Design and Analysis of Planar Monopole Antennas for Ultra Wide Band Applications

Abstract

This thesis presents the work on the design of single element and two element (MIMO) antennas. The proposed designs are analyzed for different performance parameters separately. First, a compact lotus shaped planar monopole antenna is proposed and extended by creating two slots for dual notch performance for narrow band applications. The presented antenna fabricated on a 44~38~1.58mm3 on thick FR4 substrate and covers the frequency range from 2.86 to 14.0 GHz and is fed by 50 ƒ¶ Microstrip line. The extended work of proposed antenna covers the wide range 2.8 to 11 GHz with notch frequencies at 3.458 and 5.51GHz ranging from 3.35GHZ-3.566GHz and 5.285GHz-5.771GHz frequencies. Second, a two element compact UWB MIMO Antenna systems are designed on an FR4 substrate of dimensions 44~88mm2 of a thickness 1.6mm with lotus shaped elements and antennas are placed in three different angular positions on the substrate. A fork-shaped structure is introduced in the ground plane to increase the isolation between the antennas. Simulated results of S-parameters of the proposed antenna system are obtained and a high isolation of less than -15 dB is achieved throughout the band and it is quite suitable for MIMO applications. The extended work carried out on creating a dual notch for the different designs placed in three different positions for narrowband applications. The high isolation of less than -15 dB is achieved throughout the band and notch frequencies are situated at 3.44GHz and 5.375GHz by covering WiMAX and WLAN narrow band applications. Among three the antenna placed parallel on a substrate is fabricated and measured. The measured results are well matched to the simulated results.