Compact E-band planar quasi-Yagi antenna with folded dipole driver

Abstract

A broadband planar quasi-Yagi antenna using a folded dipole driver is presented. The new antenna element is realised on a low dielectric constant substrate and it is suitable for millimetre-wave applications using low-cost thick-film fabrication. The advantage of the quasi-Yagi antenna with folded dipole driver compared to the standard quasi-Yagi antenna is a reduction in the length of the driver, which allows closer spacing of the elements for array applications on low dielectric constant substrates. Use of the folded dipole driver gives a 4:1 impedance range because of its extra parameters. The element was designed for E-band applications, but operates over a much wider bandwidth of approximately 1.3:1. Mutual coupling between two antenna elements in an array environment is investigated and results obtained are similar to conventional quasi-Yagi antenna elements. Four linear arrays, each containing four elements and having a different beamforming network, were fabricated to demonstrate the scanning capabilities of the folded dipole quasi-Yagi antenna, and measured reflection coefficient, radiation patterns and gain for each array are presented.