Home brew mobile antennas
- Thread starter rusty_tlc
- Start date
1911
Expedition Leader
Still in the thinking stages myself. I did buy a set of the military surplus fiberglass poles, and fabbed an angle bracket out of scrap steel to fit in my receiver hitch and hold the poles upright. Haven't decided what to put on top of the poles though. A beam (Yagi) antenna takes up so much room, unless I could suspend a small one from my roll cage, up near the roof.
rusty_tlc
Explorer
Are you planning something like a mobile base station?
I was thinking more in terms of an antenna for use while driving, but antennas for temporary locations would be cool to see too.
I built an interesting 2M antenna from plans in the ARRL antenna book.
I has great range and I think it would adapt well to mobile applications. I used copper wire so this one wouldn't be robust enough;
I was thinking more in terms of an antenna for use while driving, but antennas for temporary locations would be cool to see too.
I built an interesting 2M antenna from plans in the ARRL antenna book.
I has great range and I think it would adapt well to mobile applications. I used copper wire so this one wouldn't be robust enough;
1911
Expedition Leader
Yeah, sorry I am thinking of a mobile base set-up for nights.
Both of my 4WD trucks have NMO mounts so I can change-out mobile antennas as dictated by terrain. It's pretty easy to carry a variety of 2M or dual-band whips and rubber duckies of various wavelengths.
I built an interesting 2M antenna from plans in the ARRL antenna book.
I has great range and I think it would adapt well to mobile applications. I used copper wire so this one wouldn't be robust enough;
I guess it depends on where you mount it, but I would be afraid that the top disc would catch the wind and deform the antenna on a mobile installation.
rusty_tlc
Explorer
Mobile base set ups for what frequencies?
I use NMO mounts on my trucks as well. Eventually I'll get an NMO to SO 239 adapter.
The test antenna was built on a PL 259 connector first because I had a SO 239 mount laying around. PL 259 connectors are also easy to find and there are a number of antenna designs you can build on them.
I use NMO mounts on my trucks as well. Eventually I'll get an NMO to SO 239 adapter.
The test antenna was built on a PL 259 connector first because I had a SO 239 mount laying around. PL 259 connectors are also easy to find and there are a number of antenna designs you can build on them.
Tennmogger
Explorer
Here are some pictures of mobile antennas presently in use. As you can see I like to build the bases a little differently, and primarily for HF use. The red lumps are stand-off insulators normally used to support buss bars and heavy components inside electrical equipment. They work well at RF and internal capacitance is low, on the order of 5 to 10 pF. That's better than some professional bases. They are reasonably cheap, very robust, and mount anywhere. You can see how they are fed in the pictures, with large home made copper washers as terminals. Just bolt them to the roof rack, roll bar, fender, where ever.
I tap the insulators for 3/8" x 24 if they aren't already. If the parts don't have 3/8" x 24, I modify them. That matches many antenna mounts, and everything fits together for mix and match. The antennas are various bits and pieces from commercial antennas, CB whips, end even fer-real antennas (like the Hustler mounted on the front bumper). The tiltover is a 1" x 10 (?) Shakespeare marine base, and the adapter is made from copper plumbing pieces.
A handful of CB whips from garage sales makes good building material. The stainless ones can be trimmed for 10m, and the fiberglass rods ones can be stripped and rewound. Can even make a good 2m antenna that way.
Those buss bar insulators can be coil forms, too. Just wind a larger coil out of 1/4" copper tubing and mount it across the insulator. Insert that higher up in the mast to resonate the antenna. Various pieces of aluminum tubing with 3/8 x 24 ends make antenna extenders to 'tune' for different frequencies.
Bob
WB4ETT
Attachments
rusty_tlc
Explorer
How many antennas do you need to cover the HF band?
Tennmogger
Explorer
Just one more!!
DaveInDenver
Middle Income Semi-Redneck
It probably wouldn't hold up as a mobile being rigid, but if you tape the 4 holes in the body of the PL-259 and pour epoxy (not JB Weld, regular epoxy) into the barrel, it would help make it weatherproof and more solid. Wouldn't help that it'll bend, though.
I built an interesting 2M antenna from plans in the ARRL antenna book.
rusty_tlc
Explorer
As I mentioned in the OP this version is made out of copper and certainly wouldn't stand up to trail use. In the first post I was thinking of "mobile" as in moving from one location to another, not necessarily for use while actually moving. As is it would make a nice compact antenna for use in a mobile base station or even as a stealth urban antenna.
That said I think the coil portion of the design posted could be rotated to the vertical and the whole thing made out of spring steel with a stainless steel capacitance hat. Which would make a pretty robust antenna with a very low profile.
I'd fill the center with epoxy as suggested then add a shrink wrap layer in stages to get a really good seal on the PL-259.
That said I think the coil portion of the design posted could be rotated to the vertical and the whole thing made out of spring steel with a stainless steel capacitance hat. Which would make a pretty robust antenna with a very low profile.
I'd fill the center with epoxy as suggested then add a shrink wrap layer in stages to get a really good seal on the PL-259.
1911
Expedition Leader
Rusty, since you started this thread I have bought a mobile HF radio and a Buddipole antenna. OK, so the Buddipole is not home-brew, but it is very versatile, like the Tinkertoys or Erector Set of antennas, and completely portable. You can rig-up pretty quickly from the parts in a bag, antennas that will resonate on anything from 2M to 40M, and with a few extra pieces you can make one for 60M and 80M as well. I'm having fun with it on a tripod and 8' mast at home, but looking forward to getting it out in the back country with the the Land Cruiser also. Again, this a portable antenna, not a mobile.
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AFBronco235
Crew Chief
I've been thinking about a J-pole for my rig, but I have a pretty unique mounting point in mind for it that fairly robust. Namely, the brackets for the original tire carrier that I no long use since I swapped to a bumper mounted carrier. The original brackets were designed to hold something MUCH heavier than the J-pole, but I wouldn't want to do any forest trail riding with it.
I realize that this pic is a few years old and probably moved on, but it occurred to me that the whole thing could be reinforced with a sleeve of some kind, probably a PVC tube, that supported the top weight while still allowing the copper to maintain its shape, as well as protecting the bare copper from the elements. Cap both ends of the tube and add a mounting bracket and you'd be set. The only downside I could foresee is that the plastic walls of the protective tube could impair reception/xmit, but I'm not sure if that would be true or not.
I realize that this pic is a few years old and probably moved on, but it occurred to me that the whole thing could be reinforced with a sleeve of some kind, probably a PVC tube, that supported the top weight while still allowing the copper to maintain its shape, as well as protecting the bare copper from the elements. Cap both ends of the tube and add a mounting bracket and you'd be set. The only downside I could foresee is that the plastic walls of the protective tube could impair reception/xmit, but I'm not sure if that would be true or not.