Slow-Wave Half-Mode Substrate Integrated Waveguide 3-dB Wilkinson Power Divider/Combiner Incorporating Nonperiodic Patterning

A half-mode substrate integrated waveguide (HMSIW) with developed microstrip polyline unit cells etched on the waveguide surface is investigated in this letter. Modified analysis of the effective electrical parameters analysis is proposed. By applying the modified retrieval method, effective permittivity and permeability are extracted accurately to further describe the influence of the proposed structure, as well as slow-wave effect. Then, a compact 3-dB Wilkinson power divider/combiner based on polyline-patterned slow-wave HMSIW is developed for broadband microwave applications. The prototype achieves a fractional bandwidth of 91.7%, with the amplitude and phase variations less than 0.5 dB and ±4°, respectively. Compared with some reported SIW and HMSIW power divider, this letter achieves a size reduction of 40% and a bandwidth enlargement over 50%, illustrating its suitability for practical broadband applications.