A 10-GHz Single Sideband Modulator With 1-kHz Frequency Shift (Correspondence)

A single sideband modulator which frequency shifts a 10-GHz signal by 1 kHz and which suppresses the carrier and unwanted sideband by 65 dB and >57 dB, respectively, with respect to the wanted sideband, is described. The modulator comprises two commercially available double sideband modulators and a readily constructed high-pass filter. Using the modulator in one arm of a microwave bridge, phase shtits and changes in attenuation of <1/spl deg/ and 0.05 dB have been measured; the low modulating frequency allows audio-frequency circuitry to be used to measure the phase shift and attenuation.