Models based on fuzzy inference systems (FISs) for calculating the resonant frequency of rectangular microstrip antennas (MSAs) with thin and thick substrates are presented. Two types of FIS models, Mamdani FIS model and Sugeno FIS model, are used to compute the resonant frequency. The parameters of FIS models are determined by using various optimization algorithms. The resonant frequency results predicted by FIS models are in very good agreement with the experimental results available in the literature. When the performances of FIS models are compared with each other, the best result is obtained from the Sugeno FIS model trained by the least- squares algorithm.

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Comparison of mamdani and sugeno fuzzy inference system models for resonant frequency calculation of rectangular microstrip antennas

The emerging applications for wearable electronics have experienced enormous growth over the last decade. Antennas, being one of the critical components in modern wireless devices, thus need to be specifically designed to function while being worn and bent. In this paper, we present a systematic investigation of the effects of bending applied on wearable patch antennas over cylindrical surfaces. The resonant frequency variations and radiation pattern variations have been studied by simulating and measuring patch antennas that are bent by different angles. A frequency shift plot with respect to bending radius has been generated to target antennas for various wearable applications. An analytical approach has been presented to study the effect of resonant frequency shifting for both E- and H-planes bending. A lumped element circuit model is used to interpret the E-plane bending from different perspectives. One of the main objectives of this paper is to develop useful design-oriented charts and provide a better understanding of the effects of antenna bending to assist wearable antenna designers.

A Systematic Investigation of Rectangular Patch Antenna Bending Effects for Wearable Applications

This article presents a small, low-profile planar microstrip antenna that is applicable for both WLAN and WiMAX applications. The goal of this paper is to design an antenna which can excite triple-band operation with appreciable impedance bandwidth to combine WLAN/WiMAX communication specifications simultaneously in one device. The designed antenna has a compact size of 10 × 26 mm 2 . The proposed antenna consists of an inverted U-shaped slot radiator and a defected ground plane. Overall the design method and parametric study found appropriate dimensions, which provides three distinct bands I from 2.40 to 2.52, II from 3.40 to 3.60 and III from 5.00 to 6.00 GHz that covers entire WLAN (2.4/5.2/5.8 GHz) and WiMAX (2.5/3.5/5.5) bands. Finally, a prototype antenna was fabricated and experimentally characterized to verify the design concept as well as to validate the simulation results. Thus the simulation results along with the measurements show that the antenna can simultaneously operate over WLAN and WiMAX frequency bands.

Design of a compact U-shaped slot triple band antenna for WLAN/WiMAX applications

A series of curved microstrip antennae with defected ground structure for multiband are proposed, which are more smaller, conveniently conformal, wider radiation beam and suitable for WLAN terminal for difierent environment. The relation between the main geometry parameters and the antennas' characters are studied with the cavity model method and EM simulation, and the optimum size antenna is achieved later. If keeping the other parameters but increasing the curving angle fi, the return loss is almost good at f = 2:45GHz, but poor at f = 5:25GHz and 5.8GHz. After slight tuning the key parameters, these curved antennae all can work at f = 2:45GHz, 5.25GHz and 5.8GHz, and their patterns in the plane that is vertical to the curve axes become more wider or even omni- directional with the curving angle fi increasing, which are verifled by experiment, their measured gain are 2dB{6.3dB.

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The development of curved microstrip antenna with defected ground structure

Tri-band microstrip antenna design for wireless communication applications

Computation of the broadband matching potential of a microstrip antenna requires the wideband lumped equivalent circuit of the antenna. The general topology of the equivalent circuit of rectangular microstrip patch antennas has been used to model the feed- point impedance of microstrip antennas over a wide frequency band and equivalent circuit parameters are determined using optimization techniques. The proposed procedure overcomes the problems of physical realizability of the equivalent circuit and estimation of the starting values of the optimization. Applying this technique, wideband lumped equivalent circuits of a rectangular and E-shaped microstrip antenna have been computed which are in good agreement with measurement data from 0.1 to 6 GHz.

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Mohammadali Ansarizadeh

Papers

An approach to equivalent circuit modeling of rectangular microstrip antennas