High Speed Microwave Phase Shifters Using Varactor Diodes

A reflection type microwave phase shifter is described which is similar to the units developed by Hardin, Downey, and Munushian. It employs the voltage-variable capacitance of varactor diodes as the adjustable element. The ``pill type'' diodes tune their associated circuit through a resonance to produce phase shifts of over 90°. With proper adjustment of the tuning—a simple procedure—the output amplitude is made essentially constant. The use of two series diodes mounted back-to-back permits higher power operation, although the unit is essentially a low power device.