Beamforming network using dual band-dual beam reduced size Butler matrices

Abstract

The results of reduced-size cascaded Butler matrices developed for dual-band and dual-beam applications are presented in this paper. The meander-line technique, an acceptable approach for reducing the size of the radio frequency element, was proposed for reducing the size of coupler design. The proposed system is capable of covering wireless local area network (WLAN) frequencies operating at 2.45 GHz and 5.8 GHz. Compared to the conventional size; the proposed couplers were reduced in size by 63 % and 56 % at 2.45 GHz and 5.8 GHz, respectively. The proposed, cascaded Butler matrices have the ability to exhibit two types of beams, i.e., narrow and broad, by feeding the signal into the respective input port of the Butler matrix. The proposed design was etched from an inexpensive FR4 substrate. The methodology enabled the reduction of the area of the Butler matrix. A meander line with an area of 96 mm × 125 mm was used to replace the conventional, straight transmission line. This reduced the area of the Butler matrix by 36 % compared to the conventional matrix. The actual measurements showed very good agreement with the results obtained from simulations