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Home Brew APRS Antenna

newtech

newtech

Well Known Member
Patron
Santa brought me a Byonics Micro-Track RTG transmitter for Christmas. With our January 14th departure for Florida rapidly approaching I made up a Home Brew Antenna for the bottom of our RV-7A. Some of you might be interested in how I made my fiberglass belly mount antenna.

I started out with an aluminum mounting plate cut out of .040" sheet, a BNC through pannel connector with a solder mount, a 1/16" piece of copper coated steel gas welding rod, balsa wood to encase the antenna in something that looked like it belonged on an airplane and fiberglass materials to vacuum bag it all into a nice looking finished part.

Along with all of the above materials I used my trusty old "Lil Sucker" vacuum pump, that was made from an old refrigerator compressor.
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The antenna with the aluminum mounting flange, BNC Connector, 1/16" antenna wire soldered into the BNC connector and balsa wood sanded to an airfoil encasing the antenna wire:
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The antenna is wrapped in two layers of Rutan weave 8 oz. fiberglass cloth that was cut on the bias and applied with a very wet coat of West Systems epoxy. Next the wet messy assembly was wrapped with teflon coated peel ply followed by two layers of paper towel to act as a bleeder layer and the whole mess wrapped in blue vacuum bagging plastic. The vacuum bag is then sealed with vinyl construction caulk and a vacuum is drawn using the trusty "Li'l Sucker".
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After curing for about four hours or so, using fast cure hardener, all the bagging materials are removed and a butcher knife is used to rough trim the edges of the fiberglass:
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If all went well you should end up with something looking like this:
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Here are all of the consumables, less the fiberglass and vacuum bagging materials:
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I will get the antenna mounted tomorrow and will post some pictures of it installed on the airplane. If all goes well you should be able to see the track from the test flight at http://www.aprs.fi enter W9BOJ for the track to display.
 
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Boom-ee-rang! That cool antenna will be scattering those beacons like crazy :D Hurry up with the patent! Do you need a beta tester?
 
Very cool

I really like seeing things like this. I don't have the skills/equipment/materials/need/etc. to necessarily "copy" it, but it is pretty awesome to see what people apply through ingenuity.

Nicely done.
 
Steve,

What a neat project. You have me looking at my COMANT 122 COMM antenna with balsa wood and fiberglass fairing ideas!

Looking at aprs.fi now, and I see what looks like your test drive on the ground from 5 JAN...will look for the flight!

Nice work!!

Cheers,
Bob
 
Success!

Looks like your antenna was getting pings while you were taxiing out to the runway!

Great job!:D
 
Steve,

Looks like you're back on deck...pretty nice track. Couple thoughts (all FWIW...this turned out really slick!!)

For the following, check out Sam's thread on tracker settings:

You can change the symbol from a car to a plane, so HAMs and other observers know its a plane (part of that safety aspect of APRS).

Looks like smart beaconing may be off...that would give you better tracks in the turns, if you enable it.

Your MIC-E shows "off duty", and that can be changed to something else to reflect that you are moving...or you can turn that off to reduce the data flow (I did that after some advice from Allen and others)

Looks like your tracker is set to send altitude and speed info only every few hits...you might be able to increase the frequency of that a little, if desired.

Most of the packets looked pretty good, and the path was described as a "good path", so things look good!

Pete, Sam and others may have other ideas for ya, but this sure looks like a good test of that "lil sucker" antenna! :D

Happy trackin'!

Cheers,
Bob
 
Thanks to all who came before me

Thanks for all of the input. I was pretty satisfied with the first time out. I will be taking my laptop over to the airport today to update the setup configuration and if todays snow holds off long enough I may get another test flight in today.

Yesterdays flight was pretty cool; Vince Frazer, a.k.a. FlyBoy Accessories, joined up on my right wing, in his F1 Rocket, during the outbound leg. Wish I had a camera; better yet wish we had a camera plane :D
 
Just got back from todays flight and all appears well. My GPS lost lock a couple of times but all in all I think the configuration is pretty close. Thanks to all the experts that helped. My tracks can now be followed by my tail number N14SE rather than my call sign W9BOJ.
 
newtech said:
Just got back from todays flight and all appears well. My GPS lost lock a couple of times but all in all I think the configuration is pretty close. Thanks to all the experts that helped. My tracks can now be followed by my tail number N14SE rather than my call sign W9BOJ.
Click to expand...

That's more like it, Steve. Not sure why some of the beacons don't have full info, however.....

Happy Trackin'!
 
Sam Buchanan said:
That's more like it, Steve. Not sure why some of the beacons don't have full info, however.....

Happy Trackin'!
Click to expand...

I think the problem is with the GPS wiring to the MT-RTG. I noticed the green led flashing for several minutes a few times. My installation is pseudo Rube Goldberg with both the GPS and RTG being powered through Cigarette Lighter adapters. With us leaving in a few days for Hollywood Beach I really didn't want to touch any wiring behind the panel. Thanks to you and your web site and Bob Mills for the help in tweaking the setup configuration.

