Synthesis of high-power broadside-coupled thick striplines including narrow lateral shielding

Design diagrams are presented for the direct synthesis of broadside-coupled striplines, for the most frequent case of a 3dB coupler. The diagrams are based on point-to-point numeric optimisation by a field solver. The influences of the thickness of the striplines as well as of the lateral shielding are both covered. For lateral space constraints, an optimum geometry ratio is identified, leading to narrow lateral walls. For a frequency of 100 MHz, a meandered 2*1kW coupler with copper rods as striplines within an aluminium housing has successfully been manufactured by automated milling, validating the design procedure