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Is this possible? Theroy question...
Is it possible to make a mobile 10m antenna that is
physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
On Wed, 13 Apr 2005 11:53:52 -0500, "Ken Bessler"
wrote: Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? Hi Ken, If you push more power through it. Aside from that, how much better is better? If you start out with a miserable quarterwave and replace it with a sterling (pun may be intended) shorter antenna; then, yes, the shorter one "may" be better. Why don't you first start by defining what efficiency your quarterwave whip exhibits? You may be surprised how hard it is to "better." 73's Richard Clark, KB7QHC |
NO
"Ken Bessler" wrote in message news:A8c7e.14295$up2.5543@okepread01... Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
Ken Bessler wrote:
Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? Define "better". -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Fred W4JLE wrote:
"Ken Bessler" wrote: Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? NO I just ginned up a 5 foot tall antenna with 3.8 dBi gain. That's half the height and considerably more gain than a 1/4WL whip. With more time, I could do better. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
"Cecil Moore" wrote in message
... Ken Bessler wrote: Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? Define "better". -- 73, Cecil http://www.qsl.net/w5dxp I knew someone would ask that. Better: higher eirp for a 100w transceiver. -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
Ken Bessler wrote:
Better: higher eirp for a 100w transceiver. So how does 3.8 dBi gain from a five foot tall antenna sound? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
I am sure you did Cecil, however I understood the question to be a shorter
single element mobile antenna. I suspect he was looking at the shorter loaded antennas with gains far in excess of your paltry 3.8 dBi. See any CB site for examples. One loaded antenna is touted as having 7.2 dB gain. but then again it was a "super coil" rated for 10,000 watts. Other than that, "The angels have left the pinhead". "Cecil Moore" wrote in message ... Fred W4JLE wrote: "Ken Bessler" wrote: Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? NO I just ginned up a 5 foot tall antenna with 3.8 dBi gain. That's half the height and considerably more gain than a 1/4WL whip. With more time, I could do better. -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Fred W4JLE wrote:
I am sure you did Cecil, however I understood the question to be a shorter single element mobile antenna. Well, that's why I asked for a definition of "better". And he didn't say a "single element" was better so a 10-element beam might be the way to go. :-) -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
"Cecil Moore" wrote in message
... Fred W4JLE wrote: I am sure you did Cecil, however I understood the question to be a shorter single element mobile antenna. Well, that's why I asked for a definition of "better". And he didn't say a "single element" was better so a 10-element beam might be the way to go. :-) -- 73, Cecil http://www.qsl.net/w5dxp Sorry - let me elaborate *why* I posted the question. I wanted to know if it was possible for any single mobile antenna less than a 1/4 wave could outperform a 10m 1/4 wave whip. Like for example a loaded 5/8 wave whip. As I understand it no whip less in size than a 1/4 wave can be more efficiant than it's larger cousin due to resisitave losses in the loading coil. Right or wrong? Long answer is OK. :-) -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
A loading coil does not make an antenna longer. It simply cancels the
capacitive reactance of a short radiator. A 5/8 wave is using the associated coil to match the impedance. Ergo if it is 5/8 it can't be shorter than a 1/4 wave. Cecil's 10 element mobile 10 meter beam aside, the answer is still NO to your original question. "Ken Bessler" wrote in message news:u1g7e.14448$up2.9536@okepread01... "Cecil Moore" wrote in message ... Fred W4JLE wrote: I am sure you did Cecil, however I understood the question to be a shorter single element mobile antenna. Well, that's why I asked for a definition of "better". And he didn't say a "single element" was better so a 10-element beam might be the way to go. :-) -- 73, Cecil http://www.qsl.net/w5dxp Sorry - let me elaborate *why* I posted the question. I wanted to know if it was possible for any single mobile antenna less than a 1/4 wave could outperform a 10m 1/4 wave whip. Like for example a loaded 5/8 wave whip. As I understand it no whip less in size than a 1/4 wave can be more efficiant than it's larger cousin due to resisitave losses in the loading coil. Right or wrong? Long answer is OK. :-) -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
Fred W4JLE wrote: A loading coil does not make an antenna longer. It simply cancels the capacitive reactance of a short radiator. The other way to cancel the capacitive reactance of course, is to make the antenna longer. ac6xg |
Cecil Moore wrote: Ken Bessler wrote: Better: higher eirp for a 100w transceiver. So how does 3.8 dBi gain from a five foot tall antenna sound? Like a 1/4 wvae vertical for 6M. -- 73, Cecil http://www.qsl.net/w5dxp w3rv |
"Cecil Moore" wrote in message ... Ken Bessler wrote: Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? Define "better". -- 73, Cecil http://www.qsl.net/w5dxp If the quarter-wave whip is made of ss, then you can make a better antenna by plating it with copper - or - gold - etc - or replace it with a better conductor. Then use a better transmission line. Then park the vehicle on top of a very high mountain to work dx. so, .... conditionally - yes. |
Would you care to postulate the dB increase by plating with copper or gold?