With a little bit of luck with the weather we will be dropping bread crumbs all the way from Evansville, IN (3EV) to Hollywood, FL (KHWO) Friday
 
newtech said:
I think the problem is with the GPS wiring to the MT-RTG. I noticed the green led flashing for several minutes a few times. My installation is pseudo Rube Goldberg with both the GPS and RTG being powered through Cigarette Lighter adapters. With us leaving in a few days for Hollywood Beach I really didn't want to touch any wiring behind the panel. Thanks to you and your web site and Bob Mills for the help in tweaking the setup configuration.

With a little bit of luck with the weather we will be dropping bread crumbs all the way from Evansville, IN (3EV) to Hollywood, FL (KHWO) Friday
Click to expand...

Drop a couple on top of DCU as you fly over. Have a great trip!
 
Steve,
I admire you craftsmanship. I am just shy of starting or buying an RV something 7 or 8 I hope and my amateur radio stuff basically has been all
HF... so with the APRS system operates on 2 meters I guess. and can be viewed I saw from your post from almost any computer or 2 meter rig with that capability.

Two questions.
How did you bury the antenna in the balsa wood. cut a groove and lay the wire in.

What do you mean when you state cut the cloth on the bias... I am no expert when it comes to fiberglassing but guess with all the work on the RV you could get pretty good at it.

Thanks
Smilin' Jack Hunt
WB4JKY
EAA/AOPA
Corporate Pilot
CL601-3A/ H800XP
 
newtech said:
I think the problem is with the GPS wiring to the MT-RTG. I noticed the green led flashing for several minutes a few times. My installation is pseudo Rube Goldberg with both the GPS and RTG being powered through Cigarette Lighter adapters. With us leaving in a few days for Hollywood Beach I really didn't want to touch any wiring behind the panel. Thanks to you and your web site and Bob Mills for the help in tweaking the setup configuration.

With a little bit of luck with the weather we will be dropping bread crumbs all the way from Evansville, IN (3EV) to Hollywood, FL (KHWO) Friday
Click to expand...

Steve,

Do you have the tracker connected to your airplane's GPS? What kind is it? Just wondering...and certainly understand not wanting to dive behind the panel just before a big X-C...just asking for trouble (AMHIK! :rolleyes:)

And OBTW, just passing what Pete and Sam have taught me! They even monitored test flights live (like we did yours), and Pete texted me while I tested it with feedback! I did similar with Pat Hatch, via phone and his Zulu! Us BB droppers gotta stick together!!

Say hi to Vince when you see him again, and have a great trip.

My spare Comant 122 may be looking at a balsa/glass overcoat soon, when I do some minor winter glass repairs and mods! Thanks for the idea!!

Here's a mostly unrelated APRS track, just for fun...what 20 minutes or so of dogfighting an RV-8 then coming back into the break looks like!

11010aprs.png


Cheers,
Bob
 
Smilin' Jack said:
What do you mean when you state cut the cloth on the bias...
Click to expand...

Typical Rutan BID (bidrectional) fiberglass has fibers running parallel to the edge and perpendicular to the edge. If you cut it at 45 degrees to the edge the fiberglass rounds curves mo better.
 
Smilin' Jack said:
Steve,
I admire you craftsmanship. I am just shy of starting or buying an RV something 7 or 8 I hope and my amateur radio stuff basically has been all
HF... so with the APRS system operates on 2 meters I guess. and can be viewed I saw from your post from almost any computer or 2 meter rig with that capability.
Click to expand...

Jack,

Be sure you read the stickies at the top of the APRS forum:

http://www.vansairforce.com/community/forumdisplay.php?f=104

This is cool stuff for a ham. :)
 
I really need to get into this

I have just passed my professional engineering exam so i have all kinds of time that I am not studying now..:)

Frank
 
rvmills said:
Steve,

Do you have the tracker connected to your airplane's GPS? What kind is it? Just wondering...and certainly understand not wanting to dive behind the panel just before a big X-C...just asking for trouble (AMHIK! :rolleyes:)
[snip]
Here's a mostly unrelated APRS track, just for fun...what 20 minutes or so of dogfighting an RV-8 then coming back into the break looks like!
[snip]
Bob
Click to expand...

I have a panel mounted Garmin 696 that will drive the APRS when I build my new panel this Spring; right now I am using an old Lowrance 600C. Both the Lowrance and APRS plug into Cig. Lighter Sockets for power. The antenna is the only part that is permanently mounted.

Vince is in our EAA Chapter. We spent a good number of EAA meetings at his airplane factory when he was building.

Dog fighting is good :D
 
Steve,

Now that you have a functioning APRS transmitter, you should consider placing a link to your tracking page in your signature. Makes an easy way to find you without trying to figure out which "callsign" you're using...

