best antenna to use with no or minimal ground plane

[towerdog]

What antenna design would be best to use when no or minimal ground plane is available, such as a man portable system utilizing only the metallic frame of a rucksack, or say, on a inflatable boat. Also how does the antenna on my 2m HT work without ground plane (well it works poorly) and it is a rubber duck, but I also seen what appear to be just a straight 1/4 whip, like a Diamond or a Nagoga, do these have some sort of loading in the base. I am thinking for 10m that something along the lines of a Firestick or other fiberglass continous loaded would work best but I may be wrong.

Also, the best handheld 11m radio I ever used, in my opinion anyway, was a Realistic TRC-211, that had a telescopic 4 foot center loaded antenna. All of the old Realistic handhelds I owned had 2 metal plates on each side, each one had a lug attached to it from the PCB, so with this radio, is the persons body used as the ground plane?

 

[W5LZ]

I think you've provided your own clue as to how those "no groundplane" antennas work when you talked about those 'plates' on the sides of handi-talkies. That's also how most mobile antennas get their "groundplanes" too, even if it isn't very obvious. It isn't just a matter of those 'plates', or a vehicle's metal body, or the feed line, it's also the 'dirt' or water, or other things (your body), under/near those metal 'plates' and vehicle bodies which provide additional 'ground' through induction or capacitive coupling. The same sort of 'coupling' provided by the magnets on that mag-mounted antenna. See where that's going?? So, extend that sort of thinking a bit. How could you provide, or increase that inductive/capacitive coupling in an antenna system such as a bak-pack, or raft? There is always that 'other half' of the antenna somewhere. It may not be very obvious, but you can bet it's there. For current to flow (RF current too), there has to be both a (+) and a (-). If you eliminate one of those, there is no flow...
- 'Doc

 

[Moleculo]

The easiest thing to do is to use some sort of 1/2 wave antenna. A dipole comes to mind as the easiest. You can also build / buy 1/2 wave vertical HF antennas that are basically a 1/2 wave dipole but with some type of matching system to provide the "other half" of the antenna. Even a J-pole can be built for 10 meters, although it starts to become rather large.

 

[Quiksilver]

X2 on the dipole!

 

[wcsd106]

Instead of a dipole, how about a J-Pole which would offer a minimal amount of gain. There are several different ways to build one.. You can build from copper tubing, TV twinlead, etc.

The twinlead J-Poles can be rolled up and stored in a bugout bag or you can fully encase one in PVC pipe and use it just about anywhere.

I have a J-Pole mounted at about 30 feet.. Mine is made from Solid 3/8" Aluminum rod that has been welded together.

Edit: The J-Pole is only feasible as a portable antenna for VHF and above... the length required for a CB or 10 meter J-pole would be far too much to manage as a portable antenna.

I would make do with whatever I could come up with for CB & 10 meter frequencies, and keep a 1/2 wave dipole, some coax, and some dacron rope rolled up and stored in my pack for when I make camp.

 

[Lazybones1222]

vertical ladder line fed dipole