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The article highlights the development of various ultrawideband (UWB) filter types in the U.S. It states that the multiple-mode resonator (MMR) structures and three-line microstrip structures, which has a good passband frequency performance, are widely adopted as an effective form of wideband filter. It notes that the proposed UWB bandpass filters (BPF) can achieve a wide passband, while providing a narrow notch band.

A new microstrip open loop resonator bandpass filter (BPF) for wireless local area networks (WLAN) with a wide stopband response is presented in this article. The BPF consists of a pair of A12 open loop resonators and two additional resonators operating at the center frequency of 2.44 GHz. The novel resonator consisting of asymmetrical spurlines and quarter-wavelength open-circuited stubs are used at the input and output (I/O) feed lines to improve the stopband characteristics. The current distribution is demonstrated and analyzed. For the out of band spurious response suppression, its stopband attenuation loss is better than 20 dB from 2.6 to 10 GHz, and its insertion loss is as low as 1.05 dB. Good agreement is achieved between simulated and measured results. [ABSTRACT FROM AUTHOR]

The article focuses on a study which found that the use of defected-ground-structure (DGS) cells results in a low-pass filter (LPF) that reduces passband insertion loss and are more compact compared to conventional DGS-based lowpass filters. It states that DGS cells are effective building blocks for high-performance and high-frequency filters. Furthermore, the LPF are necessary components in the modern communications systems.

The article focuses on the retrodirective arrays that fits the compact designs. The detrodirective arrays represent a form of antenna array, which is capable of traits such as self-beam tracking, high reaction speed, and low cost. The antenna configurations are suited for a variety of different applications in radar, satellite-communications and wireless communications in radio-frequency-identification (RFID) products.