Circular Microstrip Disk Antenna Research Articles

Study of Stacked High Tc Superconducting Circular Disk Microstrip Antenna in Multilayered Substrate Containing Isotropic and/or Uniaxial Anisotropic Materials

In this paper, we present a rigorous full-wave analysis able to estimate exactly the resonant characteristics of stacked high Tc superconducting circular disk microstrip antenna. The superconducting patches are assumed to be embedded in a multilayered substrate containing isotropic and/or uniaxial anisotropic materials (the analysis is valid for an arbitrary number of layers). London’s equations and the two-fluid model of Gorter and Casimir are used in the calculation of the complex surface impedance of the superconducting circular disks. Numerical results are presented for a single layer structure as well as for two stacked circular disks fabricated on a double-layered substrate.

A Circular Disc Microstrip Antenna with Dual Notch Band for GSM/Bluetooth and Extended UWB Applications

A microstrip antenna with a circular disc design and modified ground is proposed in this paper. Circular shapes of different size have been slotted out from the radiating patch for achieving extended ultra wideband (UWB) with GSM/Bluetooth bands with maximum bandwidth of 17.7 GHz (0.88-18.6 GHz). Further, characteristic of dual notch band is achieved, when a combination of T and L-shaped slots are etched into the circular disc and ground plane respectively. Change in length of slots is controlling the notch band characteristics. The proposed antenna has rejection bandwidth of 1.3-2.2 GHz (LTE band), 3.2-3.9 GHz (WiMAX band) and 5.2-6.1 GHz (WLAN band) respectively. It covers the frequency range of 0.88-18.5 GHz with the VSWR of less than 2. Also, an equivalent parallel resonant circuit has been demonstrated for band notched frequencies of the designed antenna. The gain achieved by the proposed antenna is 6.27 dBi. This antenna has been designed, investigated and fabricated for GSM, Bluetooth, UWB, X and Ku band applications. The stable gain including H & E-plane radiation pattern with good directivity and omnidirectional behavior is achieved by the proposed antenna. Measured bandwidths are 0.5 GHz, 0.8 GHz, 1.1 GHz and 11.7 GHz respectively.

Design of a Circular Disc Microstrip Antenna Loaded By Annular Ring

The research contained in this thesis is a theoretical study of antenna design and calculation of the radiation fields using electric fields integral equation (EFIE) and magnetic field integral equation (MFIE). These equation have been converted, using the method of moments formulation of electromagnetic radiation in this these based onthe bodies of revolution (BoR),which are generated by revolution a planar curve about an axis called axis of symmetry. To find an unknown electric current density on the surface of the conductor ,and both unknowns electric and magnetic density current on the surface of the dielectric which are responsible for the generation of radiationfields in the space for the components (Eθ ,Eφ) ,the surface currents was represented by a set of basis functions that give the Fourier series because the body has a circular symmetry property and then select a set of weighted functions to find a linear system by using Galerkin method which requires that the weighted functions are equal to the complex conjugate of the current JW = )( * .

Analysis and Design of the Circular-Disk Microstrip Antenna with a Shorting Pin

In this paper, a special circular-disk microstrip antenna is discussed, and the cavity-mode solution is given. The influence of the shorting pin on the resonance frequency is discussed, and a formula for the approximate calculation of k is presented. The results of simulation using Ansoft's HFSS and calculations of the main mode are presented through several design examples, and the results were a good fit. The results showed that this novel method is particularly applicable to the design of feeds for double-deck or multilayer microstrip antennas.

Resonant Frequency of Air Gap Tuned Circular Microstrip Antenna with Anisotropic Substrate and Superstrate Layers

Resonant frequency characteristics of air gap tuned circular microstrip antenna with uniaxially anisotropic substrate and superstrate layers is analysed in Hankel Transform domain using recursive equivalent circuit modelling. The effects of uniaxial anisotropy on the resonant frequency are investigated as the function of anisotropy ratio values of substrate and superstrate materials. According to the results, resonant frequency of anisotropic antenna exhibits incremental or decremental shifts with respect to isotropic one due to adjustment of the layer anisotropies and the thickness of the air gap. Thus, it is important to properly adjust layer anisotropies of the circular disk microstrip antenna for its efficient operation in microwave and communication systems applications.

