Determination of resonant frequencies of triangular and rectangular microstrip antennas, using artificial neural networks

This paper presents models that can be used in the design of microstrip antennas for mobile communications. The antennas can be triangular or rectangular. The presented models are compared with deterministic and empirical models based on artificial neural networks (ANN) presented in the literature. The models are based on Perceptron Multilayer (PML) and Radial Basis Function (RBF) ANN. RBF based models presented the best results. Also, the models can be embedded in CAD systems, in order to design microstrip antennas for mobile communications.

New contributions to the determination of resonance frequencies of rectangular microstrip antennas by neural networks

This paper uses artificial neural networks (ANN) to compute the resonance frequencies of rectangular microstrip antennas (MSA), used in mobile communications. Perceptron Multi-layers (PML) networks were used, with the Quasi-Newton method proposed by Broyden, Fletcher, Goldfarb and Shanno (BFGS). Due to the nature of the problem, two hundred and fifty networks were trained, and the resonance frequency for each test antenna was calculated by statistical methods. The estimate resonance frequencies for six test antennas were compared with others results obtained by deterministic and ANN based empirical models from the literature, and presented a better agreement with the experimental values.

A Wideband Rectangular Microstrip Antenna Using an Asymmetric t-shaped Feed

An electromagnetically coupled T-shaped microstrip feed used to enhance the impedance bandwidth of a rectangular microstrip antenna is reported. The proposed antenna offers a 2:1 VSWR bandwidth of -36% with an increase in gain of 0.8 dB

Design of Compact Reconfigurable Dual Frequency Microstrip Antennas Using Varactor Diodes

The design of a compact, single feed, dual frequency dual polarized and electronically reconfigurable microstrip antenna is presented in this paper. A square patch loaded with a hexagonal slot having extended slot arms constitutes the fundamental structure of the antenna. The tuning of the two resonant frequencies is realized by varying the effective electrical length of the slot arms by embedding varactor diodes across the slots. A high tuning range of 34.43% (1.037–1.394 GHz) and 9.27% (1.359–1.485 GHz) is achieved for the two operating frequencies respectively, when the bias voltage is varied from 0 to −30 V. The salient feature of this design is that it uses no matching networks even though the resonant frequencies are tuned in a wide range with good matching below −10 dB. The antenna has an added advantage of size reduction up to 80.11% and 65.69% for the two operating frequencies compared to conventional rectangular patches.

Simple approach to determine resonant frequencies of microstrip antennas

A simple approach for accurate determination of the resonant frequencies of microstrip antennas of regular geometries is developed and presented. In this approach, a generalised empirical formula for the computation of effective dielectric permittivity is given which takes into account the ratio of the fringing area to the area of the patch. A correction to the equivalent side length of an equilateral triangular patch, previously published, is modified and a new formula is given. A correction to the effective dimensions of an elliptical microstrip antenna is also carried out. Numerical results obtained for the resonant frequencies of elliptical, circular, rectangular and equilateral-triangular microstrip antennas are in good agreement with the available theoretical and experimental results reported by others. The present approach is more efficient, simpler and more accurate

Performance of microstrip antennas in the presence of EBG in an indoor localization system

Indoor localization systems in nowadays is a huge area of interest not only at academic but also at industry and commercial level. The correct location in these systems is strongly influenced by antennas performance which can provide several gains, bandwidths, polarizations and radiation patterns, due to large variety of antennas types and formats. This paper presents the design, manufacture and measurement of a compact microstrip antenna, for a 2.4 GHZ frequency band, enhanced with the use of Electromagnetic Band-Gap (EBG) structures, which improve the electromagnetic behavior of the conventional antennas. The microstrip antenna with an EBG structure integrated allows an improvement of the location system performance in about 25% to 30% relatively to a conventional microstrip antenna.

Microstrip antennas for mobile telephone handset with reduced radiation hazards

A novel antenna configuration comprised of two circular micro strip antennas (CMAs) resonating in the TMtt and TM2, modes, producing radiation characteristics suitable for a mobile telephone handset, is presented. The antennas operating at the same frequency are placed back to back with a separation comparable to the thickness of a typical handset. The radiation pattern consists of a region of reduced radiation intensity, which minimizes the radiation hazards to the user

Wide Band Rectangular Microstrip Antenna using Symmetric T-shaped Feed

Bandwidth enhancement of a rectangular microstrip antenna using a T-shaped microstrip feed is explored in this paper. A 2:1 VSWR impedance bandwidth of 23% is achieved by employing this technique. The far-field patterns are stable across the pass band. The proposed antenna can be used conveniently in broadband communications

FDTD analysis of a symmetric T-strip fed wideband rectangular microstrip antenna

A theoretical analysis of a symmetric T-shaped rnicrostripfed rectangular microstrip antenna using the finite-difference titnedoniain (FDTD) method is presented in this paper. The resonant frequency, return loss, impedance bandwidth, and radiation patterns are predicted and are in good agreement with the measured results

L-strip excited wideband rectangular microstrip antenna

This paper presents the outcome of the experimental studies performed on L-strip fed compact rectangular microstrip antenna. The effect of the feed parameters upon the characteristics of the antenna is studied in detail. The antenna offers an impedance bandwidth of nearly 20% and is suitable for broadband applications

DEVELOPMENT AND ANLAYSIS OF BROADBAND L·STRIP FED MICROSTRIP ANTENNAS

The thesis is the outcome of the experimental and theoretical Investigations on novel feeding techniques for bandwidth enhancement of microstrip patches. The new feeding techniques provide bandwidth enhancement without deteriorating the radiation characteristics of the antenna. The antenna is analysed using finite Difference Time Domain (FDTD) method. The predicated results are compared with the experimental results and excellent agreement is observed. The results are also verified using IE3D simulation software. The antenna is suitable for personal and broadband communications.

DEVELOPMENT AND ANALYSIS OF DUAL FREQUENCY MICROSTRIP ANTENNAS

Department of Elecctronics, Cochin University of Science and Technology

Development and Analysis of Microstrip Antennas For Dual Band Microwave Communication

The thesis explores the outcome of the exhaustive theoretical and experimental investigations performed on Octagonal Microstrip Antenna configurations. Development of the MATLAB TM backed 3D-Conformal Finite Difference Time Domain (CFDTD)Modeller for the numerical computation of the radiation characteristics of the antenna is the theme of the work. The predicted results are verified experimentally and by IE3D TM simulation. The influence of the patch dimensions,feed configurations,feed dimensions and feed positions upon the radiation performance of the antenna is studied in detail. Octagonal Microstrip Antenna configurations suitable for Mobile-Bluetooth application is dealt in detail. A simple design formula for the regular Octagonal geometry is also presented. A compact planar multi band antenna for GPS/DCS/2.4/5.8GHz WLAN application is included as appendix A. Planar near field measurement technique is explained in appendix B.

Investigations on Reconfigurable Dual Frequency Microstrip Antennas Controlled by PIN Diodes and Varactors

In this work,we investigate novel designs of compact electronically reconfigurable dual frequency microstrip antennas with a single feed,operating mainly in L-band,without using any matching networks and complicated biasing circuitry.These antennas have been designed to operate in very popular frequency range where a great number of wireless communication applications exist.Efforts were carried out to introduce a successful,low cost reconfigurable dual-frequency microstrip antenna design to the wireless and radio frequency design community.