Abstract
This study presents a co-planar waveguide (CPW)-fed shunt mode zeroth-order resonant (ZOR) antenna with an improved gain and radiation efficiency. The proposed antenna consisting of two symmetric unit cells has an open ended composite right/left handed (CRLH) transmission line structure. The unit cell of the proposed antenna consists of a series metal-insulator-metal (MIM) capacitor and two shorted shunt stub inductors. In order to reduce the antenna size and to improve its efficiency, a straight metal-strip line, bent by 900, was used as the shunt inductor, replacing the more tradi- tional meander line. As a result, the total electrical size of the fabricated ZOR antenna consisting of two unit cells was 0.22 λ 0 ⨉ 0.22 λ 0 . The measured gain and efficiency of the fabricated antenna have been enhanced to 3.07 dBi and 75 %, re- spectively, at the zeroth-order resonant frequency of 2.97 GHz, an enhancement over previously presented antennas.
Highlights
Zeroth-order resonant (ZOR) antenna manufactured on microstrip transmission lines has attracted great interest in the small antenna applications
Many techniques have been employed in order to miniaturize the composite right/left handed (CRLH) transmission line (TL) unit cell size, such as using meander line shunt stubs [1] or using the Sievenpiper’s mushroom structure[2]
The simulated and measured return loss |S11| of the fabricated ZOR antenna are shown in CRLH unit cells
Summary
Zeroth-order resonant (ZOR) antenna manufactured on microstrip transmission lines has attracted great interest in the small antenna applications. Many techniques have been employed in order to miniaturize the composite right/left handed (CRLH) transmission line (TL) unit cell size, such as using meander line shunt stubs [1] or using the Sievenpiper’s mushroom structure[2]. The peak gain and radiation efficiency of this antenna were 0.87 dBi and 70%, respectively. In order to further reduce the antenna size, a spiral slot structure on the ground was used[3]; the measured peak gain and radiation efficiency of this antenna were – 0.28 dBi and 62%, respectively. Small ZOR antennas employing a CRLH resonator made up of two or three cells suffer from a low radiation efficiency and poor gain in the zeroth-order resonant mode[4].
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