"Hal Rosser" wrote in message . .. "Cecil Moore" wrote in message ... Ken Bessler wrote: Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? Define "better". -- 73, Cecil http://www.qsl.net/w5dxp If the quarter-wave whip is made of ss, then you can make a better antenna by plating it with copper - or - gold - etc - or replace it with a better conductor. Then use a better transmission line. Then park the vehicle on top of a very high mountain to work dx. so, .... conditionally - yes. |
On Wed, 13 Apr 2005 20:10:29 -0400, "Fred W4JLE"
wrote: Would you care to postulate the dB increase by plating with copper or gold? Hi Fred, Could be up to 3 or more dB over an unspecified quarterwave efficiency (±3dB, offer void where permitted by law). 73's Richard Clark, KB7QHC |
Depends on the customer. If the customer is really building a CB antenna,
then I could claim 12 db gain. But to you folks, I wouild say the gain is marginal at best. But it would be a "better" antenna. Wouldn't you say a gold-plated antenna is better than a stainless steel antenna? After all, it cost a bunch more and the mfgr claims 12 db gain. --- the part about parking on top of a mountain is the best part of the recipe. - and gives the most gain. (height-gain). "Fred W4JLE" wrote in message ... Would you care to postulate the dB increase by plating with copper or gold? "Hal Rosser" wrote in message . .. "Cecil Moore" wrote in message ... Ken Bessler wrote: Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? Define "better". -- 73, Cecil http://www.qsl.net/w5dxp If the quarter-wave whip is made of ss, then you can make a better antenna by plating it with copper - or - gold - etc - or replace it with a better conductor. Then use a better transmission line. Then park the vehicle on top of a very high mountain to work dx. so, .... conditionally - yes. |
It was in comparison to a stainless steel whip. let me be more specific. The
coating of either copper or gold (your choice) of up to 50 mils over the stainless. Any other plating to allow the proper plating of the copper or gold shall be limited to 5 mils and materials normally used to facilate plating over SS. Compare in dB SS whip before plating to SS whip after plating. I am sure I have left out something else that may generate yet another waltz on the head of the pin. "Richard Clark" wrote in message ... On Wed, 13 Apr 2005 20:10:29 -0400, "Fred W4JLE" wrote: Would you care to postulate the dB increase by plating with copper or gold? Hi Fred, Could be up to 3 or more dB over an unspecified quarterwave efficiency (±3dB, offer void where permitted by law). 73's Richard Clark, KB7QHC |
On Wed, 13 Apr 2005 22:30:17 -0400, "Fred W4JLE"
wrote: I am sure I have left out something else that may generate yet another waltz on the head of the pin. Hi Fred, How thick was the original radiator? Stainless steel's fine for larger diameters, the pits for small diameters. 73's Richard Clark, KB7QHC |
Richard Clark wrote:
How thick was the original radiator? Stainless steel's fine for larger diameters, the pits for small diameters. Speaking of skin effect, consider a threaded rod on edge with all those hills and valleys. /\/\/\/\/\/\/\/\/\/\/\ |\ \ \ \ \ \ \ \ \ \ \ | /\/\/\/\/\/\/\/\/\/\/\ Does skin effect force the RF to flow up and down the hills and valleys thus increasing the VF of the threaded rod? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups ---= East/West-Coast Server Farms - Total Privacy via Encryption =--- |
Cecil Moore wrote:
Richard Clark wrote: How thick was the original radiator? Stainless steel's fine for larger diameters, the pits for small diameters. Speaking of skin effect, consider a threaded rod on edge with all those hills and valleys. /\/\/\/\/\/\/\/\/\/\/\ |\ \ \ \ \ \ \ \ \ \ \ | /\/\/\/\/\/\/\/\/\/\/\ Does skin effect force the RF to flow up and down the hills and valleys thus increasing the VF of the threaded rod? In a related fashion, if you have a sort of reverse copperweld, that is to say copper wire plated with steel, does the skin effect mean the RF is confined to the steel? Since skin effect has to stop somewhere - I mean insulated wire doesn't have the RF try to run on the insulation, at what point does skin effect stop, resistance of the outer part of the wire as a factor? Does skin effect and insulation have any relationship with velocity factor? Or have I opened my mouth and removed all doubt as the old saying about stupidity goes? 8^) - Mike KB3EIA - |
Does skin effect force the RF to flow up and down
