receiver. Receiver is located on the first floor, and is grounded via a thick wire to the earth pin of the house. Typical reception sounds like this: http://users.pandora.be/dirk.claessens2/div/not_grounded.wav ...humming, hissing, hard to decode, nightmare. In despair - and against all advise in antenna textbooks (ground loops!) - I have never seen "ground loops" mentioned in an antenna book. Ground loops are a main problem in audio frequency equipment, not in HF. In high frequency equipment GROUND EVERY POINT YOU CAN to create a quasi-reference potential area as large as possible. The usual way to overcome stray noise from nearby sources a 1.) Electrostatic shielding of the antenna. Use coax for the horizontal dipoles, and ground the coax shield at the ends but do not create short circuited loops. (do not confuse with "ground loops") 2. Use a noise eliminator which feeds a phase shifted signal from a small local antenna into a combining network. 3. Improve grounding as you did. To me it is not quite clear what happened in your case, but antennas are and have always been much try-and-error. w. I decided to make an additional earth point at the balun. I drove two 1 meter 1/2 inch copperpipes into the ground, and connected these to the shield of the RG58 at the balun. Grounding at the receiver was unchanged. The result was stunning: http://users.pandora.be/dirk.claessens2/div/grounded.wav QRM totally gone! Can anyone explain this? Thanks for any insight - Dirk- Hide quoted text - - Show quoted text -- Hide quoted text - - Show quoted text - Hi, let me clarify your problem. The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit instead of the usual series circuit. For most efficient radiation both the capacitance and the inductance must act as a energy storage such that when the terminals are shorted the energy is released in a burst such that radiation can begin, the electrical circuit by the way is often called a TANK cuircuit. In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation and thus it travels up the outside of the coax where it can radiate or become part of the "real resistance" of the radiator in a similar way a vertical 1/2 wave antenna would do when half of the applied energy is absorbed by the ground. Per the replies you will see what these currents are named when one has an antenna that wants to work as a full wave length long even tho a 1/2 wave length of the radiator is missing for max efficiency. Hope that helps Regards Art KB9MZ |
Aerial grounding and QRM pick-up: theory & practice
On 2007-09-21, Richard Clark (67.168.144.41) wrote in
message Please keep in mind that the same coax shield can support TWO currents: one on the outside and one on the inside. Even though it is the same metallic conductor, the shape creates two circuits because RF currents on the outside cannot penetrate to the inside (that is how it shields). Instead, those currents on the outside travel to a common point such as the feed and gain entrance. This is complicated, but I now (begin to) understand the true source of the problems I had in the past. I'm not going to post a list here of antennas I've been experimenting with to get rid of the QRM... [..] The soil here is partly clay/ partly sand. In winter it becomes quite moist. Would that adversely affect the situation? It has happened to me (Seattle = Rain City). The "earth" connection you use at the AC plug is NOT a shield, instead it is a safety ground. It is in close proximity to a lot of noisy circuits. [..] So the safety ground is a bad RF ground in most situations. Thanks again for the clarification Richard! -- Dirk. No trees were killed in the creation of this message; however, many electrons were terribly inconvenienced. http://users.pandora.be/dirk.claessens2 |
Aerial grounding and QRM pick-up: theory & practice
On 2007-09-22, art (74.133.197.189) wrote in
message .com In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation and thus it travels up the outside of the coax where it can radiate or become part of the "real resistance" of the radiator in a similar way a vertical 1/2 wave antenna would do when half of the applied energy is absorbed by the ground. Sure, Navtex is broadcasted on 518/490 KHz. Even a 1/4 wavelength antenna is beyond my real estate capabilities. :-( Per the replies you will see what these currents are named when one has an antenna that wants to work as a full wave length long even tho a 1/2 wave length of the radiator is missing for max efficiency. Hope that helps Regards Art KB9MZ Thanks for the info Art, it is appreciated. 73 - Dirk -- Dirk. No trees were killed in the creation of this message; however, many electrons were terribly inconvenienced. http://users.pandora.be/dirk.claessens2 |
Aerial grounding and QRM pick-up: theory & practice
In article ,
Dirk Claessens wrote: On 2007-09-21, Richard Clark (67.168.144.41) wrote in message Please keep in mind that the same coax shield can support TWO currents: one on the outside and one on the inside. Even though it is the same metallic conductor, the shape creates two circuits because RF currents on the outside cannot penetrate to the inside (that is how it shields). Instead, those currents on the outside travel to a common point such as the feed and gain entrance. This is complicated, but I now (begin to) understand the true source of the problems I had in the past. I'm not going to post a list here of antennas I've been experimenting with to get rid of the QRM... [..] The soil here is partly clay/ partly sand. In winter it becomes quite moist. Would that adversely affect the situation? It has happened to me (Seattle = Rain City). The "earth" connection you use at the AC plug is NOT a shield, instead it is a safety ground. It is in close proximity to a lot of noisy circuits. [..] So the safety ground is a bad RF ground in most situations. Thanks again for the clarification Richard! i know this is prob a dumb question reading the last part i agree but i say how come ? they say all points are to be tied together at enterance of house so what is the diff between any two proper grounds connect points then? |
Aerial grounding and QRM pick-up: theory & practice
On 2007-09-22, ml (151.205.97.125) wrote in
message i know this is prob a dumb question reading the last part i agree but i say how come ? they say all points are to be tied together at enterance of house so what is the diff between any two proper grounds connect points then? From a safety viewpoint all ground points are equal. For _RF_ however, one ground point _may_ be better then another, depending on how the wiring goes through the house, and where the ground wire is picking up QRM, hence Richard's suggestion to feed the receiver from a wall outlet in another room. |
Aerial grounding and QRM pick-up: theory & practice
"art" wrote
The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit. For most efficient radiation both the capacitance and the inductance must act as a energy storage such that when the terminals are shorted the energy is released in a burst such that radiation can begin. ... In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation ___________ Note (for one example of many) that in an antenna system consisting of a 1/2-wave, center-fed dipole driven by a matched, balanced transmission line, the dipole itself radiates virtually all of the r-f energy present at the antenna feedpoint. The radiation efficiency of a system as in the above example, but using a full wave dipole is no better than the 1/2-wave version, other things equal. The full wave version just has a different radiation pattern. RF |
Aerial grounding and QRM pick-up: theory & practice
From a safety viewpoint all ground points are equal.
