A Dual-Polarized Frequency-Reconfigurable Low-Profile Antenna With Harmonic Suppression for 5G Application

A dual-polarized frequency-reconfigurable low-profile antenna with harmonic suppression for 5G application is presented in this letter. The proposed design consists of a pair of +/- 45 degrees polarized frequency-reconfigurable dipole antennas, two vertically placed feeding structures with filtering branches, and an artificial magnetic conductor (AMC) surface. By introducing the U-shaped structure, a better impedance matching performance is achieved in two bands. Measured results show that the proposed antenna can operate at 3.24-4.03 and 4.44-5.77 GHz by controlling the ON-OFF of PIN diodes, and port isolation of two bands is greater than 25 dB. What is more, two-octave harmonic suppression is realized by loading the filtering branches. In order to obtain stable unidirectional radiation pattern in the operating bands and low-profile characteristic, a dual-band 4 x 4 AMC reflector is fabricated. Finally, a maximum gain of 6.86 dBi in low frequency band and 8.14 dBi in high frequency band are obtained. Besides, the height of the proposed antenna is 0.1 lambda at 3.3 GHz. Experimental results show that the antenna can meet the needs of the 5G communication.