Xiao Wei Shi

Compact UWB Bandpass Filter With Dual Notched Bands Based on SCRLH Resonator

This letter presents a novel ultra-wideband (UWB) band-pass filter (BPF) with dual sharply rejected notch-bands based on a simplified composite right/left-handed (SCRLH) resonator. The basic UWB BPF is comprised of four folded shunt quarter-wavelength short-circuited stubs separated by connecting lines with length of λg0/4 and λg0/2, respectively. The SCRLH resonator is studied and employed to introduce the dual notched bands. Good insertion/return losses are achieved as demonstrated in both simulation and experiment.

Compact UWB Bandpass Filter With Triple-Notched Bands Using Triple-mode Stepped Impedance Resonator

In this letter, a compact ultra-wideband (UWB) band-pass filter (BPF) with triple-notched bands is presented using a novel triple-mode stepped impedance resonator (SIR). The basic UWB BPF is comprised of four folded shunt quarter-wavelength short-circuited stubs separated by connecting lines with length of λg0/4 and λg0/2, respectively. The proposed coupled triple-mode SIR is found to have the advantages of introducing triple-notched bands and providing higher degree of freedom to adjust the resonant frequencies. The simulated and measured results are in good agreement with each other, showing good wideband filtering performance with sharp rejection skirts outside the passband.

Compact Balanced Dual- and Tri-Band BPFs Based on Coupled Complementary Split-Ring Resonators (C-CSRR)

Two multi-band balanced bandpass filters (BPFs) are proposed by embedding multi-band coupled complementary split- ring resonators (C-CSRRs) into a balanced stepped-impedance microstrip-slotline transition structure. The proposed C-CSRR is made from two or three nested CSRRs with a pair of coupling slotlines in the open end of each ring, which can result in dual-band or tri-band bandpass responses, respectively. It is found that a high and wideband common-mode (CM) suppression can be achieved for the proposed filters. Moreover, the center frequencies of the differential-mode (DM) passbands are independent from the CM responses, which significantly simplify the design procedure. In order to validate its practicability, two balanced BPFs with two and three DM passbands are fabricated and good agreement between simulated and measured results is observed.

Compact Balanced Dual- and Tri-band Bandpass Filters Based on Stub Loaded Resonators

A stub loaded resonator (SLR) is presented in this letter, which can achieve dual-band or tri-band differential-mode (DM) bandpass response with a high common-mode (CM) suppression. By changing the length of the center-loaded stub, the resonant frequency of the CM can be varied without affecting that of the DM. This helps in simplifying the design and tuning processes of the balanced filters. In order to validate its practicalbility, two balanced bandpass filters (BPFs) with two and three DM passbands and good CM suppression are designed. Good agreement between simulated and measured results is observed. To our best knowledge, the proposed balanced tri-band BPF is the first ever reported.

Design of a compact ultra-wideband bandpass filter with two notched bands

In this paper, a compact ultra-wideband (UWB) band-pass filter (BPF) with two steep rejected notch-bands is proposed. The designed UWB BPF is realized by cascading two interdigital hairpin resonator units with asymmetric open loading stubs and a spiral slot on microstrip line. The asymmetric loading stubs and spiral slot are studied and adopted to introduce notched bands. The lengths and the widths of the stubs and slots can control the notched band in a desired frequency. Finally, simulated results are presented, which are in good agreement with the measured results.

Compact UWB power divider with unequal distribution ratio

A compact ultra-wideband (UWB) power divider with unequal distribution ratio is proposed in this paper. The UWB power divider is based on the conventional unequal Wilkinson power divider with two folded shunt quarter-wavelength short-circuited stubs separated by quarter-wavelength connecting lines at each output ports. The unequal distribution ratio is achieved by adjusting impedance ratio of two output ports. In addition, a single resistor is properly placed between two output ports for improving isolation. Finally, the simulated results are presented, which are in good agreement with the measured ones.

Artificial bee colony algorithm for time-modulated circular antenna array synthesis

Low side-lobe radiation patterns of circular antenna arrays with uniform amplitude excitations can be realized by the time modulation technique is presented in this paper. The artificial bee colony (ABC) algorithm is adopted to optimize the excitation phases and the switch-on time intervals of each element of the time modulated circular array (TMCA). Several synthesis experiments show that the TMCA can be successfully used for the synthesis of low SLLs even if the amplitude excitations are uniform.

A novel wideband waveguide-to-microstrip transition with waveguide stepped impedance transformer

A novel wideband waveguide-to-microstrip transition is presented in this paper. A printed fan-shaped probe is used, while a waveguide stepped impedance transformer is utilized to broaden the bandwidth further. With an optimized design, a relative bandwidth of 27.8% for -20dB return loss with a center frequency of 15GHz is achieved. The simulated insertion loss in this bandwidth is less than 0.29dB. A back-to-back transition is fabricated and measured. The measured result is similar to that of simulation.

Design and Analysis of a Folded Printed Inverted-F Antenna for Bluetooth Applications

A novel microstrip-fed folded planar inverted-F antenna (PIFA) is proposed in this letter. It is implemented by printing radiating conductors on an FR4 phone main board. A prototype with a small area of 16X4.5 mm2 has been constructed and analyzed. It is found that the 10-dB impedance bandwidth is approximately 5% centered at 2.45 GHz, with reasonable agreement between simulation and measurement. The proposed antenna is extraordinarily suitable for Bluetooth application (2.400-2.484 GHz).