Description
Firstly, an array of unique mode dipoles (lengths: λ/2, λ, 3λ/2, 2λ) above a High Impedance Surface (HIS) is investigated. The antenna has an acceptable impedance matching at the design frequency (4.6 GHz) in which the array of dipoles backed with a dog-bone shaped HIS structure creates a directional radiation pattern in the bore sight direction of antenna aperture. The impedance matching and the effect of the HIS reflector are discussed and presented.Then, a dual mode printed dipole antenna backed by similar HIS structure as mentioned above, was studied for directional pattern behavior and pattern reconfiguration application. The antenna consists of a half wavelength dipole (Mode 1: λ/2) and a higher order full wavelength dipole (Mode 2: λ). An integrated balance to unbalance (balun) feed network is introduced in each of the antenna modes. The dual mode antenna and the HIS design were fabricated on a 30mil Rogers RT/Duroid 5880 material. The fabricated antenna was testedand verified for impedance matching, radiation and pattern reconfiguration performance. Finally, a cavity backed dual polarized massive multiple input multiple output (MIMO) antenna panel is realized with printed dipoles as radiating elements for future 5G communications with frequency band from 4.9 GHz –6 GHz. Two dipoles (unit element) are placed at an angle of 45o and 135o gives slant polarization and good isolation. The dipoles and the tapered balun are printed on the 30mil Rogers 5880 substrate. A 4x4 sub-array of the similar cross dipoles is designed, fabricated, and experimentally verified to have good impedance matching, isolation, envelope correlation coefficient (ECC), radiation characteristics suitable for MIMO application and beamforming capability in digital domain is also verified for 4x4 sub-array. The 16x16 panel array employing 4x4 subarrays is also verified for beamforming. The 4x4 sub-array provided beam scan of +/-45o and the 16x16 panel array provided +/-500 beam scan. Further, simultaneous beams from the 16x16 array using digital beamforming approach are also shown for multi-user environment. Such an array can be generalized for multiple simultaneous beams which can be used for base station applications.
