Miniaturised triple‐band antenna loaded with complementary concentric closed ring resonators with asymmetric coplanar waveguide‐fed based on epsilon negative transmission line

Abstract

This study presents an open‐ended triple‐band miniaturised metamaterial (MTM) inspired antenna based on the epsilon negative‐transmission line (ENG‐TL). The zeroth‐order resonance (ZOR) and first‐order resonance (FOR) characteristics are implemented using the ENG‐TL theory. The proposed MTM antenna consists of rectangular and square‐shaped complementary concentric closed ring resonator (CCCRR) in the left and right half of the asymmetric coplanar waveguide (CPW) ground plane, respectively. The CCCRR generates an extra coupling capacitance and inductance, which help for improving the gain at ZOR mode and better impedance matching at higher‐order mode. The resonance characteristic of the antenna is controlled by the shunt elements due to its open‐ended boundary condition. The proposed triple‐band MTM antenna offers measured −10 dB impedance bandwidths of 8.54% (1.12–1.22 GHz), 10.25% (2.22–2.46 GHz) and 35.75% (2.94–4.22 GHz). All these three bands show good impedance matching with appropriate gain and high radiation efficiency and also having an omnidirectional pattern in the xz‐plane and dipolar type pattern in the yz‐plane. The designed antenna shows an overall dimension of 0.11λ0 × 0.11λ0 × 0.006λ0 at ZOR frequency (1.16 GHz).

Miniaturised tri‐band rhombus‐shaped metamaterial‐inspired antenna with gain enhancement using complementary closed ring resonators

“…In CPW antennas, higher bands are typically derived from the contribution of radiators and grounds which are on the same plane. Therefore, CPW-fed antennas suffer from inconsistent patterns in the higher bands while monopole antennas consistently provide omni-directional pattern in the higher bands [11,13,15,21].…”

“…But observed gain at above bands are not found up to the marks and is negative in lower band. It has been studied in recent literature that this problem of gain deterioration can be addressed by employing CSRR and CCCRR [21]. This technique is found feasible for CPW-fed structures, when suffering from very low gain.…”

“…In an another recent work, gain of the coplanar waveguide (CPW)-fed based, MTM-inspired antenna has been improved by employing concentric complementary closed ring resonators (CCCRRs) into both of the CPW ground planes. It has been mentioned that 'CCCRR generates an extra coupling capacitance and inductance which helps for improving the gain at ZOR mode' [21].…”

“…The principle behind miniaturisation is inspired by the design equations for ZOR frequency at open boundary conditions. CCRR has been employed to offer the extra coupling capacitance that results in improving the gain at frequency of interest (ZOR frequency) as explained in [21]. Proposed antenna achieves 50% miniaturisation with respect to antenna without MTM and 17.55% miniaturisation with respect to antenna without meandered line inductors.…”

A CPW‐fed band notched wideband circularly polarized ZOR antenna based on CRLH‐TL approach

“…Due to this bandwidth enhancement of the metamaterial antenna is one of the popular research topics . Metamaterial antennas can also be realized by epsilon negative transmission line (ENG‐TL) . In Refs.…”