This directional coupler is based on W1GHZ paper " High-Power_Directional_Couplers_with_Excellent_Performance.pdf ".
It is designed for measurements in the range 50-450 MHz up-to 5 kW, Design coupling is ~44 dB @ 144 MHz.
It works also well under these frequencies but, with less coupling.At 1300 MHz, poor SWR & directivity to expect.
For UHF - SHF, up-to 2.4 GHz, see W1GHZ descriptions in his paper.
SWR and Directivity are ok for amateur accurate enough power & SWR measurements.
Box dimensions are 9"x7"x2", this is a standard "BUD" aluminium box, available at Radiospares, Mouser and others.
Measurements 20-450 MHz
Measurements Low Bands
Measurements 1150-1350 MHz
Power detection calculations
For now, That's All Fox !!!!!
To arrive soon: Quadratic display calculator circuit.
Dominique - firstname.lastname@example.org OR