Qinfen Xu

A compact filtering Wilkinson power divider with harmonic suppression based on lumped components is presented in this paper. The new divider uses two 5th-order elliptic-function low-pass filters to replace the quarter wavelength microstrip lines of the conventional Wilkinson power divider. The structure combines the power divider and the filter into a complete device. By integrating elliptic low-pass filters with the power divider, the proposed structure can suppress harmonics due to the filter’s band-notched characteristic. The power divider demonstrates a measured suppression of 37.1 dB for the second harmonic, 36.6 dB for the third harmonic, 38.6 dB for the fourth harmonic respectively. The harmonic suppression is higher than 20 dB from 2.75 to 7.035 GHz. Furthermore, lumped components are utilized to achieve improvement on size reduction. Compared with the conventional divider, the proposed structure effectively reduces the size by 77 %. The insertion loss is 3.2 dB at the center frequency (1.45GHz).

A novel miniaturised dual‐band bandpass filter (BPF) using improved split ring λ /4 resonator and stepped impedance resonator (SIR) is proposed. A simple analysis is given for each resonator. By tuning the geometric parameters of the resonators, the two passbands of the BPF can be adjusted separately. Source‐load coupling is adopted to achieve more transmission zeros in the stopband. The new dual‐band BPF, which has a miniature circuit size of 0.18 × 0.18 λg , presents narrow and sharp passband characteristics. Good agreement is found between simulated and measured results, which verify the high‐frequency selectivity.

A novel dual‐band Wilkinson power divider (WPD) is designed for the purpose of operating at two arbitrary frequencies. The theory and design procedure of the novel component are presented in detail. For demonstration, a dual‐band WPD with operating frequencies of 1.0 and 2.6 GHz is proposed, fabricated and tested. The good agreement between the measured and simulated results confirmed the design concept. Measurements show that insert losses both at the two central frequencies are less than 3.3 dB. Both return loss and port isolation have good performances, which are more than 21 and 28 dB separately.