For _RF_ however, one ground point _may_ be better then another, depending on how the wiring goes through the house, and where the ground wire is picking up QRM, hence Richard's suggestion to feed the receiver from a wall outlet in another room. =================== Even better: If no AC is required but say 12 -14 V-DC , run the receiver from a sealed lead-acid battery and only have a RF earth. My complete station runs on 12V batteries (charged by 2 solar panels and a wind gen) ,resulting in NO mains born interference . If charging from mains ,one could switch-off charging while receiving and only put charger on battery or batteries while transmitting. however when the batteries are on the charger all the time the batteries will probably 'absorb' any mains noise ; moreover the mains power supply unit then does not need to supply peak current to the transmitter ,just the average current which for a typical 100 W PEP transmitter (even with compression) is not more than approx. 8 Amperes. In such a situation the station will also always be available (for some time) during a power outage ......emergency comms. With batteries the supply voltage will on average be below 13.8 V ,hence the transmitter output will be slightly lower resulting in a signal which will be lower but never more than a small fraction of 1 S-point. Note : When reducing power by a factor 2 the resulting signal will be reduced by half 1 S-point. Frank GM0CSZ / KN6WH |
Aerial grounding and QRM pick-up: theory & practice
On Sat, 22 Sep 2007 16:05:39 +0100, Highland Ham
wrote: Even better: If no AC is required but say 12 -14 V-DC , run the receiver from a sealed lead-acid battery and only have a RF earth. If charging from mains ,one could switch-off charging while receiving and only put charger on battery or batteries while transmitting. Hi Frank, You are a proponent of one of my suggestions; yes, battery operation (as I have as well) solves many issues. My complete station runs on 12V batteries (charged by 2 solar panels and a wind gen) ,resulting in NO mains born interference . however when the batteries are on the charger all the time the batteries will probably 'absorb' any mains noise ; This is true only if the interfering voltage appears across the battery - a rare occurrence unless you are mobile and speaking of generator/alternator whine. If batteries are float charged, then there is a path from the radio, through the batteries, to the charger, to the mains and common mode follows that path. Similar common mode paths of (in)convenience take time to discover - like an external DSP powered by a wall-wart. 73's Richard Clark, KB7QHC |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 07:22, "Richard Fry" wrote:
"art" wrote The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit. For most efficient radiation both the capacitance and the inductance must act as a energy storage such that when the terminals are shorted the energy is released in a burst such that radiation can begin. ... In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation ___________ Note (for one example of many) that in an antenna system consisting of a 1/2-wave, center-fed dipole driven by a matched, balanced transmission line, the dipole itself radiates virtually all of the r-f energy present at the antenna feedpoint. The radiation efficiency of a system as in the above example, but using a full wave dipole is no better than the 1/2-wave version, other things equal. The full wave version just has a different radiation pattern. RF |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 07:22, "Richard Fry" wrote:
"art" wrote The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit. For most efficient radiation both the capacitance and the inductance must act as a energy storage such that when the terminals are shorted the energy is released in a burst such that radiation can begin. ... In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation ___________ Note (for one example of many) that in an antenna system consisting of a 1/2-wave, center-fed dipole driven by a matched, balanced transmission line, the dipole itself radiates virtually all of the r-f energy present at the antenna feedpoint. The radiation efficiency of a system as in the above example, but using a full wave dipole is no better than the 1/2-wave version, other things equal. The full wave version just has a different radiation pattern. RF I don't know what your credentials are for you to make such a statement but it is a free world after all! A quad radiator is a wave length radiator with a gain more than a half wave as one sample. Computor programing confirmes more radiation from full wave antennas and mathematics according to Maxwell,s rules substantiate it. I can understand not believing computor programs but I am very interested in any mathematical data that would support your stand which is contrary to the mathematics that I and others support. What you are stating is that an attena in a series cuircit format produces the same radiation as a parallel or tank cuircuit. I am more than eager to read the contrary mathematical proof that is contrary to the mathematics that I hold true. You may have hit on the true explaqnation of radiation which Einstein, Planck and many others went to their grave without solving it Regards Art KB9MZ.....XG |
Aerial grounding and QRM pick-up: theory & practice
"art" wrote
A quad radiator is a wave length radiator with a gain more than a half wave as one sample. In your first post you wrote, "The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit," and that is what I responded to. Now you are writing about gain. Efficiency and gain are not synonymous. Both of the dipole antennas in my previous post will radiate nearly 100% of the r-f energy available from a matched, balanced source connected to their input terminals. Therefore the radiation efficiency of those two configurations does not favor the 1-wave over the 1/2-wave, which was your opening premise. They won't have the same gains in every direction, because their radiation patterns are different. Same for your quad and "half wave" example. RF |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 12:33, "Richard Fry" wrote:
