Compact tunable crossover with wide tuning range using coupled lines

A compact design of tunable crossover with a wide tuning range is presented. The proposed crossover structure is based on a two-section coupler interconnected with two varactors to achieve tuning frequency range from 0.6 GHz to 1.4 GHz. The overall size of the crossover is 0.12λg ×0.02λg (λg is the guided wavelength at working frequency), which is much more compact than previous counterparts. An excellent return loss (more than 20 dB), insertion loss (less than 1 dB) and isolation (more than 15 dB) of the proposed crossover are verified by EM simulations.