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Comparing Shortwave Antennas With RTL-SDR And Python

Measuring the efficiency of antennas in absolute phrases that may contain numerous pricey apparatus and specialised amenities. For sensible packages, particularly when development antennas, evaluating efficiency in relative phrases is simpler. Using reasonable RTL-SDR dongles and Python, [Eric Urban] used to be in a position to examine the efficiency of two shortwave/HF antennas, and documented all the procedure.

The two antennas in query used to be a unmarried band inverted-L and smaller broadband T3FD antenna. [Eric] first amassed efficiency knowledge for each and every over few days, hooked up to split PCs with RTL-SDRs by means of low-pass filters. These had been set as much as obtain FT8 transmissions, a well-liked virtual ham radio mode, which allowed [Eric] to automate knowledge assortment utterly. GQRX, a instrument receiver, transformed the alerts to audio, which used to be then piped into WSJT-X for demodulation.

Data for each and every won FT8 transmission used to be recorded to a log document. [Eric] additionally changed GQRX and WSJT-X to provide him all of the far off regulate options he had to mechanically trade frequencies. Between the two antenna setups, greater than 100,000 FT8 transmissions had been logged. Using the recorded knowledge and Python he when compared the choice of won transmissions, the gap, and the heading to the transmitters, the usage of the site data integrated in lots of FT8 transmissions. Where the similar transmission used to be won via each antennas, the signal-to-noise ratios used to be when compared.

From all this knowledge, [Eric] used to be in a position to be told that the inverted-L antenna carried out higher than the T3FD antenna on three of the four frequency bands that had been examined. He additionally found out that the inverted-L looked to be “deaf” in one specific path. Although the exams weren’t best possible, it’s spectacular how a lot sensible knowledge [Eric] used to be in a position to collect with cheap {hardware}.

Some different DIY antennas we coated just lately come with a hybrid helical for the usage of a geosynchronous ham radio repeater, an off-center dipole, and a directional antenna created from coat hangers.  So move forth and try to tame the black magic of RF!