Compact dual‐band circularly polarised antenna with omnidirectional and unidirectional properties

Abstract

A novel dual‐band circularly polarised (CP) antenna is presented in this study. The proposed antenna is composed of a U‐slot patch and four sequentially rotated shorted monopoles. Different from conventional omnidirectional CP antennas with shorted monopolar patches, a novel capacitively coupled technique is proposed to achieve good impedance matching, which makes it possible to generate unidirectional CP patterns simultaneously. This antenna can generate omnidirectional CP radiation patterns in the global positioning system L1 band (1575 ± 5 MHz) for navigation application and unidirectional CP radiation patterns in the 2.4‐GHz industrial, scientific, and medical band (2.40–2.48 GHz) for municipal wireless networks. The dual‐band performance can be tuned separately. Experimental results confirm the good performances of a compact antenna with the size of 0.26 λ0 × 0.26 λ0 × 0.026 λ0. The obtained 10‐dB impedance bandwidths can cover the two required bands. The 3‐dB axial ratio (AR) bandwidths cover the lower band and the upper band from 2.425 to 2.46 GHz. In addition, a wide 3‐dB AR beamwidth of 200° is obtained at 2.45 GHz. The simple structure and good performances make this antenna a good candidate for handheld devices and vehicular applications.

Tri‐band planar monopole antenna with two circularly polarised bandwidths for WiMAX applications

“…11. The pattern at 2.1 GHz is omnidirectional in the yz-plane (ϕ = 90°) and bidirectional in the xz-plane (ϕ = 0°) as expected from a monopole antenna [16]. The high cross-polarisation level in the xzplane of the LP band is as a result of the extra current on the antenna's ground plane due to the compact nature of the antenna [17,18].…”

“…However, antennas in [13,14] offer a single impedance (or S 11 ) band with multiple AR bands. Some omnidirectional CP antenna designs have also been proposed in [15,16]. However, such antennas exhibit complex structures or narrow bandwidths.…”

Dynamically Switched Dual-Band Dual-Polarized Dual-Sense Low-Profile Compact Slot Circularly Polarized Antenna Assisted With High Gain Reflector for Sub-6 GHZ and X-Band Applications

“…Integrating an SIW cavity in a bow-tie slot antenna dual band gains of 6.1/5.4 dBi with dual-band dual-polarized characteristics is achieved in [11]. In [12], a U-slot patch with four sequentially rotated shorted monopoles of a CP antenna is designed to achieve dual-band dual-mode with gains 0.8/6.8 dBi is achieved for GPS applications. A simple compact dual-band square slot antenna with dual-sense CP radiation for WLAN/Wi-Fi applications is discussed in [13], with dual band gains 4.2/3.4 dBi.…”

Compact triband circularly polarized planar slot antenna loaded with split ring resonators

“…Many dual‐band CP antennas are designed using patches and slots . Planar slot antennas with the loading of parasitic elements like patches, stubs and slots are designed to achieve dual band CP . The stubs and slot loaded designs have complex feeding mechanisms to achieve circular polarization.…”