Dual-Band Circularly Polarized Antenna with Circular Polarization in the Endfire Direction in Metal-Bezel Smartphones for n256-Band Direct Phone-to-Satellite Communication

In this article, a dual-band circularly polarized (CP) antenna with circular polarization in the endfire direction in metal-bezel smartphones for n256-band direct phone-to-satellite communication is proposed. The dual-band CP antenna features a rectangular folded loop and a floating parasitic branch. Both a horizontally polarized 1-wavelength folded dipole mode of the rectangular folded loop and a horizontally polarized 0.5-wavelength mode of the floating parasitic branch are orthogonal to a vertically polarized 1-wavelength mode of the rectangular folded loop, enabling the dual-band CP operation in endfire direction. Also, the integration of the dual-band CP satellite antenna with a cellular antenna covering the 704-960 and 1710-2690 MHz frequency bands is realized. For the dual-band CP antenna, the measured -6 dB impedance bandwidths are 130 MHz (1920-2050 MHz) for the uplink of the n256-band, and 65 MHz (2160-2225 MHz) for the downlink of the n256-band. The measured 3 dB axial ratio (AR) bandwidth covers 1980-2070 and 2160-2270 MHz frequency bands for the uplink and downlink of n256-band, respectively. The dual-band CP antenna mainly radiated the left-hand CP (LHCP) wave, and the measured peak gains in the uplink and downlink frequency bands are 0.9 and 1.92 dBic, respectively. Additionally, the measured -6 dB impedance bandwidths of the cellular antenna are 704-976 and 1660-2780 MHz with average efficiencies of 56% and 59%, respectively. The proposed antenna with the characteristic of dual-band CP radiation beams in the endfire direction of the phone is a promising candidate for direct phone-to-satellite communication in modern smartphones.