Miniaturization and harmonic suppression branch-line coupler using short-circuit anti-coupled line

In this article, short-circuit anti-coupled lines structure is applied to design a miniaturised microstrip branch-line hybrid coupler. The proposed structures can achieve both a significant reduction of size and harmonic suppression. As the short-circuit anti-coupled lines structure is constructed entirely from microstrip lines, the couplers can be easily fabricated using conventional printed-circuit board process. The performance of the proposed couplers is as good as that of the conventional structures and deep harmonic suppression in addition. The design and simulation have been performed using full-wave analysis based on ADS Momentum.