A novel compact and broadband asymmetric coplanar wave guide (ACPW) antenna is presented. A method to extend the bandwidth of a metamaterial-inspired antenna based on a composite right/left-handed transmission line (CRLH-TL) and a modified ground plane is proposed. The ACPW antenna has a broadband characteristic by placing the zeroth-order resonance (ZOR), first-positive-order resonance (FPOR) of short-ended CRLH-TL and the modified ground plane's two resonances, which are half and one lambda resonances, at all different frequencies with proper frequency intervals. The prototype of the proposed antenna has been implemented and measured. The measured -10 dB fractional bandwidth is 109.1% (from 2.69GHz to 9.15GHz) with high efficiency of over 65% and a low profile of 0.32 ×0.19 (where is the free-space wave length at the first resonant frequency).Index Terms-Bandwidth enhancement, asymmetric coplanar waveguide (ACPW), composite right/left-handed transmission line (CRLH-TL), compact antenna.
A cylindrical tightly coupled dipole array antenna (C-TCDA) based on Munk's planar TCDA theory, the elements of which are placed on the surface of a cylinder, is introduced and analyzed in this study. The explicit field components of the transverse electromagnetic (TEM) waves existing in the C-TCDA for both polarizations are given. Moreover, the embedding impedance characteristics of the C-TCDA are presented and compared with those of planar TCDA. Analysis results show that the C-TCDA has similar impedance characteristics to the planar TCDA and thus can be implemented in a similar manner. The design of a dual-polarized omnidirectional octagonal TCDA, which has a 3.08:1 bandwidth (from 0.73 GHz to 2.25 GHz) with a voltage standing wave radiation (VSWR) of less than 2 and a low gain variation of less than 1.8 dB at broadside for both polarizations, is also proposed. When scanning up to ±30° in the θdirection, the array operates in the same frequency band with a VSWR of less than 2.05 and a low gain variation of less than 2 dB for both polarizations. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ
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