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#1
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G5RV in horizontal L
Guy. My best option is to install a G5VR but having one half bend back 90
degrees horizontally so that when you look down from the top it is L shaped. My question is, will this degrade performance very much and in what way. Many thanks and regards, John ZL2TTM |
#2
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"News Xtra" wrote in message
... Guy. My best option is to install a G5VR but having one half bend back 90 degrees horizontally so that when you look down from the top it is L shaped. My question is, will this degrade performance very much and in what way. Many thanks and regards, John ZL2TTM Need more information: How high is the antenna, what type of transmission line do you plan on using, and what frequencies will it be used on? Bending the antenna will reduce the real part of the input impedance, thus increasing transmission line losses. It will also tend to increase its directivity in the direction of the "vee". The G5RV antenna tends to exhibit higher transmission line losses. See the extensive analysis at www.vk1od.net Suggest you obtain the free download of EZNEC from www.eznec.com then you can analyze the antenna for yourself. Also there are many free programs available for transmission line analysis. Probably Reg (G4FGQ) has one for free. Regards, Frank (VE6CB) |
#3
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I've had poor luck even using the G5RV as an inverter V.
Dave - W5GT "Frank" wrote in message news:iXIMe.184795$9A2.66584@edtnps89... "News Xtra" wrote in message ... Guy. My best option is to install a G5VR but having one half bend back 90 degrees horizontally so that when you look down from the top it is L shaped. My question is, will this degrade performance very much and in what way. Many thanks and regards, John ZL2TTM Need more information: How high is the antenna, what type of transmission line do you plan on using, and what frequencies will it be used on? Bending the antenna will reduce the real part of the input impedance, thus increasing transmission line losses. It will also tend to increase its directivity in the direction of the "vee". The G5RV antenna tends to exhibit higher transmission line losses. See the extensive analysis at www.vk1od.net Suggest you obtain the free download of EZNEC from www.eznec.com then you can analyze the antenna for yourself. Also there are many free programs available for transmission line analysis. Probably Reg (G4FGQ) has one for free. Regards, Frank (VE6CB) |
#4
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"W5GT" wrote in message ... I've had poor luck even using the G5RV as an inverted V. Dave - W5GT "Frank" wrote in message news:iXIMe.184795$9A2.66584@edtnps89... "News Xtra" wrote in message ... Guy. My best option is to install a G5VR but having one half bend back 90 degrees horizontally so that when you look down from the top it is L shaped. My question is, will this degrade performance very much and in what way. Many thanks and regards, John ZL2TTM Need more information: How high is the antenna, what type of transmission line do you plan on using, and what frequencies will it be used on? Bending the antenna will reduce the real part of the input impedance, thus increasing transmission line losses. It will also tend to increase its directivity in the direction of the "vee". The G5RV antenna tends to exhibit higher transmission line losses. See the extensive analysis at www.vk1od.net Suggest you obtain the free download of EZNEC from www.eznec.com then you can analyze the antenna for yourself. Also there are many free programs available for transmission line analysis. Probably Reg (G4FGQ) has one for free. Regards, Frank (VE6CB) |
#5
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A G5RV is really an inefficient collinear antenna, so it needs to be a
flatop, not a Vee or L. Model it and you will see it is a 'long' (on 20 meters) Extended Double Zepp. The extra length improves the pattern into multiple lobes at the cost of some gain. A true EDZ has more gain, but only one very narrow broadside lobe off each side. The G5RV has 3 lobes off each side. "W5GT" wrote in message ... I've had poor luck even using the G5RV as an inverter V. Dave - W5GT "Frank" wrote in message news:iXIMe.184795$9A2.66584@edtnps89... "News Xtra" wrote in message ... Guy. My best option is to install a G5VR but having one half bend back 90 degrees horizontally so that when you look down from the top it is L shaped. My question is, will this degrade performance very much and in what way. Many thanks and regards, John ZL2TTM Need more information: How high is the antenna, what type of transmission line do you plan on using, and what frequencies will it be used on? Bending the antenna will reduce the real part of the input impedance, thus increasing transmission line losses. It will also tend to increase its directivity in the direction of the "vee". The G5RV antenna tends to exhibit higher transmission line losses. See the extensive analysis at www.vk1od.net Suggest you obtain the free download of EZNEC from www.eznec.com then you can analyze the antenna for yourself. Also there are many free programs available for transmission line analysis. Probably Reg (G4FGQ) has one for free. Regards, Frank (VE6CB) |
