Comments on: GMRS J-Pole Antenna http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/ Technology, Linux, Photography, Science, Cycling, Outdoor Activities and other interests. Tue, 07 Feb 2012 01:50:50 -0700 hourly 1 http://wordpress.org/?v=3.1.4 By: estefan2020 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4772 estefan2020 Tue, 07 Feb 2012 01:50:50 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4772 I have not tried this, but you could try using magnetic wire (has a non conductive coating around it) and place it in the middle of the original spiral antenna. using the largest gague that will fit inside the spiral. I have not tried this, but you could try using magnetic wire (has a non conductive coating around it) and place it in the middle of the original spiral antenna. using the largest gague that will fit inside the spiral.

]]> By: estefan2020 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4771 estefan2020 Tue, 07 Feb 2012 01:24:56 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4771 You can google" 70cm colinear antenna" and use 465.13125Mhz and build a 6ft backpack antenna, for hiking, though murs radios will handle terrain much better You can google” 70cm colinear antenna” and use 465.13125Mhz and build a 6ft backpack antenna, for hiking, though murs radios will handle terrain much better

]]> By: estefan2020 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4770 estefan2020 Tue, 07 Feb 2012 01:17:19 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4770 you can Google "j-pole calculator" and enter 465.13125Mhz which is between the highest channel 14 and the lowest channel 15. Use cable lmr-400 or lmr-600 to connect which is ultra low loss cable. though I have to admit, purchasing murs 5 channel radios will give you much better distance, as it uses lower frequency even at 2 watts, the range will be considerably better. you can Google “j-pole calculator” and enter 465.13125Mhz which is between the highest channel 14 and the lowest channel 15. Use cable lmr-400 or lmr-600 to connect which is ultra low loss cable. though I have to admit, purchasing murs 5 channel radios will give you much better distance, as it uses lower frequency even at 2 watts, the range will be considerably better.

]]> By: Joseph http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4762 Joseph Wed, 21 Dec 2011 16:18:58 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4762 Have any of the people trying to improve FRS reception tried taping a 6" piece of 14 gauge wire to the back of the radio so that it starts at the antenna base and extends below the radio case. This is called a "tiger tail" and has been used successfully by amateur radio operators for years. Most users claim the device should be electrically connected to the antenna, but one commercial unit no longer in production was just stuck to the case and presumably inductively coupled to the antenna much like a counterpoise. I just wonder if anyone has tried this and perfomred any controlled radio range tests? I don't know if this violates the FCC regulation against modifying a FRS antenna since you aren't changing the radio as built. Joseph Have any of the people trying to improve FRS reception tried taping a 6″ piece of 14 gauge wire to the back of the radio so that it starts at the antenna base and extends below the radio case. This is called a “tiger tail” and has been used successfully by amateur radio operators for years. Most users claim the device should be electrically connected to the antenna, but one commercial unit no longer in production was just stuck to the case and presumably inductively coupled to the antenna much like a counterpoise. I just wonder if anyone has tried this and perfomred any controlled radio range tests? I don’t know if this violates the FCC regulation against modifying a FRS antenna since you aren’t changing the radio as built.

Joseph

]]> By: Dan http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4263 Dan Sun, 01 May 2011 15:54:28 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4263 Nice for a 6 year old thread, Im wondering how many mods actually bought an swr meter from radio shack the easiest way to tune the antenna. Even with radios 3-5watts you will want to optimize the standing wave. I may have missed reading the calculations to adjusting for velocity factor x .95 for the measurements. For a greater gain a super j can be used as well, a little more to add to. Everyone wants to get the most out of their radio, but the main talk here is centered around gmrs which is at a uhf range. There are radios that run at the 144 mhz (2meter) range. Lower the frequency raise the length of the antenna, but also the signal at 5 watts HT low power can travel much further. These radios also have the ability to transmit on 1 frequency, and receive on another, able to make use of local repeaters that take your transmission, and transform it to 50 or 100 watts, which goes even further. You see that these frs/gmrs radios have a fixed antenna for a reason, they are technically designed for really short range. You want more range out of your hand radio, step up to 2 meter. GMRS is near the 70cm band, and for those who choose, can make due with a mono band 70cm 1/4, 1/2 or 5/8ths commercial antenna, and request a bnc, sma, or what ever connector is used for around $35. Nice for a 6 year old thread, Im wondering how many mods actually bought an swr meter from radio shack the easiest way to tune the antenna. Even with radios 3-5watts you will want to optimize the standing wave.

I may have missed reading the calculations to adjusting for velocity factor x .95 for the measurements. For a greater gain a super j can be used as well, a little more to add to.

Everyone wants to get the most out of their radio, but the main talk here is centered around gmrs which is at a uhf range. There are radios that run at the 144 mhz (2meter) range. Lower the frequency raise the length of the antenna, but also the signal at 5 watts HT low power can travel much further. These radios also have the ability to transmit on 1 frequency, and receive on another, able to make use of local repeaters that take your transmission, and transform it to 50 or 100 watts, which goes even further. You see that these frs/gmrs radios have a fixed antenna for a reason, they are technically designed for really short range. You want more range out of your hand radio, step up to 2 meter.

GMRS is near the 70cm band, and for those who choose, can make due with a mono band 70cm 1/4, 1/2 or 5/8ths commercial antenna, and request a bnc, sma, or what ever connector is used for around $35.

]]> By: Marc http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4253 Marc Mon, 14 Mar 2011 21:24:21 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4253 Everything you need to know is in the article. Just read it. Everything you need to know is in the article. Just read it.

