Bent Two-Leaf Antenna Radiating a Tilted, Linearly Polarized, Wide Beam

A novel antenna composed of two bent conducting strips (leaves) above a conducting ground plane (designated as the bent two-leaf antenna, abbreviated as BeToL) is investigated to form a tilted, linearly polarized, wide H-plane radiation beam. For this, one conducting leaf of the BeToL (whose height is small: approximately 0.1 wavelength) is excited and the other is used as a parasitic element. First, analysis is performed under the condition that the ground plane is of infinite extent. It can be found that the BeToL realizes a desirable tilted wide beam (HPBW > 150° in the H plane) with low cross polarized radiation (less than -30 dB). The radiation mechanism of this tilted beam is explained using the currents that flow on the conducting leaves. Next, analysis is carried out using a finite square ground plane. It is revealed that, as the side length is decreased, the direction of maximum radiation in the elevation plane (E plane) shifts upward from the ground plane. The frequency response of the input impedance remains almost the same as that when an infinite-size ground plane is used, as long as the side length of the square ground plane is greater than one wavelength. The antenna characteristics when a portion of the ground plane is removed are also discussed.