Homebrew HF mobile antenna

This antenna covers 6-20m but doesn't cover 40m. This is due to a couple of reasons,firstly it started life as a center loaded antenna. The bits i was using were all from the shack "junk box" and it soon became apparent the coil was simply too big to have in the center of the antenna. So the base loaded was born. The coil has more inductance than needed for 20m but not enough for 40m but i can't bring myself to take apart for the sake of around four redundant turns on the coil.My best dx to date using this antenna with the 817ND was LU2NI in Argentina at a distance of 6792 miles. Not bad for an antenna costing around £10.

As you can see i have modified the tri mount.The third magnet was taken off and this now is the anchor point to the car. The boot mount has also been modified to be an earth point and is bonded to the boot lid. This was to allow a good earth to the car body . From there all body panels,exhaust and everything that would accept straps has been bonded. The black box on the rear of the magmount is the shunt matching section for the 17 and 20m bands.The earth strap from the coil is made from the shield of old RG213 and is used for the bonding of the car body panels also.The radiator section is made from two top sections of an old silver rod with a 3/8 screw section at the base and a whip stud pressed into the top section to take the 4 foot steel whip.You can see in the top photo the joins in the radiator.This was done due to the bottom 3/8 connector body being thicker than the top whip connectors body and so was done to simply to accomodate the two differant body sizes. step up/step down,whichever way you want to look at it.

www.k0bg.com has lots of good information regarding mobile installations.

This was my first attemp at a mobile antenna and i was quite happy with the build quality and the on air results. My next mobile project is a multiband to include 40m and then a center loaded antenna with a set of coils for each band.REMEMBER a good earth is a must ,bond as much as you can using earth straps. It really does pay off.