"art" wrote A quad radiator is a wave length radiator with a gain more than a half wave as one sample. In your first post you wrote, "The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit," and that is what I responded to. Now you are writing about gain. Efficiency and gain are not synonymous. Both of the dipole antennas in my previous post will radiate nearly 100% of the r-f energy available from a matched, balanced source connected to their input terminals. Therefore the radiation efficiency of those two configurations does not favor the 1-wave over the 1/2-wave, which was your opening premise. They won't have the same gains in every direction, because their radiation patterns are different. Same for your quad and "half wave" example. RF O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. You could I suppose compare a series antenna with a parallel circuit i.e. a tank circuit that could reinforce your point and that is what I hoped you would come up with to bolster your point without resorting to a computor program based on Maxwellian laws. There is much discussion about what creates radiation and I thought you may have come up with something that we can all learn from. Eventually even tho the past masters have died some one, possibly you, will discover that which has eluded all, even quallified scientists with huge resumes. I am willing to give you a hearing which does not often happen on this newsgroupAs an aside I suspect that a single quad element will beat a dipole anyway regardles of what the fields differences that you point to but again I am very interested in any mathematics that defends your possition possibly starting witha parallel versus a series arrangement since it is very clear whatstarts radiation in the parallelcase but unknown mathematically for the series circuit. Very best regards Art Unwin....KB9MZ |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 15:40, art wrote:
On 22 Sep, 12:33, "Richard Fry" wrote: "art" wrote A quad radiator is a wave length radiator with a gain more than a half wave as one sample. In your first post you wrote, "The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit," and that is what I responded to. Now you are writing about gain. Efficiency and gain are not synonymous. Both of the dipole antennas in my previous post will radiate nearly 100% of the r-f energy available from a matched, balanced source connected to their input terminals. Therefore the radiation efficiency of those two configurations does not favor the 1-wave over the 1/2-wave, which was your opening premise. They won't have the same gains in every direction, because their radiation patterns are different. Same for your quad and "half wave" example. RF O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. You could I suppose compare a series antenna with a parallel circuit i.e. a tank circuit that could reinforce your point and that is what I hoped you would come up with to bolster your point without resorting to a computor program based on Maxwellian laws. There is much discussion about what creates radiation and I thought you may have come up with something that we can all learn from. Eventually even tho the past masters have died some one, possibly you, will discover that which has eluded all, even quallified scientists with huge resumes. I am willing to give you a hearing which does not often happen on this newsgroupAs an aside I suspect that a single quad element will beat a dipole anyway regardles of what the fields differences that you point to but again I am very interested in any mathematics that defends your possition possibly starting witha parallel versus a series arrangement since it is very clear whatstarts radiation in the parallelcase but unknown mathematically for the series circuit. Very best regards Art Unwin....KB9MZ- Hide quoted text - - Show quoted text - Wait a minuit! you stated that a half wave antenna was nearly 100% efficient and therein may be the true answer A quad is often considered as two dipoles even tho there is only one feed point thus efficiency per unit!Then one can refer to efficiency per unit length. Is that your point? Art |
Aerial grounding and QRM pick-up: theory & practice
"art" wrote
O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. _________ Please post your definition of "efficiency," in this context. RF |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 16:02, "Richard Fry" wrote:
"art" wrote O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. _________ Please post your definition of "efficiency," in this context. RF Power in vs power out of a system. I know how to do this for a parallel circuit ala a tank circuit where energy is released in equilibrium fashion. For a half wave dipole you can't have two energy containers so you may or may not be heading for excess end effects because of high voltage looking for where it has to go. (Personally I don't know how a half wave radiates because that form vuews the cyclic current continually radiating as the time variant which is contrary to all other radiations i.e. a spark plug, ahydregen bomb which is a bigger container that a flyback transformer and a bigger container will always beat a small container with respect to out going accelleration of energy, particles or plasma which ever you may prefer)without any known proof.I believe that is why the quad was designed to get away from the spark plug type emmissions at the ends of the radiator. On the other side of the coin, since both a quad and a 1/2 wave dipole is assumed to be suitable drivers for a yagi array both must be bi directional so gain is applicable when comparing these radiators I would would think! Best regards Art |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 16:47, art wrote:
On 22 Sep, 16:02, "Richard Fry" wrote: "art" wrote O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. _________ Please post your definition of "efficiency," in this context. RF Power in vs power out of a system. I know how to do this for a parallel circuit ala a tank circuit where energy is released in equilibrium fashion. For a half wave dipole you can't have two energy containers so you may or may not be heading for excess end effects because of high voltage looking for where it has to go. (Personally I don't know how a half wave radiates because that form vuews the cyclic current continually radiating as the time variant which is contrary to all other radiations i.e. a spark plug, ahydregen bomb which is a bigger container that a flyback transformer and a bigger container will always beat a small container with respect to out going accelleration of energy, particles or plasma which ever you may prefer)without any known proof.I believe that is why the quad was designed to get away from the spark plug type emmissions at the ends of the radiator. On the other side of the coin, since both a quad and a 1/2 wave dipole is assumed to be suitable drivers for a yagi array both must be bi directional so gain is applicable when comparing these radiators I would would think! Best regards Art Richard , I have been reviewing antenna fundamentals as per the engineering handbook by Jasik second edition where it states "The method of computing radiation patterns foir thin linear radiators is basic regardless of length or complexity of shape " if one assumes that the current from point to point is sinosoidal. This statment is consistent with the present assumption that the time variant current is sinosoidal at every point along the length of the antenna. Well I have clearly shown for a parallel circuit you cannot pursue this assumption anymore even tho the books state otherwise. The books are not incorrect if the mathematics produced by such a assumption is correct which mathematicians often do when there is an absence of knoweledge to the contrary. What I am declaring is the tank circuit ala parallel circuit which demands a full wave length antenna is the most efficient because the assumption by mathematicians is incorrect. Following Gauss's laws for static and enlarging the format to a dinamic situation i.e. time varient then the demand is for a arrangement in "equilibrium" which cannot be attained with anything other that a full wave length. Following this logic mathematically it concurrs with Maxwells laws and any computor program will move away from any half wave radiator if you ask for maximum gain and allow it to computeaway from a planar arrangement under Maxwells laws.