PDA

View Full Version : Help with new custom setup


sdixon747
11-15-2016, 03:22 AM
I recently put a deposit down to have a new trailer custom built. This gives me the opportunity to optimize my shack and antenna setup. I plan on running two runs of coax to the back and two more to the roof. The roof will be basically clean, ie no air conditioners (basement air) but will have a fairly large solar array. The overall design is still being finalized, but the overall length will be between 42 and 44 feet.

So now to the big question. Ground plane? I guess that theoretically a copper plate covering the entire roof would be ideal, but very expensive and not practical. So, looking at various ground plane solutions, and weighing the cost/benefit of each, what would be best solution? Copper wire run in a radial pattern on the roof? Copper foil? Maybe put nothing up there and just use the steel of the frame? Would copper in the floor (closer to the ground) be better? What do you think?

Thanks very much for your input.

Steve
KJ4YGY

wa8yxm
11-15-2016, 09:52 AM
What bands do you plan to work out of the RV
For practical reasons vertical antennas are not going to be roof mounted for HF, only VHF and then likely not for six less it folds down

For 70cm you only need a 35cm circle for a ground plane, tha't is a bit over 1 foot diameter.

For 2 Meters a 1 meter circle (38" in this case, or 19" radius)

Just divide the wavelength by 2 to get the circle size for the ground plane.

For HF. go with something mounted to teh bumper/frame, if it's a TT mount to the tong, if it's a 5er extend a frame rail enough to attach something like a Screwdriver.. OR do what I did (not the best option) and use a Auto-Tuner (marine grade) and attach a long wire and throw it up in trees (not always allowed).

For 10 or 20 meters you can string a dipole along the roof.. I do plan on doing that some day, I currently have a side rail on one side of the roof (1/2 inch copper tubing, soldered (electrical solder) connecitons, hooked to the Antenna Tuner with stranded copper 10ga (what I had in stock)). and plan on putting a second rail (PVC) also half inch painted on the other side, it will hold a 10/20 meter dipole.

But for most hf bands. roof mounts just are not the best choice.

Though a DDRR antenna might work for 10 or even 20 if properly designed.

NOTE that contrary to popular belief, Dipoles DO NOT NEED A GROUND PLANE. There are also VHF antenna designs (and UHF) that do not require a ground plane.

sdixon747
11-15-2016, 12:37 PM
Antennas on the roof will have to be folding as the trailer height will be 13' 3". I have considered using a Tarheel screwdriver on a folding mount on the roof, or an Eagle One vertical or the like on the back. The radios that will be installed are a Kenwood TS-480SAT and an Icom IC-2820H. I know that 160m is not practical in an RV, but I would like to be able to tune 80m through 70cm. The Tarheel is just a thought. I'm open to all viable solutions. I'm asking now because it will be so much easier to run coax, grounding straps, power hookups etc. while it's being built rather than trying to retrofit.

N3LYT
11-16-2016, 08:40 AM
I use a LilTarheel with a mount on the rear bumper it works for me. It's only good to 6 meters and if you change the stinger to some thing longer it kind of rules out 6 meters. I'll assume your going to use the VHF/UHF on a different antenna. I'm thinking your new camper will have a fiberglass roof so maybe some sort of counter poise would help.