Multilayer Multi-Section Broadband LTCC Stripline Directional Couplers

Multi-section multi-layer LTCC stripline couplers are designed. The use of reentrant cross section helps achieve precise design values of coupling otherwise restricted by limitations posed by the LTCC technology. Interconnection of different sections of the coupler by a stepped stripline transition between different layers of the structure is shown to enable the realization of broad band coupling performance. The cascading of wideband 8.33 dB couplers enables the realization of tight coupling over a very wide fractional bandwidth.