Zedong Wang

Broadband Circularly Polarized Patch Antenna With Parasitic Strips

A patch antenna with parasitic strips is presented for wideband circular polarization. In order to broaden the axial-ratio (AR) bandwidth of the original corner-truncated patch, four parasitic strips are sequentially rotated and gap-coupled around the patch. A capacitive-coupled feed with a small disc on the top of the feeding probe is utilized to obtain a wide impedance-matching bandwidth. Moreover, another disc-loaded shorting pin is placed at the center of the antenna to adjust the squint beams and improve the gains along +z-axis. Measured results show that the proposed antenna with a low profile of 0.13λ0 obtains a global bandwidth of 24% (2.32-2.95 GHz) for |S11| <; -10 dB, AR <; 3 dB, and average gain of 8 dBic.

A Miniaturized CPW-Fed Antipodal Vivaldi Antenna With Enhanced Radiation Performance for Wideband Applications

A miniaturized coplanar waveguide (CPW)-fed antipodal Vivaldi antenna (AVA) is presented in this letter. Elliptically shaped strip conductors are used to lower the antenna operating frequency. With two pairs of tapered slots and circularly shaped loads, the radiation performance in lower operating band can be greatly enhanced. The fabricated prototype of this proposed antenna with a size of 90 ×93.5 ×0.8 mm3 was measured to confirm the simulated results. The wide measured impedance band from 1.32 GHz to more than 17 GHz for can be obtained. Meanwhile, the good measured radiation patterns with gain 3.5- 9.3 dBi in end-fire direction achieve in the whole measured working band.

Design of a Low-Profile Dual-Polarized Stepped Slot Antenna Array for Base Station

In this letter, a microstrip-fed dual-polarized stepped-impedance (SI) slot antenna element with a low profile is first proposed. The antenna is composed of two pairs of SI slots excited by two orthogonal stepped microstrip feedlines. The broadband characteristic is achieved by combining the fundamental and spurious resonances of the SI slot resonators, while the good cross polarization is mainly due to the introduction of the shorting pins. Secondly, based on the proposed antenna, a four-element antenna array is designed, constructed, and measured for base-station applications. Measured results demonstrate the bandwidths (return loss ) of the antenna array are 46.9% (1.55-2.5 GHz) and 38.7% (1.69-2.5 GHz) for Port 1 and Port 2, respectively. The isolation between the two ports is greater than 35 dB, whereas the cross-polarization level maintains lower than -27 dB across the entire operating band. In addition, the antenna array prototype achieves average gains of 13.5 and 13.9 dBi for horizontal polarization and vertical polarization, respectively.

A Broadband Dual-Element Folded Dipole Antenna With a Reflector

A wideband dual-element planar folded dipole antenna is proposed in this letter. It is composed of a pair of asymmetric coplanar strip folded dipoles. The dual-element folded dipole antenna is fed by a microstrip feedline. With suitable design of the asymmetric coplanar strip folded dipole and the microstrip feedline, a 10-dB return-loss operating bandwidth of 107% (1.23 ~ 4.07 GHz) is achieved. By adding a metal plate, a wideband unidirectional antenna can be obtained with a measured impedance bandwidth of 113% (1.15 ~ 4.07 GHz) with better than 10 dB return loss. Its fabricated prototype is also measured with stable unidirectional radiation patterns in working band 1.13 ~ 3.3 GHz with a gain in + z-direction higher than 8.2 dBi and a front-to-back ratio better than 11.5 dB.

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).

UWB Monopole Antenna with Triple Band-Notched Characteristic Based on a Pair of Novel Resonators

In this paper, a novel microstrip-fed compact antenna with triple band-notched characteristics is presented for ultrawideband (UWB) applications. The antenna consists of a circular radiating patch, a 50› microstrip feed line, a partially slotted ground plane, and a pair of modifled capacitance loaded loop (MCLL) resonators. The novel resonators are symmetrically located in the vicinity of the feed line to achieve triple band-notched characteristics, such as 3.4{3.7GHz for WiMAX, 5.15{5.825GHz for WLAN, 7.25{8.395GHz for X-band satellite communication. The good performance of triple notched bands, stable gain and omnidirectional radiation patterns in the operating bands make the proposed antenna a good candidate for UWB utilization.

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.

A Novel Design of Folded Dipole for Broadband Printed Yagi-Uda Antenna

In this paper, a printed wideband Yagi-Uda antenna with a novel folded dipole driver is proposed. The folded dipole driver is comprised of a folded dipole and a microstrip feedline which functions as an internal balun to mainly determine its wide impedance bandwidth. With the optimized parameters, an operating band of 1:69GHz » 2:72GHz can be obtained. Besides the folded dipole driver, the broadband printed Yagi-Uda antenna also consists of three directors and a re∞ector. Its wideband performance is mainly determined by the folded dipole driver, while the re∞ector and directors improve its performance slightly. By optimizing the geometrical parameters of the folded dipole driver, a bandwidth of 61.8% (1:53GHz » 2:93GHz) for return loss being higher than 10dB is achieved. The proposed printed Yagi-Uda antenna is realized on FR4 substrate with a measured operating bandwidth of 62% (1:51GHz » 2:94GHz), a ∞at gain (5:6dB » 7:3dB), more than 10dB front-to-back ratio and lower than i15dB cross-polarization level.

Design of a Dual-Band High-Gain Antenna Array for WLAN and WiMAX Base Station

A dual-band 3 ×2 antenna array with high gain is presented in this letter. A dual-band folded dipole antenna is utilized as the antenna array element. A broadband symmetric feed network is designed to maintain each array element with the identical current magnitude and phase. The antenna array has a low profile of 12 mm (about 0.1λL; λL is the wavelength in free space at the lowest operating frequency). Dual bands 2.3 ~ 2.56 and 3 ~ 4.2 GHz for return loss (RL) being higher than 10 dB can be obtained in simulation, while two 10-dB RL bands 2.31 ~ 2.51 and 3.1 ~ 4.15 GHz in measurement cover the wireless local area network (WLAN, 2.4 ~ 2.48 GHz) and Worldwide Interoperability for Microwave Access (WiMAX, 3.3 ~ 3.8 GHz). The measured results also show that this planar antenna array has a high gain 14.3 ~ 15.1 dBi (2.31 ~ 2.51 GHz), 16.2 ~ 17.3 dBi ( 3.1 ~ 4.15 GHz) in + z-direction and a low cross-polarization level <; - 26 dB.

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.