No abstract

This article presents a wideband, dual-polarized antenna array with inverted BoR elements. The antenna structure is based on the conventional body-of-revolution (BoR) element, but the structure is inverted; i.e., instead of metallic cones, the elements are metalized cavities inside a dielectric block. This structure allows a more lightweight and low-cost design since all-metal parts are not needed. In addition to the inverted BoR structure, this paper proposes a feeding system that is fully integrated into a 5-mm-thick standard printed circuit board. The designed antenna operates at 2-6 GHz, providing 3:1 impedance bandwidth with an active reflection coefficient (ARC) < −10 dB. The ARC<−10 dB criterion is fulfilled for all beam-steering angles up to ±50 • in all planes. The operation of the simulated antenna array was verified by measuring a built prototype. The measurement results are in good agreement with the simulations. However, the radiation efficiency of the prototype was approximately 11% inferior than that of the conventional all-metal BoR array due to conduction losses caused by the metalization of the used dielectric.

Mutual coupling, or equivalently, the isolation between antennas, is a key parameter in antenna system design. In this work, a new quantity is proposed to obtain spatial information about mutual coupling. The new quantity is named the weak-coupling density. This quantity is a real-valued scalar and can be visualized as a three-dimensional density in space. It is also shown that there is a strong correlation between regions with a positive (negative) weak-coupling density and decreasing (increasing) the coupling when placing an absorber in that region. This predictive ability is a useful feature, which is tested here for three numerical cases. The results are robust to the shape of the platform, and it persists over neighboring frequencies. By placing absorbers based on the weak-coupling density, it is possible to reduce the required amount of absorbers to obtain a certain mutual coupling reduction. The visualization results and predictions of absorber positions are compared with a Poynting vector based method. Placing absorbers based on the weak-coupling density had a larger impact on the mutual coupling, compared to the predictions with the Poynting vector based method in the investigated cases.

No abstract

Direction-of-arrival (DoA) estimation accuracy can be degraded due to installation effects, such as platform reflections, diffraction from metal edges, and reflections and refraction in the radome. To analyze these effects, this paper starts with a definition of the term installation error related to DoA estimation. Thereafter, we present a postprocessing method, which can be used to determine the DoA estimation accuracy for installed antennas. By computing synthetic signals from the installed far-field data, it is possible to analyze the installation errors described above, in addition to analyzing array model errors. The method formulation is general, thus allowing generic array configurations, installation configurations, and direction-finding algorithms to be studied. The use of the presented method is demonstrated by a case study of a wideband four-quadrant array. In this case study, we investigate the installation errors due to a single-shell radome. Thereafter, the effects of platform reflections are also analyzed, for an antenna placement in the tail of a fighter aircraft. Simulation results are presented for both the monopulse and the MUltiple SIgnal Classification direction-finding algorithms.