Comparison of the Radiation Efficiency for the Dielectric Resonator Antenna and the Microstrip Antenna at Ka Band

The radiation efficiency of a dielectric resonator antenna (DRA) and a microstrip antenna (MSA) at Ka band is investigated numerically and experimentally. For direct comparison, one cylindrical DRA and one circular disk MSA were designed with similar feeding networks for operation at around 35 GHz. The efficiency of both devices was measured using the directivity/gain (D/G) method and the Wheeler cap method, in both of which the losses in the test system and the feeding structure were taken into account for calibration purposes. A good agreement between measured and simulated results for both methods is found, when considering the effect of the sampling interval and cross-polarization in the D/G method and the effect of the metallic cap size in the Wheeler cap method. It is finally demonstrated that the radiation efficiency of the DRA is significantly higher than that of the MSA at millimeter wave frequencies.

A Novel Broadband Compact Circular Disk Microstrip Antenna for Wireless Applications

A novel shape of microstrip antenna which is electromagnetically coupled to a conventional circular disk microstrip antenna (CMSA) mounted on a ground plane and spaced by a layer of foam is studied by simulation and experiment to operate at 5.2GHz for Wireless Local Area Networks (WLANs). The novel shape proposed has a size reduction of 85% as compared to the conventional circular disk patch antenna operating at the same frequency. It is found that the bandwidth of this antenna ranges from 4.8GHz up to 6.15GHz considerably when an optimum foam thickness is provided. The suggested design is optimized using the full wave simulation software package Zeland IE3D based on the method of moments (MoM). The experimental results agree well with the simulated one. Microstrip antennas have the attractive features of low proflle, light weight, easy fabrication pro- cess, and conformability, but these antennas inherently sufier from the narrow bandwidth. Since the world is going wireless, current advancements in communication technology and signiflcant growth in the wireless communication market and consumer demand demonstrate the need for smaller, broadband and reliable antennas. Therefore, bandwidth enhancement and size reduction are becoming the major design considerations for practical applications. Several useful techniques applied to improve the bandwidth and size reduction are presented in (1). In particular, adding a capacitive component to the input impedance of the radiating patch that compensate for the inductive component of the feeder by embedding a cutting slots in it such as E-shape (2,3), V- shape (4), and U-shape (5,6) leads to increasing the percentage bandwidth as long as the resonance frequencies of the patch and the slot are close to each other. Moreover, using more than one layer of resonance patch that is coupled electromagnetically to each other instead of planar structure in order to meet the demand of small size will efiectively enable the bandwidth to increase. These parallel layers are incorporated to introduce another resonance. Since the bandwidth is inversely proportional to the dielectric constant r of the substrate, a layer of foam is employed to decrease the efiective dielectric constant eff and increasing the total thickness of the antenna at the same time.

Computation and optimization of resonant frequency and input impedance of a coax‐fed circular patch microstrip antenna

AbstractMicrostrip antennas are important elements of today's wireless communication networks. In their various applications, it is critical to provide wide band operation around the resonant frequency providing good impedance match between the antenna element and the feed. In this study, new, simple, and accurate computation of resonant frequency and input impedance of double‐layered, coaxial fed circular disk microstrip antenna with air gap is performed. In the analysis, new effective radius and permittivity expressions are used in simple and modified form including modal effects. Then, a new approach is proposed to provide input impedance matching at resonant frequency via the application of microgenetic algorithm for wide band operation. The accuracy of theoretical calculations and impedance matching approach are presented for various structural parameters and operational modes of the antenna. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2263–2267, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22675

Resonant frequency of an air gap tuned circular disc microstrip antenna

In this study, the formulation and the computation of the resonant frequency of an air gap tuned circular disc microstrip antenna are simplified, with improved accuracy, by using a new and very simple effective permittivity expression which is valid for thin and thick gaps. Very good agreement between the theoretical and the experimental resonant frequency values is obtained for the various structural parameters and operational modes.

Proximity-coupled stacked circular-disc microstrip antenna with slots

The design and measured results of a proximity-fed stacked circular-disc antenna are described. The antenna has an impedance bandwidth of 26%, centred around 4.2 GHz, a gain of 8 dBi, and -30 dB cross-polarisation. An essential feature of the design is the presence of four linear slots in the bottom patch of the stacked arrangement.

Simple and Accurate Formula for the Resonant Frequency of the Circular Microstrip Disk Antenna

Simple and Accurate Formula for the Resonant Frequency of the Circular Microstrip Disk Antenna

Simple and accurate formula for the resonant frequency of the circular microstrip disk antenna

A simple algebraic formula for the resonant frequency of a circular microstrip disk antenna as a function of the effective radius and of the fringing capacitance has been derived which is valid for electrically-thick dielectric substrates. Accuracy of the theoretical results of resonance is compared with previous theories and measured data. >

Broadband characteristic of an offset aperture-coupled dual circular disk microstrip antenna

Offset aperture-coupled dual-patch microstrip antennas with rectangular or triangular patches have been demonstrated to have broadband characteristics . An aperture-coupled dual-patch circular disk microstrip antenna with offsetting is investigated experimentally. A 2:1 SWR bandwidth of ~37% is obtained. The radiation patterns and gain of the antenna are determined.

