Improvement of mode uniqueness for OAM communication using a loop array with reflector plane

摘要

Mode uniqueness in an orbital-angular-momentum (OAM) communication scheme is improved to obtain excellent performance at the 5-GHz band. The mode uniqueness is shown by analysis and numerical calculation to be improved by combining loop antennas and a reflector plane. With 4-element loop antenna arrays, the current isolation that is the index for the mode uniqueness is 18.4 dB, 27.9 dB, and 41.0 dB for distances of 10 mm, 5 mm, and 2 mm between the reflector and the array, respectively. With the arrays for the distance of 5 mm, 4-value multiplexing characteristics for short-range (30 mm) communication were estimated. The simulated and measured transmission isolations are more than 23.6 dB and 19.2 dB, respectively. The measured transmission isolation is improved by 7.2 dB compared with the array without the reflector [4]. For long-range (1 m) communication with paraboloids and the array, the simulated transmission isolation is as large as 30.4 dB, which shows that the improvement of the current isolation by the reflector is also extremely effective for the long-range OAM communication.