The MicroVert antenna, designed by Jürgen Schäfer, DL7PE, is a short, base loaded antenna that uses the coax shield as a counterpoise. Of course, this antenna is probably not the right choice for the DX-Hunter, but a very cheap, small and easy to build antenna and ideal for travelling and portable operation.
The following pictures shows my first versions for 7 MHz and 14 MHz. The antennas body are made out of a 16.5mm diameter PVC tube used for electrical installation. The radiator is made of 20mm x 1.5mm aluminium tube. One antenna can be manufactured within less than one hour.
A first test with the 14 MHz version mounted in my basement (2m below ground level!) shows reception reports about 3 S-units below my 5/8-lambda vertical. Contacts with YU, UA3, 4L8 and EA9 were easily made at first call with 100 W output.
|MicroVert antennas for
left: 14 MHz, total length 65cm (26inch)
right: 7 MHz, total length 100cm (39inch)
|14 MHz coil
(1mm CuL for 100W Tx power working fine)
|Clamp for fast h/v mounting from Hardware Store||Adjustment Element (8mm diam.)
(not necessary if antenna is designed correctly)
VSWR Curves for 40m and 20m (can easily tuned with adjustment element op top)
Lately I have received several inquiries about the dimensions of the antenna, which differ between the Excel sheet and the data from the Online calculator. I can say that there are many ways to build this antenna and you take the material you have. A longer radiator requires fewer turns of the coil and vice versa, but of course affects efficiency.
Please note that only the inner conductor of the RG58 cable is connected to the antennas coil. The shield is NOT connected at this point!