Calibration of Biconical Antennas by Vertically Stacking Method

A new way is proposed, and verified by experiment, to measure the free-space antenna factor (F_a) of biconical antennas over 30 to 300 MHz by the standard antenna method. The antennas were horizontally polarized above a metal ground plane. The usual method of calibrating electromagnetic compatibility antennas is to place two antennas at a given separation in a horizontal plane. Biconical antennas have a uniform H-plane pattern, making it possible to stack the antennas in a vertical plane. The (F_a) measured with the new method is in close agreement (difference less than 0.6 dB) to that with the vertically polarized method from the FDIS IEC international standard CISPR 16-1-6. Because the antennas are stacked vertically, a smaller ground plane can be used. Because the antennas are horizontally polarized, the vertically routed cable is orthogonal to the antenna so the interaction of cable and antenna is minimized.