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#32
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It is a truism
On 11/14/2014 8:36 AM, Jerry Stuckle wrote:
On 11/13/2014 6:12 PM, wrote: FBMboomer wrote: On 11/12/2014 1:50 PM, gareth wrote: It is a truism that short antennae are poor inefficient radiators, and no amount of infantile bluster by Americanoramuses will change that. The truth does not need the violence of abuse to force its way down people's throats. A perfect example is a G5RV on 75 meters. They suck. When someone joins our group rag chew on 75, and they have a poor signal, The first thing I ask is "Are you using a G5RV". We all have a chuckle when they answer yes and then ask how we knew. :-) False logic. You don't know how many people with good signals are using G5RV's, because you only ask those with poor signals. Trying to prove with math that short antennae work as well as say a 1/2 wave dipole may give someone great sport. However, in the real world, short antennae suck big time. I have been an American for most of my life. Please do not paint us all with the same brush. Yes and no. Depending on their design, short antennas can be very efficient. See http://www.futurity.org/radio-wave-c...phones-801322/ for an example. But others are correct. The antenna itself is an efficient radiator; it's the matching network that lowers *antenna system* efficiency. Any dipole type antenna will suck on 75M if mounted less than about 100 feet, or about .4 wavelengths. Below that you are warming clouds. So now it's 100 feet? It used to be 60 feet. But I have proof that is not the case. So do a lot of other hams I know. Your "facts" are for an idealized installation. Reality is much different, and will never get the ideal specifications you claim. snip I strongly encourage you to use a "loaded" 1 foot long dipole on 75 meters. This will prove you are right and we can all listen to the proof. :-) |
#33
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It is a truism
On 11/14/2014 2:49 PM, Ralph Mowery wrote:
"Jerry Stuckle" wrote in message ... On 11/14/2014 12:34 PM, wrote: You ignore the fact this is an idealized environment. That is NEVER the case in a real installation. I have WAS on 75 SSB (from Iowa) with an inverted Vee. The top was only 50' in the air. And late at night in the wintertime I had pretty solid communications over much of the continental U.S. (back in the late 70's and early 80's). Antennas NEVER work "as predicted" - and anyone who claims they do does not understand antenna operation. Antennas 'always' work as predicted. People just don't always factor in everything in the prediction. Just as I worked a station on 432 MHz with 25 watts to a 1/4 wave ground plane that was about 1000 miles away. Nice bit of tropo that day. I bet I could put up a g5rv at 30 feet on some rare country and get loads of 5/9 signals no mater how many times the calls had to be repeatd. Please do put up your G5RV. We could all do with less QRM. And sure, all antennas work as predicted. I love the irony. --- This email is free from viruses and malware because avast! Antivirus protection is active. http://www.avast.com |
#34
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It is a truism
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#35
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It is a truism
On 11/13/2014 7:06 PM, Wimpie wrote:
El 13-11-14 21:39, FBMboomer escribió: On 11/12/2014 1:50 PM, gareth wrote: It is a truism that short antennae are poor inefficient radiators, and no amount of infantile bluster by Americanoramuses will change that. The truth does not need the violence of abuse to force its way down people's throats. A perfect example is a G5RV on 75 meters. They suck. When someone joins our group rag chew on 75, and they have a poor signal, The first thing I ask is "Are you using a G5RV". We all have a chuckle when they answer yes and then ask how we knew. :-) Trying to prove with math that short antennae work as well as say a 1/2 wave dipole may give someone great sport. However, in the real world, short antennae suck big time. I have been an American for most of my life. Please do not paint us all with the same brush. I agree that in many practical circumstances electrically small antennas do not perform well. I also know that having an antanna is better than nothing. The smaller the antenna, the more difficulties you will experience to get radiation out of it (heat radiation doesn't count). In free space you can make a rather efficient antenna with say maximum size of 0.03lambda, as long as you are a good electron tamer. If not, electrons escape from the structure showing a nice corona, or full breakdown occurs. Examples are tuned loops and short dipoles with capacitive end plates and series inductors to arrive at some nice impedance. Tuning in the shack with lots of cable and a bad ferrite balun between tuner and antenne mostly results in good VSWR but low efficiency (as many people know). In real world even a very small very efficient antenna may not perform as expected Close to the antenna (say within 0.1 lambda), reactive fields are very strong and they increase rapidly when reducing the distance. This is also valid for "magnetic loops" (that Jennings HV vacuum capacitor or thick potato cutter/slicer is for a reason). When you put such a nice small antenna close to lossy dielectric (building materials, ground, etc), significant part of the RF power may be dissipated in that lossy dielectric materials. In case of short monopoles, lots of power is mostly dissipated in the ground/counterpoise system (saline wetlands, sea and large metallic surfaces excepted). Of course we can solve this with lots of burried radials, or somewhat less elevated radials, but such solutions don't qualify for an electrically small antenna anymore. Wimpie, Let them use short antennas. Do not discourage them. It makes more room on 75 for those of us using full size antennas and power. They can talk around the block about how great there antenna is, and not bother anyone else. I hope the biggest antenna they ever use is a G5RV. |
