This Equivalent Capacitance Fixture is used for the verification and calibration of the active monopole antennas.
The ECF-12K is a capacitance fixture used for system checks and the calibration of active monopole antennas. This fixture simulates the self-capacitance of the monopole rod and is used in place of the actual element.
With recent changes to our Active monopole antenna (converting the input connection from a BNC to a more rugged ¼-20 input) our element diameter changed to 6.17mm (Average). It is our recommendation to use a 12 pF for the ECSM fixture (Model ECF-12K) as per ANSI C63.5:2017, CISPR 16-1-6:2017 and SAE ARP-958E:2021. The formula for calculating the capacitance is (per ANSI C63.5:2017, CISPR 16-1-6:2017 and SAE ARP-958E:2021):
Other fixtures are available as an option. The 10pF capacitator (model ECF-10 with a BNC connector) is available and only recommended when following older standards.
MIL-STD 461G Appendix A.5.18 states that: “The nominal 10 pF capacitor used with the rod antenna in 188.8.131.52c(3) as part of the system check simulates the capacitance of the rod element to the outside world. The actual rod capacitance depends on its width, so the manufacturer’s recommended value should be used if available.”
NOTE: MIL-STD 461 prohibits the use of other types of calibration networks or voltage dividing fixtures. Stray capacitance may exist in such fixtures. The ECF-12K is designed to work with the recent ANSI C63.5:2017 and CISPR 16-1-6:2017 standards and can be used to perform MIL-STD 461 antenna performance verification. As stated in MIL-STD 461G Appendix A: “The actual rod capacitance depends on its width, so the manufacturer’s recommended value should be used if available.”