Rabindra K. Mishra

Neural network-based CAD model for the design of square-patch antennas

An artificial neural network (ANN) has been developed and tested for square-patch antenna design. It transforms the data containing the dielectric constant (/spl epsiv//sub r/), thickness of the substrate (h), and antennas dominant-mode resonant frequency (f/sub r/) to the patch length (l).

ANN techniques in microwave engineering

In the last two decades, artificial neural network (ANN) technology has leaped forward and is now being applied in different areas such as speech recognition, control, telecommunication, remote sensing, pattern recognition, etc. ANN application to the field of microwaves is very recent. This article reviews the development of neural network techniques, introduces some basic concepts involved in it, and gives a comprehensive survey of neural network application to different branches of microwave engineering.

A Compact UWB Bandpass Filter With Embedded SIR as Band Notch Structure

In this letter, an ultrawideband (UWB) bandpass filter with a band notch is proposed. The UWB BPF (3.1-10.6 GHz) is realized by cascading a distributed high-pass filter and an elliptic low-pass filter with an embedded stepped impedance resonator (SIR) to achieve a band notch characteristic. The notch band is obtained at 5.22 GHz. It is shown that the notch frequency can be tuned by changing the impedance ratio of the embedded SIR. A fabricated prototype of the proposed UWB bandpass filter is developed. The inband and out-of-band performance obtained by measurement, EM simulation, and that with an equivalent circuit model are in good agreement.

Tuning of microstrip antenna on ferrite substrate

The permeability variation of a ferrite substrate with an axial DC magnetic bias field along with the RF excitation of a microstrip antenna leads to multiresonant behavior. A study of tuning the patch antenna on a ferrite substrate to exploit this feature is reported, along with the associated theoretical analysis and experimental findings. >

Applications of neural networks in wireless communications

In recent years, the art of using neural networks (NNs) for wireless-communication engineering has been gaining momentum. Although it has been used for a variety of purposes and in different ways, the basic purpose of applying neural networks is to change from the lengthy analysis and design cycles required to develop high-performance systems to very short product-development times. This article overviews the current state of research in this area. Different applications of neural-network techniques for wireless communication front ends are briefly reviewed, stressing the purpose and the way neural networks have been implemented, followed by a description of future avenues of research in this field.

Designing rectangular patch antenna using the neurospectral method

This paper presents a new method for developing computer-aided design (CAD) models, using spectral domain (SD) formulation. Using the artificial neural network (ANN) technique, a combination of continuous function and delta functions constitutes the spectral domain Greens functions. We obtain closed-form formulas for integration involving these equations. Another neural network relates different antenna parameters. Utilizing the reverse modeling for patch dimension determination, it becomes useful as a CAD model for patch antenna design. Designs, of simple rectangular patch antennas, serve as illustration of this method.

An artificial neural network model for effective dielectric constant of microstrip line

A backpropagation network structure is presented for the calculation of the effective dielectric constant (/spl epsiv//sub eff/) of microstrip lines. Results of the network are compared with those of the spectral-domain (SD) technique.

An ANN Application for Fault Finding in Antenna Arrays

A very flexible approach of locating fault elements in antenna arrays is proposed using artificial neural networks (ANN). The network takes samples of radiation pattern of the array with fault elements and maps it to the location of the faulty element in that array. The developed methodology is tested for a linear array and the same can easily be extended for planar arrays also. The developed network can be used at the base stations to find out the number and location of the fault elements in the array in space platforms

Design Formula for Sierpinski Gasket Pre-Fractal Planar-Monopole Antennas [Antenna Designer's Notebook]

An improved formula for determination of resonant frequencies in different Sierpinski modes is developed from other existing formulas, using physical and analytical reasoning. The superiority of the proposed formula over other existing formulas is verified by comparing the results with those from experiments and simulations. A design formula for the side length of the generating Sierpinski triangle is also proposed by algebraic rearrangement of the formula for the resonant frequency.

Perturbed Sierpinski Carpet Antenna With CPW Feed for IEEE 802.11 a/b WLAN Application

A printed antenna useful for IEEE 802.11 a/b WLAN application is proposed in this letter. The antenna adopts a modified Sierpinski carpet geometry in planar monopole configuration. Design steps to achieve the desired resonance characteristics are discussed. Return loss characteristics suggest that the antenna is also suitable for HiperLAN2 system. The peak realized antenna gain is around 3.2 dBi at the lower band and 4.5 dBi at the higher band.