Travel Trailer Antenna

[WRYN359]

I have a 26' travel trailer and am planning on putting a Retevis RTS-97 GMRS repeater in it. I'll likely also use that repeater as the base station when camping so I can always have it on and not worry about having an HT on me always when the kids go off hiking/biking/whatever. They can just take an HT with them and we'll all be good. I need antenna advice. I'm currently thinking about mounting a 6-24ft telescoping aluminum pole on a pivot to the rear bumper so I can collapse it for travel but get me height when the antenna is in use. The pole has a 3/4 acme thread, so I'm thinking I can weld an acme nut to a pizza pan or some other metal disc to create a ground plane. I'm thinking about using a magnetic base mount of some sort so that when I travel I can place the antenna on the back bumper and not have to worry about unwiring it, just coil the extra coax and hang it off the spare tire or something. Then when I set the camper up I just spin on my ground plane, attach my mag mount, and extend the pole. I'm looking for alternative ideas for a reasonably priced mast (pole I'm looking at is about $60) as well as ideas for the mag mount, coax, and antenna. I figure I may need up to 50' of coax to get from the top of my pole to the repeater, so a lot of the integral mag mount/coax setups won't work. Since The coax will be moved on a weekly basis, I'm thinking I will need something stranded but again am open to advice. Thanks in advance.

[BoxCar]

The coax used for mag mounts is very lossy in lengths over 25 feet. You are better off using a half-wave antenna with LMR 400 or equivalent cable.

[BoxCar]

Well, a 6dBm gain antenna won't affect the area you could cover as the radiation pattern wouldn't be that much different from a unity gain omnidirectional. It would flood the area with 4 times the power fed into the antenna, though. You may want to consider the MFJ-1917 Telescopic pole for your antenna mast, it reaches a tad over 40 feet high but collapses down to less than 5 feet.

[WRNN959]

We mounted a 25' telescoping flag pole to the front tongue of our travel trailer. It collapses to about 5' and the pole mounts in a stub that stays permanently attached to the trailer frame. Takes less than five minutes to install and extend the flag pole for setup or tear down. I'm considering installing an NMO antenna mount at the top of the pole for GMRS comms. When traveling the flag pole stows in the bed of the truck. In my case the coax will stow under my propane storage cover when not in use. 

 

[WRXB215]

@WRYN359 Sounds like a cool project. Did you consider using a 1/2 wave dipole? No need for a ground plane.

[tweiss3]

https://www.arcantenna.com/products/laird-mbcn-nmo-to-nfemale-antenna-adapter-ground-plane-radials-vhf-uhf

Mounts to the pole no problems, then use any mobile antenna you want; quarter wave, half wave, 5/8's, all will work well.

[WRYN359]

11 minutes ago, tweiss3 said:

Mounts to the pole no problems,

Was thinking magnetic mount though so I don't have to connect/disconnect the cable every time we go somewhere. I'm concerned that while connectors are relatively low loss, over the course of a summer' or two worth of camping the conductor connections may not be as tight even if the threads are tight and I will get excess signal loss. Maybe that's not a valid concern, which would be great because then I could use more of a base station style antenna rather than a mobile style antenna.

[tweiss3]

Just now, WRYN359 said:

Was thinking magnetic mount though so I don't have to connect/disconnect the cable every time we go somewhere. I'm concerned that while connectors are relatively low loss, over the course of a summer' or two worth of camping the conductor connections may not be as tight even if the threads are tight and I will get excess signal loss. Maybe that's not a valid concern, which would be great because then I could use more of a base station style antenna rather than a mobile style antenna.

I wouldn't worry about the connector. If you really are concerned, then don't disconnect the cable from the antenna. You have to coil the cable anyways when the pole is collapsed, keep it attached. You are correct, you can use a base style antenna as well. 

[WRYN359]

41 minutes ago, WRXB215 said:

@WRYN359 Sounds like a cool project. Did you consider using a 1/2 wave dipole? No need for a ground plane.

