Development of a Compact Broadband Folded Hybrid Coupler on Multilayer Organic Substrate

We present the design and fabrication of a wide bandwidth folded hybrid coupler on a multilayer organic substrate. The coupler is designed with a tandem connection of two 5-sections with a coupling of 8.34 dB. We propose a novel center coupling structure that achieves tight coupling while being compatible with printed circuit board fabrication processes. The folded coupler achieves a bandwidth of 2 to 18 GHz with 42% reduction in size.