I thought I would take a step back today and review my diversity reception investment. Along the way, I will try to answer the question “is it worth it”?
Short answer is yes, depending on your goals. My goals were to reduce interference and improve radio reception across medium and high frequencies from an ordinary suburban location. As described previously, my design consisted of switched wideband active loop antennas and a dual channel coherent receiver.
After experimenting with various loop amplifier designs, I settled on the commercial AAA-1C unit from LZ1AQ in Bulgaria. His wonderful design lets you switch between various active loop and dipole configurations remotely. You can see the control units above left, complete with power and configuration switching. On the right, you can see two loops in orthogonal (90º) configuration, with the amplifier in the small white box. Two of these are positioned E-W along my fence, 100 feet apart.
For dual channel receivers, I can select either the SDRplay RSPduo or Afedri SDR-Net. Overall, the RSPduo performs best on HF, while the AFE-822x is a charm on medium wave. Both provide diversity tuning by adjusting the amplitude and phase of each channel.
My support structures are all 3D printed plastic which I have described in other posts previously. Even without a 3D printer, you can find a variety of ways to mount these antennas and controls. My loops are made from aluminum core PEX, but you could use copper or aluminum just as easily.
Performance? Well, reducing RFI from noisy neighbors works great. You will also be surprised by how well wideband active loops compare to traditional antennas that you can fit onto a city lot. Wideband antennas and wideband receivers work together very well, as long as you can manage the gain and prevent local AM overload.
Diversity Reception Investment By The Numbers
So, how much would you need to spend on a diversity reception investment? My suggestion is around US$600 if you are starting from scratch.
A pair of AAA-1C active antenna amplifiers, plus loop materials like aluminum core PEX, will run you around US$300. These are fairly easy to assemble and mount. You can get a dual channel coherent receiver, like the RSPduo or Afedri for around US$300.
Over the next while, I will dig into how phased loop arrays work. This will include my empirical discoveries, analytical formulas, and perhaps even some antenna simulation.