Not really, for the simple reason that I think the easiest way to do the mount for quick attach/detach without having to put excess wear on my connectors is by doing a magnetic mount so the antenna can always be connected. Then I just move the mount from the pole to the bumper for travel.

[WRYN359]

6 minutes ago, tweiss3 said:

I wouldn't worry about the connector. If you really are concerned, then don't disconnect the cable from the antenna. You have to coil the cable anyways when the pole is collapsed, keep it attached. You are correct, you can use a base style antenna as well. 

I haven't come up with a practical way to store the antenna during transport if it's connected unless it's got a magnetic base.

[WRQG411]

We do this setup at the river in north Idaho where we have no cell service.  Most of us have side-by-sides and carry handhelds if there isn't a mobile is installed in the machine.  The RT97s works well for this scenario.  My antenna is a 10-ft comet on an aluminum pole that's about 15-ft' long and strapped to the tongue of the trailer.  I used a cig plug connected to the batter and the power cord from the repeater kit.  There are mountains all around us, but we've been able to get 10 to 15 miles out from the repeater and still get in with mobiles on most of our rides.  The HT's are ok out to about 6 miles.

The trailer stays there all summer so I never take the antenna down, and only kill power to the repeater when we aren't there.  I know that doesn't help with your wanting to stow for transport.  

If I was going to change anything, I'd buy another hitch mount for my rear bumper and a collapsible 25' flag pole and a different antenna with slightly less gain to help with the terrain we're in.

[WRYN359]

1 hour ago, WRQG411 said:

We do this setup at the river in north Idaho where we have no cell service.  Most of us have side-by-sides and carry handhelds if there isn't a mobile is installed in the machine.  The RT97s works well for this scenario.  My antenna is a 10-ft comet on an aluminum pole that's about 15-ft' long and strapped to the tongue of the trailer.  I used a cig plug connected to the batter and the power cord from the repeater kit.  There are mountains all around us, but we've been able to get 10 to 15 miles out from the repeater and still get in with mobiles on most of our rides.  The HT's are ok out to about 6 miles.

The trailer stays there all summer so I never take the antenna down, and only kill power to the repeater when we aren't there.  I know that doesn't help with your wanting to stow for transport.  

If I was going to change anything, I'd buy another hitch mount for my rear bumper and a collapsible 25' flag pole and a different antenna with slightly less gain to help with the terrain we're in.

That's something else I need to figure out is how much gain I want to run. I'm thinking somewhere in the 3-6 range may be good, but I'm still new to this so I could be way off.

[WRYN359]

18 hours ago, WRNN959 said:

We mounted a 25' telescoping flag pole to the front tongue of our travel trailer. It collapses to about 5' and the pole mounts in a stub that stays permanently attached to the trailer frame. Takes less than five minutes to install and extend the flag pole for setup or tear down. I'm considering installing an NMO antenna mount at the top of the pole for GMRS comms. When traveling the flag pole stows in the bed of the truck. In my case the coax will stow under my propane storage cover when not in use. 

 

That's a great idea! Love it!

[WRNN959]

3 hours ago, WRYN359 said:

That's a great idea! Love it!

It's the type that is designed for tailgating where folks put the vehicle tire on the base plate to temporarily hoist the flag. I mounted the foot to the bottom of my trailer tongue for a permanent mount that just takes a few seconds to deploy the flag pole. The flag pole is sold by a veteran owned company called Service First. They have several versions to choose from. The one I bought was a complete kit with flag and hardware. 

There's a 3/8-24 threaded socket at the top of the pole for the round finial. I plan to use that thread to mount and NMO antenna base with ground plane radials. It should just take a minute or two to install the antenna before extending the mast to full height. 

Here's a link to the flag pole I bought.    https://www.amazon.com/gp/product/B0BG6NBVC6/ref=ppx_yo_dt_b_asin_title_o01_s01?ie=UTF8&psc=1