( By the way I always refer to a full wavelength radiator which by no means infers a center feed. In my case I usually follow the end fed aproach because of a dual windings but in opposite directions) If Maxwell had in his portfolio an expanded Gaussuian law for making his jigsaw complete the overall picture would have been completed in no time. Unfortunately he did not have this at hand but instead used Faraday and others input to arrive at the correct answer but with gaps in the info provided. It is for that reason I persued this analogy which is new and contrary with existing assumptions even tho the eventual answers are the same. BUT the analogy of assumption of time varient current of itself produces radiation is incorrect at least for a parallel circuit, aspark plug with a flyback transformer or even the emmisions of a nuclear explosion. I don't think there is a need to dither on the subject anymore since nobody knows how a fractional wavelength antenna really works whereas I am promoting a view of an arrangement in equilibrium and the commonly used approach by Gauss and others with respect to a closed arbitary field. Enjoyed the discussion tho, very thought provoking. Regards Art antennas |
Aerial grounding and QRM pick-up: theory & practice
On Sep 22, 5:40 pm, art wrote:
O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. If it does, I doubt it's enough to measure on the air.. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. I've never seen it here. For that reason, I hardly use loops. Neither vertically oriented, or horizontal as for NVIS use. I don't see them as worth the extra trouble. Being I tested them on 75m using NVIS paths, a noticable difference in efficiency should have been readily apparent. It wasn't. In fact, I usually has slightly better performance using the dipoles, which I think was due to the bulk of the max current portions of the antenna being higher above ground in general. The loop sagged a bit in areas, and wasn't all that high above ground. The more wire near the ground, the more ground loss in general. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. Where is the math? You should find a very slight difference at best.. It's common knowledge that even a short piece of wire 1/10 of a wave long will radiate nearly all the power that is applied to it. You can go lots shorter than that if you want. If even a short piece of wire will radiate nearly all the power applied to it, what is the point on harping about some magical properties of a full wave length of wire? Art, you are starting to bark at the moon I'm afraid... I was going to comment on some of your other posts, but I think I'll spare you the increase in blood pressure. All I can say is that you are starting to wander off in mumbo jumbo land again.. Replacing known science with conjured mumbo jumbo is no way to live. MK |
Aerial grounding and QRM pick-up: theory & practice
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Aerial grounding and QRM pick-up: theory & practice
If you'll look back at some of Art's postings, you'll see that he
consistently uses the word "efficiency" in a way that's contrary to the universally accepted definition. His meaning of the word is more like gain, but sometimes including communication effectiveness in some way. In fishing through earlier postings, you'll also see that I implored him many times to either use such words as they're universally understood, or else explicitly define what he means by them. The reason for the requests was to help him communicate what he was trying to say, rather than leave a trail of misunderstanding and confusion. All my requests did, however, was make him intensely angry with me, and no definitions were given or change in usage made. I hope this recent round of requests for clarification will have more effect than I was ever able to accomplish. Roy Lewallen, W7EL |
Aerial grounding and QRM pick-up: theory & practice
"art" wrote
I don't think there is a need to dither on the subject anymore since nobody knows how a fractional wavelength antenna really works Read Kraus' "Antennas...," 3rd edition, Section 2-12 and related text. |
Aerial grounding and QRM pick-up: theory & practice
On 22 Sep, 20:36, Walter Maxwell wrote:
On Sat, 22 Sep 2007 19:19:18 -0700, wrote: On Sep 22, 5:40 pm, art wrote: O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. If it does, I doubt it's enough to measure on the air.. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. I've never seen it here. For that reason, I hardly use loops. Neither vertically oriented, or horizontal as for NVIS use. I don't see them as worth the extra trouble. Being I tested them on 75m using NVIS paths, a noticable difference in efficiency should have been readily apparent. It wasn't. In fact, I usually has slightly better performance using the dipoles, which I think was due to the bulk of the max current portions of the antenna being higher above ground in general. The loop sagged a bit in areas, and wasn't all that high above ground. The more wire near the ground, the more ground loss in general. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. Where is the math? You should find a very slight difference at best.. It's common knowledge that even a short piece of wire 1/10 of a wave long will radiate nearly all the power that is applied to it. You can go lots shorter than that if you want. If even a short piece of wire will radiate nearly all the power applied to it, what is the point on harping about some magical properties of a full wave length of wire? Art, you are starting to bark at the moon I'm afraid... I was going to comment on some of your other posts, but I think I'll spare you the increase in blood pressure. All I can say is that you are starting to wander off in mumbo jumbo land again.. Replacing known science with conjured mumbo jumbo is no way to live. MK Art, it distresses me to read the misleading statements you profess to be true in your posts. There is no difference in the 'efficiencies' between a full-wave and a half-wave dipole. Let's assume the wire size and conductivity of each dipole is such that we can say they both radiate 98 percent of the power delivered to them. Let's also say that the same amount of power is delivered to both dipoles. What now is the difference in the radiation between the two dipoles? snip Walt. I have no problem with Maxwells laws but I do have a problem with a mathematical stunt to measure radiation of a half wave dipole based on one having to accept that at all points on the radiator the current is