BALANCED AND BALUN DIPLEXERS DESIGNED USING CENTER-GROUNDED UNIFORM-IMPEDANCE RESONATORS

摘要

A balanced diplexer and a balun diplexer, both with high isolation, are proposed in this article. First, a balanced bandpass filter (BPF) operating in GSM (with a center frequency of 1.92 GHz) and the other in WLAN (with a center frequency of 2.45 GHz) were designed using ordinary uniform-impedance resonators (UIRs) and center-grounded UIRs. Next, the two balanced BPFs were combined through two T-junctions to form a six-port balanced diplexer. Finally, a five-port balun diplexer was obtained by removing from the balanced diplexer one of the two T-junctions along with the microstrip feeding lines connected to it and by carefully adjusting the structural dimensions of the other T-junction. A satisfactory agreement is validated between simulated and measured results.