I have been playing with dual channel SDR for a few years. But in 2020 diversity reception took a major leap forwards with RSPduo and phased array.
What a wonderful year. In August, I obtained use of an SDRplay RSPduo dual channel receiver. Its companion software enables the use to phase two channels, each with its own antenna, against each other. My first experiments proved that the RSPduo can be used to null local RFI as well as the ANC-4.
But my real leap forwards came in October with adding a second wideband loop to form a phased array along a 30 meter baseline. My wideband loop array provides excellent beamforming and noise nulling on medium and high frequencies.
To compliment the empirical results, I explain the math behind phasing two spaced antennas, and used an Excel spreadsheet to calculate array factor and antenna patterns.
So for me, 2020 diversity reception really ended the year on a high note. Several years of imagining came together with a working system that’s probably as good as you can build on a small city lot. The RSPduo is everything I could ask for on HF, while the Afedri dual channel really shines on medium wave, including Trans-Pacific DX from Japan and Korea.
My dual loop array is oriented for east-west endfire patterns, but also provides some north-south directivity in broadside mode. I also find it really neat to change antenna patterns in software by manipulating I/Q data on the computer screen.
Year in Review 2020 Diversity Reception – End of the Road
Unfortunately, having achieved these milestones, I can’t think of any more experiments or improvements in this area of my radio hobbies. Other than just using and enjoying the system, of course.
I would encourage hams and shortwave listeners to build and experiment with wideband active loops, dual channel receivers and phased antennas. You will find these to be good low-cost investments with a high return.
You can also use an active loop array for ham radio receiving, especially on lower HF. But that will require some stringent transmit-receive switching, possibly including powering off the active antenna amplifier while transmitting with anything more than QRP.