the hills and valleys thus increasing the VF of the threaded rod? -- 73, Cecil http://www.qsl.net/w5dxp ------------------------------------------------ Yes it does. Skin depth in metals at HF is only a very few thousandths of an inch, and less. The current has nowhere else to go except up, over, and down the humps of the screw threads. But in practice, the RF resistance is not increased very much because the diameter of a screw is usually very much greater than the diameter of, say, an antenna wire, and so its resistance is already quite low before it is threaded. ---- Reg. |
A Steel over Copper conductor -
At very high frequencies current will flow only on the outer surface of the steel according to the conductivity of steel. As frequency decreases, current will flow in the copper only when skin depth in the steel is greater than the thickness of the steel covering. As frequency decreases further current will begin to flow deeper in the copper according to the conductivity of copper. The resulting resistance of the composite structure is the resistance of the steel layer in parallel with the resistance of the layer of copper, taking the currents flowing in each layer into account. But at HF, unless the steel layer is microscopically thin, the resulting resistance will be practically the same as that of a solid steel conductor. ---- Reg, G4FGQ |
Reg Edwards wrote:
Skin depth in metals at HF is only a very few thousandths of an inch, and less. The current has nowhere else to go except up, over, and down the humps of the screw threads. Imagine a rod with 60 degree notches cut out of it such that the RF path is twice as long as is the rod. VF = 0.5? 1/4WL vertical = 117/F? 75m vertical = 31ft? -- 73, Cecil http://www.qsl.net/w5dxp ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Imagine a rod with 60 degree notches cut out of it
such that the RF path is twice as long as is the rod. VF = 0.5? 1/4WL vertical = 117/F? 75m vertical = 31ft? -- 73, Cecil ================================= Yes Cecil, I am imagining. Now what ? ---- Reg |
Reg Edwards wrote:
Imagine a rod with 60 degree notches cut out of it such that the RF path is twice as long as is the rod. VF = 0.5? 1/4WL vertical = 117/F? 75m vertical = 31ft? Yes Cecil, I am imagining. Now what ? Reg, a very efficient 31 ft. resonant 75m vertical would be a good thing, right? -- 73, Cecil, W5DXP ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
Imagine a rod with 60 degree notches cut out of it such that the RF path is twice as long as is the rod. VF = 0.5? 1/4WL vertical = 117/F? 75m vertical = 31ft? Yes Cecil, I am imagining. Now what ? Reg, a very efficient 31 ft. resonant 75m vertical would be a good thing, right? -- 73, Cecil, W5DXP ============================== Cec, now I can see what you're getting at. Firstly, wrong - the difference between a very efficient antenna and a very efficient antenna is absolutely negligible and not worth the extra labor involved. Secondly, the expected 4-fold increase in loading inductance to tune the antenna to one half of the original resonant frequency, as a result of cutting threads or slots in the fat antenna rod, does not and cannot occur. But you win first prize for ingenuity. ;o) ---- Reg, G4FGQ |
"Reg Edwards" wrote in message ... Imagine a rod with 60 degree notches cut out of it such that the RF path is twice as long as is the rod. VF = 0.5? 1/4WL vertical = 117/F? 75m vertical = 31ft? Yes Cecil, I am imagining. Now what ? Reg, a very efficient 31 ft. resonant 75m vertical would be a good thing, right? -- 73, Cecil, W5DXP ============================== Cec, now I can see what you're getting at. Firstly, wrong - the difference between a very efficient antenna and a very efficient antenna is absolutely negligible and not worth the extra labor involved. Secondly, the expected 4-fold increase in loading inductance to tune the antenna to one half of the original resonant frequency, as a result of cutting threads or slots in the fat antenna rod, does not and cannot occur. But you win first prize for ingenuity. ;o) ---- Reg, G4FGQ At frequencies such that the groove spacing is a half wavelength one might see resonance effects. Imagine a stack of discones. Probably just another worthless academic curiosity. And it's THEORY! 73, H. NQ5H |
I think it would be possible to alter the "beam width" of the omni-antenna
(mobile) and so make it "better." If you take the time to learn EZNEC or MMANA you can view this for yourself in the plot of the radiation pattern.... Regards, John "Ken Bessler" wrote in message news:A8c7e.14295$up2.5543@okepread01... Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will preform better than a 1/4 wave whip? -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
"John Smith" wrote in message
