Ham Radio Maker

Wednesday, 03 April 2019 19:00

Building an EU1KY Antenna Analyzer Featured

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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 Digikey.com 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.

OSL

Afterwards, I built a 2 meter ground plane antenna. 

2m Antenna
2 meter ground plane antenna

Measurment

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 arrl.net address (callsign ke0rje).

Read 6025 times Last modified on Monday, 23 August 2021 23:19
Ron

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