Study of an internally matched helical beam antenna

An internally matched helical beam antenna has been designed and constructed. The helix winding of a helical antenna was designed to be a slow wave section by placing a ground copper sheet on the inner side of the winding and inserting a dielectric sheet between the winding and the ground copper sheet to form a distributed capacitance along the antenna. By carefully adjusting the internal inductance of the helix winding and the distributed capacitance, the antenna can radiate in the axial mode and be internally matched to the 50- Omega transmission line feeding it. With this arrangement, the dimension of such an antenna can be much smaller than that for an ordinary helical beam antenna at the same operating condition. Details of the antenna design and experimental results are presented.<
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