Abstract-A novel robust adaptive beamforming method for conformal array is proposed. By using interpolation technique, the cylindrical conformal array with directional antenna elements is transformed to a virtual uniform linear array with omni-directional elements. This method can compensate the amplitude and mutual coupling errors as well as desired signal point errors of the conformal array efficiently. It is a universal method and can be applied to other curved conformal arrays. After the transformation, most of the existing adaptive beamforming algorithms can be applied to conformal array directly. The efficiency of the proposed scheme is assessed through numerical simulations.

Abstract-A fast and simple parameter estimation algorithm, joint azimuth angles, elevation angles and polarization parameters of incident sources for an arbitrary conformal array is proposed. Based on 2-D Discrete Fourier Transform (2-D DFT), the computational complexity can be reduced significantly compared with traditional 2-D space-search MUSIC or polynomial rooting (search-free) methods. The antenna elements can be mounted on arbitrary curved surfaces or platforms. Conformal array characteristics, such as directional radiation patterns of the elements and polarization are taken into consideration. Numerical simulations based on real-world conformal arrays are provided to demonstrate the performance of the proposed method.

Conventional beamformers suffer from problems of finite samples, desired signal pointing errors, as well as imperfect array. A simple and robust beamformer based on the manifold separation technique (MST) is proposed in this letter to alleviate these problems. Using MST, the steering vector of an arbitrary array can be modeled as the product of an array sampling matrix and a vector with a Vandermonde structure. Robust characteristics are found by using this transformation. The analysis is verified via simulations based on a real-world semispherical conformal antenna array.Index Terms-Conformal antenna array, manifold separation technique (MST), robust beamformer.

A novel compact multi-band frequency selective surface (FSS) with dual passbands and wide upper stopband is presented. The proposed FSS was originally a double-layer structure. The grid-double square loops (G-DSLs) are located at the bottom to achieve the dual passband characteristics. In order to realize wide upper stopband, a modified square ring and a Jerusalem cross (M-SR-JC) element structure at top and bottom are used. Considering the higher power engineering applications, the final FSS uses a multi-layer structure. The FSS provides two pass-bands centered at 3.8 and 5.8 GHz with relative bandwidths of 18.4% and 13.5%, respectively. It also provides wide stopband characteristics from 10.8 GHz to 14.5 GHz. The simulation and measurement are in good agreement. The novel FSS with dual passbands and wide upper stopband is compact; easy to design and fabricate, and achieves relatively stable multi-band response under different polarization states and different incident angles. The proposed FSS can better meet the engineering requirements.