International Journal of Applied Electromagnetics and Mechanics 46 (2014) 483–490 483 DOI 10.3233/JAE-141784 IOS Press ANFIS model for determining resonant frequency of rectangular ring compact microstrip antennas Ali Akdagli a,∗ , Abdurrahim Toktas b , Mustafa Berkan Bicer a , Ahmet Kayabasi c , Deniz Ustun d and Kasim Kurt e a Department of Electrical – Electronics Engineering, Faculty of Engineering, Mersin University, Yenisehir, Mersin, Turkey b Department of Information Technologies, Mersin University, Yenisehir, Mersin, Turkey c Department of Electronics and Automation, Silifke – Tasucu Vocational School of Selcuk University, Silifke, Mersin, Turkey d Department of Software Engineering, Faculty of Tarsus Technology, Mersin University, Tarsus, Mersin, Turkey e Department of Physics, Science and Letter Faculty, Mersin University, Yenisehir, Mersin, Turkey Abstract. In this work, a model constructed with the adaptive neuro – fuzzy inference system (ANFIS) for estimating the resonant frequency of rectangular ring compact microstrip antennas (RRCMAs) in UHF band is proposed. A total of 108 RRCMAs having different parameters related to the antenna dimensions and dielectric substrate were simulated with the help of electromagnetic packaged software IE3D TM based on method of moment (MoM) to generate the data pool for training and test processes of the ANFIS model. While 96 RRCMAs were employed for training, the remainders were used for test the ANFIS model. The resonant frequencies were computed with the average percentage errors (APE) as 0.014% and 0.666% for training and test, respectively. The accuracy of proposed model was successfully demonstrated by comparing with the results of a method over the simulated data previously published in the literature. Further to inspect the validity of the ANFIS model, a RRCMA operating at 2.44 GHz was designed and fabricated for this work, and the accurate results concerning the resonant frequency were achieved. Keywords: Compact microstrip antennas, rectangular ring, resonant frequency, neuro-fuzzy, ANFIS 1. Introduction Conventional microstrip antennas with rectangular, circular, triangular shapes owing to their attractive features of light weight, low profile, easy fabrication, low cost, and conformability to mounting on the mainboard have been presented and used in the literature [1–3]. By contrast with superior features above said, microstrip antennas also have some practical shortcomings such as low gain, low efficiency and ∗ Corresponding author: Ali Akdagli, Department of Electrical – Electronics Engineering, Faculty of Engineering, Mersin University, Ciftlikkoy, Yenisehir, 33343, Mersin, Turkey. Tel.:+90 324 361 0001; Fax: +90 324 361 0001; E-mail: akdagli@ mersin.edu.tr. 1383-5416/14/$27.50 c  2014 – IOS Press and the authors. All rights reserved