sinosoidal. There is no distinct analysis with the specifics of radiation. period. Using a parallel circuity ala tank circuit insights are produced that radiation is created by the shorted energy containers of capacitance and inductance which is an intrinsic part of any radiator in distributed form. The tank circuit is well documented. So the question now becomes, at least for full understanding of radiation is how does a half wave radiator follow the format shown by a spark plug with a flyback transformer or a full wave radiator or even the blast from a nuclear bomb? Yes, a half wave antenna also has distributed inductance and capacitance energy containers but how is the mechanism shown by the tank circuit implimented when the arrangement is not in equilibrium? Now I think I know what happens but I am interested in contrary thoughts from those skilled in the arts without the retoric. As an aside, why does computor programs drift away from planar form radiators as well to full wave radiators when the computor is asked to compute for maximum gain? Is this like the quadratic equation with four answers where you get to determine the imaginary answers? I would suggest for starters those that are skilled in the art quantify the energy used for end effect radiation either in the normal atmosphere or in the rarified atmosphere of Quito Equador when Tesla type emmissions are visable? Without assumptions ofcourse!!!! Regards Art |
Aerial grounding and QRM pick-up: theory & practice
art wrote:
I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. What if the 1/2 wave dipole was made of super-conducting material, i.e. zero loss except for radiation? -- 73, Cecil http://www.w5dxp.com |
Aerial grounding and QRM pick-up: theory & practice
On 23 Sep, 07:29, "Jimmie D" wrote:
"art" wrote in message ups.com... On 22 Sep, 07:22, "Richard Fry" wrote: "art" wrote The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit. For most efficient radiation both the capacitance and the inductance must act as a energy storage such that when the terminals are shorted the energy is released in a burst such that radiation can begin. ... In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation ___________ Note (for one example of many) that in an antenna system consisting of a 1/2-wave, center-fed dipole driven by a matched, balanced transmission line, the dipole itself radiates virtually all of the r-f energy present at the antenna feedpoint. The radiation efficiency of a system as in the above example, but using a full wave dipole is no better than the 1/2-wave version, other things equal. The full wave version just has a different radiation pattern. RF I don't know what your credentials are for you to make such a statement but it is a free world after all! A quad radiator is a wave length radiator with a gain more than a half wave as one sample. Computor programing confirmes more radiation from full wave antennas and mathematics according to Maxwell,s rules substantiate it. I can understand not believing computor programs but I am very interested in any mathematical data that would support your stand which is contrary to the mathematics that I and others support. What you are stating is that an attena in a series cuircit format produces the same radiation as a parallel or tank cuircuit. I am more than eager to read the contrary mathematical proof that is contrary to the mathematics that I hold true. You may have hit on the true explaqnation of radiation which Einstein, Planck and many others went to their grave without solving it Regards Art KB9MZ.....XG I dont know his credentials either but Richard is absolutly correct. Efficency is the ability to radiate the signal and not turn it into infra-red energy and has nothing to do with gain. The Math: Efficiency = (power applied to the antenna system - power turned into heat by the antenna system)/power applied to the antenna system. Doesnt take a computer, doesnt take Maxwell or Einstien to explain. 5th grade math works pretty well in this case. The best thing the OP can do for his existing antenna is install a good ground system and impedance matching networks, antenna tuner. If I were really serious about it I would invest in an antenna analyzer so I would know when my antenna is tuned for optimum match to my radio and log the settings of my tuner. With the ground system and antenna type he has I am sure the ground resistance is soaking up most of his signal. He would surely benifit from improving his ground system. Jimmie- Hide quoted text - - Show quoted text - In comparing two antennas with similar omni direction radiation field I state that gain in the field is indicative of increased radiadion but that is a side issue brought up as often is in this newsgroup in tha absence of a point by point debate. That method of responding is pretty much used by all polititions. If you state what you THINK makes the "best antenna" from accurate empirical data then I have no problem with what you say, I just don't agree with it. I say that because you focussed on drive or feed impedance when it is well known that a matching impedand does not infer we have a matching impedance in the system. Am illustration of the point. The new touted antenna from Rohd island university proclames a shortened antenna with a 52 ohm matching impedance. Since a half wave antenna is not in equilibrium the energy for themissing half must go somewhere. In the case of the new antenbna the extra energy went back into the feed line and possibly could have radiated from there and not the antenna. The ground plane that you put forward infers that the ground plane is the other half of a equivalent full wave dipole, and it may well be if one can say that the ground plane radiates and prevents the ground wasting the energy. Personally I don't believe that ground radials radiate but that is O.K. So how is this new fangled antenna corrected to radiating efficiently. How is that done? The antenna uses an inductive turnsfor shortening a antena thatis not in equilibrium so to bring it into equilibrium you add a mirror immage of the antenna including the windings and connect the two at the top together with the image antenna wound over the initial antenna such that the extra indunct becomes balanced( not cancelled) and thus one can feed it at the two wire extremities. Now you have no end effects energy losses and the circulating current has no need to find a way to balance the circuit by seeking the ground or backtracking up the feed line.It takes no time at all to prove this with a small home made antenna and it is that what I was sugesting from the beginning. By the way this is exactly what the scientific community has been pursuing with the anttena therom of merging electrical and magnetic field as well as others. Until now nobody was aware that if Gauss had continued with his static theorem and enlargened it to a dinamic basis more information about radiation would be revealed with consequenct advances as to what creats or starts radiation rather than continueing with a situation founded on a assumption of which there is no proof. The theorem of an extended gaussian logical strategy to bring it into the format of radiation production destroys the present assumptions alluded to both in mathematical term and also in empirical terms without deviation from Maxwells laws with the extra proof that computor programs built around Maxwells laws also confirms the equilibrium position. Now I have no problem with people that all existing designs are better but for sure industry and the younger generation is not opposed in reviewing perceived improvements since they are not addicted to preventing change. The bottom line is that a person asked for info and it is upto him to choose which he will accept and one should not get into distress if counter information becomes chosen. Have a great day Regards Art KB9MZ |
