W. Hu

Compact Tri-Band Rectangular Ring Patch Antenna with Asymmetrical Strips for WLAN/WiMAX Applications

A novel rectangular ring patch antenna with tri-band operation is presented for WLAN and WiMAX applications. The proposed antenna consists of a rectangular ring patch and a pair of straight strips with different lengths. By placing the two strips asymmetrically with respect to the microstrip feed line, the proposed antenna can operate in triple bands. The 10 dB return loss bandwidths of them are 310 MHz (2.39–2.70 GHz), 490 MHz (3.38–3.87 GHz) and 2680 MHz (4.82–7.50 GHz) respectively, which can cover both the WLAN bands (2.4–2.484 GHz, 5.15–5.35 GHz, and 5.725–5.825 GHz) and the WiMAX bands (2.4–2.6 GHz, 3.4–3.6 GHz, 5.25–5.85 GHz). In addition, the overall dimensions of this proposed antenna are 36 mm (length) × 20 mm (width) × 1 mm (thickness), which is compact compared to conventional tri-band antennas.

Bandwidth Enhancement of a Printed Slot Antenna With a Pair of Parasitic Patches

A printed microstrip-line-fed slot antenna with a pair of parasitic patches for bandwidth enhancement is proposed in this letter. By using the parasitic patches along the microstrip feed line, an additional resonance is excited, and a good performance of bandwidth enhancement can be obtained. The proposed antenna is designed and manufactured successfully. The measurement shows a good agreement with the simulation. From the measured results, the enhanced impedance bandwidth, defined by voltage standing wave ratio (VSWR) less than 2, is about 136% ranging from 2.1 to 11.1 GHz. In addition, stable and nearly omnidirectional far-field radiation patterns are observed over the entire operating band.

Dual-band dual-polarized printed antenna for wireless communication

A novel dual-band dual-polarized antenna design with high isolation and low cross-polarization is presented. An arc-coupled annular ring and a special coaxial-fed slot patch are employed as the radiating elements at lower and upper bands, respectively. Measurements show that the 10-dB impedance bandwidths reach 27.9% (1.66–2.19u2009GHz) and 18.4% (5.09–6.12u2009GHz). The port isolation for both bands is better than 30u2009dB. Moreover, stable and symmetrical radiation patterns at slanted polarizations are achieved, and the measured cross-polarization level is less than dB within the above-mentioned bands.

Design of a wideband bandpass filter based on signal-interaction concepts

A novel wideband bandpass filter (BPF) based on signal-interaction concepts is presented in this paper. Two transmission paths with a wideband double-sided parallel-strip line 180° inverter and a 3λ/4 transmission line are employed to transmit signals from Port 1 to Port 2. By introducing two λ/4 shorted lines, the passband transmission performance of the BPF can be improved effectively. The experimental results demonstrate that the proposed BPF can achieve three transmission zeros and good harmonic suppression in the whole operating band ranging from 1.35 to 3.41u2009GHz, with 3-dB fractional bandwidth of 86%.

Design of a novel wideband quasi-elliptic filter based on SIR and asymmetric coupled lines

Stepped impedance resonator (SIR) and asymmetric coupled-line sections are used to design a novel fifth-order wideband bandpass filter in this paper. Even- and odd-mode technique is introduced to design and analyze the filter. The proposed filter possesses the characteristics of spurious-free response up to the third harmonic frequency with two transmission zeros on each side of the passband, thus resulting in the improved selectivity. One prototype with 3-dB fractional bandwidth of 53% (2.2–3.79u2009GHz) is fabricated for demonstration, and good agreement can be observed between simulated and measured results.