Doubly Helical Antenna by Spiro Mode Maintaining Radiation

We are presenting by this paper on helical antennas which find important applications in communication systems, primarily because of their circular polarization and wide bandwidth. The helical antenna, first introduced by Kraus in 1946, The geometry of larger helical shape type antenna, which is a doubly helical structure, is fully described by five independent parameters, with the including two radial dimensions, two pitch angles, and the number of turns. Radiation properties of this antenna are examined both theoretically and experimentally. The obtain simulation result by the Numerical Electromagnetic Code is used. A large number of cases with different radii, pitch angles, and number of turns are investigated. Results for far-field patterns, gain, axial ratio, and bandwidth are presented. The influence of parameters on radiation properties are examined. Several prototypes of the antenna were constructed and tested using an outdoor antenna range. Measured far-field patterns are presented over a wide range of frequencies. The measured and computed radiation patterns are in good agreement. The results of this study indicate that the proposed antenna provides circular polarization and high gain over a wide frequency range. The one think is most important of this antenna which is size compared with a conventional helical antenna made of straight wire shaped into a helix.