Aerial grounding and QRM pick-up: theory & practice
Roy Lewallen wrote:
If you'll look back at some of Art's postings, you'll see that he consistently uses the word "efficiency" Oh, this thread had me a bit confused. I didn't see where you guys suddenly started taking about efficiency, where did that come from? Now Roy clears things up for me, it was due to a posting by "Art." See, Art is in my killfile, and my good old newsreader effectively clobbered his post. Art has been in my killfile for months now, permanently, because it always seemed whenever he posted something it resulted in a rash of waste-of-my time replies, of folks trying to straighten him out, and I don't think anyone ever has. So now that this thread has deteriorated..... "Aerial grounding" goes in my killfile. CUL. So that I don't get flamed too much, I will start a posting on a little project I am working on here, which is incomplete. I am titling it "Beverage antenna, feedline pickup." Rick K2XT |
Aerial grounding and QRM pick-up: theory & practice
On 23 Sep, 06:37, Cecil Moore wrote:
art wrote: I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. What if the 1/2 wave dipole was made of super-conducting material, i.e. zero loss except for radiation? -- 73, Cecil http://www.w5dxp.com Can you have a tank circuit without resistance? Is I sq R now not applicable anymore? Glad to see you commenting. Art |
Aerial grounding and QRM pick-up: theory & practice
On Sat, 22 Sep 2007 19:18:24 -0700, art wrote:
Richard , I have been reviewing antenna fundamentals as per the engineering handbook by Jasik second edition where it states Equation (1-1) efficiency = power radiated by antenna / power accepted by antenna There is absolutely nothing stated here about "Gain" because radiation is in every direction. An antenna is a passive device, it cannot exhibit gain. Johnson and Jasik sez: "if one has a lossless antenna, the directivity and gain are identical." Equation (1-2): "The total power radiated from the antenna is" the measurement of radiation intensity in watts/sr in every direction from an antenna. Equation (1-4): "Directivity is the measure of the ability of an antenna to concentrate radiated power in a particular direction." which is a sub-portion of the total radiation. We can measure the total power of all radiation (EZNEC provides this); we can measure the power accepted by an antenna (EZNEC provides this); we can measure the power in a particular direction (EZNEC provides this). "The method of computing radiation patterns foir thin linear radiators is basic regardless of length or complexity of shape " There is for EVERY length. "if one assumes that the current from point to point is sinosoidal. "for the case of a thin half-wave radiator which can be assumed to have a sinusoidal current distribution" This statement is NOT about efficiency and it specifically recites what can be said about: 1. radiation patterns; 2. radiation resistance; 3. "gain" (directivity); 4. input Z. We, in this group, quite typically express ALL of these qualities for ANY antenna on the basis of SPECIFIC physical dimensions and frequency. When we do, there is barely a half dB variation in any answer, and often better when all SPECIFIC physical dimensions and frequency are provided by the claim maker. As you often fail to provide this SPECIFIC information, then your claims descend into the category of myth and superstition (you can call it hope and desire). What I am declaring is the tank circuit ala parallel circuit which demands a full wave length antenna is the most efficient because the assumption by mathematicians is incorrect. This is superstition. This Voodoo can be easily tested. The first part of equation (1-1) from the authors you quote demand you supply the SPECIFIC power accepted by an antenna. You also fail to supply the second part of equation (1-1) that states the SPECIFIC power radiated by the antenna. Voodoo = 100% So, to SPECIFIC counter proofs: A half wave antenna in free space: length = 33.43 feet wire diameter = #12 wire frequency = 14.28127 MHz input Z = 72.12 ąj0.00 Ohms Power accepted by antenna = 100W Power radiated by antenna = 100W Efficiency = 100% Absolutely same antenna in free space at its full wavelength frequency: length = 33.43 feet wire diameter = #12 wire frequency = 28.463975 MHz input Z = 4257 ąj0.00 Ohms Power accepted by antenna = 100W Power radiated by antenna = 100W Efficiency = 100% BOTH antennas exhibit radiation patterns IDENTICAL to Johnson and Jasik. BOTH antennas exhibit input Zs IDENTICAL to Johnson and Jasik. BOTH antennas exhibit radiation patterns IDENTICAL to Johnson and Jasik. BOTH antennas exhibit radiation resistances IDENTICAL to Johnson and Jasik. BOTH antennas exhibit radiation gain (directivity) IDENTICAL to Johnson and Jasik. When either of these two are off-center fed the efficiency DOES NOT CHANGE: Power accepted by antenna = 100W Power radiated by antenna = 100W Efficiency = 100% nobody knows how a fractional wavelength antenna really works Total ignorance reveals: Voodoo = 100% Equation (1-1) and (1-2) are for any size antenna. All of this stuff is in the FIRST TWO PAGES OF THE BOOK. On the very first page of "Fundamentals of Antennas" "If the current distribution on a wire is known ... then the radiation pattern and the radiated power can be computed." Marconi could measure current distribution 100 years ago. The authors, of course, give treatments for antennas of all sizes, otherwise the book would only be three pages long. Arthur, stop coloring the pages with your crayons long enough to try reading at least these three pages. :-0 73's Richard Clark, KB7QHC |
Aerial grounding and QRM pick-up: theory & practice
"Richard Clark" wrote ... On Sat, 22 Sep 2007 19:18:24 -0700, art wrote: Richard , I have been reviewing antenna fundamentals as per the engineering handbook by Jasik second edition where it states Equation (1-1) Massive snip of good stuff Arthur, stop coloring the pages with your crayons long enough to try reading at least these three pages. :-0 73's Richard Clark, KB7QHC Richard: I love to watch you tilt at windbags!!!! Mike W5CHR |
Aerial grounding and QRM pick-up: theory & practice
On Sep 23, 11:18 am, art wrote:
