Ultra-wideband bandpass filter using multilayer microstrip-slot-microstrip coupled structure

A bandpass filter that uses broadside-coupled structures and covers the ultra-wideband (UWB) frequency range (3.1-10.6 GHz) is presented. It utilizes a broadside-coupled microstrip-slot-microstrip structure with embedded low-pass filter to achieve the required UWB performance. The simulated and measured results of the proposed filter prove its UWB performance with about 0.4-dB insertion loss, more than 17-dB return loss, and less than 0.3-ns peak-to-peak deviation in the group delay across the UWB passband. The filter has a wide high cutoff band that extends beyond 20 GHz. It has a compact size with overall dimensions of 1.5 x 2.5 cm(2). (C) 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1053-1056, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.2590