Abstract
In this paper, a series of novel reconfigurable-bandwidth notched-wideband bandpass filters (NWB BPFs) with controllable notch bands are proposed. The proposed filters start from a passive filtering structure, which is formed by a terminated cross-shaped resonator (TCSR) with a pair of parallel-coupled lines and two open-ended stubs. Theoretical analysis finds that the filter bandwidth can be independently controlled by the TCSR, while the center frequencies and bandwidth of notch bands are mainly controlled by the rest parts. According to this, a BPF with controllable notch bands can be designed. To achieve the reconfigurable-bandwidth NWB BPFs with controllable notch band, whose bandwidth and center frequency can be maintained unchanged under different work states, two PIN diodes and a varactor are employed. By controlling the work states of PIN diodes, three bandwidth states can be achieved with fixed center frequency. By controlling the applied voltage on the varactor, other NWB BPF with independently tunable lower passband edge can be realized. For verification, three prototypes are designed and measured. The measured results agree well with the theoretical analysis and simulated ones, verifying a simple and effective design approach of reconfigurable-bandwidth NWB BPFs.
Highlights
Because of the desired properties, i.e., low cost and profile, compact size, and easy integration with other devices, the microstrip filters have been extensively used in the wireless communications systems, such as, 4G, WiFi, and sensing radars
Some reconfigurablebandwidth Notched-wideband bandpass filter (NWB bandpass filters (BPFs)) with controllable notch band, whose bandwidth and center frequency are fixed under different work states, can be realized by inserting two PIN diodes and a varactor into terminated cross-shaped resonator (TCSR)
To the best knowledge of authors, such reconfigurable-bandwidth BPFs with controllable notch band, whose center frequency and bandwidth are fixed under different work states, have never been reported before
Summary
Because of the desired properties, i.e., low cost and profile, compact size, and easy integration with other devices, the microstrip filters have been extensively used in the wireless communications systems, such as, 4G, WiFi, and sensing radars. In the high data-rate and multi-standard remote-sensing and telecommunication systems, notched-wideband (NWB) BPFs with good filtering responses are urgently needed to eliminate the unexpected in-band interference Such filters have been designed by different techniques, which can be classified into four main categories: 1) the introduction of additional notch resonators [13] – [15]; 2) asymmetrical coupled fed lines [16], [17]; 3) embedded open stubs [18], [19]; 4) intrinsic zeros of multi-mode resonators (MMRs) [20], [21]. Some reconfigurablebandwidth NWB BPFs with controllable notch band, whose bandwidth and center frequency are fixed under different work states, can be realized by inserting two PIN diodes and a varactor into TCSR. To the best knowledge of authors, such reconfigurable-bandwidth BPFs with controllable notch band, whose center frequency and bandwidth are fixed under different work states, have never been reported before.
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