Single-arm helical antenna with width of arm varying periodically for tilted beam

A single-arm helical antenna with the width of the arm varying periodically for a circularly polarised (CP) tilted beam is introduced. The proposed antenna radiates a CP tilted beam, when the following two conditions are met: (i) the circumference of the proposed antenna is >4λ₀/3 (λ₀ is the wavelength in free space at the centre frequency) and (ii) the width of the arm varies periodically. The designed procedure reveals that the maximum radiation direction of the tilted beam is not sensitive to a change in frequency. The simulated and measured results show that the designed antenna radiates a CP tilted beam with θ_max = 32°. The measured 10 dB return loss bandwidth is 12.8% from 2.33 to 2.65 GHz, and the experimental results of the radiation pattern, gain and axial ratio are also presented.