... I think it would be possible to alter the "beam width" of the omni-antenna (mobile) and so make it "better." If you take the time to learn EZNEC or MMANA you can view this for yourself in the plot of the radiation pattern.... Regards, John Thanks John but that's not what I meant. For the record, I'm trying to understand some manufacturer's claims that the antenna they sell, while smaller than a 1/4 wave whip on 10m, puts out a better signal. Here are the rules: 1) The antenna is at least 25% shorter than a 1/4 w whip 2) The antenna is made with ordinary materials - no friggin gold. 3) The antenna is omni-directional & vertically polarised 4) The feedline is Flexi 4XL, aka CQ-102 5) The antenna is mounted dead center on the roof of a van. 6) The antenna's mount is non magnetic - I.E. There is a good DC/RF ground at both the base of the antenna & the radio. The way I see it is there is no way to make an antenna that meets all those rules and STILL has more than 2.14dbi gain due to resistave losses. Am I right? -- 73's es gd dx de Ken KGØWX Grid EM17ip, Flying Pigs #1055, Digital On Six #350, List Owner, Yahoo! E-groups: VX-2R & FT-857 |
Thanks John but that's not what I meant. For the record,
I'm trying to understand some manufacturer's claims that the antenna they sell, while smaller than a 1/4 wave whip on 10m, puts out a better signal. ================================ There ARE such things as Human Rights. Antenna salesmen have to make a living. They have wives, children and mortgages just like anybody else. |
"Ken Bessler" wrote
For the record, I'm trying to understand some manufacturer's claims that the antenna they sell, while smaller than a 1/4 wave whip on 10m, puts out a better signal. Here are the rules: 1) The antenna is at least 25% shorter than a 1/4 w whip 2) The antenna is made with ordinary materials - no friggin gold. 3) The antenna is omni-directional & vertically polarised 4) The feedline is Flexi 4XL, aka CQ-102 5) The antenna is mounted dead center on the roof of a van. 6) The antenna's mount is non magnetic - I.E. There is a good DC/RF ground at both the base of the antenna & the radio. __________ A perfectly "omni" azimuth pattern is unlikely from a v-pol whip of any length when mounted on the roof of a van, however ~ 2.15dBi lobes could exist in some directions. The electrical environment around the van will shape the pattern further. This could be modeled in NEC to give some insight into the situation. RF |
Ken, KG0WX wrote:
'Is it possible to make a mobile 10m antenna that is physically shorter than a 1/4 wave whip yet will perform better than a 1/4 wave whip?" In general, the full-sized 1/4-wave whip is a very good compromise mobile antenna because it can be self-resonant, and it is almost omnidirectional in azimuth. Physically, slightly shorter than a CB antenna, it is readily available by trimming a CB antenna to resonance, literally, or by using a low-loss variable capacitor in series. It is possible to use an antenna less than 1/4wavelengrh against ground as an efficient radiator but it requires care to minimize loss. Shortening the radiator reduces its vertical directivity. If gain is the performance measure, vertical directivity lost by shortening must be replaced, perhaps by horizontal directivity. Gain from horizontal directivity needs to cover not only lost vertical directivity, but losses caused by loading too-short elements in the array. These elements may produce horizontal directivity where none exists with a sole avertical element. In the September 1973 "QST" is "A Bite Size Beam". This article refers the reader to an earlier March 1973 QST article by Sevick, "The W2FMI Ground-Mounted Short Vertical". Summary: Can you do it? Yes. Is it practical? Maybe. Best regards, Richard Harrison, KB5WZI |
On Wed, 13 Apr 2005 12:49:29 -0500, Cecil Moore
wrote: I just ginned up a 5 foot tall antenna with 3.8 dBi gain. That's half the height and considerably more gain than a 1/4WL whip. With more time, I could do better. What is the dBi gain of a 1/4 ground plane? -- 73 for now Buck N4PGW |
