Dual-Band and Triple-Band Filtering Power Dividers Using Coupled Lines

Abstract

In this brief, new dual-band and triple-band filtering power dividers (FPDs) with sharp frequency selectivity are proposed. Firstly, the dual-band FPD is developed and mainly composed of a quarter-wavelength three-line parallel coupled line structure, five transmission lines, and a pair of short-ended parallel coupled lines. Based on this specific structure, with two extra transmission lines imported, a triple-band FPD is further attained. Multiple transmission zeros are generated successfully in the above two designs, thus leading to a sharp skirt selectivity. For the above FPD designs, only a single isolated resistor is arranged between the two side lines of three-line parallel coupled line for nice port-to-port isolation within wide passbands. For demonstration, a prototype dual-band FPD operating at 2.38 and 3.80 GHz with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.67{\lambda }\text{g}\,\,{\times }\,\,0.68{\lambda }\text{g}$ </tex-math></inline-formula> , and a triple-band FPD operating at 2.38 GHz, 3.42 GHz, and 3.91 GHz with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.66{\lambda }\text{g}\,\,{\times }\,\,0.68{\lambda }\text{g}$ </tex-math></inline-formula> are designed, fabricated, and tested, respectively.