30-GHZ MULTIBEAM ANTENNA USING BILAYER BUTLER MATRIX CIRCUITS

We propose a novel feeding circuit for a 30 GHz planar multibeam anten na applied to high-speed wireless communication systems. The feeding c ircuit is a bi-layer 8-port Butler matrix constructed with phase adjus ted slot-coupled hybrids and branch-line hybrids. The new circuit conf iguration eliminates troublesome vias and line crossings, so it can be manufactured by traditional photolithograph. The feeding circuit is d esigned by using the spectral domain moment method considering bonding film effects. A prototype of a multibeam antenna which has seven penc il-beams with 10 degrees beamwidths is manufactured and tested. the be am scan angle error is less than 3 degrees at 30 GHz.