PA0RDT design active antenna

LF to HF active antenna.

Receive Antenna for LF to HF

Well, as amateur radio operators, we have so many frequencies available for us to experiment on, how do we monitor them all? At LF and MF frequencies, any resonant antenna length can be quite prohibitive, even for the humble suburban back yard. Most antennas are a compromise, so, is there something that can be used for LF, MF, and a good part of the HF? Yes, there is! Enter the PA0RDT Active Mini Whip antenna.
Firstly, the original idea and article for this version seems to be credited to Roelof Bakker, PA0RDT. Secondly, there is also some different variations of this active antenna design on the internet. The main reason seems to stem from people's desire to eliminate as much noise as possible, hence the inclusion of extra isolation from ground loops/currents by including additional rf chokes and 1:1 matching transformers. These rf techniques make valid sense and should be considered for each installers application.

Let's see

Several prototypes have been built by myself and I have included some photos here. The active antenna is such an easy project to build from scratch. Most people, I dare say, could build one in an evening's or two session.I have ended up utilising the additional isolation features and have included an article from Derek, G3GRO, in the links section that include these. Main use has been for LF and MF reception. Additional filtering has been required to overcome broadcast interference. YMMV.

Active Antenna - #1

 First prototype built. Here's the  active antenna head.

RF Isolated Biased Tee

 Here's an inside view of the rf  isolated biased tee. Note use of  insulated bnc connector.

Active antenna housing

 Recycle and re-use. A used  supplement container will do  nicely.

Active Antenna - #2

 This is the second version. I've  tidied the layout up a little.

Underside of #2

 I've double the antenna size to  see what effect it had.

Up the back...

 Mounted on a squid pole down  the back yard.

Useful Links

  • G3GRO's PA0RDT Mini Whip Antenna article
    • Download PDF article containing schematic and construction details.


VK5FQ website
12/02/14 Start build of new website.


Steph - VK5FQ
Adelaide, South Australia,