20 countries on MW with a very small antenna I listen the radio stations on medium wave 530–1700 kHz via a WEB SDR located in the Netherlands. My goal is to listen a maximum of countries via this very small antenna.
https://mwlistener.blogspot.com/
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PA0RDT antenna (Mini-Whip)
Information about the antenna
The PA0RDT antenna is a very small antenna for the case you aren't allowed or able to put a long wire antenna up in the air. It's made of some electronic components for a few bucks and a copper plate. The size of that copper plate ist about 80mm x 32mm. So it's very small.
Potential of such a small antenna
Since I'm SWL for many years I'm always looking for several types of antennas. So I found the Mini-Whip on the internet. What is this small antenna able to? And what frequencies is it able to receive? Well, I tried a lot with it. So I can say that this antenna should be able to receive from 10kHz to 21MHz. So you can receive 77kHz or 60kHz time signals just as the stations on the 15m ham radio band. If you'e using software like WSPR it's possible to catch stations >16.000 km away from you :) Sometimes it seems that the antenna is doing it's job on 10m band, also. Only for strong stations, maybe.
What do you need
0. this document: www.radiopassioni.it/pdf/pa0rdt-Mini-Whip.PDF
1. copper plate
2. a 12 V power supply > 100mA
3. some m of RG58 or similar antenna cable (50 ohm)
4. a place where you can put the antenna on - the higher the better
5. PVC pipe or similar case
6. electronical parts - resitors etc.
Price
It's very cheap. You have to pay about 10,00 € to 20,00 € depending on what parts you have at home. Like PVC pipe or resitors etc.
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The system is currently composed of a "Mini-Whip" antenna, a homebuilt SDR board (as pictured; see here for background) which samples the entire shortwave spectrum and sends all of this via a gigabit ethernet link to a PC, where a special version of the WebSDR server software processes it. The Mini-Whip is based on a design from PA0RDT (google finds it); see here and some older pictures here. The active receiving element is about 5 by 10 cm large. Such an antenna only works well with a good grounding; ours is on top of a 20m high building, the upper part of which is all metal.