#36
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It is a truism
On 11/13/2014 9:21 PM, Channel Jumper wrote:
But most people do not have access to tower that can get their dipole antenna 100' off the ground for 75 meters! The G5RV was designed to work on 20 meters. The ladder line is the matching network. It does not perform well on 10 or 40 meters. That usually has something to do with a cut dipole not working well on anything that is the first harmonic. A portion of this planet is inhabited by morons that does not know that and that picks their antenna by price rather than by performance! My inverted V - 80M off center fed dipole antenna is only 30' off the ground in the middle and maybe 20' off the ground on the ends. It is fed with about 60' of LMR 400 and I can converse with anyone that I can hear. Most of the people I hear are using 600 - 1200 watt amplifiers and some other type of dipole antenna, and although their signal is louder than mine, my audio is much cleaner then theirs! To me - amplifiers are for CB'rs that are hard of hearing and thinks that you cannot carry on a conversation unless you are 20/9! When I become a O&O - the first thing I am going to do is send each and every one of those people a pink slip and have them explain why they use more power than necessary. I would keep on sending them pink slips until they either get the message - that the reason for the signal report is so you can adjust your power to the minimum amount necessary to carry on the conversation, or until the ARRL / FCC gets tired of it and sends them a greetings to come and see them and explain why they can't follow the rules! As far as these people bragging about how they pick on those that are on a G5RV - I would gladly send them pink slips also - until they reduce their power or answer for their actions in front of a FCC examiner... I would love to see how many of these people could still pass a General Class Examination and how many of them bought their license and will let it drop - if they are asked to retest... OH Channel Jumper, you will be so powerful as an O&O. Your pink slips will surely intimidate everyone. They will just operate they way you want them to operate. Just think of the satisfaction you will get sending that pink slip. Never mind that it is an exercise in impotency. Did it ever occur to you that running the power necessary to communicate is not quantifiable by any standard but your own. How little S/N ratio are you willing to hear. If you like noise instead of audio then by all means demand that your contact reduce power. |
#37
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It is a truism
On Saturday, November 15, 2014 5:25:01 PM UTC-6, FBMboomer wrote:
Yes, smaller is better. I strongly encourage you to use 1/4 inch antennas. It is like homeopathy, less is more powerful. Getting your antenna length down to microns is the answer. Are you suggesting I use a 33 ft tall mobile antenna? Or are you just being silly because you have no other alternatives? |
#38
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It is a truism
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#39
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It is a truism
On 11/15/2014 6:17 PM, FBMboomer wrote:
On 11/14/2014 8:36 AM, Jerry Stuckle wrote: On 11/13/2014 6:12 PM, wrote: FBMboomer wrote: On 11/12/2014 1:50 PM, gareth wrote: It is a truism that short antennae are poor inefficient radiators, and no amount of infantile bluster by Americanoramuses will change that. The truth does not need the violence of abuse to force its way down people's throats. A perfect example is a G5RV on 75 meters. They suck. When someone joins our group rag chew on 75, and they have a poor signal, The first thing I ask is "Are you using a G5RV". We all have a chuckle when they answer yes and then ask how we knew. :-) False logic. You don't know how many people with good signals are using G5RV's, because you only ask those with poor signals. Trying to prove with math that short antennae work as well as say a 1/2 wave dipole may give someone great sport. However, in the real world, short antennae suck big time. I have been an American for most of my life. Please do not paint us all with the same brush. Yes and no. Depending on their design, short antennas can be very efficient. See http://www.futurity.org/radio-wave-c...phones-801322/ for an example. But others are correct. The antenna itself is an efficient radiator; it's the matching network that lowers *antenna system* efficiency. Any dipole type antenna will suck on 75M if mounted less than about 100 feet, or about .4 wavelengths. Below that you are warming clouds. So now it's 100 feet? It used to be 60 feet. But I have proof that is not the case. So do a lot of other hams I know. Your "facts" are for an idealized installation. Reality is much different, and will never get the ideal specifications you claim. snip I strongly encourage you to use a "loaded" 1 foot long dipole on 75 meters. This will prove you are right and we can all listen to the proof. :-) I suggest you stop trolling. You obviously have too much time on your hands (and too little brains to do anything productive). No wonder you wish to remain anonymous. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
#40
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It is a truism
FBMboomer wrote:
On 11/15/2014 6:23 PM, wrote: On Saturday, November 15, 2014 5:25:01 PM UTC-6, FBMboomer wrote: Yes, smaller is better. I strongly encourage you to use 1/4 inch antennas. It is like homeopathy, less is more powerful. Getting your antenna length down to microns is the answer. Are you suggesting I use a 33 ft tall mobile antenna? Or are you just being silly because you have no other alternatives? If a short antenna is just as good as a full size dipole, than why not use a 1/4 inch antenna. Or might there be something said for large full size antennas? Or could it be, size actually matters. I love clueless latecomers... -- Jim Pennino |
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