Radiation Pattern Synthesis and Mutual Coupling Compensation in Spherical Conformal Array Antennas

This paper presents a novel technique based on Hybrid Spatial Distance Reduction Algorithm (HSDRA), to compensate the effects of deformity and mutual coupling occurred due to surface change in conformal arrays. This antenna surface deformation shifts the position of null points and loss of the main beam resulting in reduced antenna gain along with substantial undesirable effects on the antenna performance. The proposed algorithm, which cumulatively incorporates the Linearly Constraint Least Square Optimization (LCLSO) and Quadratically Constraint Least Square Optimization (QCLSO) techniques, is formulated to minimize/reduce the absolute distance between the actual (simulated/measured) radiation pattern and the desired radiation pattern while keeping the direction of main beam and nulls position under control. In particular, a 4x4 conformal microstrip phased array from planar surface is deformed to prescribe spherical-shape surface with various radii of curvature, is validated. For the enhancement of Gain of the conformal array antenna, Gain Maximization Algorithm is also proposed, the simulated results of which is compared to the traditional Phase compensation technique and unconstraint least squares optimization. The analytical results for both planar and spherical deformed configurations are first evaluated in MATLAB and then validated through Computer Simulation Technology (CST).

Millimeter Wave Fuze Radome Design Based Bandpass Frequency Selective Surface

This paper studies a fuze radome system applied to millimeter waves. The system consists of feed antenna, radome, planar FSS array or curve conformal array. Microstrip antenna is used as the feed antenna. Based on the principle of equispaced and equal period respectively, cross units loading single layer dielectric form planar and curve FSS array. The FSS radome system can improve the permeability of hood to electromagnetic waves (EM) of passband, and reduce the interference of complex EM in the external environment to the system. The FSS radome will not deteriorate radiation characteristics of the feed antenna. The planar FSS radome has a passband of 98.2 GHz to 101.55 GHz with -10dB relative bandwidth of 3.35%. The curve FSS radome has a passband of 96.3 GHz to 101.8 GHz with -10dB relative bandwidth of 5.5%. In addition, the radiation characteristics of the proposed system are analyzed. It is found that the radiation pattern of the antenna is basically consistency before and after loading the radome.

Conformal Array Geometry for Hemispherical Coverage

Conformal arrays may be a viable solution in many antenna applications requiring a wide angular coverage with sufficiently high directivity values, so it is worth comparing different 2D conformal array geometries to satisfy these requirements. To this end, first, the singular value decomposition (SVD) of the radiation operator is exploited to determine the maximum directivity values an array can reach in the whole observation domain. A numerical study based on the maximum directivity and, hence, on the SVD is then proposed to select the array geometry complying with some given requirements. Therefore, the performances achievable by some array geometries (a semi-circumference, a trapezoidal, and an angle array) are analyzed, and the one assuring a better hemispherical coverage is suggested. Furthermore, such an SVD-based study is usefully exploited to determine which panels of a multi-faceted array must be fed to reach some assigned specifications.