Jing-Li Guo

Pattern Synthesis of Conformal Array Antenna in the Presence of Platform Using Differential Evolution Algorithm

A synthesis method based on differential evolution algorithm is proposed for conformal antenna arrays in the presence of platform. With the desired phase weights determined by the scan angle and array geometry, the amplitude weights of elements are optimized by differential evolution algorithm to drive down the side-lobes. Both the effect of platform on radiation pattern of conformal array and the mutual coupling between the elements are taken into account by calculating the antenna array and platform simultaneously using the method of moment. Application of adaptive integral method reduces the storage and computation time needed by the method of moments.

A Swallow-tailed Wideband Planar Monopole Antenna with Semi-elliptical Base

A novel swallow-tailed wideband planar monopole antenna with semi-elliptical base is presented. The impedance and radiation properties of the proposed monopole antenna are investigated experimentally. The study indicates that the proposed monopole antenna yields the maximum bandwidth from 1.22 GHz to more than 15 GHz for VSWR<2 with the optimum ellipticity ratio of the antennas semi-elliptical base and the height of the feeding post. The radiation performance is also discussed and shown to be acceptable over a wide frequency range.

The Tri-Band Performance of Sleeve Dipole Antenna

In this paper broadband characteristics of sleeve antenna are analyzed using the Method of Moments. The sleeve antennas property of three frequency bands is investigated. The first and third operating bands come from the driven dipole, while the second operating band is due to the height of the sleeve and the distance between the driven dipole and the sleeve. Some numerical results are presented and discussed.

Fast and Accurate Wide-Band Analysis of Antennas Mounted on Conducting Platform Using AIM and Asymptotic Waveform Evaluation Technique

The adaptive integral method (AIM) in conjunction with the asymptotic waveform evaluation (AWE) technique is presented for wide-band analysis of antennas in the presence of electrically large conducting platforms. In the AWE technique, the Padé approximation solution obtained by matching the coefficients of the Taylor series (namely, moments) is utilized to achieve fast frequency sweeping. Besides the calculation and storage of the high order frequency derivatives of impedance matrices, the AWE technique requires repeatedly solving the linear system for the moments. Thus the AIM is employed to reduce matrix storage and to accelerate all the matrix-vector multiplications in both the linear system for the moments and the iterative solver. Furthermore, a localized self-box inclusion (SBI) preconditioner is used to accelerate the solution procedure of the linear system for the moments. Finally, three numerical examples are given and discussed. The input admittance and return loss of the antennas over a given frequency band are obtained by AIM and AIM-AWE method, respectively. The good agreements show that the proposed hybrid technique can greatly reduce the computation time without loss of accuracy.

Analysis of Antenna Array with Arbitrarily Shaped Radomes Using Fast Algorithm Based on VSIE

The moment method (MoM) based on volume-surface integral equation (VSIE) combined with the adaptive integral method (AIM) is applied to analyze antenna array radiation in the presence of arbitrarily shaped radomes. The application of AIM reduces the computational complexity of MoM, which leads eclectically large-sized radomes with metal reflecting ground can be analyzed accurately and efficiently. Some radomes terminated by metal plane is presented and the effect of the metal plane on the radiation of antenna is analyzed.

Electromagnetic analysis of coupled conducting and dielectric targets using MoM with a PRE-conditioner

An effective pre-conditioner for the method of moments (MoM) solution to the coupled volume-surface integral equation is presented to calculate electromagnetic scattering from conducting and dielectric targets. In this MoM solution to the integral equations, the target is discretized using triangular patches for conducting surfaces and tetrahedral cells for dielectric volume. Based on the characteristics of impedance matrix, an accurate method is used to improve the convergence speed when the iterative solver is employed. In comparison with other pre-conditioners, some numerical examples are also presented with high efficiency.

Fast Analysis of Body-of-Revolution Radomes with Method of Moments

By taking advantage of the rotational symmetry, the electromagnetic characteristic of the body of revolution (BOR) radome is fast analyzed by the method of moments (MoM) based on the mode decomposition technique. First, the MoM matrix equation governed by the surface integral is established and the theoretical model is reduced in dimension by using the mode decomposition technique in view of the objects structure characteristic. Then, the integrals in the mode decomposition of the incident field are replaced by the fast Fourier transform (FFT), thus the decomposition coefficients of all modes on a given annulus can be fast and easily obtained through one FFT. Due to the surface equivalent electric and magnetic currents gotten by solving the matrix equations having the form of superposition of mode components, the analytical approach is used to substitute for the integral in the calculation of the far field pattern, so the computing time is greatly reduced. Examples are presented to demonstrate the accuracy and efficiency of the proposed method in this paper.

A New Fitness Function for Optimizing the Matching Network of Broadband Antennas by Genetic Algorithm

A new fitness function for the genetic optimization of broadband antennas is proposed. Compared with the previous fitness functions, the one presented in this paper takes not only voltage standing wave ratio and gain but also frequency into consideration. In practical communication system, higher gain needed in the high frequency band of the antenna, so it is more suitable. An impedance matching network for an antenna in 30 MHz to 88 MHz is studied lastly.

Wideband and Omni-Directional Antenna for DVB/GSM Applications

A novel planar monopole antenna for the digital video broadcasting (DVB) signal reception in the UHF band (470–862 MHz) and mobile communications in the GSM850/900 band (824–960 MHz) is presented. The proposed antenna consists of a modified planar monopole and a rectangular ground plane with two planar sleeves. By adjusting the sleeves, a wide bandwidth can be obtained easily. The influence of various parameters on antenna characteristics has been investigated. Simulated and measured results show a wide bandwidth of 735 MHz (465 MHz–1.20 GHz) with the VSWR less than 2.0 and omni-directional radiation properties. Details of the proposed antenna design and experimental results of the constructed prototypes are presented

Dual-Band Slot Helix Antenna for Global Positioning Satellite Applications

A slot helix antenna working in Global Positioning System (GPS) L1 and L2 bands is proposed in this paper. Adopting sequential rotation technique, the proposed antenna is equipped with six helix radiation arms and fed by a microstrip line with folded shape. The whole antenna can be built on a full printed circuit board; so, it is easy to process the proposed antenna. The circularly polarized radiation mechanism of a circular array is analyzed in a new perspective to guide the design. A double-faced slot radiation structure is also established for dual-band operation. Additionally, a traveling wave feeding network suitable for the proposed antenna is presented. The experimental results show that the proposed antenna has good properties in GPS L1 and L2 bands.