Building an EU1KY Antenna Analyzer

So I got my Technician license April 2018 and wanted to get started in the amateur radio 2M band. Knowing that I would want to make a good antenna, I figured that I would need an antenna analyzer. I looked at the costs of analyzers on the market and decided to DIY. That’s when I found the EU1KY.

Assembled EU1KY Antenna Analyzer
My assembled EU1KY Antenna Analyzer

I assembled the analyzer using the required instructions for the EU1KY open source project (EU1KY wiki page) after ordering boards for the RF unit (I have extra boards for sale on my Ebay Site).

Under the hood
Under the hood

Note: The RF front end board mounts onto an
STM32F746G-DISCO Development Board (available from for about $60). Under the connectors for the RF board there are some surface mounted jumpers. The board comes with them soldered onto SB3/SB5. Move them to SB1/SB4 and then check them for continuity. Check that SB3/SB5 are non-continuous.

Jumpers on stm32f7-discovery board
Move jumpers on stm32f7-discovery board

Connect I, V and Gnd from RF board to blue audio on Discovery board like this.

For calibration, an Open/Short/Load (OSL) test kit is needed. I built mine from some spare SMA PCB board components. The 50 Ohm load has two 100 Ohm resistors in parallel and can be made more attractive by using 0805 SMD resistors. You could even do three 150 Ohm resistors in parallel to achieve the 50 Ohm target value.


Afterwards, I built a 2 meter ground plane antenna. 

2m Antenna
2 meter ground plane antenna


Used analyzer to scan 144Mhz – 148 Mhz …

The results:

S11 Graph
S11 graph
SWR graph
SWR graph

I welcome any discussion on this project. Just add comments below or email me at my address (callsign ke0rje).

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5 Responses to Building an EU1KY Antenna Analyzer

  1. Ron KE0RJE says:

    If you visited me at the Mid-winter Madness Hamfest in Buffalo, MN today, I wanted to thank you for letting me showcase the Antenna Analyzer RF board kit that I am selling. If you have any questions, please leave comments here.

  2. Ron says:

    Had a question at show if Analyzer will work with Rig Expert Antscope Android app. It does not because that requires a Bluetooth connection. May need some investigation if Can get blutooth on a ST discovery platform?

  3. Ron says:

    Also, had a question at Mid-winter Madness show about “at what frequency does it start using 3rd harmonic?” The answer is at 200Mhz. This is a configuration parameter, and when set, the unit must have Open-Short-Load (OSL) calibration re-run.

  4. Mike says:

    Thanks for looking up the crossover to 3rd harmonic thing for me.

    Do you know what is the specific reasoning for using 200? Could it be 230 for instance in order to include 222MHz in the first harmonic?

    Nice seeing you at the hamfest,

    • Ron says:

      The RF front end board uses the Si5351A I2C-PROGRAMMABLE ANY-FREQUENCY CMOS CLOCK
      GENERATOR chip and it generates frequencies from 2.5kHz to 200Mhz. I read this article and it may be possible to try getting first harmonic up to 230. Si5351A Synthesizer Where the 3rd harmonic kicks in is definable in the software.

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