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International Journal of Antennas and Propagation
Volume 2013 (2013), Article ID 847859, 7 pages
http://dx.doi.org/10.1155/2013/847859
Research Article

Generation of OAM Radio Waves Using Circular Vivaldi Antenna Array

State Key Laboratory of Microwave and Digital Communication, Tsinghua University, Beijing 100084, China

Received 5 March 2013; Accepted 10 April 2013

Academic Editor: Yuan Yao

Copyright © 2013 Changjiang Deng et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

This paper gives a feasible and simple solution of generating OAM-carrying radio beams. Eight Vivaldi antenna elements connect sequentially and fold into a hollow cylinder. The circular Vivaldi antenna array is fed with unit amplitude but with a successive phase difference from element to element. By changing the phase difference at the steps of 0, ±45°, ±90°, ±135°, and 180°, the OAM radio beam can be generated with mode numbers 0, ±1, ±2, ±3, and 4. Simulations show that the OAM states of ±2 and ±3 are the same as the traditional states, while the OAM states of 0, ±1, and 4 differ at the boresight. This phenomenon can be explained by the radiation pattern difference between Vivaldi antenna and tripole antenna. A solution of distinguishing OAM states is also proposed. The mode number of OAM can be distinguished with only 2 receivers.