Input impedance of circular-disk microstrip antennas with a dielectric cover

A spectral-domain analysis of a coaxially fed circular-disk microstrip antenna with a dielectric cover is presented. Numerical results are given on input impedance, resonant frequency, and impedance bandwidth of the TM11 mode. It is found that the dielectric cover reduces the resonant frequency, decreases the resonant resistance, and increases the impedance bandwidth. © 1992 John Wiley & Sons, Inc.

Effect of Substrate on the Radiation Modes of a Circular Disk Microstrip Antenna

The effects of dielectric constant and thickness of substrate on the directional pattern of a circular microstrip disk antenna, excited at higher order modes, is studied theoretically using the stratified dyadic Green s function method based on reflection and transmission matrices. Substrate with dielectric constant ≈ 6 is found to give highest directional gain for 0.1 λ0 thickness value. It is suggested that the higher order modes such as TM13 mode can be effectively used in antenna arrays by a judicious choice of array synthesis.

Analysis of a probe-fed microstrip disk antenna

The input impedance of a probe-fed, annular-ring-loaded, circular-disk microstrip antenna is analysed using three methods of increasing complexity and sophistication. The first method uses a new variational formula which is more suitable for antennas driven by a voltage gap. The second method uses a mode-matching method where the field inside the coaxial line is expanded in terms of waveguide modes. The third method uses the mode-matching method with a diaphragm at the coaxial aperture. The mode-matching methods are identical to the variational formula under the single-mode approximation. However, when a diaphragm is present, the single-mode approximation is insufficient, implying that the variational formula is inaccurate when a diaphragm exists. The theory is used to study the effect of the gap capacitance at the coaxial aperture on the input impedance of the microstrip antenna. It is found that this gap capacitance is important when the dielectric substrate is thick.

Far field analysis of spherical-circular microstrip antennas by electric surface current models

The far field radiation patterns of a circular disk microstrip antenna mounted on a sphere are studied theoretically. The radiator is replaced by an assumed surface current distribution. The effects of the dielectric layer and the metallic sphere are rigorously taken into account by the spectral domain Green's function formulation. In the spectral domain represented by the vector Legendre series, the Green's function matrix is diagonal. The results are verified by comparison with results obtained from the cavity model theory. The cavity model agrees asymptotically with the present method for the case of a thin dielectric substrate.

Spectral domain analysis of microstrip antennas with an airgap

AbstractThe circular disk microstrip antenna with an airgap between the dielectric substrate and the ground plane is formulated using the spectral domain method. The complex resonant frequencies of the structure is determined using Galerkin's procedure. Some available experimental data are compared with the present method.

A ring cavity antenna of wide beamwidth

AbstractMobile telecommunication systems by satellite meet the requirement of antenna radiation pattern of wide beamwidth. The wide beamwidth of the circular microstrip disk antenna is obtained by high dielectric constant substrate. However, the dielectric losses and difficulty in manufacturing are problems for high dielectric constant materials.Wide beamwidth is obtained also using the antenna with an electrically small magnetic current loop.This paper presents the ring cavity antenna without dielectric materials. It also has electrically small magnetic current loop. Antenna characteristics calculated by the cavity model showed that the ring cavity antenna has wide beamwidth. Theoretical values are verified also by the measured radiation pattern and the input impedance.

Analysis of the annular-ring-loaded circular-disk microstrip antenna

A rigorous analysis of the natural resonance frequencies and input impedance characteristics of an annular-ring-loaded (ARL) circular-disk microstrip antenna is presented. Using vector Hankel transforms, the problem is formulated in terms of vector dual-integral equations. Galerkin's method is then used to solve the equations to obtain the resonance frequencies and the current distribution on the conductive patches arising from a probe excitation. Due to the singular nature of the current distribution, the singularity subtraction method has been used to accelerate the convergence of basis function expansions. Experiments for determining resonance frequencies and input impedance characteristics of an ARL circular-disk microstrip antenna with various substrate thicknesses have been made. The theoretical results are in good agreement with the experimental data even when the thickness of the substrate is 0.1 substrate wavelength. It is shown that this theory can be used to analyze some microstrip antennas with an electrically thick substrate, including the analysis of mutual coupling between conductive patches or between the path and the feed of a microstrip antenna.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>