Array Antenna Composed of Bent Four-Leaf Elements

Inhalt:
A one-dimensional array is designed to radiate a linearly polarized fan beam. The radiation element in this array is a modified loop antenna with a sleeve, and is composed of four bent segments. One of the four segments is excited, while the remaining three are parasitic. The structure is designated as the bent four-leaf (BeFoL) element. The BeFoL is designed to have a tilted radiation pattern in the vertical plane (x-z plane). After presenting the design of the element, an array is constructed by arranging the BeFoL elements along one dimension (y axis). Analysis of the array reveals that the radiation pattern in the horizontal plane (x-y plane) becomes sharper as the number of BeFoL elements (n) is increased, while the radiation pattern in the x-z plane remains unchanged. A half-power beam width (HPBW) of 6deg is obtained for n = 16, with a directivity of D = 19 dBi. It is also found that, except for the two outermost elements, the array elements for n = 16 have almost the same input impedance.