C.L. Mak

Experimental study of a microstrip patch antenna with an L-shaped probe

The L-shaped probe is shown to be an attractive feed for the thick microstrip antenna (thickness around 10% of the operating wavelength). A parametric study on the rectangular patch antenna is presented. It is found that the antenna attains 36% impedance bandwidth (SWR/spl les/2) as well as gain bandwidth and about 7-dBi average gain. A two-element array fed by L-probes is also proposed. Experiments show that the array design can substantially suppress the cross polarization of the proposed antenna. Both the antennas have stable radiation patterns across the passband. Moreover, the measured resonant frequencies of the proposed antenna agree well with an existing formula and the L-probe does not have much effect on the resonant frequency.

Miniature wide-band half U-slot and half E-shaped patch antennas

The U-slot patch antenna, a single-layer single-patch antenna on a relatively thick substrate (/spl sim/0.08/spl lambda//sub 0/), is a wide-band antenna with an impedance bandwidth in a range of 20%-30%, which is about an order of magnitude larger than that of the regular patch antenna. Recently, it was shown that a half U-slot patch antenna, with half of one of the dimensions of the U-slot patch, maintains similar wide-band behavior. The half-structure was also successfully applied to the U-slot with shorting wall. In this paper, new results on half structures, not previously published, are presented. First, the shorting pin technique is used to reduce the size of the half U-slot patch antenna. By both simulation and experimental studies, it is concluded that the impedance bandwidths, radiation patterns, radiation efficiencies and gains of the half-structures are comparable to the corresponding full structures. Bandwidth of 28.6% and radiation efficiencies exceeding 90% are obtained for the half U-slot patch with shorting pin. Radiation patterns are stable across the matching band. Second, it is shown that a structure obtained from halving the E-shaped patch, which is a derivative of the U-slot patch, also maintains its wide-band behavior.

Analysis and design of L-probe proximity fed-patch antennas

In this paper, the finite-difference time-domain (FDTD) method is employed to analyze L-probe proximity-fed rectangular patch antennas. Numerical results for the input impedance, co- and cross-polarization radiation patterns are presented and compared with the measurements. Good agreement between the computed and measured results is obtained. The effects of geometric parameters on the characteristics of the L-probe patch antenna are extensively studied. For design purposes, the variation of input impedance at resonance with different geometric parameters is plotted on a Smith chart. Mutual coupling between two L-probe patch antennas is also investigated.

High-gain and wide-band single-layer patch antenna for wireless communications

A technique employing the use of parallel feeds is applied to the recently proposed L-probe coupled patch antenna design. By employing only two L-probes, with proper separation, for feeding one single patch, a twin-L-probe coupled patch antenna is designed with both high-gain (10 dBi) and wide-band [25%, standing wave radio (SWR) /spl les/ 1.5] characteristics. In addition, the 1-dB-gain bandwidth is around 26%, which covers the impedance bandwidth. Furthermore, a noticeable suppression of cross-polarization radiation is observed. Simulation results are in good agreement with those noteworthy characteristics obtained from experiments. The proposed antenna is suitable for modern mobile communication applications.

Wideband L-strip fed microstrip antenna

A new proximity feeding technique, in the form of an L-shaped probe, was applied to a coaxial-fed microstrip antenna, resulting in 35 % bandwidth. In this paper, a broadbanding technique with the utilization of an L-strip is introduced. Without the use of any matching network or stub and slots on the patch, the impedance bandwidth of proximity coupled antennas can be widened significantly.

Wideband half U-slot patch antennas with shorting pin and shorting wall

Microstrip antennas have the advantages of low profile, light weight and ease of fabrication. However, they have narrow bandwidth and relatively large size in the microwave frequency range. One design which gives wideband operation is the U-slot patch. Applying shorting wall and shorting pin techniques results in further improvements (Guo, Y.X. et al., Micro. and Opt. Tech. Lett., vol.28, p.328-30, 2001; Shackelford, A.K. et al., Electronics Lett., vol.37, p.729-30, 2001). The areas of small wideband patch antennas can be further reduced, by a factor of two, by using a half U-slot instead of the full U-slot (Deshmukh, A.A. and Kumar, G., IEEE AP-S Digest, p.876-9, 2003). Two miniaturized wideband half-U-slot patch antennas with shorting pin and shorting wall have been designed. Simulation results show that the bandwidth and gain of the reduced size antennas are similar to those of the original full U-slot structure in both cases. Measurement results confirm the simulation results on the half-U-slot patch with shorting wall. Experimental results on the second design are in progress.

A Vertical Patch Antenna for Dual-Band Operation

A new dual-band vertical patch antenna for broadside radiation is described. The antenna is fed by a proximity-coupled probe, which maintains the advantages of the original single-band vertical patch antenna, such as small size, wide bandwidth and simple structure. The achieved bandwidths are 7% and 26%, respectively, at the lower and upper frequency bands.

Dual-band and CP vertical patch antennas

New geometries are proposed for the newly invented vertical patch antenna (VPA) for dual band operation and circular polarization generation respectively. The dual-band VPA maintains the advantages of the singleband VPA, such as small size, wideband and simple structure. For the circularly polarized (CP) VPA, it exhibits a gain of 8dBi over 3dB axial ratio bandwidth of 4%

High-gain and wide-band single-layer twin-L coupled patch antenna

The technique of parallel feeds is applied to the recent L-probe coupled patch design. A twin-L-probe coupled patch antenna is designed with both high-gain (10 dBi) and wide-band (25%, SWR les 1.5) features. The 1dB-gain-bandwidth is around 26%, which covers the operating band. A noticeable suppression of cross-polarization radiation is also observed. Simulation results are in good agreement with those noteworthy characteristics obtained from experiments

A dual-band vertical patch antenna with size reduction

A new feeding technique is proposed for the newly invented vertical patch antenna (VPA) for single and dual band operations. The new feeding method reduces the projection area and remains simple in structure and wide bandwidth, while the dual-band VPA maintains the advantages of the single-band vertical patch antenna, such as small size, wideband and simple structure