Search

Half-mode substrate integrated waveguide (HMSIW) switchable unit, built by HMSIW section with loaded single or multi-microstrip shunt stub(s), was proposed in this work. Both shorted and opened stubs were studied, investigated and compared, bandwidth enhancement method for proposed switchable units was proposed and demonstrated. Based on these switchable units, narrowband and broadband HMSIW single-pole-single-through (SPST) switches, SIW SPST switch and SIW/HMSIW-based single-pole-double-through (SPDT) switch were designed, fabricated and measured. Good performances were observed experimentally for these proposed circuits, showing the advantages of proposed concept and an excellent candidate for switchable or reconfigurable SIW/HMSIW circuits or systems. [ABSTRACT FROM AUTHOR]

A novel dual-wideband bandpass filter with controllable bandwidths is presented in this article. Two passbands for the WLAN band are realised based on a multimode resonator with three open stubs. The bandwidth of the two-order passbands with even or odd mode can be adjusted by appropriately selecting the characteristic impedance of the multimode resonator. A planar microstrip dual-wideband bandpass filter prototype with a 3-dB fractional bandwidth of 16.7% and 9.2% is designed and fabricated. High selectivity and good in-band performance can be achieved in the dual-wideband bandpass filter. [ABSTRACT FROM AUTHOR]

This article presents a compact microstrip dual-band bandstop filter (BSF), in which one λg/4 defected ground structure (DGS) pair is utilised to realise one stopband while two stepped impedance resonators (SIRs) help obtain another stopband and suppress the spurious harmonics. The design strategies and the equivalent circuits are introduced in detail. The measured results indicate 43.8% and 18.7% fractional bandwidth in the two stopbands (2.4 GHZ and 5.2 GHz) respectively, and the return loss is greater than 15 dB in the whole passband. In addition, size reduction can be conveniently achieved by adjusting the length of the SIRs and DGS. [ABSTRACT FROM AUTHOR]

Two high selectivity wideband filtering crossovers using stub-loaded ring resonators are proposed in this paper. Cascaded coupled lines and open stubs are used to generate two/four transmission zeros each near the crossover passbands. In addition, patterned grounded conductor in the ground plane can enlarge the coupling coefficient for the coupled lines with increasing the even-mode characteristic impedance, and the isolated conductor placed inside the slot can decrease the odd-mode characteristic impedance. Two filtering crossovers operated at 2.2 GHz with bandwidths of 27.5% from 1.945 to 2.55 GHz are designed and fabricated. They show good return loss more than 20 dB and nice insertion loss less than 1.7 dB in passband. [ABSTRACT FROM PUBLISHER]

Two novel second-order dual-band bandpass filters (BPFs) with high isolation and high selectivity using coupled lines are realised with a T-shaped bandstop structure. The centre frequencies of the two dual-band BPFs can be adjusted to the desired values by changing the coupling coefficients and characteristic impedances of the two transmission paths. Two dual-band BPFs located at 1.87 and 2.53 GHz and 1.9 and 2.42 GHz are designed and fabricated for demonstration. Good agreements can be observed between simulated and measured performances. [ABSTRACT FROM PUBLISHER]

A low-loss tunable tri-pole band-pass filter is presented in this study. To achieve tri-pole response, the tri-mode crossed resonator is adopted in the design. Resonant property is analyzed based on the transmission line theory. Analysis reveals that the first three resonant frequencies and two inherent transmission zeros (TZs) of the proposed resonator can be tuned by the suitable loading capacitances. To decrease the passband insertion loss, the varactor diodes and dc block capacitors are in series connected between the feeds and resonator. Furthermore, to achieve high skirt selectivity, source-load coupling is also introduced to create a TZ near the lower edge of the passband. A demonstration tunable tri-pole filter is designed, fabricated, and measured. The measured results show that the new filter has the wide passband frequency tuning range of 33.3%, low insertion loss of less than 1.6 dB, and high selectivity. [ABSTRACT FROM AUTHOR]

A compact tri-band bandpass filter using input/output cross coupling is proposed. Three passbands can be adjusted by changing the characteristic impedance of the T-shaped structure with a shorted stub. The three passbands are designed to operate at 1.85, 3.5 and 5.2 GHz based on the T-shaped structure. Four transmission zeros are used to realise high selectivity for the passbands. Good agreement can be observed between the measured and simulated results. [ABSTRACT FROM AUTHOR]

This study presents an low-temperature cofired ceramic (LTCC) V-band cross-coupled band-pass filter using substrate-integrated waveguide cavities. Two antisymmetric U-shaped slots connected by via is proposed to construct the negative coupling structure, which is simple and especially useful for 60 GHz applications. Moreover, the U-slot structure possesses a wide range of realizable coupling coefficients from −0.008 to −0.075. An experimental LTCC fourth-order filter was fabricated for demonstration, achieving a bandwidth of 12% (7.2 GHz) at 59.6 GHz with superior frequency selectivity. [ABSTRACT FROM AUTHOR]

Two novel wideband balanced networks with wideband common mode suppression and arbitrary power-dividing ratio are proposed in this paper. The differential/common mode equivalent circuits of the balanced networks can be easily reduced based on the matrix transformation. Microstrip-slotline 180° phase inverters loaded with four isolation resistors are used to realize high isolation for the power division output ports. Two planar wideband equal and unequal power division balanced networks with bandwidths of 33% of (1:1, equal) and 39% (1:2.22, unequal) for the differential mode and over 120% common mode suppression (0.96–3.6 GHz, |Scc21, 31| < –10 dB) are designed and fabricated. [ABSTRACT FROM AUTHOR]