A Method of Substrate Shaping to Improve Gain of Active-Element Pattern for Small Arrays

This letter proposes a method of substrate subtraction to improve the gain of an active-element pattern for individual elements in a small array. The proposed method is applied to a three-element controlled reception pattern antenna array, whose radiating elements are printed on a high-dielectric ceramic substrate. Then, three identical fan-shaped areas, placed between the array elements, are subtracted from the substrate, and their shapes are adjusted to avoid unnecessary power losses caused by the fringing field effect, leakage fields, and surface currents. The effects of the subtracted areas are also investigated as parametric studies to demonstrate the effectiveness of the proposed substrate shaping method. The results show that the gain can be increased by 0.7 dB due to lower effective dielectric loss compared to the full substrate.