Multiband hybrid for WiFi

Abstract

Nowadays, there are many wireless communications systems with multiple standards. One of the example is the WiFi systems with IEEE802,11b/g for 2.4 GHz and IEEE802.11a for 5 GHz. For the integration of the circuitry in these systems, it is great interested to develop multiband microwave circuits that can operate at two or more arbitrary frequency bands. This report is targeted on the hybrid coupler which is with a wide range of application in RF and Microwave circle. Two multiband hybrid couplers were simulated and fabricated for detail analysis. First, a branch line multiband coupler with open circuit stub covering frequency 2.45 GHz and 5.25 GHz was investigated. Second, a multiband hybrid coupler covering frequency 2.45 GHz, 5.25 GHz and 5.8 GHz was investigated. The multiband hybrid coupler employs rectangular disk hybrid coupler and open circuit stubs. In order to demonstrate the application of the hybrid coupler, a multiband butler matrix based on the rectangular disk hybrid coupler and Schiffman Phase Shifters are also fabricated for detail analysis. The butler matrix is a kind of beamforming network that can be used to feed the antenna array and build the multiport amplifier.