Hong-Wei Deng

Compact Balanced-to-Balanced Microstrip Diplexer With High Isolation and Common-Mode Suppression

In this letter, a compact balanced-to-balanced microstrip diplexer with high isolation and common-mode (CM) suppression is proposed for wireless local area networks (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously. The proposed diplexer is designed via the combination of two balanced bandpass filters (BPF) without extra junction matching network. Both BPFs are composed of uniform impedance resonators (UIR) and short- ended microstrip parallel-coupling feedlines. Finally, the proposed diplexer is fabricated and measured. The measured differential-mode (DM) isolation in the two passbands is more than 33 dB. While for the CM signal, the insertion loss is below 30 dB in the two operation bands. The simulated and measured results exhibit a satisfactory agreement to validate the proposed configuration. The diplexer size is only 0.26λg ×0.38λg, where λg is the guided wavelength at 2.45 GHz.

COMPACT QUINTUPLE-MODE UWB BANDPASS FILTER WITH GOOD OUT-OF-BAND REJECTION

In this paper, a novel compact quintuple-mode UWB bandpass fllter (BPF) with sharp rejection skirt and wide upper- stopband performances is realized using stub-loaded multiple-mode resonator (MMR). The proposed resonator is formed by attaching two pairs of circular impedance-stepped open stubs in shunt and a pair of short-circuited stubs to high impedance microstrip line. By simply adjusting the radius of circular impedance-stepped open stubs and the lengths of short-circuited stubs, the flrst flve resonant modes of the resonator can be roughly allocated within the 3.1{10.6GHz UWB band meanwhile the high resonant modes in the upper-stopband can be suppressed. The short stubs in pairs can generate two transmission zeros near the lower and upper cut-ofi frequencies, leading to sharper rejection skirt outside the desired passband. Finally, a quintuple- mode UWB BPF is designed and fabricated, and the measured results demonstrate the feasibility of the design process.

COMPACT DUAL-MODE OPEN STUB-LOADED RESONATOR AND BPF

A compact dual-mode open stub-loaded resonator and bandpass fllter (BPF) is proposed in this paper. The resonator, which is formed by attaching a disc-shaped open stub and circular open stubs in pairs to a high impedance microstrip line, generates two operating modes in the desired band, and the even-mode resonance frequency can be ∞exibly controlled by the disc-shaped open stub at central plane, whereas the odd-mode one is flxed. The four transmission zeros are created to sharpen the rejection skirt, suppress two high harmonic resonant modes and deepen upper-stopband, respectively. Experimental results of the dual-mode fllter which incorporates this resonator with parallel-coupled feed line with tuning stub at 5.8GHz show good agreement with the simulated ones. The size for the resonator is only 4:7 £ 3:4mm (0:29‚g £ 0:21‚g in which ‚g is the guided wavelength of 50› microstrip at 5.8GHz).

Compact Wideband Bandpass Filter with Quadruple-Mode Stub-Loaded Resonator

In this letter, a novel compact wideband bandpass fllter (BPF) is proposed using quadruple-mode resonator formed by attaching a short-circuited stub at the center plane and two identical impedance-stepped open stubs to high impedance microstrip line. The resonator can generate two even-modes fm1, fm3 and two odd-modes fm2, fm4 in the desired band. The even-mode resonant frequencies can be ∞exibly controlled by the short-circuited stub, whereas the odd-mode ones are flxed. When the open stubs are attached to the center plane nearby, they can be mainly applied to adjust fm3, fm4 into desired passband as the high odd-mode and even-mode resonant frequencies are vulnerable to their electronic lengths. Two transmission zeros near the lower and upper cut-ofi frequencies are separately created by the short-circuited stub and interdigital feeding lines, leading to a high rejection skirt. A wideband BPF with the fractional bandwidth 64% is simulated, fabricated and measured. The measured results agree well with the EM simulations.

Compact band-notched UWB printed square-ring monopole antenna

A simple and compact ultra wideband (UWB) printed monopole antenna with band-notched performance is proposed in this paper. The antenna is partially grounded so that the Q value is depressed and the impedance bandwidth is broadened. A small strip bar is loaded at the centre of the square ring radiator and the impedance bandwidth of the antenna overlapped with IEEE 802.11 a is rejected consequently. The measured bandwidth of the proposed antenna occupies about 7.69 GHz covering from 3.11 GHz to 10.8 GHz with expected notched band from 5.12 GHz to 5.87 GHz. The geometry parameters of the antenna are investigated and optimized with HFSS. A quasi-omnidirectional and quasi-symmetrical radiation pattern in the whole band is also obtained. As a result, this kind of band-notched UWB antenna requires no external filters and thus greatly simplifies the system design of UWB wireless communication.

