Null-Steering Metaspiral Antenna

Nul1-steering is demonstrated using a metaspiral antenna, which has two feed points and an extremely low-profile structure on the order of 1/100 wavelength. The metaspiral antenna radiates a left-handed circularly polarized (CP) wave at a low design frequency and a right-handed CP wave at a high design frequency. A null-field point is created within the CP radiation pattern at these two frequencies. For this, the excitation amplitude and phase at one feed point are changed, while those at the other feed point are fixed. It is found that the intensity of the radiation field at the null-field point is less than −25dB.