A new simple UWB ring filter with flexible band-notch characteristics

This paper proposes a novel design of a simple Ultra-Wideband (UWB) bandpass filter in microstrip technology. This design demonstrates controllable filter characteristics with respect to its passband and band-notch frequencies. The filter is constructed of a single annular ring resonator fed by two orthogonal feed lines connected by a 90° microstrip bend. The filter size, without the input/output transmission lines, does not exceed (11mm×11mm). The insertion loss of the filter is below 0.33 dB over the whole frequency band. It additionally shows a low and flat group delay response. Such proposed filter structure can be a suitable candidate for new UWB filters required for different UWB systems and applications.