A novel compact Wilkinson power divider with controllable harmonic suppression and simple structure

In this paper, based on the equivalent circuit of spiral-shaped CPW resonators, a novel compact cascaded inhomogeneous coupled-line (CIHCL) with two tunable transmission zeros is proposed to replace the quarter-wavelength microstrip line of the conventional power divider (CPD). The modified power divider with CIHCL could achieve the same frequency responses of CPD and also realize controllable harmonic suppression with compact size. To verify the expected results, two power dividers with different harmonic suppression ratios are designed and one of them is fabricated to demonstrate the performances of the proposed power divider. The simulated and measured results illustrate that the return loss and isolation at center frequency 3GHz are better than 25dB and the insert loss is better than 0.4dB. In addition, about 30dB suppression for second and third harmonic is achieved.