Design and Operation of Dual/Triple Band Slotted Microstrip Monopole Antenna for Wireless Applications

Abstract

Wireless communications have been developed widely and rapidly in the modern world especially during two decades. The future development of the personal communication devices will aim to provide speech, image and data communication at anytime and any where around the world. This indicates the future communication terminal antenna must meet the requirement of multi-band or wide band to sufficiently cover the possible operating bands. However, the difficulty of antenna design increases when the number of operating frequency band increases. In addition for miniaturization the wireless communication system, the antenna must also be small enough to be placed inside the system. However in order to transmit and receive more information large bandwidth are required and bandwidth enhancement is currently a popular research area. The aim of thesis is to design a broad band Dual/Triple frequency rectangular microstrip patch antenna for wireless communication system and study the effect of various antenna parameters like patch length (L), Patch (P), Width (W), substrate parameters viz relative dielectric constant, substrate thickness etc. Here, coplanar waveguide feed is used to excite the patch antenna. In this thesis, three designs have been proposed for broad banding of patch antenna. The proposed antennas have been modelled, designed and simulated using Computer Simulation Technology Microwave Studio Version 2010 (CST MWS V 10.0). The designs include slotted patch, reduced ground plane and defected ground structures. The maximum impedance bandwidth is achieved by reducing the size of ground plane and embedding a slot in ground. First design is presented for dual banding of microstrip antenna for wireless applications. The resonating applying behaviour of MPA proposed antenna depend upon embedding multiple slots length in the patch and by applied coplanar feed line the performance of proposed patch antenna improved as compared to rectangular patch without coplanar waveguide (CPW) feeding mechanism. The dual band antenna covers WLAN and WiMAX bands viz 2.4 GHz to 2.7 GHz and 5.2 GHz to 6.3 GHz and its fabrication and measurement has been attempted in this thesis. The antenna parameters like operating frequency, Voltage Standing Wave Ratio (VSWR), bandwidth, return loss, directivity and gain are analysed for each antenna configuration. The return loss of dual band antenna is - iv 21.88 dB and -36.99 dB at resonant frequencies. The directivity of antenna is 2.15 dBi and 2.88 dBi and the gain of antenna is 2.21 dBi and 2.54 dBi respectively. Second design is slotted and stubbed antenna for triple band in this antenna H and two U Shape slots embedded in radiating patch which offer a wide bandwidth which is suitable for WLAN and WiMAX applications. The design offers a bandwidth 259 MHz, 889 MHz and 185 MHz at resonate frequencies 2.01 GHz, 3.59 GHz and 5.70 GHz. The return loss of antenna is -15.44 dB, -22.63 dB, -23.50 dB. The gain and directivity of antenna is 2.29 dBi, 2.68 dBi, 4.66 dBi and 2.21 dBi, 2.76 dBi, 4.13 dBi respectively. Third design is Trident shaped triple band monopole antenna which have three resonating path through which three resonances are occurring at 2.74 GHz, 3.96 GHz and 6.03 GHz which are reserved for WLAN, WiMAX and IMT applications. The triple band covering the frequency bands (2.55 GHz-2.90 GHz), (3.77 GHz-4.11 GHz) and (5.68 GHz-6.45 GHz). The directivity of antenna 4.41 dBi, 3.31 dBi and 3.94 dBi and gain of antenna 4.47 dBi, 2.93dBi and 3.63 dBi respectively. The fabrication and testing of the dual band slotted microstrip antenna has also been accomplished using VNA model No: E5071C. A Comparison between simulated and measured results has also been demonstrated in this thesis.