Calibration of a multi-octave phased array

A linear array of vertically polarised log periodic dipole antennas (LPDAs) is an appropriate choice for an HF skywave radar transmit system. Multi-octave operation over the entire HF band is typically required, with a phase-scanning capability over a wide azimuth angular sector of ±45 degrees or more. Each LPDA array element can be driven from a separate power amplifier with independent phase and amplitude control available at the individual element level. Phases and amplitudes are chosen to produce a beam in the desired direction with suitable sidelobe levels. In order to determine the element phases and amplitudes, the location of the element phase centers must be known. The determination of the phase centre locations is discussed