In-Band Scattering Suppression for Compact and Low-Profile Linear Antenna Arrays Using Periodic Characteristic Mode Analysis

This article presents a scattering suppression technique for compact and low-profile linear antenna arrays. Periodic characteristic mode analysis (PCMA) is implemented to reveal the scattering mechanisms, using an X-band (8.0–12.0 GHz) antenna array as an illustration. It is found that the scattering at 8.0 GHz primarily comes from the center of the ground plane, while the scattering at 12.0 GHz is dominated by the edges of the ground plane. To reduce the scattering at 8.0 GHz, interdigital patches are integrated over the radiation aperture to create a reverse current that counteracts the scattering current on the ground plane. In addition, parasitic patches with shorting pins are introduced to convert the horizontal current into the vertical current, further suppressing the scattering at 12.0 GHz. The suppression technique is applicable for linear antenna arrays with small transverse dimensions. It does not increase the profile height and can enhance the gain of the array. The effectiveness of this technique is validated through a $2\times 8$ finite array. The antenna array operates in the 8.0–12.0-GHz range with a scanning range of ±45°. Moreover, the in-band monostatic radar cross section (RCS) is reduced by at least 10 dB compared to the reference array.