This portable passive magnetic loop antenna kit is designed for receive-only use with sensitive SDR and radio receivers. The loop is formed from coaxial cable and uses a phase inverter together with a T-shaped low-loss wideband balun, requiring no tuning or external power.
Frequency coverage
- Primary HF response: approximately 10 kHz to 30 MHz.
- VHF response can extend up to approximately 300 MHz with a suitable receiver and installation.
- Passive design with no amplifier or external DC power required.
- No mechanical tuning capacitor is required.
- Receive-only maximum signal power is approximately 250 mW.
Assembly
- Connect the two loop branches between the phase inverter and the two balun inputs.
- Connect the transmission-line cable from the balun output to the receiver input.
- Form a symmetrical loop without sharp bends or tension at the SMA connectors.
- Place the loop away from computers, switching power supplies and digital cables.
- Rotate the loop to reduce local interference or peak the desired signal.
Receiver requirements
Passive loops produce a relatively low signal level and perform best with receivers that have a low noise figure and good dynamic range. A less sensitive receiver may require a suitable low-noise preamplifier, but amplification can also increase overload from strong local stations.
Installation notes
- Indoor placement near a window often reduces building attenuation.
- Outdoor use requires weatherproofing around the balun, phase inverter and connectors.
- Avoid repeated bending of semi-rigid coaxial sections.
- Actual response depends on loop geometry, feed line, nearby objects and receiver impedance.
Important limitation
This antenna is intended for reception. Do not connect it to a transmitter or apply RF power beyond the stated passive component limit. The product is an unbranded loop kit using a YouLoop-style architecture and should not be represented as an official Airspy product.
