Abstract: A phase shifter/modulator which provides linear phase control of a microwave continuous wave carrier signal. Linear phase shift range in excess of 360 degrees is provided as a result of linear variation in control voltage. A reference signal, at a subharmonic of the output carrier signal frequency, is injected into a highly linear fractional range reflection type phase shifter. This fractional phase modulated signal is input to a field effect transistor (FET) based frequency/phase multiplier. The frequency/phase multiplier translates the subharmonic reference signal to the desired output carrier frequency with the full 360 degree phase shift range imposed on the output carrier signal.

Abstract: A direct QAM modulator for generating a high power QAM modulated signal at microwave frequencies comprises a hybrid to create the required RF signals for I and Q paths. In each path, a rat-race coupler is used to get the in phase and out of phase RF signal. The subsequent circuit blocks in each path consist of a single pole double throw switch (SPDT) switched by the polarity of the incoming data, a reflection attenuator, implemented by using forward biased pin diode terminations and controlled by the absolute values of the baseband pulse amplitude modulation (PAM) signal, and a variable reflection phase shifter to adjust for the phase error. To realize modulated signal filtering and to compensate for the nonlinearities, a combined prefiltering and predistortion block is used to shape the baseband PAM signal in each path. Finally, a power combiner is used to combine signals from the two paths into one high power QAM modulated and filtered output signal at microwave frequency.

Abstract: A Gaussian Minimum Shift Keying modulator that provides direct modulation of a carrier signal, produced by a single microwave high power voltage controlled oscillator. A continuous phase frequency shift keyed modulated signal with a modulation index of 0.5 is produced at the desired output frequency using a full 360 degree linear continuous phase modulator, controlled by a linear baseband signal that is the integral of the binary baseband information signal. This modulated signal is used as the reference signal for a phase locked high power voltage controlled oscillator. The phase locked loop provides frequency tracking and Gaussian spectral shaping to the modulated output signal.