The way I see it is there is no way to make an antenna that meets all those rules and STILL has more than 2.14dbi gain due to resistave losses. Am I right? I was a friend of Jim Taylor and Jim Taylor Jr. of Taylor Radio back in the good-ole CB days. Sitting at lunch one day we were discussing the old Big-Stick and Grand Slammer antennas (I think those are the names of the 5/8 wave base verticals most popular in that day). They told me that the market ting departments of the two companies made more antenna gain progress than their engineering departments did. I was slow to understand the statement at that time, so they explained that every time one came out with an ad, the competitor had to match or beat it. While the comparisons started with a 1/4 wave vertical, Jim said that if it continued, antenna manufacturers would have to start comparing gain to their antennas against loaded coat-hangers. In the truck stops, there are several antennas that are shortened 5/8 antennas. I think that is the case with Fire-stick. I can't tell you if it has a gain or loss over a 1/4 wave whip. Just a side-note tho... I have a 706 MKII in the car. I had a 6 meter whip on a mag-mount connected to the HF side where I was listening to a local beacon. I removed the 6 meter whip and replaced it with a White GMS/Volvo CB whip about an inch shorter (the cb antenna is just under 4 feet long.) The signal of the 6 meter beacon came up from 1/2 to full scale. I swapped back and forth and tested the SWR to make sure. The CB antenna was maximum SWR but sounded considerably better. I have several of these antennas so I am planning to try to trim one for 6 meters and use it instead of the whip I am using now. I don't have enough data to determine what causes the improvement, but I believe I have ruled out propagation. Buck N4PGW -- 73 for now Buck N4PGW |
Just a side-note tho... I have a 706 MKII in the car. I had a 6
meter whip on a mag-mount connected to the HF side where I was listening to a local beacon. I removed the 6 meter whip and replaced it with a White GMS/Volvo CB whip about an inch shorter (the cb antenna is just under 4 feet long.) The signal of the 6 meter beacon came up from 1/2 to full scale. I swapped back and forth and tested the SWR to make sure. The CB antenna was maximum SWR but sounded considerably better. I have several of these antennas so I am planning to try to trim one for 6 meters and use it instead of the whip I am using now. I don't have enough data to determine what causes the improvement, but I believe I have ruled out propagation. You should have checked several becons in diffearant directions. A few years back a friend and I had several 2 meter antennas that would fit the same mount. While checking out several repeaters in differant directions we found one antenna would be beter in one direction and another in a differant direction . It may have been due to the differance in the lobes of the antennas and the height of the repeaters. |
Buck wrote:
What is the dBi gain of a 1/4 ground plane? Rule of thumb: zero dBi -- 73, Cecil, W5DXP ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
On Mon, 18 Apr 2005 10:49:31 -0400, Buck wrote:
What is the dBi gain of a 1/4 ground plane? Hi Buck, -0.22dBi to +2.2 dBi depending on the proximity of ground and the level of screening with radials. 73's Richard Clark, KB7QHC |
On Mon, 18 Apr 2005 11:20:01 -0700, Richard Clark
wrote: -0.22dBi to +2.2 dBi depending on the proximity of ground and the level of screening with radials. I take it that +2.2 is with radials on an elevated ground plane? -- 73 for now Buck N4PGW |
On Mon, 18 Apr 2005 15:33:06 GMT, "Ralph Mowery"
wrote: Just a side-note tho... I have a 706 MKII in the car. I had a 6 meter whip on a mag-mount connected to the HF side where I was listening to a local beacon. I removed the 6 meter whip and replaced it with a White GMS/Volvo CB whip about an inch shorter (the cb antenna is just under 4 feet long.) The signal of the 6 meter beacon came up from 1/2 to full scale. I swapped back and forth and tested the SWR to make sure. The CB antenna was maximum SWR but sounded considerably better. I have several of these antennas so I am planning to try to trim one for 6 meters and use it instead of the whip I am using now. I don't have enough data to determine what causes the improvement, but I believe I have ruled out propagation. You should have checked several becons in diffearant directions. A few years back a friend and I had several 2 meter antennas that would fit the same mount. While checking out several repeaters in differant directions we found one antenna would be beter in one direction and another in a differant direction . It may have been due to the differance in the lobes of the antennas and the height of the repeaters. Thanks, That was the only 6 meter beacon I could hear. I knew/know that the one beacon wouldn't be a good sample but I was/am still surprised that the difference was 1/2 scale on the radio. It went from scratchy to full quieting and full scale. I didn't spend much time on it as my objective was to trim the antenna for ten meters. It is interesting though. Buck -- 73 for now Buck N4PGW |
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