#6
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Jim Leder wrote:
A G5RV is really an inefficient collinear antenna, so it needs to be a flatop, not a Vee or L. Model it and you will see it is a 'long' (on 20 meters) Extended Double Zepp. Jim, your statement is a little confusing. I know you mean that the G5RV is 1/4WL too long to be called an Extended Double Zepp on 20m. An EDZ is a single frequency antenna. The 102' G5RV is an EDZ on 11.5 MHz. EDZ length = 1170/F. And, you're right, G5RV's perform better as a flat-top. My modified G5RV performs as well as my 130' doublet fed with ladder- line, given the slightly different radiation patterns. I vary the length of the G5RV series matching section as follows: 3.8 MHz 23 ft., 7.2 MHz 35 ft., 10.125 MHz 20 ft., 14.2 Mhz 29 ft., 18.14 Mhz 36 ft., 21.3 MHz 27 ft., 24.95 MHz 29 ft., 28.4 Mhz 22.5 ft. -- 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 =---- |
#7
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Cecil, no argument. All I meant was the theory behind a G5RV is the same as
an EDZ. Nothing more. The G5RV provides a better pattern than an EDZ at the expense of some gain, but basically the design criteria is the same. The original G5RV was never intended to be anything but a 20 meter antenna (at least as far as I've read). The fact that it works on other bands is just icing. I use a 'modified' G5RV, similar to what Cebik describes on one of his web pages (think it's the ZS6BKV design) and found it to be a better G5RV than the original and it's shorter. Think mine is around 94 feet long. I've also built a 20 meter EDZ (still have it rolled up in the garage) and found it to be a great antenna but the beamwidth was too narrow to live with. BTW, for what ever reason it worked really well on 15 also. My 94' antenna works well on 40,20,17,12 and part of 10. It will load on 75, but not sure how well it radiates. SWR on the other 5 bands is under 2.5:1 at resonance with 40 and 20 under 2:1. Holy cow, I would never argue with you guys. I guess my main point is that all of these type of antennas are collinear type antennas and to get the best performance from them, they need to be in a flat top configuration. However, you work with what you have and if that dictates a Vee or L configuration, then you do it. 73's Jim "Cecil Moore" wrote in message ... Jim Leder wrote: A G5RV is really an inefficient collinear antenna, so it needs to be a flatop, not a Vee or L. Model it and you will see it is a 'long' (on 20 meters) Extended Double Zepp. Jim, your statement is a little confusing. I know you mean that the G5RV is 1/4WL too long to be called an Extended Double Zepp on 20m. An EDZ is a single frequency antenna. The 102' G5RV is an EDZ on 11.5 MHz. EDZ length = 1170/F. And, you're right, G5RV's perform better as a flat-top. My modified G5RV performs as well as my 130' doublet fed with ladder- line, given the slightly different radiation patterns. I vary the length of the G5RV series matching section as follows: 3.8 MHz 23 ft., 7.2 MHz 35 ft., 10.125 MHz 20 ft., 14.2 Mhz 29 ft., 18.14 Mhz 36 ft., 21.3 MHz 27 ft., 24.95 MHz 29 ft., 28.4 Mhz 22.5 ft. -- 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 =---- |
#8
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Having said that it's a poor inverted V, it does a great job as a flat top.
I've worked quite a bit of DX on 75 and 40 with my G5RV at 20'. Dave - W5GT "W5GT" wrote in message ... I've had poor luck even using the G5RV as an inverted V. Dave - W5GT "Frank" wrote in message news:iXIMe.184795$9A2.66584@edtnps89... "News Xtra" wrote in message ... Guy. My best option is to install a G5VR but having one half bend back 90 degrees horizontally so that when you look down from the top it is L shaped. My question is, will this degrade performance very much and in what way. Many thanks and regards, John ZL2TTM Need more information: How high is the antenna, what type of transmission line do you plan on using, and what frequencies will it be used on? Bending the antenna will reduce the real part of the input impedance, thus increasing transmission line losses. It will also tend to increase its directivity in the direction of the "vee". The G5RV antenna tends to exhibit higher transmission line losses. See the extensive analysis at www.vk1od.net Suggest you obtain the free download of EZNEC from www.eznec.com then you can analyze the antenna for yourself. Also there are many free programs available for transmission line analysis. Probably Reg (G4FGQ) has one for free. Regards, Frank (VE6CB) |
#9
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I predict it will change the pattern, change the input impedance and
probably otherwise work well. Sometimes you have to get along with what you have rather than what you want. Modern rigs like to see 50 ohms, so plan on using something to match your transmission line and go for it. On Wed, 17 Aug 2005 09:52:45 +1200, "News Xtra" wrote: Guy. My best option is to install a G5VR but having one half bend back 90 degrees horizontally so that when you look down from the top it is L shaped. My question is, will this degrade performance very much and in what way. Many thanks and regards, John ZL2TTM |
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