High Carrier Rejection for a 3.7 to 4.2 GHz BPSK Modulator

This paper presents the performances of a 3.87 GHz balanced modulator, which is used for a fourphase remodulation demodulator. This modulator uses planar technology with slotlines and microstrip lines engraved on an Epsilam-type substrate, and two beam-lead Schottky diodes. Under modulation up to 50 MHz, carrier and even harmonic rejection of better than 50 dB is obtained, with transmission losses lower than 2 dB. In direct application of this study, 2 GHz BPSK modulators have been produced.