Abstract: A switch is particularly advantageous for calibration of signal phase between transmitters, and other uses. The switch has a first data input adapted to input a transmit signal from a first transmitter, a first data output, at least one and preferably multiple bidirectional data ports, and a control input adapted to selectively couple in a first case the first data input to one of the bidirectional data ports, and in a second case one of the bidirectional data ports and the first data input to the first data output. By coupling one data port of the switch to a data port of another identical switch, a transmit signal from another transmitter can be ported to the first said switch, and both signals output to a feedback circuit that finds the phase difference and applies it to a new signal input to one of the transmitters. Beamforming and MIMO uses are also detailed.

Abstract: A switch is particularly advantageous for calibration of signal phase between transmitters, and other uses. The switch has a first data input adapted to input a transmit signal from a first transmitter, a first data output, at least one and preferably multiple bidirectional data ports, and a control input adapted to selectively couple in a first case the first data input to one of the bidirectional data ports, and in a second case one of the bidirectional data ports and the first data input to the first data output. By coupling one data port of the switch to a data port of another identical switch, a transmit signal from another transmitter can be ported to the first said switch, and both signals output to a feedback circuit that finds the phase difference and applies it to a new signal input to one of the transmitters. Beamforming and MIMO uses are also detailed.

Abstract: A quadrifilar helix antenna has four inter-twined helical antenna elements offset from one another by 90°. The elements are identical and each can be defined by an axial coefficient z, a radial coefficient r, and an angular coefficient &thgr;.