In comparing two antennas with similar omni direction radiation field I state that gain in the field is indicative of increased radiadion ... ....yes, but radiation only in limited az/el sectors, at the expense of loss of radiation in the other sectors. The field gain in a particular direction is due to the change in pattern shape, not an increased radiation efficiency of the "better" antenna. For the same input power accepted by different antennas, the total power radiated into the volume of space is the same, no matter what the shapes of their respective radiation envelopes. |
Aerial grounding and QRM pick-up: theory & practice
On 23 Sep, 11:45, "Jimmie D" wrote:
"Walter Maxwell" wrote in message ... On Sat, 22 Sep 2007 19:19:18 -0700, wrote: On Sep 22, 5:40 pm, art wrote: O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. If it does, I doubt it's enough to measure on the air.. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. I've never seen it here. For that reason, I hardly use loops. Neither vertically oriented, or horizontal as for NVIS use. I don't see them as worth the extra trouble. Being I tested them on 75m using NVIS paths, a noticable difference in efficiency should have been readily apparent. It wasn't. In fact, I usually has slightly better performance using the dipoles, which I think was due to the bulk of the max current portions of the antenna being higher above ground in general. The loop sagged a bit in areas, and wasn't all that high above ground. The more wire near the ground, the more ground loss in general. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. Where is the math? You should find a very slight difference at best.. It's common knowledge that even a short piece of wire 1/10 of a wave long will radiate nearly all the power that is applied to it. You can go lots shorter than that if you want. If even a short piece of wire will radiate nearly all the power applied to it, what is the point on harping about some magical properties of a full wave length of wire? Art, you are starting to bark at the moon I'm afraid... I was going to comment on some of your other posts, but I think I'll spare you the increase in blood pressure. All I can say is that you are starting to wander off in mumbo jumbo land again.. Replacing known science with conjured mumbo jumbo is no way to live. MK Art, it distresses me to read the misleading statements you profess to be true in your posts. There is no difference in the 'efficiencies' between a full-wave and a half-wave dipole. Let's assume the wire size and conductivity of each dipole is such that we can say they both radiate 98 percent of the power delivered to them. Let's also say that the same amount of power is delivered to both dipoles. What now is the difference in the radiation between the two dipoles? The only difference is in the SHAPE of the radiation patterns--the full-wave dipole will have a somewhat narrower lobe in the direction broadside to the dipole than that of the half-wave dipole, therefore deriving slightly more gain IN THAT DIRECTION than that of the half-wave, but with less gain than the half-wave in all other directions. Consequently, the total integrated power in either radiation pattern will be exactly the same!!! If you want to express the mathematics of the conditions I described here according to J.C.Maxwell's equations, you will find that Maxwell's equations fit the conditions EXACTLY. Walt, W2DU If any difference at all exist it is that the full wave antenna would be ever so slightly less efficient due to the ohmic losses of the extra wire. Jimmie- Hide quoted text - - Show quoted text - Give me the proof not a opinion when there are so many . Art KB9MZ |
Aerial grounding and QRM pick-up: theory & practice
On 23 Sep, 12:02, "Dave" wrote:
"Jimmie D" wrote in message ... "Walter Maxwell" wrote in message .. . On Sat, 22 Sep 2007 19:19:18 -0700, wrote: On Sep 22, 5:40 pm, art wrote: O.K. I may have muddied things. I hold to the fact that a one wavelength dipole will always radiate at a higher efficiency than a 1/2 wave dipole. If it does, I doubt it's enough to measure on the air.. The example I gave as for an instance was a quad versus a 1/2 wave dipole. This is readily seen by any operator empirically. I've never seen it here. For that reason, I hardly use loops. Neither vertically oriented, or horizontal as for NVIS use. I don't see them as worth the extra trouble. Being I tested them on 75m using NVIS paths, a noticable difference in efficiency should have been readily apparent. It wasn't. In fact, I usually has slightly better performance using the dipoles, which I think was due to the bulk of the max current portions of the antenna being higher above ground in general. The loop sagged a bit in areas, and wasn't all that high above ground. The more wire near the ground, the more ground loss in general. Mathematically it is proven that way also even tho both are in accordance to Maxwell's laws. Where is the math? You should find a very slight difference at best.. It's common knowledge that even a short piece of wire 1/10 of a wave long will radiate nearly all the power that is applied to it. You can go lots shorter than that if you want. If even a short piece of wire will radiate nearly all the power applied to it, what is the point on harping about some magical properties of a full wave length of wire? Art, you are starting to bark at the moon I'm afraid... I was going to comment on some of your other posts, but I think I'll spare you the increase in blood pressure. All I can say is that you are starting to wander off in mumbo jumbo land again.. Replacing known science with conjured mumbo jumbo is no way to live. MK Art, it distresses me to read the misleading statements you profess to be true in your posts. There is no difference in the 'efficiencies' between a full-wave and a half-wave dipole. Let's assume the wire size and conductivity of each dipole is such that we can say they both radiate 98 percent of the power delivered to them. Let's also say that the same amount of power is delivered to both dipoles. What now is the difference in the radiation between the two dipoles? The only difference is in the SHAPE of the radiation patterns--the full-wave dipole will have a somewhat narrower lobe in the direction broadside to the dipole than that of the half-wave dipole, therefore deriving slightly more gain IN THAT DIRECTION than that of the half-wave, but with less gain than the half-wave in all other directions. Consequently, the total integrated power in either radiation pattern will be exactly the same!!! If you want to express the mathematics of the conditions I described here according to J.C.Maxwell's equations, you will find that Maxwell's equations fit the conditions EXACTLY. Walt, W2DU If any difference at all exist it is that the full wave antenna would be ever so slightly less efficient due to the ohmic losses of the extra wire. Jimmie don't claim that until you have modeled it in full. it "may" What does "may" infere? Is it it 'may' or 'may not' or 'I am not sure' or 'I don't know'? I am not willing to procede with what you say unless you can be more difinitive. What does a house built on sand do? snip ragards Art KB9MZ....XG |
