Varactor-tuned coupled-line oscillatory system

Expressions are obtained for the analysis of a varactor-tuned coupled-line microwave oscillatory system. The method makes it possible to choose the geometry of the lines in such a manner as to obtain maximum tuning with minimum capacitance-overlap of the varactor. As an example, calculations are presented for an oscillatory system based on coupled asymmetric striplines, with frequency being tuned in the 1.27-1.59 GHz range for a tuning band of 22.5%.