Theory and experiment of a coaxial probe fed hemisphericaldielectric resonator antenna

A hemispherical dielectric resonator antenna fed by a coaxial probe is studied both theoretically and experimentally. The Green's function for the evaluation of the input impedance is derived rigorously and expressed in a form convenient for numerical computations. The method of moments is used to obtain the probe current from which the input impedance of the DR antenna is calculated. Both delta gap and magnetic frill source models are considered. Moreover, the results using a reduced kernel as well as the exact kernel are presented. Both entire basis (EB) and piecewise sinusoidal (PWS) expansion modes are used and the results are compared. The effects of the probe length, feed position, and dielectric constant on the input impedance are discussed. Finally, the theoretical radiation patterns for the first three resonant modes (TE₁₁₁, TM₁₀₁, and TE₂₂₁) of the DR antenna are presented     

Impedance matching of tapered slot antenna using a dielectrictransformer

A new impedance matching technique for tapered slot antennas using a dielectric transformer is presented. The technique is demonstrated by measuring the input impedance, VSWR and the gain of a Vivaldi antenna (VA). Measured results at Ka-band frequencies are presented and discussed     

Broadband CPW fed stacked patch antenna

A broadband CPW fed stacked patch antenna well suited for integration with monolithic and optical integrated circuits is presented. The antenna is designed with a bandwidth of 40% on a high dielectric constant feed substrate. The predicted and measured input impedance and far field radiation patterns are given     

FDTD analysis of probe-fed cylindrical dielectric resonator antenna

The finite-difference time-domain (FDTD) method is employed to analyze a probe-fed cylindrical dielectric resonator antenna. Numerical results for the input impedance and radiation patterns of the dielectric resonator (DR) antenna operating in HEM_11δ mode are presented and compare favorably with measurements. The effects of various parameters on the characteristics of the DR antenna are studied. Fabrication imperfection effects and the cross-polarization characteristics of this type of DR antenna are also investigated for the first time     

Modeling of a monopole partially buried in a grounded dielectricsubstrate by the modal expansion method

The input impedance of a monopole antenna partially buried in an infinite grounded dielectric substrate and fed by a coaxial transmission line is calculated by the modal expansion method. The effect of the dielectric substrate on the antenna's radiated power and input impedance is numerically examined     

New analytical input impedance calculation for fast design of printed narrow slot antenna

In this article, fast and simple closed-form relations are presented to calculate input impedance of filamentary-excited printed narrow slot antenna on electrically thin dielectric substrate near to half wavelength resonance frequency. This antenna is a complementary structure of thin printed dipole antenna. The obtained formulations have been verified numerically by a commercially available full-wave electromagnetic simulator and then a prototype antenna has been produced. Experimental measurements are realised on the antenna and these measurement values of input impedance also have verified analytical relations and numerical simulations. It is shown that analytical, numerical and experimental results are close to each other. Therefore, these relations can be utilised as an initial design step just before making detailed numerical analyses. Besides, the given relations can be easily realised in CAD-oriented platforms for fast calculations.     

Input impedance of a probe-fed circular microstrip antenna with thick substrate

A method of computing the input impedance for the probe fed circular microstrip antenna with thick dielectric substrate is presented. Utilizing the framework of the cavity model, the fields under the microstrip patch are expanded in a set of modes satisfying the boundary conditions on the eccentrically located probe, as well as on the cavity magnetic wall. A mode-matching technique is used to solve for the electric field at the junction between the cavity and the coaxial feed cable. The reflection coefficient of the transverse electromagnetic (TEM) mode incident in the coaxial cable is determined, from which the input impedance of the antenna is computed. Measured data are presented to verify the theoretical calculations. Results of the computation of various losses for the circular printed antenna as a function of substrate thickness are also included.     

Resonance properties of dielectric-loaded short unipoles

Measurements are presented that show that the input impedance of a coaxially fed short unipole can be brought to resonance by encasing the antenna in a slab of high-permittivity dielectric material. The physical action and likely application of this new antenna configuration are discussed.     

On the modeling of metal strip antennas contiguous with the edge ofelectrically thick finite size dielectric substrates

A solution to the problem of radiation by a narrow metal strip antenna contiguous with the edge of a dielectric substrate is presented where the substrate has parameters such that its electrical thickness is appreciable. Such an antenna may be useful at millimeter wavelengths as an integrated phased array element forming a part of a monolithic microwave integrated circuit (MMIC). A suitable geometry for this application is illustrated and an efficient computational procedure developed. Comparisons with experimental results for the input impedance and far-field radiation patterns show excellent agreement. The influence of the dielectric substrate on the performance of an antenna designed to operate at approximately 60 GHz is discussed. Two examples, the first involving the analysis of a coplanar strip transmission line fed antenna and the second involving impedance matching and control of cross-polarized radiation using a folded strip dipole, are given to illustrate practical applications of the analytical method to design problems     

