A phase-matching method for antenna phase center determination basing upon site insertion loss measurement in OATS

The phase center of directional antennas, such as log-periodic dipole array (LPDA), varies with frequencies and is easily influenced by surroundings. This forms a dominant error for antenna calibration due to an undefined actual distance between the radiation and reception points. This paper concentrates on the phase center determination for broadband wire-element EMC antenna. A novel method named as phase-matching is developed, which uses the measurement data of site insertion loss (SIL) between an antenna under test (AUT) and a reference antenna with a definite phase center in an open area test site (OATS). Precise broadband calculable dipole antennas are utilized in this work. Both the theoretical derivation and validations are presented in this paper. The determination error based upon usages of measurement data is about 60 mm around 250 MHz, and is reduced to 15 mm around 900 MHz.