UWB Bandpass Filter Using Cascaded Miniature High-Pass and Low-Pass Filters With Multilayer Liquid Crystal Polymer Technology

Abstract

This paper presents a new ultra-wideband (UWB) bandpass filter that is formed by cascading miniature high-pass and low-pass filters implemented with multilayer liquid crystal polymer technology. The miniature high-pass and low-pass filters can be designed independently and the design procedures are described. Experiments are carried out to validate the designs. Small sizes for the fabricated high-pass filter, low-pass filter, and UWB bandpass filter are achieved, which are 4.0 mm × 4.4 mm (0.162 ¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> × 0.178 ¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ), 4.56 mm × 4.9 mm (0.185 ¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> × 0.198 ¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ) and 5.1 mm × 8.86 mm (0.207 ¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> X 0.359 ¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> ), respectively, where ¿ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</sub> is the guided wavelength at 6.85 GHz. Excellent performance is obtained for all the measured filters, including low insertion losses and high selectivity. Due to its simple structure and excellent performance, the proposed UWB bandpass filter is favorable for practical UWB communication and radar systems.