For an example, take a look at my signature, or Sam Buchanan's, etc.
 
newtech said:
I think the problem is with the GPS wiring to the MT-RTG. I noticed the green led flashing for several minutes a few times. My installation is pseudo Rube Goldberg with both the GPS and RTG being powered through Cigarette Lighter adapters. With us leaving in a few days for Hollywood Beach I really didn't want to touch any wiring behind the panel. Thanks to you and your web site and Bob Mills for the help in tweaking the setup configuration.

With a little bit of luck with the weather we will be dropping bread crumbs all the way from Evansville, IN (3EV) to Hollywood, FL (KHWO) Friday
Click to expand...

We made it to KHWO yesterday; great weather and great flight. After reviewing the APRS track I noticed the following info pack:

2011-01-15 13:50:18z
221 MPH 133? alt 6365 ft
W9BOJ
[SW3W6P via WIDE2-1,qAr,N4CKV-4]

Gotta love these RV's
 
Nice work!
Considered doing the same thing myself. The actual design of the antenna, how is that done? Ie the "1/16 piece of copper coated steel gas welding rod" part...
 
matt said:
Nice work!
Considered doing the same thing myself. The actual design of the antenna, how is that done? Ie the "1/16 piece of copper coated steel gas welding rod" part...
Click to expand...

I will be making a second antenna for my hangar mate's RV-7 when we get back from Florida. Will do a complete construction article for our EAA newsletter. It should answer most questions and will even test the efficiency of the new antenna.
 
matt said:
Nice work!
Considered doing the same thing myself. The actual design of the antenna, how is that done? Ie the "1/16 piece of copper coated steel gas welding rod" part...
Click to expand...

Steve's antenna is a very nice bit of craftsmanship. However, the electrical part of it is very simple, just a length of welding rod. Here is my admittedly less attractive (but highly functional) APRS antenna built from 1/8" stainless welding rod and a couple of coax connectors:

tracker-5.jpg


Scroll to almost 1/2 way down this page for details:

http://thervjournal.com/tracker.htm

Maybe this will show the simplicity of the actual element. I ran com versions of this antenna for many years on a couple of aircraft.
 
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Sam Buchanan said:
Steve's antenna is a very nice bit of craftsmanship. However, the electrical part of it is very simple, just a length of welding rod. Here is my admittedly less attractive (but highly functional) APRS antenna built from 1/8" stainless welding rod and a couple of coax connectors:

tracker-5.jpg


Scroll to almost 1/2 way down this page for details:

http://thervjournal.com/tracker.htm

Maybe this will show the simplicity of the actual element. I ran com versions of this antenna for many years on a couple of aircraft.
Click to expand...


That looks simple enough.
Bending the antenna, should that be done at any particular length and/or angle?
 
matt said:
That looks simple enough.
Bending the antenna, should that be done at any particular length and/or angle?
Click to expand...

Probably......but I don't know what angle that would be. I was just trying to keep the antenna out of the grass. ;)

Keep in mind we are using airborne transmitters that can see to the horizon. Some folks have even found that a looped piece of TV twinlead in a wingtip will make an effective antenna. :D
 
Bdalporto said:
I'm thinking of using an inexpensive AS antenna.
http://www.aircraftspruce.com/catalog/avpages/stainlessantenna.php
I think I'll just need to cut it down to 19.45" to match the frequency.Brian
Click to expand...

On one of the threads, someone noted that the miss-match is not enough to cause the APRS (Byonics) to have a problem and leaving it full length gives you the option to use the antenna as a backup if/when you need it. If I recall, someone said they setup the antenna to be a backup connected to a handheld.

If you are going with one of the Byonics APRS trackers, give them a call or email and see if the antenna will work as-is. I've had great customer service from them.
 
No it will not work well due to the way the antenna feedline connects to the antenna. I have had about a half dozen XCom customers contact me for repairs thinking something was wrong with their radios when it was this POS antenna that was causing problems.

I recommend Don Pansier's APRS antenna if you want something to bolt on and go.
 
Bdalporto said:
I'm thinking of using an inexpensive AS antenna.
http://www.aircraftspruce.com/catalog/avpages/stainlessantenna.php
I think I'll just need to cut it down to 19.45" to match the frequency.
Does anybody think this will work?

Brian
Click to expand...

Brian, we have a local RV-6 with a Byonics tracker driving this antenna. The pilot trimmed it as you mentioned and it works great. It ended up being very similar to the homebuilt whip I used for awhile.

I think I recall Allen stating the newest trackers are a bit more intolerant of antenna mismatches so I recommend trimming the antenna instead of leaving it at the com freq length. 19.45" should work fine.

Happy trackin'!
 
Brian

I bought a similar antenna for my com, the Rami version with the ceramic insulator. Just make sure you make a secure connection and it will be fine. I drilled a hole in the threaded shaft and soldered a BNC connector to it and then wrapped it in fiberglass. I have an antenna analyzer and got spec SWR. You may want to look up a local HAM or HAM club and ask them to help you optimize the length for your frequency.

Have fun.
 
Those cheap antennae work fine, but they absolutely need tuned to your installation to get a 2:1 VSWR or better. Has anyone been able to make their transponder antenna work?
 
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