Saturday, November 12, 2022

E-Field antenna works much better in the bush

Many years ago, when I lived in Suburban Sydney, I built an e-field or "probe" antenna. 

The benefits of these antennas is their small physical size and broad band operation including down to very low frequencies.

My home made one was disappointingly noisy. I purchased the PA0RDT mini whip and while well made, it was similarly noisy at that location. 

These days I'm at a low noise location and thought I'd give it another go.

It's certainly much better here than it was in the city but does pick up electrical noise particularly at low frequencies.

Power is fed up the coax from a little injector box that runs on 12V. For a while I ran it in to an AirSpy HF+ using SDR++ in the server mode (note that you need to get a nightly build for this feature to be there). Here's a look at 40m from a remote machine:

I'm not sure what those bands of noise are but I think they're related to power mains noise of some sort.

To test the low frequency receive performance, I set up WSJT-X to band hop 160m, 630m and 2200m. No luck on 2200m but I did receive spots from a station in VK5.

Amazing to receive a 1W signal on 475kHz from 1,380km away! Most spots were on 160m.

I'm finding that all antennas work better in the bush than they do in the city.

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