P. Li

A dual-feed dual-band L-probe patch antenna

By embedding shorting vias, a dual-feed and dual-band L-probe patch antenna, with flexible frequency ratio and relatively small lateral size, is proposed. Dual resonant frequency bands are produced by two radiating patches located in different layers, with the lower patch supported by shorting vias. The measured impedance bandwidths, determined by 10 dB return loss, of the two operating bands reach 26.6% and 42.2%, respectively. Also the radiation patterns are stable over both operating bands. Simulation results are compared well with experiments. This antenna is highly suitable to be used as a base station antenna for multiband operation.

A study of the wide-band L-probe fed planar patch antenna mounted on a cylindrical or conical surface

The characteristics of an L-probe fed planar patch antenna mounted on a cylindrical or conical surface are investigated in this paper. It is found that the wide-band characteristic of the L-probe patch antenna can be maintained with this structure and further enhanced by using a curved ground. An antenna mounted on a cylinder is built and measured to confirm the simulated results. A 10 dB impedance bandwidth of 45.2%, which is about 50% larger than that of the patch mounted on a flat ground plane, and a 3 dB beamwidth of 89/spl deg/ are achieved. This antenna, with a peak gain of 8.6 dBi, provides stable radiation patterns across the entire passband. Then an antenna with the same structure on a metallic conical ground is also evaluated. It is found that the bandwidth can be further improved when the antenna is mounted on a conical structure. The result is useful for the design of wide-band cylindrical antenna arrays with down tilted patterns.

A wideband and dual-frequency shorted-patch antenna with compact size

A capacitive-coupled shorted-patch antenna for wideband and dual-frequency operations is presented. This antenna consists of two shorted-patches in stacked configuration with a common shorting wall. By shorting the patches to the ground plane, this antenna can achieve a size reduction of 82.7% comparing to a regular half-wave patch antenna. Moreover, it has 10 dB return loss bandwidth of 48.9% and 47.7% for the lower and upper band, respectively. Furthermore, it has a flexible frequency ratio for the center frequencies of the two operating bands.

An omnidirectional high gain microstrip antenna array mounted on a circular cylinder

An L-probe fed microstrip antenna array, mounted on a cylindrical ground plane, is proposed in this paper. The characteristics of a single L-probe fed microstrip antenna are investigated by both simulation and experiment. The far field radiation pattern of the cylindrical antenna array is studied by pattern synthesis with consideration of the cylinder curvature, element number and element spacing. A high gain omnidirectional antenna array with low gain ripple in the azimuth radiation pattern is achieved.

A dual-band shorted patch antenna proximity-fed by a combined L- and Tprobe feed structure

Measured results of a dual-band shorted patch antenna excited by a combined L- and T- probe feed structure are presented. By using foam layers of thickness /spl sim/0.12/spl lambda//sub 1/ and /spl sim/0 06/spl lambda//sub 2/ (/spl lambda//sub 1/ and /spl lambda//sub 2/ represent the free space wavelength at the center frequency of the lower and upper band) to support the patches that are responsible for the lower and upper band, an impedance bandwidth (SWR/spl les/2) of 54.4% and 49 1 % have been obtained respectively. The peak gain of each band is 3 8 dB for both planes. The far field patterns are stable across the passband.

A study of the wideband L-probe fed patch antenna mounted on a metallic cylinder

The characteristics of an L-probe fed patch antenna mounted on metallic cylinders with different radius are investigated in this paper. It has been discovered that through maintaining the separation between the patch and the ground plane to be 0.12 free space wavelength, both the impedance bandwidth and beamwidth of the antenna can be enhanced to a large extent just by reducing the radius (i.e. increasing the curvature) of the cylinder. An antenna mounted on a cylinder is implemented for measurement to confirm the agreement between the simulated and the measured results. The measured 10-dB impedance bandwidth of 45.2% and 3 dB beamwidth of 89/spl deg/ are achieved, which are about 50% larger than that of the patch mounted on a flat ground plane. It has a peak gain of 8.6 dBi. The far field radiation patterns are stable across the whole passband.

A base station antenna for broadband and dual-frequency operation

By embedding shorting vias, a broadband and dual-frequency L-probe fed microstrip antenna, with flexible frequency ratio and relatively small lateral size, is proposed. The measured impedance bandwidth (S/sub 11/<10dB) of the two operating bands can reach 26.6% and 42.2%, respectively. Also the radiation patterns are stable in both operating bands. Simulation results are compared with experiments and a good agreement is observed. This antenna is highly suitable for modern mobile base station transceivers.

A wideband low-profile microstrip antenna with folded and shorted patch

The design and measurement of low-profile folded patch antenna with a short-circuited element is presented. By introducing dual-resonance, a significantly improved bandwidth of almost 30% for S/sub 11/<-10dB, which ranges from 1.48 to 1.99GHz, is achieved, while the total profile of the proposed antenna is kept in a very low level of 0.046 /spl lambda//sub 0/ only. The impedance matching, radiation patterns, and gain curve are measured and illustrated. This antenna is easy to fabricate and its performance is less susceptible to the manufacturing errors. Due to its wideband and low-profile characteristics, it is highly suitable for applications in mobile communication systems, such as PCS, DECT and PHS.

Modification of turbo equalization with LMMSE equalizer

This paper investigates turbo equalization (TE) with linear minimum mean squared error (LMMSE) equalizer, which has much lower complexity but much worse performance than TE with maximum a posteriori (MAP) equalizer because of inefficient information processing of LMMSE equalizer. Motivated by forward and backward recursions of MAP algorithm, three methods are presented to improve turbo equalization with LMMSE equalizer (TE-LMMSE). In the simulation, they all obtain more than 2.5-dB performance gain over TE-LMMSE with no or some complexity price.