HFR-4 H-Field Rod Antenna: High-Sensitivity Magnetic Field Testing

The A.H. Systems HFR-4 is a precision H-Field Rod Antenna designed for applications requiring high sensitivity in magnetic field measurements at higher frequencies. Operating efficiently across a frequency range of 5 MHz to 30 MHz, this antenna is a critical tool for MIL-STD, VDE, and TEMPEST compliance testing.

By utilizing a specialized ferrite rod core, the HFR-4 "concentrates" the magnetic component of RF signals, allowing it to achieve a much higher level of sensitivity than traditional loop antennas of comparable size. This design results in a compact, lightweight antenna (2.3" Dia. x 8") that is ideal for portable field applications. The antenna is shielded against electric fields and is highly directional, featuring deep nulls to assist in precise signal location.

To ensure accurate performance and proper operation, the HFR-4 H-Field Rod Antenna must be used in conjunction with the EHA-50B Matching Preamplifier. As a passive antenna element, the HFR-4 is specifically engineered to interface with the preamplifier's active circuitry to provide the necessary gain and impedance matching across its 5 MHz to 30 MHz frequency range. This combination converts the magnetic field strength into a measurable voltage, allowing for the high-sensitivity readings required for MIL-STD and TEMPEST testing. Attempting to operate the antenna element without this dedicated preamplifier will result in incorrect signal levels and an inability to utilize the provided calibration data.