International Journal of Recent Technology and Engineering (IJRTE) ISSN: 2277-3878, Volume-8 Issue-3, September 2019 3116 Published By: Blue Eyes Intelligence Engineering & Sciences Publication Retrieval Number: C4999098319/2019©BEIESP DOI:10.35940/ijrte.C4999.098319 Design Analysis and Performance Evaluation of Annulus Patch Antennas Mahesh Babu Kota, T.V. Rama Krishna Abstract- The paper presents a detailed investigation of various types of circular ring patch antennas and their importance in Wireless Communications, especially under satellite Frequency Applications. The main focus is considered on the typical resonant frequencies, design parameters, theoretical foundations on the shape, equivalent circuits and various applications of the ring patch antennas. Design, simulation and comparison of different structures of patches with annulus patch were also presented to justify the investigation. Index Terms- Microstrip Patch antennas, Microwave Frequency, Wireless Communications, Circular Ring patch. I. INTRODUCTION From the past few decades, planar antennas were considered as the best choice of interest to meet the requirements and specifications of microwave frequencies in wireless communications. The main reason for opting the planar microstrip antennas is their weight and compact in size, economic in terms of cost and fabrication [1]. Microstrip Antennas are available in different shapes like ring, rectangle, square circle, triangle, ring, etc. Out of these shapes, ring shape has gained unusual importance for its smaller size, flexible and miniaturization for array structures, wide bandwidth and less stored energy [2]. For Obtaining wide as well as multi-band features, ring structures are included with other geometric elements and one of the interesting features of ring patch antennas is that separation of resonant modes depends on the ring outer to inner radii ratio [3]. The circular polarisation can be easily attained with ring patches related to other shapes by simply making slots or extending the patch dimensions. Although, theoretical analysis of ring patch antennas is not a recent problem but the importance of the analyses for the designs is mandatory to fulfil the conditions and limitations of any application. The theoretical foundations for the ring patches were initiated since the usage of the ring structure has begun. From different ring structures, annular ring is most widely used shape due to its fringing effect at both inner and outer radii and high radiation performance [4]. Ring antennas act as a transitional configuration between a patch and in print loop in both geometrical as well as electrical cases. The ring structure can also be used to determine the material dielectric constant and as a radiator for medical applications [5]. The Ring structures can be of square, triangle, rectangle or circular shapes. The circular or annular ring shape is most widely used as it minimises the open-end loading effect observed in other patch structures. Revised Manuscript Received on September 15, 2019 Mahesh Babu Kota, Research Scholar, Dept. of ECE KL Deemed to be university. Green Fields Vaddeswaram, AP, India, E-Mail: kmaheshbabu@kluniversity.in T.V. Rama Krishna, Professor, Dept. of ECE KL Deemed to be university. Green Fields Vaddeswaram, AP, India, E-Mail: tottempudi@kluniversity.in Apart from this, the annular ring which possess several advantages than other structures of microstrip antennas. This paper carries out the investigation of the work done by various authors on annular ring microstrip antennas from the past few decades and the justification of the investigation through simulation and comparison of annular ring patch antenna with other structures of microstrip antennas. II. INVESTIGATION In this section, the work carried out by various authors on annular ring patches was presented. In [1] a multiband circular ring patch antenna was proposed on a patch shape configuration method with constant layout dimensions. The applications of the proposed antenna are confined to 4G wireless communications having 3 bands with their centre frequencies at 6.86GHz, 12.37GHz and 13.75 GHz having bandwidths of 270MHz, 460MHz and 480 MHz respectively and the VSWR have been maintained approximately at 1. In [6] the application is focused on C- band satellite communications and X-band under Radar applications with a rectangular patch with two concentric circular ring slots and two diamond shaped patches near the feed line. The designed is made as to obtain circular polarisation using two concentric ring circles and the enhancement of antenna gain by two diamond shaped patches. The proposed antenna provides dual bands having resonating frequencies at 6.6 GHz and 9.4GHz with S 11 of -14.7dB and -20.9dB respectively. The bandwidths obtained are 6.38- 6.8 GHz and 9.2 TO 9.6GHz with gains of 4.77dB and 6.29dB respectively. In [7] a patch antenna with concentric annular ring slot was proposed which provides bidirectional circular polarisation radiation with dual bands operating at 2.45 GHz (ISM) and 3.5 GHz (5G) bands. The two-band operation was obtained with tunnelling annular ring slots in the base as well as to maintain circular polarisation two bend structures are loaded on each annular ring inclined at 45 0 . In [8] a simple single feed circular patch antenna is proposed with asymmetrical ring-shaped arc slot pairs with extended narrow slots are implanted on both patch and ground which provides dual or multi band circularly polarized radiation. The arc slots embedded increase the impedance bandwidth through the mutual coupling between arc slot resonance and circular patch fundamental resonance and the two extended narrow slots provide circular polarisation. An extensive parametric analysis has been done on each and every parameter dimension to obtain the optimum results. In [9] the importance of a ring structure has been proved by loading a simple co-axial fed conventional circular patch antenna with a ring. This made the antenna configuration to obtain better performance than a conventional patch antenna which includes greater impedance bandwidth, high gain,