BACKGROUND:  Wireless systems using multiple antennas suffer from the problem of mutual coupling when antennas are spaced within a half a wavelength of each other. This coupling causes an impedance mismatch that reduces antenna gain. Many attempts have been made to solve the coupling problem, including coupling reduction techniques, combination of dipoles and loops and multiport matching networks. All have failed to produce the desired results.

INNOVATION:  This invention will bring high performance to small or mini platforms, such as handheld or mobile terminals, which is the ultimate goal of wireless communications. The invention involves the use of parallel information channels of multiple radiation modes formed in specially arranged closely coupled antennas. The excitation of each antenna is controlled individually, so a specially engineered arrangement of excitations will enable a combination of antennas to support one radiation mode and suppress others.

The simplest example is a pair of coupled dipoles aligned in parallel. Two parallel information channels are derived. In order to form the two parallel channels from the outputs of the two antennas, a multiport passive network rearranges the signals from the antennas. The capacity of each channel is maximized by adding an impedance matching circuit.

POTENTIAL APPLICATIONS:  Handheld or other space limited wireless applications, such as mobile phone networks and wireless LAN for homes.

DEVELOPMENT-TO-DATE:  The design has been analyzed and validated through full-wave simulators. A coupled half wave dipole doubled the data capacity in a MIMO system and formed a superdirective antenna with 5.3 dB higher gain than an ordinary dipole with a moderate current ratio. Analysis showed that with a pair of half wave dipoles at 0.1 wavelength spacing, more than 3 times the gain of a single half wave dipole was achieved.

Reference: UCLA Case No. 2006-542