Optimization of Microwave Receivers for Supression of Single Tone Spurious Interference

single-Tone Spurious (STS interference including the receiver image frequency are one of the principal causes of disturbances in Microwave (MW) Radio systems due to their high probability of occurance. This paper presents an analysis of STS effects generated because of the non-linear characteristics of the system receiver (Rx) front end frequency converter stages. The analysis results enable the development of a new semi empirical computation method. Using this method, we obtain a list of forbidden STS spot frequencies and their estimated power level for each non saturated Rx system operating channel. These results are very useful for optimizing the MW Rx front end stages to reduce significantly harmful STS interference effects below interference threshold. A modified UHF/FM/FSK radio communication system, including two frequency converter stages, is used as an example of the method´s validity for improving the MW system´s performances. A comparison between the results of the proposed STS computation program and measurements on engineering models allowed improvements of the proposed computation method and optimization of non saturated MW Rx.