In the first part, the scattering characteristics of an isolated dielectric coated conducting rod have been investigated. The types of considered coatings for the scattering analysis are realistic materials including barium strontium titanate, magnetodielectric, gallium arsenide, and silicon carbide. It is found that the gallium arsenide coating can be used to significantly reduce the scattering from a thin perfectly electric conducting cylindrical rod at specific observation angles. In the second part, the effective permittivity and permeability of metamaterials composed of two dimensional periodic arrangements of these dielectric coated conducting cylindrical rods have been studied. An increase in the double negative (DNG) bandwidth of a metamaterial composed of barium strontium titanate coated conducting rods has been observed in contrast to the corresponding bandwidth of a metamaterial composed of only barium strontium titanate material rods. Also an additional plasmonic epsilon negative (ENG) bandwidth has been found in case of a metamaterial composed of barium strontium titanate coated conducting rods. It is further studied that the widest ENG, mu negative, and DNG bandwidths exist for a metamaterial composed of gallium arsenide rods.

A solution to the problem of Gaussian beam scattering by a circular perfect electric conductor coated with eccentrically anisotropic media is presented. The incident Gaussian beam source is expanded as an approximate expression in the simple form with Taylor's series. The transmitted field in the anisotropically coated region is expressed as an infinite summation of Eigen plane waves with different polar angles. The unknown coefficients of the scattered fields are obtained with the aid of the boundary conditions. The addition theorem for cylindrical functions is applied to transfer from the local coordinates to the global ones. The infinite series can be truncated under the prerequisite of achieving the solution convergence. Only the case of transverse-electric polarization is discussed. The similar formulation of transverse-magnetic polarization can be obtained by adopting a similar method. Some numerical results are presented and discussed. The result is in agreement with that available as expected when the eccentric geometry comes to the concentric one.

This paper presents a novel dual-band (DB) dual-polarized (DP) shared aperture antenna with high isolation by using a combination of microstrip dipoles and dielectric resonator antennas (DRAs) for S and C bands, respectively. In the S band, two sets of proximity coupled stacked microstrip dipoles which crossed at the center are employed to achieve dual-linear polarization (DLP) and obtain desired bandwidth (BW), isolation, and pure polarization. The rectangle DRA with hybrid feed is selected as the C band element for its advantages of small base area and high isolation, and a 2 × 2 array is presented with the “pair-wise” anti-phase feed technique to achieve a low cross-polarized level. Moreover, benefited from the back feed scheme, the proposed antenna has a symmetrical structure and has the potential of expanding into a larger aperture. The proposed antenna has been manufactured and measured, and the results agree well with simulations, which prove the validity of the proposed design.

This paper presents a notched band ultra-wideband bandpass filter using a single perturbed quint-mode half-mode substrate-integrated waveguide cavity. The cavity is perturbed by loading four stubs at two corners of the magnetic walls of the single cavity. The variable parameters of stubs are selected to move down the first five resonant modes to the predetermined passband during the design process. Meanwhile, microstrip lines with a transition structure located on two loaded stubs are employed to feed the resonator. Moreover, the filter also firstly designs a notched band by introducing a complementary split-ring resonator inside the cavity to mitigate potential interference signals at 8 GHz (satellite communication). Finally, a prototype filter was implemented and measured to verify.

In this work, we proposed an adaptive beamformer based on a novel heuristic optimization algorithm. The novel optimization technique inspired from Fibonacci sequence principle, designated as Fibonacci branch search (FBS), used new tree's branches fundamental structure and interactive searching rules to obtain the global optimal solution in the search space. The branch structure of FBS is selected using two types of multidimensional points on the basis of shortening fraction formed by Fibonacci sequence; in this mode, interactive global and local searching rules are implemented alternately to obtain the optimal solutions, avoiding stagnating in local optimum. The proposed FBS is also used here to construct an adaptive beamforming (ABF) technique as a real-time implementation to achieve near-optimal performance for its simplicity and high convergence rate, then, the performance of the FBS is compared with the five typical heuristic optimization algorithms. Simulation results demonstrate the superiority of the proposed FBS approach in locating the optimal solution with higher precision and reveal further improvement in the ABF performance.

To prevent far-field radiation characteristics degradation while increasing bandwidth, an attempt has been made to design and fabricate a microstrip antenna. An electromagnetic band gap (EBG) structure, including a layer of a metallic ring on a layer of Rogers 4003C substrate, is used. For a better design, a patch antenna with and without the EBG substrate has been simulated. The results show that the bandwidth can be improved up to 1.6 GHz in X-band by adding the EBG substrate. Furthermore, using this structure, a dual-band antenna was obtained as well. Finally, to validate the simulation results, a comparison has been done between simulation data and experimental results which demonstrate good agreement.

A bidirectional dielectric resonator (DR) antenna array using back-to-back quasi-Yagi antenna configuration is proposed and implemented for the first time. The DR operating at higher-order TE3δ1 mode is used as a magnetic dipole, applying for the driver of quasi-Yagi antenna. Due to the high-order mode employment, the antenna gain can be enhanced. By partially loading the metallic strip on the side wall of the DR, the gain can be further enhanced. In addition, a simple dual Marchand balun is constructed for feeding the two quasi-Yagi antennas directly for bidirectional radiation. To verify the design concept, a prototype operating at the X-band is fabricated and measured. Good agreement between the simulated and measured results can be observed.

In this paper, a high gain wideband circularly polarized (CP) microstrip antenna is presented for broadband operation. The proposed structure comprised of a partially grounded printed monopole antenna loaded with a split ring resonator and a metallic reflector. By using the metallic reflector surface underneath the patch radiator results in the reflected waves in the same phase with main lobe radiation, thereby improving the gain and it also acts like a secondary radiator to generate wideband CP behavior in the proposed design. A gain enhancement of 4.3 dBi is achieved in the operating frequency band as compared with the design without a metallic reflector. The maximum gain achieved in the presented method is 8.6 dBic over the entire operating range. The proposed design shows a wideband behavior ranging from 4.30 to 9.10 GHz with the 10-dB impedance bandwidth of 71.64%. In addition, the proposed design yielded a broadside right hand CP radiation with a 3-dB axial ratio bandwidth of 33.88% from 4.98 to 7.01 GHz. The proposed antenna is fabricated and experimental results on reflection coefficient, gain, axial ratio, and radiation patterns concede well with simulation results.

In this paper, an antenna-to-antenna method to design high-efficiency polarization converters was proposed. Two in-linked split ring resonators (SRRs) were used as the fundamental unit cell, which can effectively make the original linear polarization angle deflected into a customized one (include but not limited to 90°). The same as the process of energy reception and transmitting of microstrip symmetric dipole antennas, the top SRR plays the role of a receiving antenna and the bottom one acts as a transmitting antenna. Under normal illumination, the strong coupling between electric resonance and magnetic resonance can result in high transmission and broad bandwidth. Since the two SRRs act as two independently polarization selective components, the polarization angle of transmitted waves can be easily controlled by rotating the transmitting SRRs around the center. The proposed concept and the design method are validated using numerical simulations, as well as experimental results of three examples for 45, 60 and 90° polarization angle rotation, the polarization conversion ratio of which is about 92.2, 88.9 and 91.9% from 7.5 to 10 GHz.