A 30 GHz Low Noise Down Converter

A report will be given of the development of a single ended low noise down converter to convert a signal of 1 GHz bandwidth in the range of 27.55 - 28.55 GHz to an intermediate frequency of 1 - 2 GHz. The mixer, realized in waveguide form, consists of a directional filter to combine LO and signal power and a diode mount. The latter contains the mounting assembly and the matching elements of the diode. Matching is achieved by a stepped impedance transformer at the RF-input and transforming low pass filter at the IF-output. With this mixer a conversion loss of L ¿ 5 dB is attainable; this figure then is compared with theoretical predictions.