Aerial grounding and QRM pick-up: theory & practice
Jimmie D wrote:
On 23 Sep, 12:02, "Dave" wrote: don't claim that until you have modeled it in full. it "may" Who said "may", not me Jimmie The attributions indicate that Dave said "may". -- 73, Cecil http://www.w5dxp.com |
Aerial grounding and QRM pick-up: theory & practice
I am sorry to read this. I had hoped I had stumbled upon a perpetual motion
machine. "Jimmie D" wrote in message ... [snip] No that is the point. An antenna can radiate no more energy than you put into it. If you do something to increase the field intensity in one direction the field intensity must decrease in other directions. Nothing to debate, it is a proven fact. A fact you will never accept because if you do you will also have to accept the your guassian antenna is just a delusion. It is a real shame that you have chosen a knowledge of antennas to be such an important measuring stick for the value of your existence. |
Aerial grounding and QRM pick-up: theory & practice
John, N9JG wrote:
I am sorry to read this. I had hoped I had stumbled upon a perpetual motion machine. Keep the faith baby! You just might have, he http://www.dailymail.co.uk/pages/liv...page_id=19 65 Regards, JS |
Aerial grounding and QRM pick-up: theory & practice
On Sep 24, 7:16 pm, "Jimmie D" wrote:
"art" wrote in message ups.com... On 23 Sep, 07:29, "Jimmie D" wrote: "art" wrote in message roups.com... On 22 Sep, 07:22, "Richard Fry" wrote: "art" wrote The most efficient radiator is one wave length long where it is considered to be in equilibrium with a parallel electrical cuircuit. For most efficient radiation both the capacitance and the inductance must act as a energy storage such that when the terminals are shorted the energy is released in a burst such that radiation can begin. ... In the case of a fractional wave length radiator the pendulum type radiation is not available for radiation ___________ Note (for one example of many) that in an antenna system consisting of a 1/2-wave, center-fed dipole driven by a matched, balanced transmission line, the dipole itself radiates virtually all of the r-f energy present at the antenna feedpoint. The radiation efficiency of a system as in the above example, but using a full wave dipole is no better than the 1/2-wave version, other things equal. The full wave version just has a different radiation pattern. RF I don't know what your credentials are for you to make such a statement but it is a free world after all! A quad radiator is a wave length radiator with a gain more than a half wave as one sample. Computor programing confirmes more radiation from full wave antennas and mathematics according to Maxwell,s rules substantiate it. I can understand not believing computor programs but I am very interested in any mathematical data that would support your stand which is contrary to the mathematics that I and others support. What you are stating is that an attena in a series cuircit format produces the same radiation as a parallel or tank cuircuit. I am more than eager to read the contrary mathematical proof that is contrary to the mathematics that I hold true. You may have hit on the true explaqnation of radiation which Einstein, Planck and many others went to their grave without solving it Regards Art KB9MZ.....XG I dont know his credentials either but Richard is absolutly correct. Efficency is the ability to radiate the signal and not turn it into infra-red energy and has nothing to do with gain. The Math: Efficiency = (power applied to the antenna system - power turned into heat by the antenna system)/power applied to the antenna system. Doesnt take a computer, doesnt take Maxwell or Einstien to explain. 5th grade math works pretty well in this case. The best thing the OP can do for his existing antenna is install a good ground system and impedance matching networks, antenna tuner. If I were really serious about it I would invest in an antenna analyzer so I would know when my antenna is tuned for optimum match to my radio and log the settings of my tuner. With the ground system and antenna type he has I am sure the ground resistance is soaking up most of his signal. He would surely benifit from improving his ground system. Jimmie- Hide quoted text - - Show quoted text - In comparing two antennas with similar omni direction radiation field I state that gain in the field is indicative of increased radiadion but that is a side issue brought up as often is in this newsgroup in tha absence of a point by point debate. No that is the point. An antenna can radiate no more energy than you put into it. If you do something to increase the field intensity in one direction the field intensity must decrease in other directions. Nothing to debate, it is a proven fact. A fact you will never accept because if you do you will also have to accept the your guassian antenna is just a delusion. If you look at the field of a antenna that isr radiating an equal amount in all direction the volume of the radiation consists of usefull energy in the form of radiation. If another antenna with the same energy input provides a radiation field in all directions that is equal but at a larger radius than the prior antenna field the the latter antenna has gain over the prior antenna. If you compare any fractional ground mounted antenna with a full wave antenna the radius of the field willhave a difference of aprox 3 db and the resistive impedance will have a ratio of two to one.Note that gain is a measure of one radiator level against another and is no way a distorted field of radiation that has been manipulated by an additional near by radiator. A ground plane does nothing more than balancing the circuit provided such that current does not meander back thru the feed line and a ground plane is only necessary for a fractional wavelength circuit to balance the circuit as a whole. It eats up energy that would normally provide radiation in a circuit such as a full wave radiator. Without a good ground plane the impedance to a fractional wave length is difficult and usually not efficient and a lot less than that of a radiator that does have a good ground plane which is around30 ohms resistive which is 1/2 of the resistive impedance of a full wave radiator. As far as the Gaussian antenna it is not an illusion to those with an engineering background. For those without an engineering background to enable them to follow the logic do not have the know how to discredit anything and certainly can not measure the quality of life of those with understanding. If you cannot follow the science of antennas then you are doomed to be a follower, never a leader. and certainly not a judge. I'm gone for a month or so and will not be using this newsgroup during that time. Will be back in the fall Art It is a real shame that you have chosen a knowledge of antennas to be such an important measuring stick for the value of your existence. Jimmie Jimmie |
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