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Two Channel Antenna Switch in 2022

two channel antenna switch

My big build project during 2022 was a two channel antenna switch, to control my wideband loop array and switch between multiple diversity receivers.

After a couple of years using a patch bay, I decided to explore remote controlled relay switching for my loop array. You can see the final product, mounted on a sheet to plywood, above. My project progressed in  two phases.

First, I ordered some Sainsmart relay modules designed for Arduino control. As described previously, I just wired up these relays to switch radio signals. My rough approach worked but with two problems. One was limited port isolation. Second, and the real killer, was tons of RFI introduced into the signal chain.

The culprit was the Arduino and its USB connection to the computer. So, during May-June, I took an entirely different approach.

I ordered some real antenna relay boards from E-bay, shown above left. And I switched to wireless remote control using a NodeMCU with I2C breakout boards, shown above center. My second phase approach works really well. No more RFI and pretty good (50 dB) port isolation.

I wrote a small Windows program to remote control the ESP8266 WIFI switch. Now I can just click to switch the two wideband loops between four receiver configurations. If you read my articles, you can see that building this system is pretty easy. You might try it out.

Two Channel Antenna Switch – Phase 3 Coming in 2023

Recently, I ordered a sixteen channel relay board with built-in ESP8266 WIFI control. Cost me around US $50. Because the relays, NodeMCU and I2C breakout are all on the same PCB, I will be able to get rid of more than half of my discrete wiring. Also, I picked up another antenna relay board, which will let me switch between a loop and my ham antennas on one of the channels.

My intention is to build this third version in January-February, and I will report back on its performance.

FYI, my Arduino code is written and debugged in Visual Studio with Visual Micro. And, my Windows code as always comes from RAD Studio Delphi community edition.

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