IN3LBQ on the Hühnerspiel (Amthorspitze) - photo by IN3OTD

6 dB hybrid coupler with a FT-23-43 core

Under construction...

This is a hybrid coupler similar to the design presented in the ARRL handbook; only I did not have an FT-23-77 core as recommended in my junkbox, so I used an FT-23-43 with more turns (15 turns instead of 10, as recommended for the 77 material), to keep at least the low-frequency response unchanged.
No pretty PCB was built, I just jury-rigged some right-angle SMA together...

6 dB hybrid coupler with FT-23-43 core

I have measured the coupler S-parameters on a multiport network analyzer:

6 dB hybrid coupler with FT-23-43 core measured S parameters

Its performances are not bad, works well until about 400 MHz.

This is the hybrid coupler directivity:

6 dB hybrid coupler with FT-23-43 core measured directivity