The transmit loop antenna HFRA 5159 was designed to generate well-defined magnetic fields in the frequency range from DC to 400 kHz. With slightly reduced performance, the loop can be used in the frequency range up to 2 MHz. The loop, consisting of 28 turns, is shielded against E-fields. The nickel-plated brass housing contains resistors to verify the loop current by voltage measurement. The loop antenna has a flat frequency response over the entire frequency range.
The HFRA 5159 comes with 3 BNC connectors. Connector A is used to feed the loop with a 50 Ω source with constant voltage, generating a constant magnetic field strength versus frequency. Connector C is used to monitor the loop current by measuring the voltage drop across a 10 Ω resistor.
Alternatively, the loop antenna can be driven through Connector B, which presents the loop inductance in series with the 10 Ω resistor. In this case, the loop current must be checked by measuring the voltage drop across the 10 Ω resistor. This operation mode allows for generating higher field strength levels but requires current monitoring and input voltage adjustment for each frequency.
| Frequency Range: | DC – 400 kHz |
| Loop diameter: | 250 mm |
| Self Resonance: | 600 kHz |
| Number of turns: | 28 |
| Resistor for current monitoring: | 10 W |
| Inductance: | 450 µH |
| Series resistance of the turns: | 2 W |
| Parasitic Parallel Capacitance: | 160 pF |
| Maximum Current Input A: | 70 mA |
| Input Impedance A: | 1.26 kW |
| Maximum Current Input B: | 110 mA |
| Input Impedance B: | see Diagram |
| Maximum Power: | 5 W |
| Mechanical Dimensions: | 260 x 305 x 80 mm |
| Terminals: | 3 x BNC |
| Mount: | 3/8" |
| Weight: | 450 g |