Cavity-backed slot-coupled dielectric resonator antenna excited bya narrow strip

The input impedance of the cavity-backed slot-coupled dielectric resonator antenna excited by a slender strip is investigated theoretically and experimentally. The effect of the cavity size and strip length on the input impedance are studied and discussed     

Input impedance of aperture coupled hemispherical dielectric resonator antenna

A hemispherical dielectric resonator (DR) antenna fed by a microstripline through an aperture on the ground plane is investigated both theoretically and experimentally. The broadside TE/sub 111/ mode input impedance of the antenna configuration is evaluated, and reasonable agreement between theory and experiment is obtained. The effects of the slot length and the slot width on the input impedance are studied and discussed.<>     

Moment method analysis of infinite stripline-fed tapered slotantenna arrays with a ground plane

A full-wave method of moments solution for infinite arrays of stripline-fed tapered slot antennas is described. The formulation of the problem is sufficiently general to permit performance evaluation of most of the geometries that have been proposed for stripline-fed antennas as well as of several other types of array antennas. Computed results for some well-known antenna arrays are presented to demonstrate the validity and accuracy of the method. Excellent agreement with published results has been obtained for scattering from corrugated surfaces and grounded dielectric slabs and for the input impedance of dipole and monopole arrays. Catastrophic effects such as scan blindness are accurately predicted. A sample result showing the measured and computed input impedance of a stripline-fed tapered slot antenna array is also presented     

FDTD法计算高频单极天线特性

用时域有限差分法（Ｆｉｎｉｔｅ Ｄｉｆｆｅｒｅｎｃｅ Ｔｉｍｅ Ｄｏｍａｉｎ Ｍｅｔｈｏｄ）计算天线阻抗特性,可以使用不同的激励方式,文章比较了采用不同激励方式时,天线的输入阻抗。文中的主要内容是将表面阻抗法用于ＦＤＴＤ中,计算架设在介质平面上单极天线的辐射特性,并用ＦＤＴＤ法计算了介质平面上铺设不同尺寸的导体平面时,单极天线的输入阻抗随导体平面尺寸变化的特性。     

Resonant hemispherical dielectric antenna

An antenna consisting of a resonant dielectric hemisphere on top of a ground plane is investigated. Calculations of the internal and external fields are made with emphasis on the lowest-order mode that results in efficient radiation in the direction perpendicular to the ground plane. Measured input impedance data are also presented for a practical radiator.     

Input impedance and mutual coupling of rectangular microstrip antennas

A moment method solution to the problem of input impedance and mutual coupling of rectangular microstrip antenna elements is presented. The formulation uses the grounded dielectric slab Green's function to account rigorously for the presence of the substrate and surface waves. Both entire basis (EB) and piecewise sinosoidal (PWS) expansion modes are used, and their relative advantages are noted. Calculations of input impedance and mutual coupling are compared with measured data and other calculatious.     

An integral equation and its application to spiral antennas onsemi-infinite dielectric materials

This paper presents an integral equation that can handle wire antennas on a semi-infinite dielectric material. The integral equation is reduced to a set of linear equations by the method of moments. For efficiency, the impedance matrix element Z_m,n is divided into two parts on the basis of weighted Green's function extractions. The far-zone radiation field, which is formulated using the stationary phase method, is also described. After the validity of the presented numerical techniques is checked using a bow-tie antenna, a spiral antenna is analyzed. The current distribution, radiation pattern, axial ratio, power gain, and input impedance are discussed. It is found that the radiation field inside a dielectric material is circularly polarized. As the relative permittivity of the dielectric material increases, the angle coverage over which the axial ratio is less than 3 dB becomes narrower     

Simple result for conformal-strip excited hemispherical dielectric resonator antenna

A simple result for the input impedance of a conformal-strip excited hemispherical dielectric resonator antenna is presented for the first time. The result involves only simple algebraic operations and thus, should be useful to the design engineer. The limitation of the result is discussed and explained.     

Effect of air gap on cylindrical dielectric resonator antenna operating in TM/sub 01/ mode

The results of a numerical study on the effect of an air gap on the input impedance and resonance frequency of a cylindrical dielectric resonator (CDR) antenna operating in the TM/sub 01/ mode as a function of dielectric constant are presented. The CDR resides on a conducting ground plane and is excited by a coaxial probe through the bottom of the ground plane. Some of the numerical results are validated experimentally.<>     

Calculation of the input impedance of a strip loop antenna located on a dielectric cylinder

A method for calculating the input impedance of a loop antenna (LA) located on a dielectric cylinder is developed. The integral equation (IE) for the unknown function of the current density distribution on the LA surface is obtained. A numerical method for the IE solution is described. An approximate formula for calculation of the LA input impedance is proposed. Plots of the input impedance on the LA length are given.     

介质覆盖矩形微带天线的理论与实验

本文研究了介质覆盖矩形微带天线的特性，精确的谱域全波分析方法被扩展到这类天线的分析中，给出了理论计算公式，探讨了介质覆盖层和对矩形微带天线的驻波比的影响，实验结果证实了理论计算的正确性。