Ultracompact microstrip dual‐ and triple‐band bandpass filters with a common resonator feeding structure

Abstract

Microstrip dual-and triple-band bandpass filters (BPFs) exhibiting an ultracompact size and high frequency selectivity are proposed in this study. A common resonator feeding technique is proposed and was applied to design the multiband BPFs. In the design, the first and last resonators are realised using stepped-impedance resonators and are used to form a passband that has lower operating frequencies than the passband(s) of other resonator(s). Moreover, the first and last resonators serve as the input-output feeding structure and provide a source-load coupling for the passband(s) operating at higher frequencies. Thus, finite transmission zeros can be formed over the stopband. Hence, size miniaturisation and high frequency selectivity can be achieved simultaneously. The higher operating passband(s) is (are) formed by the dual-mode stub-loaded resonator(s) to reduce the number of resonators and the overall size of a filter. To verify the design approach, a dual-band BPF centred at 1.3 and 2.58 GHz with an ultracompact circuit size of 0.048 λ g × 0.088 λ g (λ g : guided wavelength at the central frequency of the lower passband) and a triple-band BPF centred at 1.24, 2.5, and 3.5 GHz with an ultracompact circuit size of 0.15 λ g × 0.12 λ g were designed and fabricated. The measurement and electromagnetic simulation results were in good agreement.

Compact Tri-band Bandpass Filter Based on Asymmetric Step Impedance Resonators for WiMAX and RFID Systems

“…Moreover, the space, S 1 , should be minimal for achieving a lower insertion loss. Table 1 summarizes the comparison of the proposed triple-band BPF with other state-of-the-art filters in the literature, proving that the presented filter has a low insertion loss, wide bandwidth, and compact size as well as the potential to be utilized in WiMAX, RFID, and other tri-band applications [10][11][12][13][14][15][16][17][18][20][21][22].…”

“…The presented filter had serious issues regarding FBW, circuit size, poor isolation between the passbands as well as insertion losses, especially for the first and third passbands, which were greater than 3 dB. To overcome this size problem and make the filter suitable for compact wireless transceivers, in [13], a high-selectivity dualand tri-band filter was designed and implemented on Roger's substrate material using a common resonator feeding technique. However, while the presented filter had good passband insertion loss, it also had lower FBW, and its size could still be upgraded.…”

Investigation of external quality factor and coupling coefficient for a novel SIR based microstrip tri-band bandpass filter

“…The presented filter has a serious issue in FBW, circuit size, poor isolation between the passbands as well as insertion losses especially for the first and third passbands which is greater than -3dB. To overcome the size problem and make the filter suitable for compact wireless transceivers, a high selectivity dual and tri-band filter in [ 21 ], is designed and implemented on Rogers substrate material using a common resonator feeding technique. The presented filter has good passband insertion loss however, FBW and circuit size need to be upgraded.…”

Dual‐to‐quad‐band evanescent‐mode substrate‐integrated waveguide band‐pass filters

“…The challenges are mainly reported in multi-band BPFs designed by the 3D waveguide and/or substrate-integrated waveguide (SIW) structures in comparison to those of the planar structures [1][2][3][4][5][6]. Dual, triple, and quadruple BPFs have recently been designed and proposed based on planar structures [7][8][9]. While the planar structures demonstrate miniaturised multi-band BPFs, they suffer from high insertion loss for 5G systems operating at higher frequencies.…”