Mobile NVIS Loop AntennaTraditional vertical ‘whip’ antennas fitted to vehicles for high frequency communication suffer from a ‘skip zone’, where little or no communication is obtainable in a given area.

The SMC Mobile HF Loop Antenna, developed for NVIS (Near Vertical Incidence Skywave) communication across 3-15MHz, overcomes these limitations by having high radiation efficiencyand no skip zone whatsoever.

Capable of automatically tuning across its frequency range in less than a 50th of a second, it is compatible with virtually any HF transceiver including frequency hopping types without the need for a separate control.

Based on the tried and tested SMC mobile NVIS loop which is in use by organisations throughout the world, this latest version incorporates a significant upgrade to ruggedized thick-walledtubing for performance and durability.

The NEW Rugged Loop, designed with strength and durability in mind.

Frequency Range: 3.0 - 15.0 MHzUnit Weight: 15kg excluding fixingsRetracted: 1.7m x .95m x .12mDeployed: 1m height

Deployed

The front edge of the loop is angled to deflect low overhead obstacles such as small tree branches.

Colour options. More available on request.

Test Specification:MIL-STD-810E: Method 514.4:Vibration, Categorry 8 - Ground Mobile, to Figure 514.4-16 Minimum Integrity Test General.

Other versions are available for:»» Vehicle roof-bar fitment with a ‘fold-down’ facility»» Side mounting on the vehicle.

The standard loop roof bar attachment is designed for roof bars 32mm x 22mm in cross section. However attachments can be manufactured to suit your individual requirement.

\\ StrengthenedTubular Structure

South Midlands Communications Ltd. SM House, School Close, Chandlers Ford, Industrial Estate, Eastleigh, Hampshire, SO53 4BY ENGLANDTel: +44 (0)23 8024 6200 - Fax: +44 (0)23 8024 6206 - Email: sales@smc-comms.com

In receive mode, for non-scanning/frequency hopping modes the antenna is factory-set to automatically store its tuning settings for the last tuned transmit frequency for greater receive efficiency. However, if pre-defined by the user upon ordering it may alternatively be factory-set for the loop to operate ‘un-tuned’ in receive mode to allow wide-band reception for scanning modes such as ALE (Automatic Link Establishment) reception.

Specs Information

TX Power Input Range 1.5-200 Watts PEP

Continuous TX CW/Data Power 80W

Number of operating channels Unlimited

Non-Volatile Channel Memory Addresses 170 (165 TX, 5 RX)

Input Impedance Range 50 ohms

VSWR Typically less than 2:1 when tuned, (3:1 max)

DC Operating Range +10.0V to 18.5V DC, (+13.8 V DC nominal) 24V DC nominal also available on request

DC Current 230 mA average

Initial tuning response time (initial memory setting only)

2 - 20 sec per channel

Recurrent tuning response time (on-air use inc. freq hopping)

Typically less than 10 ms per channel

Operational Temperature -35° to +70°C

Coaxial Cable RG58 5m in length

Power Cable 2 Core screened, 5m in length

The radiation pattern presented by the loop at low frequencies gives maximum radiation in an arc from the front of the vehicle, over the vehicle (thus giving excellent NVIS performance) and to the rear of the vehicle. At higher frequencies, a typically ominidirectional radiation pattern is presented giving all-round long-distance coverage.

NVIS Loop Data Sheet Additions

Typical 15MHzAzimuth Pattern

Typical 3MHzAzimuth Pattern

Low frequency 3D radiation pattern, shown with loop mounted in the same plane of the vehicle, i.e. front to back

Representative near-field azimuth radiation patterns, taken at a distance of 16m, from the NVIS loop when mounted on a 4x4 vehicle. Outer scale represents -25dBm measured level with 10W RF fed to the loop system.

South Midlands Communications Ltd. SM House, School Close, Chandlers Ford, Industrial Estate, Eastleigh, Hampshire, SO53 4BY ENGLANDTel: +44 (0)23 8024 6200 - Fax: +44 (0)23 8024 6206 - Email: sales@smc-comms.com

Fixed Station Loop AntennaOperating both NVIS and Long Distance Sky Wave

As well as the compact mobile HF loop, two versions of fixed station loop antennas are also available, which operate on both NVIS and long distance sky-wave propagation modes across3-30MHz.

The two versions are a wire element loop with 3m sides, and a solid element loop with 2.5m sides, each offering similar high efficiency. These are ideal for use where space is limited, and rival the performance of much larger wideband HF wire antennas.

Colour options. More available on request.

Frequency Range: 3.0 - 30.0 MHz

Like the mobile loop, the fixed station loop is capable of automatically tuning across its frequency range in less than a 50th of a second, it is compatible with virtually any HF transceiver including frequency hopping types without the need for a separate control.

275

0

2500

120

0

Other sizes can be made upon request.Design changes may be made at any time.

Secure locking catches ATU

Example of theSolid Element Loop

Example of the Wire Element Loop

In receive mode, for non-scanning/frequency hopping modes the antenna is factory-set to automatically store its tuning settings for the last tuned transmit frequency for greater receive efficiency. However, if pre-defined by the user upon ordering it may alternatively be factory-set for the loop to operate ‘un-tuned’ in receive mode to allow wide-band reception for scanning modes such as ALE (Automatic Link Establishment) reception.

Specs Information

TX Power Input Range 1.5-200 Watts PEP (3-500w PEP version also available)

Continuous TX CW/Data Power 80W (200w for 500w PEP version)

Number of operating channels Unlimited

Non-Volatile Channel Memory Addresses 170 (165 TX, 5 RX)

Input Impedance Range 50 ohms

VSWR Typically less than 2:1 when tuned, (3:1 max)

DC Operating Range +10.0V to 18.5V DC, (+13.8 V DC nominal) 24V DC nominal also available on request

DC Current 900 mA average

Initial tuning response time (initial memory setting only)

2 - 20 sec per channel

Recurrent tuning response time (on-air use inc. freq hopping)

Typically less than 10 ms per channel

Operational Temperature -35° to +70°C

Control Cable Standard 50 ohn coaxial cable plus DC feed 3m in length