AX-81SM Active LF-HF Antenna

(Mounted using the optional WR-AC-RMB-114 base.)

The AX-81SM antenna is a compact active LF to HF antenna, ruggedized to suit harsh outdoor environments, and particularly suitable for high performance professional and military applications. Designed for surveillance and monitoring, the antenna can be useful anywhere where good performance and reliability are required, and where space is at premium.

The receive-only antenna covers the frequency range of 20 kHz to 30 MHz, or 10 kHz to 50 MHz with somewhat reduced (but still excellent) performance.

While designed to be entirely general-purpose, the AX-81SM antenna is especially suitable for the WiNRADiO G3 range of HF receivers including the G31DDC, G33DDC, G35DDCi, G313, G33EM.

The principal elements of the antenna are constructed of a low-carbon austenitic stainless steel that contains molybdenum. Austenitic (chromium and nickel content) stainless steels have high ductility (i.e. ability of a metal to plastically deform without breaking or fracturing), low yield stress and high ultimate tensile strength, when compared to a typical carbon steel. The 316L grade as used for the AX-81SM antenna also offers an especially high degree of resistance to corrosion. The choice of materials and the durable construction of the AX-81SM antenna will ensure trouble-free operation for many years.

Internally, the antenna features excellent protection against electrostatic discharge, its input automatically grounded when the antenna is not in operation (i.e. power is not applied to the antenna).

Optional accessories

The WR-AC-RMB-114 heavy duty rail-mount antenna base has a single swivelling mount. It accepts any standard antenna with a 1" diameter standard #14 thread (such as the AX-81S antenna) and can be mounted on a railing of 7/8 to 1" diameter. Material is stainless steel 316 grade.

The WR-AC-DMB-114 heavy duty deck-mount antenna base has two swivelling mounts for complete adjustability. It accepts any standard antenna with a 1" diameter standard #14 thread (such as the AX-81S antenna). Material is stainless steel 316 grade.

The WR-CMC-30 Common-Mode Choke eliminates common-mode noise from the antenna feedline, resulting in a considerable increase of the received signal quality. Common-mode noise is generated by computers and other electric or electronic appliances, and can be a problem especially in the lower portions of HF spectrum.

The Common-Mode Choke can be also very useful to provide an alternative earthing point if the AX-81S antenna itself cannot be grounded due to its location, or its ground connection is inadequate.

The WR-BT-650 Power Injector (Bias "T") provides a means of injecting DC power in a coaxial cable, to power the antenna from a remotely located power supply. It features a flat frequency response and low insertion loss.

We recommend using WiNRADiO SF-41 range of low-noise power supplies to power the antenna.

Technical Specifications
Type	Active LF-HF antenna monopole
Frequency range	20 kHz - 30 MHz @ 3 dB (excellent performance from 10 kHz to 50 MHz)
Output IP2	+60 dBm
Output IP3	+30 dBm
Supply voltage	12 V DC (min 10 V, max 14 V), supplied via the coaxial cable We recommend using a WiNRADiO *SF-41 Low-noise Linear Power Supply* together with the WiNRADiO *WR-BT-650 Power Injector*.
Supply current	80 mA @ 12 V
Impedance	50 ohm
Connector	BNC (concealed in body)
Operating temperature	-40° to 85°C
Active element length	1160 mm (3.8 ft)
Active element diameter	3 mm (0.118 in)
Body length	190 mm (7.45 in)
Body diameter	38 mm (1.45 in)
Mounting	1" diameter standard #14 thread
Overall length	1350 mm (4.43 ft)
Weight	555 g (1.22 lb)

Specifications are subject to change without notice due to continuous product development and improvement.

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AX-81SM Active LF-HF Antenna