OctaLoop3 — A shielded active H-field Loop antenna — 500KHz – 30 MHz

Included

• OctaLoop3 antenna with enclosure — 1.2 m overall diameter and approximately 3.65 m loop perimeter
• Stainless steel (RVS316) mounting bracket
• Bias-T (13.8 V) — F-type to SMA
• Short SMA-to-BNC patch cable
• 1 metre 13.8 V DC power cable with Powerpole connectors

Optional

• 10 m INTSAT-170-ELITE 75 Ω coax (2× F-type connectors)
• RVS ground peg (with F bulkhead) + RX line isolator

Product Description

The OctaLoop3 is a shielded active H-field magnetic loop engineered for low-noise MW and HF reception. Its larger 1.2 m aperture is optimized for the lower HF bands, while its geometry and shielding naturally reduce pickup of electric-field noise. The result is cleaner reception even in high-EMI urban environments.

This third-generation design adds automatic power-off grounding at the loop input and a revised, lower-loading front-end protection network while retaining the wideband balanced receive architecture of the OctaLoop2. Its deep directional nulls let operators rotate the loop to suppress noise from specific directions.

Optimized coverage is 2–10 MHz, while the antenna remains effective from approximately 500 kHz to 50 MHz. This makes the OctaLoop3 especially well suited to MW, 160 m, 80 m and 40 m reception, as well as SWL, amateur DXing, utility monitoring and SDR applications.

Key Features

• Wideband Coverage: 500 kHz – 50 MHz (optimized for 2–10 MHz)
• Larger Aperture: 1.2 m overall diameter for stronger performance on MW and lower HF
• High Linearity: balanced push-pull receive architecture for strong-signal environments
• Automatic Power-Off Grounding: both loop conductors enter a grounded, muted state when bias power is removed
• Reduced Input Loading: revised balanced protection path designed to preserve weak-signal reception
• Input Protection: multi-stage protection helps manage static and short transient events
• Common-Mode Rejection: dedicated feedline-current suppression helps keep unwanted cable-borne noise out of the signal path
• Pre-Filtering: integrated low-pass filtering reduces out-of-band interference
• Protected 75 Ω Output: broadband output interface with additional transient protection
• Bias-T Powered: 13.8 V supplied over the coax through the included injector, with on-board regulation
• Deep Nulls: sharp directional nulls for rejecting local EMI sources, especially on MW and lower HF
• Rugged Construction: full-size loop with stainless steel mounting hardware

Placement & Grounding

Mount away from power lines and buildings. Typical height: 1.2–5 m. For best common-mode isolation, use an RX line isolator near the antenna and another before the feedline enters the shack, especially on long coax runs. Ground the coax braid at the mast base; our RVS ground peg simplifies this.

Applications

• AM/MW broadcast, SWL, utilities (for example NAVTEX and time signals) and beacons
• Amateur HF reception, especially 160 m, 80 m and 40 m
• Weak-signal DXing, propagation study and SDR monitoring

Technical Data

• Frequency Range: 500 kHz – 50 MHz (optimized approximately 2–10 MHz)
• Impedance: 75 Ω
• Power Supply: 13.8 V DC via the included bias-T (approximately 180 mA)
• Polarization: magnetic (H-field)
• RF Connection: F-type antenna feed with SMA receiver output on the included bias-T
• Loop Size: 1.2 m overall diameter (approximately 3.65 m loop perimeter)
• Weight: approximately 1.2 kg
• Operating Temperature: −20 °C to +50 °C
• Pole Mount: 30–68 mm

For higher HF bands (20 m–10 m), consider the OctaLoop3 Mini, whose smaller aperture is optimized for 7–30 MHz.