Lance, KA2EJD wwrites:
Too often, I find new operators in an event, trying to use an HT with a rubber duck antenna to get into a net and not making it because the antenna just doesn’t cut it. Often they have a mag-mount, but can’t operate from their car. Unfortunately, they don’t realize that there is a way to use that mag mount antenna more efficiently.
The answer is the ‘Bazooka Ground Plane.’ A friend of mine give it this name, and it kinda stuck. As you can see from the drawings and photo it’s an easy build, with all of the materials available from the local big-box home improvement stores. The only tools needed are screwdriver, 7/16 wrench and sockets, and a drill with a 1/4″ bit.
Lance also included some written instructions.
I often advise newcomers to build a 450-Ω ladder line J-pole antenna to use with their HTs in this situation, but this is a good way to make use of an antenna that you already have. Here’s a photo of the Bazooka Ground Plane in action.
This seems like a lot of work. Why not just slap the mag mount on an appliance (stove, fridge, etc) or a cookie sheet?
I think the idea is that you’d use this somewhere where a convenient ground plane is not available, like out in the field somewhere.
Or even an outdoor A/C compressor cabinet
I used a cookie sheet on my roof put mag mount on it ran a wire from the cookie sheet to my eves an used the eves for my counter poise . You can run tuned radials from the cookie sheet instead of using the eves. I used this set up with a Htv 400b multi band antenna. Works great! Make sure you put some weight on the cookie sheet to keep it down in the wind.
These instructions are horrible.
I made a portable ground plane for my Comet SBB-7 dual band mobile antenna out of materials I had in my garage. For the base of the portable ground plane, I use a scrap piece of 16 gauge galvanized metal plate. I cut a 3” diameter circle. On one side of the circle I left a 10” long by 1 1/4” wide “pig tale” Next I drilled a hole in the center for an NMO antenna mount. Then I drilled 6 holes the size of a #24 machine thread screw around the outer edge of the 3” diameter base. I then cut 6 12 gauge brass welding brazing rods to 20” in length. I then bent all 6 radials downward at a 45º angle at 1 1/4” from the radial end that will be bolted to the 3” diameter plate. At the radial mounting end of each radial, I crimped and then soldered on a 12-10 gauge copper electrical eye lug to mount each radial to the 3” diameter plate using 10×24 stainless steel machine thread screws with washers and lock washers. The 10”long by 1 1/4” wide “pig tale”, where the pig tale meets up with the 3” diameter plate, I made a 90º downward bend so that the pig tale now becomes the mast support bracket. I welded 4 tabs, 2 on both sides of the mast support bracket. The tabs are drilled so that you can run a U bolt through to secure the portable ground plane to the antenna mast. For a temporary installation, two 1” wide by 2 1/4” diameter stainless steel automotive hose clamp are strong enough to secure the portable ground plane to a 1 1/2” OD galvanized TV antenna mast. The portable ground plane is designed so that it can easily be put up, taken down and transported to a different location when needed. This portable ground plane allows you to use a dual band NMO mobile antenna as a permanent or temporary base station antenna. It performs well with low SWR. I’v transmitted up to 100w on 2m FM with no issues.