gzeng Yin

Compact Triband Square-Slot Antenna With Symmetrical L-Strips for WLAN/WiMAX Applications

A novel triband square-slot antenna with symmetrical L-strips is presented for WLAN and WiMAX applications. The proposed antenna is composed of a square slot, a pair of L-strips, and a monopole radiator. By employing these structures, the antenna can yield three different resonances to cover the desired bands while maintaining small size and simple structure. Based on this concept, a prototype of a triband antenna is designed, fabricated, and tested. The experimental results show the antenna has the impedance bandwidths of 480 MHz (2.34-2.82 GHz), 900 MHz (3.16-4.06 GHz), and 680 MHz (4.69-5.37 GHz), which can cover both WLAN in the 2.4/5.2-GHz bands and WiMAX in the 2.5/3.5-GHz bands.

Wideband Dual-Polarized Patch Antenna With Low Cross Polarization and High Isolation

A coax-feed wideband dual-polarized patch antenna with low cross polarization and high port isolation is presented in this letter. The proposed antenna contains two pairs of T-shaped slots on the two bowtie-shaped patches separately. This structure changes the path of the current and keeps the cross polarization under -40 dB. By introducing two short pins, the isolation between the two ports remains more than 38 dB in the whole bandwidth with the front-to-back ratio better than 19 dB. Moreover, the proposed antenna achieving a 10-dB return loss bandwidth of 1.70-2.73 GHz has a compact structure, thus making it easy to be extended to form an array, which can be used as a base station antenna for PCS, UMTS, and WLAN/WiMAX applications.

Compact Printed MIMO Antenna for UWB Applications

A compact multiple-input-multiple-output (MIMO) antenna is presented for ultrawideband (UWB) applications. The antenna consists of two open L-shaped slot (LS) antenna elements and a narrow slot on the ground plane. The antenna elements are placed perpendicularly to each other to obtain high isolation, and the narrow slot is added to reduce the mutual coupling of antenna elements in the low frequency band (3-4.5 GHz). The proposed MIMO antenna has a compact size of 32 ×32 mm2, and the antenna prototype is fabricated and measured. The measured results show that the proposed antenna design achieves an impedance bandwidth of larger than 3.1-10.6 GHz, low mutual coupling of less than 15 dB, and a low envelope correlation coefficient of better than 0.02 across the frequency band, which are suitable for portable UWB applications.

A New Compact Filter-Antenna for Modern Wireless Communication Systems

Design, fabrication, and measurement of a new compact filter-antenna for modern wireless communication systems are presented in this letter. Two microstrip square open-loop resonators, a coupled line, and a Γ-shaped antenna are used and integrated to be a filter-antenna. The Γ-shaped antenna is excited by a coupled line that is treated as the admittance inverter in filter design. The Γ-shaped antenna performs not only a radiator, but also the last resonator of the bandpass filter. Therefore, near-zero transition loss is achieved between the filter and the antenna. The design procedure follows the circuit approach-synthesis of bandpass filters. Measured results show that the filter-antenna achieves an impedance bandwidth of 16.3% (over 2.26-2.66 GHz) at a reflection coefficient |S11 | <; - 10 dB and has a gain of 2.41 dBi.

A CPW-FED DUAL BAND-NOTCHED UWB ANTENNA WITH A PAIR OF BENDED DUAL-L-SHAPE PARASITIC BRANCHES

In this paper, a novel coplanar waveguide (CPW) fed dual band-notched ultra-wideband (UWB) antenna with circular slotted ground is proposed. In order to achieve two notched bands at 3.3{3.7GHz for worldwide interoperability for microwave access (WiMAX) and 5.15{5.825GHz for wireless local area network (WLAN) respectively, a pair of bended dual- L-shape branches are attached to the slotted ground. By optimizing the lengths and positions of the branches, the desired notch-bands of WLAN and WiMAX can be achieved. The prototype of the proposed antenna was fabricated and tested. The simulated and measured results show good agreement over the ultra-wideband. Besides these mechanical features, such as compact in size, easy in fabrication, the proposed antenna also shows good characteristics in its radiation patterns and time-domain behaviors. So it is a nice candidate for modern UWB communication systems.

EIGENMODE DECOUPLING FOR MIMO LOOP-ANTENNA BASED ON 180 - COUPLER

A low-cost, high isolation, printed loop-antenna system for multiple-input multiple-output (MIMO) applications in the 2.4GHz WLAN band is presented. By feeding the orthogonal eigenmodes of the array, port decoupling (S21 < i20dB) with tightly coupled elements (only 0:07‚ separation) is obtained. The orthogonal eigenmodes are realized based on 180 - coupler. Then decoupled external ports of the feed network may be matched independently by using conventional matching circuits. With this low-cost and high isolation characteristic, it is very suitable for being embedded inside a wireless access point (AP).

A Compact CPW-Fed Monopole Antenna with a U-Shaped Strip and a Pair of L-Slits Ground for WLAN and WiMAX Applications

A compact tri-band planar monopole antenna suitable for 2.4/5.2/5.8GHz WLAN and 3.5GHz WiMAX is presented. The antenna employs a U-shaped parasitic strip and a defect ground-plane structure. By inserting a U-shaped strip as a parasitic strip into a normal monopole which operates at lower band of the WLAN, one more resonance at the higher WLAN band comes out. A defect ground-plane composed of two symmetrical L-shaped slits leads to another resonance operating at WiMAX band. The proposed antenna has a compact size of 22 £ 41 £ 0:8mm 3 and ofiers good radiation and re∞ection characteristics in the above frequency bands. The measured VSWR exhibits a good agreement with the simulated one. Detailed design steps, parametric studies and experimental results for the antenna are investigated in this paper.

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.

INVESTIGATIONS OF REDUCTION OF MUTUAL COUPLING BETWEEN TWO PLANAR MONOPOLES USING TWO λ/4 SLOTS

This article presents a simple structure for reducing mutual coupling between two diversity planar monopole antennas for WLAN 5.2/5.8GHz applications. The structure has two ‚=4 (‚- wavelength in the substrate) slots cut into the ground plane between the two monopoles. In 0.5‚o (‚o-wavelength in the air) of the antenna spacing, mutual coupling was i33:3, i21:1dB at 5.2, 5.8GHz, respectively. The lowest mutual coupling of i33:3dB was achieved at 5.2GHz, which are 20.8dB improvements over the reference.

DUAL-WIDEBAND SYMMETRICAL G-SHAPED SLOTTED MONOPOLE ANTENNA FOR WLAN/WIMAX APPLICATIONS

A novel dual-wideband printed monopole antenna is proposed for wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The proposed antenna consists of a T-shaped monopole on top and dual combined G-shaped slots etched symmetrically on the ground plane to achieve a dual-wideband performance. Prototype of the proposed antenna has been constructed and tested. The measured 10dB bandwidths for return loss are 1.76GHz from 2.13 to 3.89GHz and 0.92GHz from 5.03 to 5.95GHz, covering all the 2.4/5.2/5.8GHz WLAN and 2.5/3.5/5.5GHz WiMAX bands. And this antenna also has omni-directional patterns over the lower operating range.