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Complex Antenna Controller with Relays

complex antenna controller

I have a new project using Arduino relays. It’s a complex antenna controller for my diversity receive system.

For a few years, I have been using a patch bay and BNC jumper cables to switch antennas into my diversity (dual channel) receivers. My patch bay works fine, although a bit clumsy. I have long thought about building a matrix switcher as a station improvement.

And now, with the purchase of some Arduino controlled relay modules, I am doing just that.

My main module will be an relay-based antenna switch, shown as (1) above. This will route antenna connections as channel pairs. My wideband loop antennas (A1 and A2) will be routed to any one of four dual channel receivers (R1 to R4). In addition to the loops, the switch will also route my main ham antennas and noise probes.

This antenna switch will use an 8-relay module at the output and 2 relays at the input side. In addition, I will be able to switch in a pair of Distill Broadcast AM rejection filters at (2.) This will probably require a custom PCB for relay and SMA connectors.

Finally, an 8-relay module will control mode and power for my two Active Antenna Amplifier control boards at (3.) So, that’s my vision and preliminary design. Control will be done through an Arduino Mega.

Complex Antenna Controller Considerations

At this point in time, I have two performance concerns. First, how much switching isolation can I accomplish with the Arduino relay modules. As the frequencies involved are for medium and short waves, this might work out fine. Fingers crossed.

Second, will the digital clock and switching in the Arduino introduce RFI into the system. I am hoping the opto-isolators on the relay boards will help keep Arduino hash at a distance.

Anyway, since I already have the parts, I will just build the thing and try to solve issues as I go along. If this works out, I will have a complete antenna routing solution for my diversity receiver system overall.


  1. Alan says:

    Sounds like a good plan.
    I’m also about to build something similar to switch the antenna ports on my IC-9700 to different antennas and to switch the SP DUO sdr on HF, although the latter may be a separate unit.

    Have you considered using ex military 28V relays, which the Arduino should switch easily?
    I bought a buck converter to run mine from the 12V shack supply – fortunately no RFI from it.
    The relays have SMA connectors and are good for 200W up to 3GHz, so should be OK for 23cms and down.

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