R. Ghayoula

Uniform circular phased arrays synthesis using SQP algorithm

In this paper, a uniform circular array antenna with synthesis technique based on Sequential Quadratic Programming (SQP) algorithm is discussed. The SQP algorithm is a robust method for the optimization with inequality constraints. SQP algorithm has been used for steering the main lobe and reducing the side lobe level for the radiation pattern by controlling only the amplitude of the array elements. In order to illustrate the performance of the proposed method, several examples of uniform circular antennas array patterns are performed.

Phase-only array beam control using a Taguchi optimization method

This paper introduces the developed hardware platforms of the smart antenna transmitter system and its implementation details and presents the novel concept of smart antenna system which requires digital beamforming based on Taguchi Method. This paper investigates how the implementation on STM8 of the signal processing in hardware affects the performance of the adaptive array antenna. This system shows excellent performance for the radiation pattern and capable to steering by adjusting the relative phases of the signal received or transmitted by each antenna. The objective of the design is to construct smart antenna beamforming systems with hardware-software implemented Taguchi Method.

Artificial Neural Networks ANN Approach for the Synthesis of Patch Antennas

Patch antennas plane networks have been used largely in communication systems. Their capability to change radiation pattern electronically, multi-beam capacity and high spatial resolution has made them attractive for mobile communication applications. The work presented in this paper refers to the synthesis of periodic patch antennas plane networks supplied with coaxial lines. The method of synthesis used for this type of networks lets possible an optimal approach for the desired radiation pattern specified by a gauge sensible for source excitation and space distribution of the radiant sources. The development of the synthesis is based on the neural networks technique.

A 4 bits Reflection type phase shifter based on Ga As FET

A 4 bits digital phase shifter is designed and simulated. It is based on 3-db hybrid coupler and totally twelve switches are used. The simulation results indicate an insertion loss better than -4dB, a return loss less than -20 dB and an error phase varied between 0.01° and 0.6° at 2.45 GHz. to achieve a 6 bits phase shifter, we increased the number of stages. This phase shifter present an insertion loss better than -5dB, a return loss less than -20db and an error phase varied between 0.1° and 1.7°. But, the circuit presents a large size. The Ga As FET switch used for switching is characterized by a very low DC power consumption, a fast switching speed and a low cost. Also, an array antenna of 8 patch elements connected to a 4 bits phase sifter is designed. The simulated results of the array indicate a return loss better than -10dB over 2.4-2.5 GHz and a gain equal 14 dB.

Phased uniform linear antenna array synthesis using genetic algorithm

This paper describes a new method for adaptive beamforming for a phased antenna arrays using genetic algorithm. The algorithm can determinate the values of phase excitation for each antenna to steer the main beam in specific direction. Various results are presented with −10 dB side lobes level. To improve these results, a Chebyshev model was proposed in order to decrease the level of side lobes which consists in amplitude synthesis.

Application of the neural network to the synthesis of Multibeam Antennas Arrays

In this paper, we intend to study the synthesis of the multibeam arrays. The synthesis implementations method for this type of arrays permits to approach the appropriated radiances diagram. The used approach is based on neural network that are capable to model the multibeam arrays, consider predetermined general criterias, and finally it permits to predict the appropriated diagram from the neural model. Our main contribution in this paper is the extension of a synthesis model of these multibeam arrays.

Design and analysis of a microstrip antenna array for biomedical applications

Breast cancer affects many women all over the globe and means for early detection are necessary for fast and effective treatment. Mammography, which is currently the most popular method of breast screening, has some limitations and microwave imaging seems to offer a good alternative. In this paper, a study of patch antenna array for breast cancer detection is presented. The results show that the proposed antennas design is capable of detecting the breast tumor with much improved characteristics compared to the other designs available in the literature. The capabilities and limitations of this antenna for detecting tumor models are investigated through simulations and its potential for detecting tumors in the breast is highlighted.

Circular antenna array design for breast cancer detection

Microwave imaging for breast cancer detection is based on the contrast in electrical properties of healthy fatty breast tissues. This paper presents, an industrial scientific and medical bands (ISM) comparative study of five microstrip patch antennas for microwave imaging at 2.45GHz frequency, a choice of one antenna is made for an antenna array composed by 8 antenna for a microwave breast imaging system, each element are arranged in a circular configuration, so as that every antenna element can be directly faced to the breast phantom for better tumor detection. This choice was made by putting each antenna alone on the Brest skin to study electric field, magnetic fields and current density in the healthy tissue of the breast phonton designed and simulated in Ansoft High Frequency Simulation Software (HFSS).

Beamforming multibeam antenna array using Taguchi optimization method

In this paper, an efficient method is presented to synthesize directive beam and multi-beam patterns. An optimal radiation pattern is obtained for a linear antenna array using Taguchis Optimization method. A set of phase shift weights are generated in order to steer the beamforming towards any desired direction The results of Taguchis method are validated by using array antenna patch and simulated by software CST2013 (CST microwave studio).

Synthesis of phase of conformal cylindrical arc antenna arrays referring to taguchi method

This paper presents a new approach to synthesize conformal cylindrical antenna arrays by controlling the phase excitation, to create a directive lobe using Taguchis method. The aim of our proposed method consists on the minimization of the fitness function between obtained and desired results. The results found, with the application of this method to synthesize conformal cylindrical arc antenna arrays, are validated with simulation by CST Microwave. We have used CST Microwave to simulate an 8-element conformal cylindrical arc antenna; witch has been tested in variable types of beam configurations.