Lumped Element Suspended Stripline Couplers

Recently, very compact filters have been realized in suspended stripline using a lumped element approach. In this paper, a similar approach is used to realize very small 3 dB hybrid couplers. Two examples at 1.3 GHz and 6.8 GHz are presented, resulting in relative bandwidths of 5% to 10% (at -15 dB isolation) and quite low insertion loss. For the 1.3 GHz and 6.8 GHz range, these couplers are realized in a 20 mm times 20 mm and 10 mm times 10 mm mount, respectively.