Planar Endfire CP Antenna with Enhanced Gain and Beamwidth for RFID Applications

Abstract

A novel design approach for gain and beamwidth enhancement of planar endfire circularly polarized antenna (PECPA) is proposed. For the proof-of-concept, a rhombic electric dipole structure and a basic planar microstrip magnetic dipole antenna are utilized and implemented on a single layer substrate. In order to enhance the gain, both of these two complementary dipoles work at their high odd-order modes. Meanwhile, a directive E-field component is produced by the rhombic electric dipole structure for a large axial ratio (AR) beamwidth. It is numerically verified that an endfire gain about 5.86 dBi and AR beamwidth up to} $\mathbf{1}\mathbf{1}\mathbf{0}^{\circ}$ are realized without introducing extra elements. In addition, the main beam radiates parallelly with the substrate plane. Due to its advantages, the proposed PECPA exhibits a great potential for RFID handheld devices application.