]]> By: david bastien http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4252 david bastien Sun, 13 Mar 2011 19:43:59 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-4252 hi dave my name is david do you kaow what are the measurements are to make a j pole for grms freqs 462.000 to 467.000 i have a base sm4450 maxon radio hi dave my name is david do you kaow what are the measurements are to make a j pole for grms freqs 462.000 to 467.000 i have a base sm4450 maxon radio

]]> By: marc http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3732 marc Mon, 28 Jun 2010 19:21:49 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3732 Hey Mike, I found an antenna mount that connects to a luggage rack. You can get one at any store that carries radio equipment (Radio Shack, a local ham shop, a truck stop, etc). If you don't have a luggage rack, then you might want to look into a magnetic base. You can use any metal for the material however, there are a couple things to keep in mind. The velocity factory will vary from metal to metal although, it may not matter much as the difference may not be that great. The nice thing about a car antenna as the base-material is that it is stainless steel and will last years, and is very strong. Copper and aluminum will bend easily. You should look for something that can be soldered for sure, either silver soldered like I did in this article or regular solder (copper, brass, etc). Best of luck! Hey Mike, I found an antenna mount that connects to a luggage rack. You can get one at any store that carries radio equipment (Radio Shack, a local ham shop, a truck stop, etc). If you don’t have a luggage rack, then you might want to look into a magnetic base.

You can use any metal for the material however, there are a couple things to keep in mind. The velocity factory will vary from metal to metal although, it may not matter much as the difference may not be that great. The nice thing about a car antenna as the base-material is that it is stainless steel and will last years, and is very strong. Copper and aluminum will bend easily. You should look for something that can be soldered for sure, either silver soldered like I did in this article or regular solder (copper, brass, etc).

Best of luck!

]]> By: Mike http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3723 Mike Fri, 25 Jun 2010 05:12:22 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3723 Hi Marc, Great write up. I'm planning on building one of these soon. I'm curious how you ended up attaching this to your car. Did you use some type of window mount? Also, in lieu of finding a solid FM antenna, do you have any recommendations for other materials? As long as the material is a good conductor and can be formed into the J shape you describe are there any other properties you have to worry about? Hi Marc,

Great write up. I’m planning on building one of these soon.

I’m curious how you ended up attaching this to your car. Did you use some type of window mount?

Also, in lieu of finding a solid FM antenna, do you have any recommendations for other materials? As long as the material is a good conductor and can be formed into the J shape you describe are there any other properties you have to worry about?

]]> By: Andy http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3138 Andy Sun, 22 Mar 2009 00:15:16 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3138 Marc, What happens if you don't do a choke with the coax? If I am using 75 ohm coax would the choke be the same 4-5 turns? Thanks! Marc,
What happens if you don’t do a choke with the coax? If I am using 75 ohm coax would the choke be the same 4-5 turns? Thanks!

]]> By: marc http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3136 marc Tue, 17 Mar 2009 01:01:58 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3136 Hey Andy, No need to tune to any other GMRS/FRS frequency. The middle is where is should be and it's broad enough to pick up the whole spectrum covered by the radios. A flexible design should work well as long as the total distance from the base of the j to the tip is not longer or less than 3/4 wavelength. Good luck! Hey Andy, No need to tune to any other GMRS/FRS frequency. The middle is where is should be and it’s broad enough to pick up the whole spectrum covered by the radios. A flexible design should work well as long as the total distance from the base of the j to the tip is not longer or less than 3/4 wavelength. Good luck!

]]> By: Andy http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3135 Andy Tue, 17 Mar 2009 00:23:36 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3135 Marc, Any idea if this would work with something more flexible like piano wire or bass string so it would be more like a whip? If the "D" portion were something rigid and the top of the quarter wave secured with plastic like your design? Also, would it make more sense to tune the antenna to one of the higher GMRS frequencies to capture full power transmissions or is it just not necessary? Thanks, Andy Marc,
Any idea if this would work with something more flexible like piano wire or bass string so it would be more like a whip? If the “D” portion were something rigid and the top of the quarter wave secured with plastic like your design? Also, would it make more sense to tune the antenna to one of the higher GMRS frequencies to capture full power transmissions or is it just not necessary? Thanks,

Andy

]]> By: marc http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3128 marc Tue, 03 Mar 2009 21:29:17 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3128 I don't really have a good idea of which SWR meter to recommend. Maybe someone else has a good recommendation? I don’t really have a good idea of which SWR meter to recommend. Maybe someone else has a good recommendation?

]]> By: Louis http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3125 Louis Tue, 03 Mar 2009 18:28:47 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3125 That was i did ( It may work fine if you extended “B” rather than “A” ) Many thanks , all i need now is a SWR meter, would you by recommed this swr and power meter ? http://tinyurl.com/SWR-Meter-MFJ-874 That was i did ( It may work fine if you extended “B” rather than “A” )
Many thanks , all i need now is a SWR meter, would you by recommed this swr and power meter ?
http://tinyurl.com/SWR-Meter-MFJ-874

]]> By: marc http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3124 marc Tue, 03 Mar 2009 16:14:56 +0000 http://blog.mecworks.com/articles/2005/02/27/gmrs-j-pole/#comment-3124 Louis, The section below the "j" should not affect the antenna. However, the continuation should be an extension of "A" rather than "B". The extension is usually grounded. It *may* work fine if you extended "B" rather than "A" just as long as you have the ground and signal wires connected properly (signal to A, ground to B). Let me know how it goes! Louis, The section below the “j” should not affect the antenna. However, the continuation should be an extension of “A” rather than “B”. The extension is usually grounded. It may work fine if you extended “B” rather than “A” just as long as you have the ground and signal wires connected properly (signal to A, ground to B). Let me know how it goes!

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