My first attempt failed. My second attempt to build a diversity reception antenna switch will work! Here goes.

My major project last winter as a simple SDR Receiver Matrix Switcher. I used off-the-shelf Arduino relay modules to switch antennas and receivers. Results were disappointing. My major challenges were RFI ingress and poor isolation.

So, during April, I went back to the drawing board. My new diversity reception antenna switch is now up and running in the lab. This time, I did things properly.

My new design, shown above, uses proven antenna switches and filters. I will describe these in detail shortly. I kept the Arduino relay modules, shown in orange as relay banks 1 and 2, to control the relay switches. This new system can be controlled by WIFI using NodeMCU or by USB serial using Arduino Mega.

The radio relay switches are shown in white on the left. I provide four pairs of channels. Three support my dual channel SDR receivers – RSPduo, Afedri and ANAN – which the fourth position routes antennas into my NCC-1 phaser. These switches were purchased online.

The antenna switch, shown in black, routes four antennas into two channels. My default antennas are two loops in an array. Alternatively, I can select my main ham antenna and a noise probe for reducing local RFI. My friend Jim VE6JF built this homebrew switch and it works great.

Diversity Reception Antenna Switch

Control of my AAA-1C wideband loop amplifiers (in green) is provided by relay bank 2. With this, I can switch loop patterns and modes remotely. Finally, I added in an excellent dual channel medium wave bandstop filter with remote control. I am using off the shelf filters with a DIY circuit board for switching.

Over the next few weeks, I will describe this system in detail, as well as report on results. Here’s hoping I got it right this time!