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National RF's Type HFDX Vector-Beam is an active table-top HF directional antenna that can be used to reduce or cancel man-made noise or other interfering stations. The antenna system consists of a high gain RF amplifier coupled to a tunable Faraday shielded loop antenna element. Several loop elements are available to provide coverage of frequencies in the HF spectrum. Due to the nature of a Faraday shielded loop, the antenna exhibits a sharp null through the diametric center of the loop. This null can be used to advantage to reduce or eliminate interfering stations by rotating the antenna. The undesired signals will be reduced in strength by the null notch, thus allowing better reception of the desired signal.

The internal high gain amplifier is used to compensate for the inherent inefficiency of the actual loop at the operating frequency.

Overall, the system dynamic response is about +6 dB as compared to the dynamic response of the dipole. A standard BNC female connector is provided to allow interface with virtually any communications or shortwave receiver. A single 9-volt battery is required for operation. The battery and the HF radio receiver are the responsibility of the customer to provide.

**New** Loop AA - 3.5 to 8.0 MHz loop now available. Tuned to cover the low end of the HF band, this loop offers coverage of both the 80 and 40 meter amateur radio bands. It is also ideal for low frequency noise location, especially noise radiated by dirty power line insulators. The loop incorporates a small loading coil, thus making it manageable and compatible in size with the rest of the loops.


Antenna Type: Amplified Faraday shielded loop with bi-directional, cardiodal pattern response.

Dynamic Response: Approx. +6 dB compared to a dipole, amplified response

Frequency Range: Loop BB - 1.8 to 3.5 MHz, Loop AA - 3.5 to 8 MHz, Loop A - 8 to 16 MHz,
Loop B - 15 to 30 MHz, Loop C - 30 to 55 MHz

Output Impedance: 50 ohms, nominal

Output Interface: Female BNC Connector

Controlable Gain Output: High and low gain positions

Enclosure Size: 4 L x 2 W x 1 H inches, loops not attached

Power: Single 9-volt battery, alkaline recommended


Type HFDX with one loop element     $169.95

Each additional loop element     $34.50

CA residents add sales tax, Shipping & handling additional

Overseas Customers: An additional shipping charge will be applied to orders from outside of the United States and determined after order placement. Orders from Alaska, Hawaii, and Puerto Rico may incur an additional charge, depending on the shipment service. We will notify you via email of the amount additional, if any. The customer is responsible for all and any customs or tariff charges applied to your order.

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