Design of Bidirectional Antenna Array With Adjustable Endfire Gains

The endfire gains of bidirectional antenna arrays reported previously are not adjustable. A method for controlling the gain distribution of bidirectional antenna array is presented in this letter. By introducing a weighted diagonal matrix into the method of maximum power transmission efficiency, the optimized excitations for the antenna elements can be obtained to realize the desired distribution for the endfire gains in the two opposite directions of a bidirectional antenna array. To demonstrate the feasibility of the method, a four-element printed bidirectional dipole array is designed and fabricated. Compared with the conventional designs using dipole elements, the optimized dipole antenna array can achieve a desired distribution of endfire gains with reduced size and enhanced gain. The simulated and measured results show that the endfire gain in one direction varies from 1.5 to 10.2 dBi at 2.45 GHz as the ratio of weights changes from 0 to 1. The endfire gain reaches 9.3 dBi when the radiation patterns are equally excited in both directions.