Design of a Six-Sector Switched Parasitic Planar Array Using the Method of Genetic Algorithms

Switched parasitic planar arrays, as possible implementations of smart antennas, and an efficient method of designing them are presented in this paper. The radiation pattern of an array can be controlled by a digital word, the insertion of which in the antenna feeding circuit achieves electronic beam steering. The 1s and the 0s in the digital word represent the active and short-circuited elements in the array, respectively. The aim of the design is to cover the azimuth plane with six radiation patterns, each one having 3 dB beamwidth equal to 60° and relative sidelobe level not more than –3 dB. The well-known genetic algorithms are used tooptimize the antenna performance, determining the element positions and voltage phase values. This is made feasible by selecting the digital words, among the 2^N–1 available (N-number of elements), which maximize theobjective function containing the pattern requirements of the design. The numerical results presented show a possible application of this idea. An array of seven identical dipoles /2 offers diagrams, with an average 3 dB beamwidth equal to 63°. Relative sidelobe levels lower than –3 dB are obtained. Simulations at different frequencies prove that thearraydesigned here is a narrowband one and its bandwidth is 2.5% of the carrier frequency.     

Direction-of-Arrival Estimation (DoA) Using Switched Parasitic Planar Arrays and the Method of Genetic Algorithms

An electronically controllable, switched parasitic planar array can be used for the purpose of direction finding. The method proposed in this paper exploits the electronic beam steering, achieved by simply inserting an appropriate digital word in the antenna feeding circuit, to resolve two signals. A genetic algorithm was used to determine the strengths and the angular positions of the incoming signals in the azimuth plane. The results obtained concentrate on wideband signaling in a multipath environment, with and without the presence of noise. The antenna design and the reliability of the direction-finding method are presented. The proposed method is strongly dependent on the type of the receiving antenna (a switched parasitic planar array is superior to a ``uniform' antenna with identical radiation patterns). Increasing the number of radiation patterns available improves the reliability of the method. The reliability of the method slightly deteriorates, as the angular discrimination of the incoming signals becomes smaller, but the results remain quite satisfying.     

A simulation method for bit-error-rate-performance estimation for arbitrary angle of arrival channel models

In this paper, a model for performing bit-error-rate (BER) analysis of various channel models is presented. Traditional simulation methods model the mobile radio channel as having Rayleigh fading, and are focused on the fluctuation of the amplitude of the received signal. Modern spatial models include information such as the angle of arrival of the incoming signals, the time-delay spread, and the number of multipath components. A simulation tool is developed that exploits the spatial statistical characteristics of the channel in order to derive estimates of the expected BER performance. The specific case of the geometrically based single-bounce elliptical model (GBSBEM) is presented and compared to the Rayleigh model. The impact of the employment of antenna arrays at the receiver is also examined. The possibility of determining the BER performance of communication systems, assuming arbitrary channel models, is justified.     

Multi-objective genetic optimization of Yagi-Uda arrays with additional parasitic elements

The,design of modified Yagi-Uda arrays with additional parasitic elements in the area of the radiating dipole, acting either as reflectors or directors, is presented. The genetic algorithms are employed, and various objective functions concerning gain, front-to-back ratio, and the latter combined with desired input impedance, are examined. Comparisons are made among the modified and conventional Yagi-Uda configurations for different weighting coefficients of the fitness functions. The modified Yagi-Uda array outperforms the conventional Yagi-Uda array, because it achieves higher performance standards over an extended bandwidth around 2.4 GHz.     

Indoor environments propagation simulation using a hybrid MoM and UTD electromagnetic method

Radio channel observation and characterization is indispensable in mobile communications systems development. Efficient propagation prediction is crucial for rapid and cost-effective systems deployment. On-site measurements, statistical models, propagation prediction and deterministic modeling are widely used for the qualification of radio channels. In this paper, a simulation tool for deterministic channel modeling in indoor environments is evolved. A hybrid combination of the Method-Of-Moments (MoM) and the Uniform Theory of Diffraction (Utd) is used. Statistical characteristics of a simple office room are calculated and the results are in excellent agreement with corresponding results of relative research on the field.