How directional couplers work and how to specify one — coupling factor, directivity and why directivity is the parameter that actually limits you, the difference between isolation and directivity, coupled-line and branch-line and hybrid types, and the VSWR-measurement and digital-pre-distortion applications that depend on them.
Posts by alex.novickis@gmail.com
Antennas: Gain, Aperture, and Why the Ground Plane Is Part of the Radiator
How antennas are specified and designed — directivity, efficiency and gain, the Friis link budget, effective aperture and why millimetre-wave systems need arrays, near versus far field, the common PCB antenna types, why the ground plane and enclosure are part of the antenna, and how to measure one honestly.
The Smith Chart: How to Read It, and Why It Still Matters
A practical guide to the Smith chart — the conformal map behind it, how to read constant-resistance circles and constant-reactance arcs, the landmark points, how series and shunt components move you around it, VSWR and constant-Q circles, and why a chart from 1939 is still the fastest way to think about matching.