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Surface-wave excitation from microstrip antennas is of major concern in many practical antenna applications. In this paper, the challenge of reducing the surface-wave excitation from microstrip antennas in a general way is addressed. The proposed approach is based on a theorem called the reduced surface wave (RSW) theorem. The RSW theorem suggests that by properly selecting the permittivity of the filling material inside the patch cavity, the patch will not excite the dominant TM0 surface-wave mode. A validation of this theorem is demonstrated here for the first time by comparing the mutual coupling between a pair of RSW antennas and a pair of conventional antennas. [ABSTRACT FROM PUBLISHER]

The input impedance and radiation pattern of the inset-fed rectangular microstrip patch antenna are investigated. It is concluded that a shifted cosine-squared function describes well the variation of the resonant input resistance with the feed location (point of contact between the microstrip feed line and the notch) for a given patch and substrate geometry. The parameters of the shifted cosine-squared function depend on the notch width for a given patch and substrate geometry. The cross-polarization level is seen to increase as either the notch width or depth increases. However, for a fixed input resistance level, the notch depth decreases as the width increases, so that the cross-polarization level is not very sensitive to the notch width for a fixed input resistance. [ABSTRACT FROM AUTHOR]

A new Global Positioning System (GPS) microstrip patch antenna designed for dual-band (L1/L2) operation is introduced. The antenna design is based on the reduced-surface-wave (RSW) concept and, as a result, is much less susceptible to low-angle multipath interference effects than some of the more commonly-used high-precision GPS antennas. In this paper, the radiation characteristics of this new design will be compared to a dual-band choke-ring and a dual-band pinwheel antenna. In addition to having the advantages typically associated with microstrip patch antennas, this planar dual-band antenna lacks the design complications associated with the frequently-used stacked-patch method for realizing dual-band microstrip antenna performance. Thus, the simplicity of the design, together with the reduced horizon and backside radiation levels and excellent circular polarization characteristics indicate that this new antenna design is a promising candidate for dual-band, high-precision applications. [ABSTRACT FROM AUTHOR]

Scan impedances of finite reduced surface wave (RSW) arrays are studied. Center element scan impedances of linear arrays and two-dimensionaI (2-D) square lattice arrays are calculated and compared with those of conventional microstrip arrays. Results show that compared with conventional microstrip arrays, broadside scan impedance of RSW arrays has less varia- don and converges much faster when the array size increases. Scan performance of the linear and 2D square lattice RSW arrays are also studied. Results show that the RSW array can avoid the scan blindness (when the array spacing is greater than 0.5λ0) and the scan impedance has much less variation than that of conventional microstrip array with the same array spacing. However, due to the size limitation of RSW elements, the grating lobes cannot be avoided. Hence, the scan region is limited to about 20° (with 0.75λA0 array spacing). Compared with conventional microstrip arrays with 0.5 λ0 array spacing, the results show no favor to RSW arrays. [ABSTRACT FROM AUTHOR]

Investigates the mutual coupling between reduced surface-wave microstrip antennas using an asymptotic analysis. Shorted annular ring reduced surface-wave antennas; Mutual coupling; Comparison of theoretical and measured mutual coupling; Radiation mechanism responsible for the mutual coupling.