In this paper, a highly robust antenna for omnidirectional circular polarized communication in the harsh environment at 2.45 GHz ISM frequency band is proposed based on a transparent structure. Circular polarization has been realized utilizing a combination of two magnetic and electric dipoles. The antenna is covered with a quarter wavelength layer of plexiglass to achieve desired robustness and visible light transparency. Meanwhile, it can integrate with solar cells because of the high transparency of glass to simultaneously propagate signals and harvest energy. The gain and bandwidth of the antenna are 1.7 dBi and 300 MHz, respectively. The antenna's axial ratio is achieved less than 3 dB within the bandwidth showing circular polarization behavior. The proposed compact antenna is numerically and experimentally analyzed and compared together, having a suitable agreement. In another aspect, the structure can give promising openings to enhance the propagating properties, which could generate critical advantages for real-world multifunctional applications.
A Novel beam switch antenna based on a CRLH Butler matrix is presented in this manuscript. The CRLH transmission line is proposed to increase the number of beams switch. The proposed CRLH TL has more than 100- degree phase deference with different bias voltages. By different bias voltages between 0 to 8 Volt, different combinations of phase shifts are achieved. The CRLH transmission line is added to the conventional butler matrix to increase the number of phase incremental combination and consequently the beam pattern. A 5-degree beam resolution is achieved. The measurement results follow well with the simulation result.