Abstract
This paper addresses the analysis and design of a new class of metasurface leaky-wave antennas (LWAs) that inherently have low monostatic radar cross section (RCS) for normal incidence parallel polarization. The impedance profile of these antennas is modulated with a square wave to achieve leaky-wave behavior with low RCS. The low RCS performance is justified by the concepts of generalized Snell’s law of reflection and array theory. When the reflection phase difference between consecutive periods is near 180°, the power reflected in the specular direction is minimal. It is also shown that modulating the surface impedance with a square wave still results in a high-gain fan beam similar to that of a sinusoidal modulation; however, the trade-off for obtaining a low RCS is an increase in the sidelobe level due to radiation from higher-order harmonics. A similar trade-off exists between the gain/beamwidth and RCS reduction. A prototype of an LWA with low RCS was fabricated and measured; an excellent agreement was observed between simulations and measurements.
Highlights
M ETASURFACE leaky-wave antennas (LWAs) are radiating structures with thin and light-weight geometries that are characterized by high gains and narrow beamwidths [1]
This paper intrinsically reduces the monostatic radar cross section (RCS) of the metasurface LWAs, for normal incidence parallel polarization, without increasing the overall size or thickness of the radiating structure
The RCS reduction is achieved by modulating the surface reactance with a square wave
Summary
M ETASURFACE leaky-wave antennas (LWAs) are radiating structures with thin and light-weight geometries that are characterized by high gains and narrow beamwidths [1]. LWAs has been an attractive topic ever since the high gain from sinusoidally-modulated impedance surfaces was interpreted using leaky waves in [2]. LWAs have been examined for their frequency-scanning abilities and sidelobe levels [3]. These metasurface antennas can be used for space, imaging and automotive radar applications [4]–[6]. The need to flush-mount these antennas on vehicles has motivated research on conformal antennas, which for cylindrically-curved conformal LWAs were reported in [5], [13]–[15]. Leaky-wave concepts have been used to achieve a perfect anomalous reflection [16] and to explain Wood’s anomalies [17]
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