I make and sell these antennnas. I give away the plans freely, but I will make this antenna to order for any Amatuer Radio operator who asks. The design requirements are a portable antenna, with good performance, simple materials, and minimal amount of tools to assemble, and flexibility for mounting. I will be constantly revising the design as new solutions come forward through testing and evaluation.
I designed and built this antenna in about 30 minutes, can you tell? hi hi.
On one hoseclamp, drill a 0.250 inch hole through the hose clamp band. With 6-32 hardware, attach an eyelet to the hoseclamp. Cut a 3 inch long peice of wire. Crimp and solder the jumper to the eyelet. Crimp and solder another eyelet to the other end of the jumper. Set aside.
Each radial will pass through the holes in the PVC. For each radial, bend 90 degrees the 1-2 inch of the wire. You're making an L-shape. 1 to 2 inches on one leg and the remainder of the wire for the other leg. Pass the LONG end of the radial into one pair of holes so that the short leg rests up against the side of the PVC. Rotate the PVC and keep inserting each remaining radial through the holes so that all four radials legs extend out from the PVC and each radial "short leg" is resting flush against the PVC. You may need to bend and muscle those wires into submission (see photo). Slip the hoseclamp you modified over the radial end of the PVC so that the hose clamp squeezes tightly over all the short-legs of the radials. Tighten.
The jumper should run along the side of the PVC towards the center of the pipe length.
Cut another 2 to 3 inch jumper of AWG #12 wire. Bend 90 deg. Crimp and solder an eyelet to one end.Solder On the other end of the jumper, solder a AWG #12 wire into the center post of the SO-239. See picture. Use 6-32 hardware to fasten the radial jumper to one of the four holes in the SO-239 chassis.
Locate your vertical element. I used a small aluminum rod, you can use anything. On the very end of the vertical element (see picture) drill or fasten the center-of-SO-239 jumper you just made to the very end of the vertical element. Use a hose clamp to hold the vertical element to the PVC.
Tighen both hoseclams. Tighten all 6-32 hardware. Check solder joint on SO-239 (use #12 or smaller wire for that jumper so it can fit into the small divit in the end of the SO-239 -- tin the center first, tin the jumper first then solder them for best results).
A pipe, camera tripod, anything narrower than the center of the PVC can support the antenna. The radials will block the support so the antenna will rest upon those radials within the PVC. Using something non-conductive is best to support the antenna.
If you made the vertical element out of one peice of material, then the vertical element length is fixed (unless you hack off length -- don't rush to do that yet).
The easiest way to adjust the SWR of the antenna is to bend the angle of the radials. I use about 35 to 40 degree angle from the PVC (see pictures).
If you need to add length to the center vertical element, do so.
You probably do not need to add length to the radials. You can get more variation just by adjusting the angle of the radials from the PVC.
Picture 2, showing entire mounting suggestion on tripod
Breakdown PortabilityLoosen the hoseclamps. Slide the radials out and slip inside the PVC. Loosen the vertical hoseclamp enough so the vertical element tip is at the edge of the PVC. re-tighten the hoseclamp, and re-tighten the vertical hoseclamp. Tape or plug the ends of the PVC to keep the radials inside. The vertical element, SO-239 and hoseclamp-radial connector will stay secure to the PVC if both hose clamps are tightened. If the 6-32 hardware includes lockwashers then the only tool you'll need to re-assemble is a screw driver (which also could fit inside the PVC).
(To be extra cautius, in a small zip lock, put in extra 6-32 hardware and tape inside the PVC in case you drop/lose a screw, nut or lockwasher)