Effects of arm bend and asymmetric feeding on dipole antennae

This paper describes the characteristics of modified dipole antennae whose arms are bent at their middle points. On the basis of an integral equation method, we first analyse a centre-fed half-wave dipole, paying special attention to the bending angle of the antenna arm. It is found that the bent dipole with a bending angle of 90° can be made to resonate with nearly a pure resistance of 50 Ω. Secondly, we analyse an asymmetric-fed full-wave bent dipole for the purpose of improving the directivity. Calculations show how a bidirectional beam of increased directivity can be formed as the bending angle of the arm is increased.