Xueshi Ren

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.

Dual-Band Circularly Polarized Antenna Combining Slot and Microstrip Modes for GPS With HIS Ground Plane

A dual-band circularly polarized antenna for GPS L1 and L2 bands is proposed and investigated in this letter. The dual-band design is realized based on the strategy of combining the microstrip mode and annular slot mode. The proposed antenna consists of an annular slot radiator printed on a square substrate and a high impedance surface (HIS) ground plane. The HIS, working as ground plane for microstrip mode and reflector for slot mode radiation, is settled under the square substrate to realize unidirectional radiation with low profile. Experimental results show that the proposed antenna exhibits two overlapped impedance and axial ratio bandwidth of 40 MHz (1.210-1.250 GHz) and 50 MHz (1.555-1.605 GHz) and the measured gains are about 8.0 dBic and 7.5 dBic, respectively. Very low backward radiation can also be observed in both operating bands.

Broadband Circularly Polarized Antenna With L-shaped Strip Feeding and Shorting-Pin Loading

A patch antenna with simple feeding structure for broadband circular polarization is proposed in this letter. The patch is first designed with horizontal L-shaped strip (HLS) feeding, which feeds the radiation patch at orthogonal orientations with 90° phase difference. Two minimum points can be seen in the axial-ratio (AR) curve. By loading a shorting pin to the patch, the minimum point of lower frequency moves to higher frequency, and wide AR band is obtained consequently. Measured results show that 10-dB return-loss bandwidth of 23.6% (2.09-2.65 GHz), 3-dB AR bandwidth of 17.9% (2.18-2.61 GHz), and average gain of 8.5 dBic across the operating band are achieved for the proposed antenna with a low profile of 0.09λ0 ( λ0 is the wavelength in free space corresponding to 2.4 GHz).

Modified Square Slot Antennas for Broadband Circular Polarization

Square slot antennas with modifled edges for broadband circular polarization are presented. Slots with only stubs or notches are studied and it is found that the axial ratio (AR) bandwidth is quite sensitive to the perturbations of the stubs and notches. To further enhance the AR bandwidth, slot antennas with combination of stubs and notches are proposed and wide 3-dB AR bandwidth of 15.5% (2.45{2.86GHz) is obtained. By placing a conducting re∞ector at the rear of the slot, another modifled square slot antenna is designed for practical applications, which achieves a 3-dB AR bandwidth of 6.5% (2.38{2.54GHz) and peak gain of 8.7dBic. Agreement between simulated and measured results is satisfactory.

A WIDEBAND TWIN-DIAMOND-SHAPED CIRCULARLY POLARIZED PATCH ANTENNA WITH GAP-COUPLED FEED

A novel twin-diamond-shaped antenna is presented for wideband circularly polarized (CP) radiation. By introducing a twin-diamond-shaped patch and a gap-coupled feed structure, a left- handed circularly polarized (LHCP) antenna in bore-sight direction is obtained. The gap-coupled feed structure consists of a horizontal microstrip arm of approximately 0.285‚0 at the centre frequency and two small diamonds, which greatly contributes to wideband characteristics. The experimental bandwidths of 10-dB return loss and 3-dB axial ratio (AR) for the antenna prototype are about 20% and 9.2%, respectively. The measured gain is more than 6.8dBi over the entire bandwidth.

BROADBAND SINGLE-FED SINGLE-PATCH CIRCULARLY POLARIZED MICROSTRIP ANTENNA

The paper demonstrates a novel antenna which can achieve a broad impedance bandwidth and circularly polarized bandwidth with a suspended corner-truncated square patch and a new probe-fed rectangular strip. By incorporating a probe-fed rectangular strip inside a high substantial cavity (» 0:144‚0), a broad impedance bandwidth (VSWR < 2:0) of 770MHz (31.43%) is achieved. To obtain a good circularly polarized (CP) bandwidth matching with the impedance bandwidth, two stubs with optimized lengths are loaded at the non-radiating edges of the corner-truncated square patch symmetrically. Measured results show that the CP antenna features a wide operating bandwidth of 10% ranging from 2.41GHz to 2.66GHz (VSWR < 1:5 and axial ratio < 3dB) and that of 22.45% ranging from 2.31GHz to 2.86GHz (VSWR < 2 and axial ratio < 6dB) and good radiation patterns with cross-polarization level (LHCP) lower than the co-polarization level (RHCP) by more than 20dB at the broadside direction. The average gain of this antenna is recorded as about 8.16dBi across the operating bandwidth.

BROADBAND CPW-FED CIRCULARLY POLARIZED ANTENNA WITH AN IRREGULAR SLOT FOR 2.45 GHz RFID READER

A coplanar waveguide-fed slot antenna with wideband circular polarization characteristic is presented. The proposed antenna consists of an irregular slot with a stair-shaped edge and an L-shaped feed line. The stair-shaped edge can improve the circular polarization of the antenna. The simulated and measured results show that the antenna has an impedance bandwidth (VSWR < 2) about 1040MHz (42%@2.47GHz) and an axial ratio (AR) bandwidth (AR < 3dB) about 640MHz (25.8%@2.48GHz) for 2.45GHz RFID applications. The RHCP gain in the main radiation direction varies between 2.3dBi and 3.8dBi.

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% (1.66–2.19 GHz) and 18.4% (5.09–6.12 GHz). The port isolation for both bands is better than 30 dB. 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.

Interdigitated hexagon loop unit cells for wideband miniaturized frequency selective surfaces

A single layer band-pass FSS with very small periodicity and superior bandwidth which is composed of interdigitated hexagon loop aperture unit cells is proposed in this paper. By interdigitating the unit cells at the common boundary of adjacent unit cells of FSSs, the extent of miniaturization and operating bandwidth can be significantly improved compared with convoluted ones. Simulated results shows that the merit λ1/p characterizing the extent of miniaturization is 31.4, moreover, the fractional bandwidth reaches 22.8% at normal incidence.

A conical four-arm sinuous antenna

A conical four-arm sinuous antenna with unidirectional radiation is presented. The proposed antenna consists of four sinuous metal arms printed on a conical dielectric substrate, an auxiliary feeding patch, and two modified exponentially-tapered baluns. The simulated results of active VSWR, realized gain and axial ratio in broadside direction reveal that the antenna can effectively radiate left-handed and right-handed circularly-polarized waves at frequencies ranging from 0.82-3GHz.