Unidirectional printed loop antenna

Abstract

A new type of printed rectangular loop or 100-51 transmission line. The unidirectional antenna with capacitive loads is proposed for radiation pattem is achieved by introducing two -unidirectional radiation pattern production. The arrangement presented here is shown to have a current distribution with balanced magnitude and 90' phase difference on parallel radiating edges of the loop. As a result, the printed loop is equivalent to an .gaps into ;he loop in order to produce capacitive phasing elements. It is experimentally demonstrated that a front-to-back ratio of than 2o dB and a 4.5-dBi gain can be achieved.array of two dipoles with quarter-wavelength space separation and 90' phase excitation difference. II. ANTENNA CONFIGURATIONSimulated and measured results for 1 GHz center-The geometry and optimised sizes of the frequency operation show that the new unidirectional unidirectional rectangular loop antenna are depicted printed loop antenna can achieve a front-to-hack can he easily matched. GHz. The loop is made of etched copper strips of width w=6 mm and thickness F17.5 pm printed on an RT/duroid 5880 dielectric substrate (thichess=0.254 mm, er =2.2). The antenna is centre-fed by a quafier-wavelength folded balun constructed from 5 0 0 coaxial cable.ratio of more than 20 dB, power gain of 4.5 dBi, and in l'ig. The antenna is designed to Operate at

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“…Therefore, to create a balance between the required inductance and maintain the wide operating bandwidth, an additional meandering is applied to the top portion of the structure to mitigate the impedance mismatch at 700 -780 MHz, and improve the coupling between the antenna and the parasitic patch. With this configuration, the simulated results of the final design achieve a wide fractional bandwidth of 50 % (0.65 -1.05 GHz), which is 20 % wider than the recent counterpart designs [125], [40], [101]. Moreover, its size is reduced by 73 % compared to the similar designs [125], [40].…”

“…With this configuration, the simulated results of the final design achieve a wide fractional bandwidth of 50 % (0.65 -1.05 GHz), which is 20 % wider than the recent counterpart designs [125], [40], [101]. Moreover, its size is reduced by 73 % compared to the similar designs [125], [40]. The optimum sizes of the antenna elements are presented in Table 4-VI.…”

“…For loop structures using a single capacitive loading such as a slot loaded loop, these two frequencies can be easily merged by changing the position of the capacitor on the loop, and hence forming a dipole where its resonance is at the same frequency as the loop antenna. With such a configuration, the loop antenna acts as an array of two dipole antennas that are excited with a 90 degree phase difference and hence creates a cardiac shape radiation pattern which suppresses back radiation [125]. …”

“…The idea of creating slots on a loop antenna was proposed to utilize the generated phase difference for directivity enhancement [125]. The bandwidth of the antenna at higher frequencies was then enhanced by adding a quarter wavelength parasitic patch in the vicinity of the loop [40].…”

“…However, by including the slot the resonance mechanism of the antenna is divided into two modes: a onewavelength loop and a half-wavelength dipole. The size of the slot, g, is adjusted to keep the aforementioned resonances close to each other to simplify the impedance matching process [125], [40].…”