A low-loss ultra-wide band (UWB) filter is presented, which uses miniaturized parallel coupled line along with an standard printed circuit board (PCB) technology. By analyzing even- and odd-mode impedances (in comparison with conventional parallel coupled lines) of miniaturized parallel coupled line, this structure provides tight coupling, thus, relaxing the requirements on physical dimensions width and spacing when designing broadband filters. A bandpass filter for Mode 1 (the first 3 sub-bands) in the 3.1-5 GHz band for Multi-Band Orthogonal Frequency Division Multiplexing (MB-OFDM) UWB is realized and compared with a conventional parallel coupled line filter. The experimental results show as much as 0.9 dB insertion loss improvement over the conventional counterpart.

Based on the substrate integrated waveguide (SIW) technology, a new type of varactor-tuned radial power divider has been developed with a single bias supply. The varactors are used as tuning elements and allow for a frequency agile behavior. In addition, bandwidth characteristics have been analysed with group-delay. It has been measured with a single bias supply ranging from 6 V to 12 V that the center frequency of the power divider can be adjusted from 6.6 GHz to 7.2 GHz (600 MHz, 11.5%) while maintaining a low insertion loss (< 1 dB) in the passband.