Using the single point excitation technique to measure aperture impedance over a broad frequency range

Single point excitation for hardness surveillance (SPEHS) techniques have been used to produce surface fields over a broad frequency range (essentially 1 to 100 MHz). These fields were used to measure the aperture impedance of hardened and degraded windows and doors of the electromagnetic pulse (EMP) testbed aircraft (EMPTAC). Measurements were made using wing root (normal SPEHS) as well as antenna excitation. Above 1 MHz. aperture impedance is dominated by the aperture's transfer inductance. Values of aperture impedance were comparable to, but did not exactly match, those measured using the aperture tester technique. The SPEHS technique has great potential because it facilitates shielding and conductive penetration measurements when the aircraft is pressurized and/or in flight.<>