Ed Fong J pole for civilian and mil air bands question

[coldlake11]

Has anyone made or purchased an Ed Fong J antenna to be made for the civilian and mil air bands? Is it even possible?

 

[prcguy]

The VHF air band for voice is 19MHz wide and a J-pole will not cover that very well. The UHF air band is 175MHz wide and a J-pole would be useless over that range.

Has anyone made or purchased an Ed Fong J antenna to be made for the civilian and mil air bands? Is it even possible?

 

[jaspence]

I have the ham version and it has done an acceptable job, especially considering the cost. You can contact the designer directly and see what he might be able to do. Ed's Antennas

 

[popnokick]

prcguy is spot on with his advice that j-pole antennas do not have enough radio bandwidth to cover either the VHF or UHF air bands... assuming you'd like to be able to listen with the same sensitivity and receiving capability anywhere within the allocated air bands.

 

[bb911]

A j antenna made to cover both air bands seems possible. Fong makes a 144-148 MHz, 222-225MHz, 440-450 MHz triband for ham radio, and they are very narrowband because they are used for transmitting. Yet that antenna, based on my experiences with a 2m (144-148) j, may receive both air bands quite well. Or, maybe Fong can make you a dual band for the air bands - or a triband by splitting the milair band in 2. My DIY 2m j received from 39 to 450 MHZ real well, and even up to 8ooMHz OK. Many years ago, Avanti made a scanner antenna that was akin to a j.

 

[DeepBlue]

This is partly why so many airports use discone antennas. 1 antenna to bind them all - sort of.

Sean

 

[n5ims]

A local club had Ed do a presentation and that question was asked. He indicated that he would be happy to build and tune his antenna to most any frequency within the practical design range. They would be custom and the price may be adjusted depending on the additional material and labor costs and would need to be ordered over the phone with specific specs provided. The phone call will allow him to ask questions to make sure that he will be able to translate your needs into plans for his staff.

Be aware that he was already backed up prior to things being shut down so he's probably really backed up now. Now it is possible that orders dried up enough for him to catch up so orders may be quick now as well. That would be a good question to ask on the phone call where you discuss your desires.

 

[vagrant]

An eight element or more discone antenna is what you are looking for to cover those wide frequency ranges. They can be purchased for under $50 such as the Tram 1410. Use some RG6 or LMR-400 coaxial cable depending on your budget. I would hope Mr. Fong would tell you the same.

Has anyone made or purchased an Ed Fong J antenna to be made for the civilian and mil air bands? Is it even possible?

 

[prcguy]

Yes he can tune it to any frequency within the practical design range and there is the key part, within its practical design range which is only a few percent bandwidth. It can do a small portion of the VHF air band, maybe 4 or 5Mhz and a small portion of the UHF air band, maybe 10, maybe 15Mhz at the 2:1 VSWR points but that's about it. As you get further away from the sweet spot your reception will be further diminished and it could be 20dB down at points within the 225-400MHz UHF air band.

A local club had Ed do a presentation and that question was asked. He indicated that he would be happy to build and tune his antenna to most any frequency within the practical design range. They would be custom and the price may be adjusted depending on the additional material and labor costs and would need to be ordered over the phone with specific specs provided. The phone call will allow him to ask questions to make sure that he will be able to translate your needs into plans for his staff.

Be aware that he was already backed up prior to things being shut down so he's probably really backed up now. Now it is possible that orders dried up enough for him to catch up so orders may be quick now as well. That would be a good question to ask on the phone call where you discuss your desires.

 

[bb911]

Yes he can tune it to any frequency within the practical design range and there is the key part, within its practical design range which is only a few percent bandwidth. It can do a small portion of the VHF air band, maybe 4 or 5Mhz and a small portion of the UHF air band, maybe 10, maybe 15Mhz at the 2:1 VSWR points but that's about it. As you get further away from the sweet spot your reception will be further diminished and it could be 20dB down at points within the 225-400MHz UHF air band.

Yet he's not going to be transmitting. All multi-band scanner antennas are a huge compromise, including discones.

 

[Ubbe]

Yet he's not going to be transmitting. All multi-band scanner antennas are a huge compromise, including discones.

An antennas performance are equal at both transmit and receive. I would say that the only wideband antennas that are not compromises are logperiodics and discones.

/Ubbe

 

[prcguy]

He won't be transmitting and he won't be receiving very well outside the resonant area of a J-pole. I was not making a joke at being 20dB down out of resonance, I've measured that on other types of antennas.

On the other hand a Discone will receive right about the same at 225Mhz as it does at 400Mhz and that will not be much different than a 1/4 wave ground plane across that entire range. Try doing 225 to 400MHz on a J-pole and where its resonant it will work a little better than a 1/4 wave ground plane and at other areas in may not work any better than the stock rubber duck that came with the scanner. That's how drastic it will be with a J-pole.

Yet he's not going to be transmitting. All multi-band scanner antennas are a huge compromise, including discones.