This chapter introduces two type helix antennas. One is a broadband inverted conical circularly polarized quadrifilar helix antenna (QHA). The antenna has many good characteristics, including wide beam and broad bandwidth, which are achieved by utilizing inverted conical geometry and adjusting the dimensions of the inverted conical support. The antenna is fed by a wideband network to provide 90° phase difference between the four arms with constant amplitude. The antenna impedance and axial ratio bandwidth values are more than 39% and 31.5%, respectively. The measured results coincide well with the simulated ones, which verified the effectiveness of the proposed design. Another step type helix line technology is also proposed to reduce the size of helix antenna. A small GPS helix antenna using the step helix line technology is designed, the antenna size is 0.032λ×0.032λ×0.063λ, the maximum gain is 5.3dBi, the peak to peak of circumference gain pattern within 0.3dBi, and the bandwidth is larger than 100MHz.
Author (s) Details
Nokia S-Bell Inc., Shanghai 200010, China.
Shanghai Satellite Engineering Institute, Shanghai 200240, China.
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