Overview
The Loop Antenna for magnetic fields was designed to create small to medium magnetic fields in the frequency range from 100 kHz to 300 MHz. The HFRA 5155 consists of a shielded single turn loop of 50 mm diameter. The flat frequency response is achieved using a wideband transformer.
The HFRA 5155 is equipped with two BNC-connectors, one (Input) is to feed the loop with a 50 ? signal generator or a power amplifier, the other one (Monitor) can be used to monitor the loop current by measuring the voltage drop across the built-in 10 ? resistor. The monitoring output requires a high impedance voltage probe (e.g. from an oscilloscope or a voltmeter) and is usable up to 30 MHz.
In general, but especially with high accuracy requirements and at high frequencies it is recommended to monitor the generated fieldstrength using the active magnetic field probe HFS 1546.
| Specifications | |
| Frequency Range | 100 kHz ...100 (300) MHz |
| Loop Diameter | 50 mm |
| Connector | BNC |
| Max. Input Power | 2 W |
| Impedance of Signal Generator or Power Amplifier | 50 ? |
| Impedance of Voltage Probes connected to 10 ? Monitor Output | > 10 k? |
| Maximum Loop Current | 0.44 A |
| Maximum Monitor Voltage | 4.4 V |
| Mount (Camera Thread) | 3/8" |
| Material | Brass, Nickel plated |
| Dimensions | 105 x 60 x 62 mm |
| Weight | 145 g |
Transmission between HFRA 5155 and HFS 1546 | Input Impedance at Feed Connector |
Impedance at Monitor Connector | Distance to Loop Center [cm] |
 |  |
| Distance to Loop Center [cm] |
