A Compact Frequency- and Power-Dividing Ratio-Tunable Quadrature Coupler

This paper presents a compact quadrature coupler with tunable frequency and power-dividing ratio. Wide ratio are achieved by using the novel unit instead of transmission line sections in traditional varactor-based coupler. Closed-form equations derived for design parameters. For verification, is designed based on given parameters, which demonstrate 2.0 GHz to 6.0 -20 dB 7.2 at 3 GHz. Finally, microstrip fabricated measured. The measurements agree well simulations. Under frequency-tunable state, measured 3-dB working this can be continuously adjusted from 4.7 And during adjustment process, return loss isolation always >15 dB. In ratio-tunable range -14 Moreover, maintained >20