Asymptotic extraction approach for antennas in a multilayered spherical media

An efficient algorithm is introduced to enhance the convergence of dyadic Green's functions (DGF) in a layered spherical media where asymptotic expressions have been developed. The formulated expressions involve an infinite series of spherical eigenmodes that can be reduced to the simple homogenous media Green's function using the addition theorem of spherical Hankel functions. Substantial improvements in the convergence speed have been attained by subtracting the asymptotic series representation from the original DGF. The subtracted components are then added to the solution using the homogenous media Green's function format

Moment method analysis of an archimedean spiral printed on a layered dielectric sphere

A method of moments model is presented to analyze Archimedean spirals that are printed on a layered dielectric sphere. The model is derived assuming an arbitrary location of the spiral. Input impedance, current distribution and far-field results are presented and are shown to be in good agreements with other methods

A generalized asymptotic extraction solution for antennas in multilayered spherical media

An efficient model is developed to accelerate the convergence of the dyadic Green's function's (DGF) infinite summation when the source and observation points are placed in different layers of a dielectric sphere, thereby expediting computational analysis. The proposed procedure is based on asymptotic extraction principles in which the quasi-static images are extracted from the spectral domain DGF. The effectiveness of the approach is demonstrated in a method of moment model where a microstrip antenna as well as a conformal dipole array have been studied

Electromagnetic radiation by antennas of arbitrary shape in a layered spherical media

A unified method of moments model is developed for the analysis of arbitrarily shaped antennas that are radiating next to a multilayered dielectric sphere. The curvilinear Rao-Wilton-Glisson triangular basis functions and dyadic Green's functions have been used in the model. Antennas of various geometries including spherical, circular and rectangular microstrip antennas as well as hemispherical dielectric resonators have been modeled. Input impedance and radiation pattern results are presented and shown to be in good agreement with published data

Circularly polarized dielectric resonator antenna excited by a conformal wire

A conformal spiral wire has been used to feed a dielectric resonator antenna to obtain a circular polarization. The parameters of the spiral have been optimized numerically so that minimum axial ratio (AR) and return losses are achieved. The method of moments (MoM) has been used in the analysis and the results have been validated against those from a commercial software package with a good agreement

A singly fed rectangular dielectric resonator antenna with a wideband circular polarization

A rectangular dielectric resonator antenna (DRA) that is excited using an outer-fed square spiral strip has been studied theoretically and experimentally. Utilizing such excitation has provided a circular polarization over a broad bandwidth of ${sim 14}$ in conjunction with an impedance-matching bandwidth of ${sim 11}$. The structure has been rigorously modeled using a method of moments (MoM) model. A good agreement has been attained between computed and measured results

An efficient asymptotic extraction approach for the green's functions of conformal antennas in multilayered cylindrical media

Asymptotic expressions are derived for the dyadic Green's functions of antennas radiating in the presence of a multilayered cylinder, where analytic representation of the asymptotic expansion coefficients eliminates the computational cost of numerical evaluation. As a result, the asymptotic extraction technique has been applied only once for a large summation order $n$. In addition, the Hankel function singularity encountered for source and evaluation points at the same radius has been eliminated using analytical integration

High Input Resistance Terahertz Dipole Antenna With an Isolating Photonic Band Gap Layer

A terahertz dipole antenna with a high input resistance is proposed by minimizing the effects of the supporting GaAs substrate using a two dimensional photonic band gap (PBG) layer. In additio, special attentions have been given to the choice of PBG unit cell dimensions so that the photo-mixer is illuminated by the two laser beams with no obstruction. An electromagnetic simulator has been used to optimize the antenna, and its resistance is ~2.7kΩ

A High Gain Pattern Reconfigurable Micro-strip Dipole Antenna with a Gain Enhancing Partially Reflecting Surface

A beam reconfigurable antenna with high gain is presented with low complexity switching capability. The design consists of a printed dipole antenna with reconfigurable parasitic elements that are combined with a partially reflecting surface (PRS) to provide main lobe radiation pattern switching between boresight and close to end-fire at an operating frequency of 1.81GHz. The reconfigurability is achieved using only two PIN diodes and the measured gain of the antenna is 8.5dBi gain at boresight and 14.3dBi towards the end-fire direction

Wideband mm-wave hemispherical dielectric resonator antenna with simple alignment and assembly procedures

A wideband hemispherical dielectric resonator antenna (DRA) with enhanced gain is proposed for a frequency band of 20 to 28 GHz. The precise alignment and assembly of the DRA represent key challenges at such frequencies that were addressed using three approaches: the first was based on outlining the DRA position on the ground plane, the second involved creating a groove in the compound ground plane in which the DRA is placed, and the third was based on the 3D-printing of the DRA on a perforated substrate. In all cases, the same DRA was utilized and excited in a higher-order mode using an annular ring slot. The high gain was achieved by exciting a higher-order mode, and the wideband was obtained by merging the bandwidths of the two excited modes. The alignment methods used expedite the DRA prototyping by saving substantial time that is usually spent in adjusting the DRA position with respect to the feeding slot. The proposed configurations were measured, with an impedance bandwidth of 33.33% and a maximum gain of 10 dBi observed. Close agreement was achieved between the measured and simulated results