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If you are
interested in the theory, you want Michael Ellis's page and his software
Description of software: http://michaelgellis.tripod.com/rfcoupler.html
Actual Software http://michaelgellis.tripod.com/zip/dcwin.zip
Note: for some reason the link above does not yield a download but an error about not available.
Copy the link and past into the URL line on your browser and the download works !
Some Supplementary spreadsheets that I used
If all you want is a simple circuit, Kits & Parts still sells their kit SWR Bridge Kit
Alex Directional Coupler for Hermes-Lite 2 and other applications
The Circuit below
provides a buffered low impedance output
See below for analysis file and spreadsheet
Alex Directional Coupler for HL2 - Others
Documentation Alex Directional Coupler HL2 Others.pdf
Link to OSH Park - 3@ $9.45 https://oshpark.com/shared_projects/IUwvbBNs
Analysis of the Alex power sensing circuit and expected output vs input power
and the spreadsheet for the calculations
New Directional Coupler For Test, Watt meter, Pure Signal etc.
This is a revised version of the original design below using SMT parts.
The circuit below assumes a 100 Watt transmitter and the use of the Dual AD8307 board
found on my RF_Power_Meter page to make a SWR Power meter.
Documentation New Directional Coupler.pdf
Gerbers New_DC_ 07032019.zip
Link to OSH Park - 3@ $6.80 https://oshpark.com/shared_projects/IrUiSZL7
Low Power Directional Coupler
This was made to work with my dual AD8307 board or an AD8302 Module like this ebay part.
The Dual AD8307 info can be found on my RF_Power_Meter page.
Schematic Directional Coupler and Detector.pdf
Gerbers AA Directional Coupler_03162018.zip There are no OSH Park link for this board.
Original Directional Coupler Design
I originally up this board to be a piece of test equipment to be used with the
RF_Power_Meter, but it is also useable for Pure Signal
Later found out it is very similar to the Elcraft CP-1 Coupler.
If you are interested in the theory you want Michael Ellis's page and his Excel spreadsheet
Note that the turns ratios are independent of power levels.
The core size, spacing and insulation determine the max power level.
For higher power a larger PCB and cores would be necessary.
Link to OSH Park: https://oshpark.com/shared_projects/9u4trI7X
NOTE: The link to OSH Park also allow ordering PCBs