A printed planar helix antenna

This paper presents design, fabrication and measurement results of a novel broadband, circularly polarized, planar helix antenna operating at X-band that is fabricated using printed circuit techniques. The conventional circular helix antenna is modified into a planar helix antenna, and the effect of various parameters like pitch angle, dimensions, feed and substrate, etc. on the impedance and radiation characteristics is studied. The performance parameters under investigation are S₁₁, directivity, side lobe level, and axial ratio. These parameters are obtained using CST Microwave Studio. For a design with 5 turns of the planar helix, the results of the simulations are as follows: over a frequency range of 8.3 - 11.7 GHz, S₁₁ is less than -10 dB, directivity ranges from 11.7 - 12.6 dBi, and the axial ratio ranges from 0.68 - 3.3 dB. The corresponding design is fabricated using RO4003C dielectric substrates. The measurement results match the simulation results reasonably well.