Circular antenna array for direction finding applications at 2.45 ghz

Abstract

Microstrip Patch Antennas are widely used in modern wireless communication systems due to their compact size and low cost. These patch antennas have planar structure and are low-profile and thus are very easy to fabricate and so are very popular. The objective of this thesis is to present a new single fed uniform circular array microstrip antenna. To obtain this new antenna design a study is performed to design the antenna array using microstrip antenna with four elements and eight elements. This thesis is concerned with the design of a circular array microstrip antenna that would operate in the 2.45 GHz range. This range is 2 commonly used by wireless local area devices and wireless personal area devices such as the 802.11 WIFI and mainly used for Wi-Fi and phone or Bluetooth applications. Ring arrays or circular arrays have been used in radio direction finding, radar, sonar, and many other system applications. The uniform circular arrays (UCA) have a major advantage because of the symmetry property of the UCA. It has the ability to scan a beam azimuthally through 3600 with little change in either the beamwidth or the sidelobe level. The Root-MUSIC algorithm is used for 2-D direction-of-arrival (DOA) estimation of azimuth and elevation angle with uniform circular arrays for direction finding. This thesis presented focused on designing circular array of microstrip antenna with feed network operating at 2.45 GHz. This thesis presented a design of symmetrical feed network of eight way power divider for the eight element circular array. The circular array is designed and simulated with microstrip antenna in CST Microwave Studio 2019. The microstrip antenna is designed with microstrip line feed. In microstrip feed, the patch is fed by a microstrip line that is located on the same plane as the patch. A xii matching network between the feed line and the patch such as quarter wavelength transformer. The parametric study of circular array by varying the radius of the circular array is done. It has been found that the radiation pattern of the eight element uniform circular array shows 3600 coverage with almost no side lobes for the radius (equal to = 𝛌0). The circular array of four microstrip antenna is first designed and the results show that the circular array provides 3600 scanning but has significant side lobes. The feed network for the eight element circular array is then designed in microstrip line form. A symmetrical feed network design for eight way power divider microstrip line form is also designed. Lastly, the combined circular array and the feed network design is done to obtain a single fed microstrip circular antenna array.