Hey David! Good to year from you. Wen’t to lunch with Ed Orcutt last Friday. We both thought you should have been there with us. So, do you have your licence yet? I had thought you had mentioned getting it once… Yes, I think I should get it – one of these days! 8^) Thanks for the complement on the antenna…more projects to come.

hey great antenna
i was wondering if any one has theought about making a yagi antenna for frs/gmrs. ive tried and haven’t had much luck. if any one can figure it out please email it to me at shadowx_49 (at) hotmail.com
thanks

Marc,
I’m interested in building your J-Pole antenna. My Midland GTX 400 does not have a removable
antenna. I opened the radio and removed the antenna by desoldering it from the circuit board
and inserted a male plug in its place for a coax connection. My question is that since there is no connection for ground (braided sheild of coax) will the J-Pole perform properly? I’ve looked inside three different GMRS/FRS radios and they all just have a single connection for the antenna.
Thanks for your help,

Bruce

Sorry, I didn’t mention to use RG-58 Coax.

Very nice! I was looking for ideas for a cell phone antenna and think that this might work, do you have any idea if a jpole or super jpole would work for 900mhz or 1800mhz? In any case I think that I am going to have to dig the handhelds out from the closet!

Brian

Great read. I was wondering do you have any ideas how to increase trans and receive distance on a handheld? Would like to get a greater range between two parties, especially while hiking in mountainous terrain. Your antenna would be great for a car or stationary camp, but I was looking for something more mobile. Any ideas on a better antenna construction that would just screw into the existing mount? Thanks again!

Does anyone know where to find an antenna connector for the Motorola distance DSP
FRS/GMRS radios? I want to use the J-pole with this unit.

Can you post a list or email some of the other models with removable antennas that might be available.

TIA!

Hey Marc I have a wireless camera that also has audio
is it possible to make a jpole for the reciever it has a removable antenna
and if so I may need your help in making it. it is 1.2 gighz

If you are looking for a good GMRS J-Pole antenna and don’t want to build one yourself, I highly recommend the KB9VBR J-Poless at http://www.kb9vbr.com/jpole.php They are high quality and quite affordable.

hey there. i’m really looking for a gmrs radio with external antenna.
i can’t seem to find any midland g-28 or memorex mk 1995.
are there any other items that have NOT been discontinued.
any help would be appreciated.
showroomcondition2004@yahoo.com
thanks,

let’s just say I opened up my frs/gmrs radio and replaced the internal antenna with a bnc plug with a 3/4″ lead of copper wire.. would my antenna size for 1/4 wave be 15.4cm minus the 3/4″ wire lead and minus the 1/2″ or so for the male bnc plug? or would you make the antenna exactly 15.4, disregarding the distance of wire and metal from the actual electronics and the antenna connector? thanks for help on my theoretical project!

whitman

thanks for the quick response! okay I’ve looked up the rg174 and I’m understanding that as long as the connector and/or cable is shielded, it’s not added in the antenna length calculation. Next step is making a jpole for it! figure I could have the actual connection point be a downward facing male bnc and have the low “D” length just bend around the connector. If I get all of this working, I’ll post a picture (computer rendered of course) of what it would look like if I had done it. thanks for the help!

whitman

Hi folks .. I read with interest this thread. I found a web page that gives all the dimensions for the J-Pole with the frequency of FRS/GMRS being
around 462.5 Mhz. The long radiator is 18.24 inches and the short on is 6.12 inches. The spacing between the two is .6 inches and the coax connection is also .6 inches up from where the long and short connect. However, the point I want to make is how did the makers of this J-Pole get .6 inches spacing between the long and short. Think about it, if you use standard copper plumbing the T connector and 90 degree angle will never get that close. It’s impossible. I have no idea on how you all did that, but I would be interested to know how. On anther note, I have a VHF/UHF vertical antenna for my Ham radio. The UHF range for Ham is 440 to 448 Mhz. I thought about how good the SWR might be at 462.5 Mhz. Luckily, I have an antenna analyzer from MFJ and
guess what, the SWR is 1.2 to 1. It’s even better than my Ham band. I said wow! So I promptly modified my Midland GXT-450. I took the rubber duckie antenna and installed a piece of coax in it’s place. The other end of the coax, I installed a PL259 connector. I had to have the batteries external to the radio as it would not all fit in for my radio. I tried it and wow, does it ever work. I just tested it with my sister at her house and it goes like crazy. I just did it today and I have yet to get any real distance tests but we’ll see how it goes. Let me know if you have any questions. I’ll keep an eye on this page. Maybe I should get a web page or something. If you all ask, then I’ll do something like that as I took pictures of my modify. Cheers!

Wow, over 3 years old and still a great piece of info. Hope Marc is still around to answer more questions. The base. Do I mount the base on the chassis of the vehicle, or do I mount it like the standard car radio, isolating the stub from chassis ground?

Remember, GMRS/FRS radios REQUIRE an FCC licence.

David

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?

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.