Sylmar Hang Gliding Association

I just got a falcon 3 and my boss gave me his old Kenwood handheld 2m radio. He had mentioned something about j-pole antennas so I did some research and I was curious if anyone has ever attached one to their glider. I found this neat article for making one:

http://www.iw5edi.com/ham-radio/files/j ... l-band.pdf

There were a few things I wasn't sure about - first off, is it really even necessary? Adding more cables tends to complicate things, so I didn't know if that would be more of a hassle than it was worth. I could conceivably lower the transmission power of the radio, so that would be a benefit on battery life. I was also wondering if the metal structures of the glider would be problematic and affect the signal strength.

So yeah, just kinda curious about the whole thing. I wanted to know if anyone's strung one of those antennas somewhere through their glider and found it to be particularly beneficial.

Thanks!
Mike

I'm the least HAMstered of the club, but I can guess why we don't use J-poles.

1. Rubber-ducky are plenty for the line of sight we have when flying.
2. Power savings are negligible, as our flights aren't long enough to expend a full battery. Once you land, battery charging in the car is easy to do.
3. For 20$ you can buy a 2-meter (we rarely/never use 70cm) tuned full wave designed to integrate in your harness. With an antenna like this, I have heard of people talking from crestline to the far desert.


Please take everything I said with a grain of salt.

OP wrote:I'm the least HAMstered of the club, but I can guess why we don't use J-poles.

1. Rubber-ducky are plenty for the line of sight we have when flying.
2. Power savings are negligible, as our flights aren't long enough to expend a full battery. Once you land, battery charging in the car is easy to do.
3. For 20$ you can buy a 2-meter (we rarely/never use 70cm) tuned full wave designed to integrate in your harness. With an antenna like this, I have heard of people talking from crestline to the far desert.


Please take everything I said with a grain of salt.

Yea, a dipole is the best, cheapest solution. You can put in in your harness and it will get better signal transmission and reception than anything you are liable to mount to the glider, with far less hassle.

You do have to mount it properly, but there are lots of pilots who can help you with that.

And you can buy one cheap or make one even cheaper. The only tools needed are wire cutters/strippers and a tape measure.

stebbins wrote:Yea, a dipole is the best, cheapest solution. You can put in in your harness and it will get better signal transmission and reception than anything you are liable to mount to the glider, with far less hassle.

You do have to mount it properly, but there are lots of pilots who can help you with that.

And you can buy one cheap or make one even cheaper. The only tools needed are wire cutters/strippers and a tape measure.

Sweet! Yeah, that does sound much easier than using a j-pole antenna. Do you have any links to a website that shows materials and lengths to make it. Is this something that should still be tested with a SWR meter? I should have a new harness (it'll be a knee hanger) shortly and it would be neat to build and test the antenna.

Not sure if it makes any difference, but this is the radio that I've got:

http://www.universal-radio.com/catalog/ht/th78a.html

My boss had a couple of them and gave me this one. The batteries were shot (NiCDs from '95 I think), so I bought the battery adapter box and some Eneloop NiMH 2000mAh batteries, so that should keep it running a lot longer than any NiCD battery pack ever did.

One neat part about the radio is that it's been modded so that it can listen on a much wider frequency range. Since it's a dual band radio, I could listen in on Burbank while talking on SHGA field's frequency.

I'm going to also start studying for the no-code Technician test, too... hope to get that done in the next few weeks.

Fun stuff!!

Thanks,
Mike

edited 6.20.2018

barton wrote:strip back the outer sheath 20.012202562538135 inches, this is the 1/4 wavelength for the 147.510 Mhz frequency. twist the ground

Now, does the length of cable from the connector to the stripped section matter, or is it just the length the stripped section that's critical?

braid, then configure as in orion's pictorial. way over kill for what we use the radio's for. make sure you are using RG-58 coax cable, you are looking for a 50 ohm impedance transmission line. RG-59 looks just like it in size, so read the label to ensure you have the correct cable type/best transmission line match possible.

Part of my reason for doing this is just to learn more. If it's a major hassle to put it in my harness, I might just use the rubber duck antenna, but I figured I'd try and set it up anyways.

the rubber duck that is sold with a radio is best used as a planter stick. make the 1/4 wave dipole, or spend ~ 30 bucks for a after market antenna, there are plenty to choose from. Look for the highest gain you can afford, usually expressed as dBi. simple is better.... or KISS

Do you have any links to simple aftermarket antennas, otherwise I might head on over to the local electronics store tomorrow and see if they have the supplies. While I don't have the crimper, they should be able to do the crimping for me. I'm assuming I need a 50 ohm BNC as well, correct?

Thanks for your help!
Mike

edited 6.20.2018

Does anyone have a SWR meter that they could bring to the LZ? While it's probably overkill, I think it would still be neat to try and tune my antenna to be as effective as possible.

Thanks!
Mike

Remember that when you tune it it will be maximized for only one frequency.

Move to one end or the other of the 2m band, and you change the length by several 1/10'ths of an inch.

However, set it right for the middle of the band, and you'll get great reception (but not the "best") throughout the band.

I've never used an SWR meter, and I've talked to other HG pilots over 100 miles away when I was high. Once I talked to a pilot who was on the ground over 90 miles away - of course, I was at 16k feet....

All with a piece of coax cut to the length Barton mentioned, or thereabouts.

One last note: Radio shack sometimes carries an RG58 cable that is a female to female BNC connector that is 10 or 12 feet long. Buy one of those, cut it exactly in half, then use each one as an antenna, as per Barton's instructions. Now you have a spare, and you only paid a few bucks, and didn't need to splice a connector to the RG58...

Erwin has an SWR meter and he's in the landing area every day.