A STUB-LOADED TRIPLE-MODE SIR FOR NOVEL HIGH SELECTIVITY DUAL-WIDEBAND MICOSTRIP BPF DESIGN

In this letter, a novel high selectivity dual-wideband microstrip bandpass fllter (BPF) is proposed using two stub-loaded triple-mode stepped-impedance resonators (SIR) which are the same type but with difierent sizes. The SIR is formed by attaching one T-type open stub at the center plane and two identical short- circuited stubs symmetrically to stepped-impedance open microstrip line. And it can generate one odd mode approximatively determined by the stepped-impedance microstrip line and two even modes ∞exibly controlled by the loaded stubs. Either of the SIRs in this fllter can not only separately generate one passband but also control the passband performance. Due to the intrinsic characteristics of the SIR, four transmission zeros can be created to improve the selectivity. A dual-wideband fllter with the fractional bandwidth 14.9% for the flrst band from 3.09GHz to 3.58GHz and 10.2% for the second band from 4.99GHz to 5.53GHz is designed and fabricated. The fllter is evaluated by experiment and simulation with good agreement.

HIGH SELECTIVITY DUAL-MODE BANDPASS FILTER WITH SOURCE-LOADED COUPLING

In this letter, a novel high selectivity microstrip fllter with source-loaded coupling is proposed using the dual-mode resonator. The resonator can generate one odd mode and one even mode in the desired band. The folded stepped-impedance open stub at the central plane can control the even mode resonant frequencies, whereas the odd mode ones are flxed. A transmission zero is created near the lower cut-ofi frequency due to the main path signal counteraction. Two additional transmission zeros attributed to source-loaded coupling are generated near the upper cut-ofi frequency and in the upper-stopband. A dual- mode fllter prototype is simulated, fabricated and measured. The EM simulated and measured results are presented and excellent agreement is obtained.

NOVEL UWB BPF USING QUINTUPLE-MODE STUB- LOADED RESONATOR

In this letter, a novel compact UWB bandpass fllter (BPF) with sharp rejection skirt is realized using quintuple-mode stub-loaded resonator. The resonator can generate three odd-modes and two even-modes in the desired band. By simply adjusting the lengths of open stubs in shunt and short-circuited stubs, the flrst flve resonant modes of the resonator can be roughly allocated within the 3.1{ 10.6GHz UWB band meanwhile the sixth resonant mode in the upper- stopband can be suppressed. The pair of short stubs can generate two transmission zeros near the lower and upper cut-ofi frequencies, leading to a sharp rejection skirt. A quintuple-mode UWB BPF is designed and fabricated and the measured results demonstrate the feasibility of the design process.

Compact ultra-wideband CPW monopole antenna with dual band-notched

A simple and compact ultra-wideband CPW-fed printed monopole antenna with dual band-notched performance is presented in this paper. The proposed antenna has the bandwidth from 3.01 GHz to over 12 GHz with dual stop bands at 3.5 GHz WiMax and 5.8 GHz WLAN which are achieved by a simple circular slot and a compact coplanar waveguide resonant cell respectively. The geometry parameters of the antenna are investigated and optimized with HFSS. A quasi-omnidirectional and symmetrical radiation pattern in the whole band is also obtained. As a result, this kind of band-notched UWB antenna requires no external filters and can be applied in the UWB communication systems with the anti-jamming ability or low interference ability to other wireless systems.

High Rejection Broadband BPF with Triple-Mode Stub-Loaded Resonator

In this letter, a novel broadband bandpass fllter (BPF) with compact size and high rejection performance is proposed using the triple-mode stub-loaded resonator. The resonator is formed by attaching one T-type open stub at the center plane and two identical short-circuited stubs symmetrical to high impedance microstrip line. It can generate one odd-mode resonant frequency fm2 and two even- mode fm1, fm3 in the desired band. The fm2 can be approximately determined by the high impedance microstrip line. The short-circuited stubs and T-type open stub can be applied not only to separately adjust the fm1 and fm3 while the other two keep relatively stationary, but also to separately create transmission zero near the lower and upper cut-ofi frequencies, leading to a high rejection skirt. As a result of the source-load coupling, two transmission zeros in the upper-stopband are generated to deepen and widen the upper-stopband. A high rejection BPF with the fractional bandwidth 76% is simulated, fabricated and measured. The measured results agree well with the EM simulations.