Jiao-Jiao Xie

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.

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).

Compact dual band-notched UWB antenna with hexagonal slotted ground plane

A novel compact dual band-notched ultra-wide band antenna with hexagonal slotted ground is proposed. By inserting two pairs of L-shaped branches symmetrically into the slotted ground plane, two notched bands, 3.3–3.7 GHz for worldwide interoperability for microwave access and 5.15–5.825 GHz for wireless local area network, are achieved, respectively. A prototype of the proposed antenna is designed, fabricated, and tested. By optimizing the length of the L-shaped branches and the gap between them, the desired bandwidth of VSWR (voltage standing wave ratio) less than 2.0 can be achieved, ranging from 2.5 to 11 GHz, except two stop-bands of 3.1–4.0 and 5.0–6.0 GHz. The simulated and measured results of the proposed antenna have shown a reasonable agreement between them. The proposed antenna has a compact size, ultra wide bandwidth, good radiation characteristics, and good time-domain behaviors. It is very suitable for modern wireless communication applications.

A NOVEL TRAPEZOIDAL SLOT PATCH ANTENNA WITH A BEVELED GROUND PLANE FOR WLAN/WIMAX APPLICATIONS

A novel trapezoidal slot patch antenna with an embedded trapezoidal strip is proposed for satisfying wireless local area network (WLAN) and worldwide interpretability for microwave access (WiMAX) applications simultaneously. The proposed antenna consists of a rectangular radiation patch with an etched trapezoidal slot and an embedded trapezoidal strip on the top and a beveled ground on the bottom side. By carefully selecting the width of the radiation patch and length of the beveled ground, the proposed antenna can generate two separate bands. The measured results show that the 10dB return loss bandwidths of the proposed antenna are 430MHz (2.30{2.73GHz) and 3460MHz (3.21{6.67GHz), which can cover both the WLAN bands (2.4{2.484GHz, 5.15{5.35GHz, and 5.725{ 5.825GHz) and the WiMAX bands (2.4{2.6GHz, 3.4{3.6GHz, and 5.25{5.85GHz). Furthermore, good omnidirectional radiation patterns with appreciable gain are obtained over the operating bands.

A WIDEBAND MAGNETO-ELECTRIC DIPOLE ANTENNA USING CPW STRUCTURE

A new wideband magneto-electric dipole antenna using coplanar waveguide (CPW) structure is proposed in this paper. The proposed antenna consists of a pair of horizontal triangular patches and two vertically oriented L-shaped strips. By introducing triangular patches working as an electric dipole, the antenna can operate in a wide band. With the use of L-shaped strips equivalent to a magnetic dipole, the antenna is low in proflle. A microstrip feed line is located between the two L-shaped strips to form a coplanar waveguide structure and excite the antenna. By carefully adjusting the gap between the feed line and the strips, the impedance bandwidth can be improved largely. A parametric study is performed to provide information for designing and optimizing such an antenna. A prototype is fabricated and measured. The simulated and measured results show that the impedance bandwidth for SWR less than 2 of the proposed antenna is 58.7% (1.95{3.57GHz). Due to the complementary nature of the antenna, the proposed antenna has a unidirectional radiation pattern with low-polarization and low back-lobe radiation over the whole operating band. Furthermore, the gain of the antenna is stable across the entire bandwidth.