60 GHz Down Converters for Satellite Low Noise Receivers

Since recent years, millimeter waves (MMW) are finding an increasing role in satellite communication systems. Concerning commercial application inter-orbit and inter-satellite communication at MMW, around 60 GHz and medium data rates, are very attractive because of their intrinsic immunity versus earth interference and their feasibility, with limited accomodation constraints. In this sense advanced studies are in progress in order to evaluate a possible experimental mission about a 59/64 GHz communication payload, for demonstration of ISL/IOL application. Concerning low noise receivers basically three different approaches can be identified: low noise mixers, parametric amplifiers and transistor preamplifiers. This paper on the basis of impressive results obtained on a MMW mixer, demonstrates that at present resistive diode mixers do represent a reliable and performing solution for MMW low noise receivers, whereas transistor preamplifiers (commercially available HEMT´s) still show some problems and paramps do appear difficult to implement (pump frequencies in excess of 150 GHz).