Glocom

GA-114A HF NVIS Antenna

HF Radio Antenna for Mobile/Shipborne Communication

[Key Features]

■Near Vertical Incidence Skywave (NVIS) Propagation ■All terrain coverage - no skip zone in HF band ■High efficient ATU with minimum VSWR ■Rugged construction - easy to installation ■Flexible mounting options ■Compatibility with GR-100 & GR-150 HF radio ■Folding antenna structure - compact size

[Applications]

■Humanitarian & peacekeeping ■Police & customs Drug enforcement & private security ■Military & paramilitary ■Border patrol ■Mining, oil & gas ■National guard ■Public & commercial ■Aid & relief, emergence service ■Forestry & transportation ■Deep sea fishery

NVIS propagation

Propagation refers to the path a radio frequency signal travels when radiated from antenna. There are three main types of propagation commonly used in vehicle HF SSB systems:

Skywave - the signal radiates at a low angle towards the horizon and is refracted by the ionosphere to return back to earth at a long distance away from the source
Groundwave - the signal radiates along the ground directly from the radiating antenna following the contour of the earth
NVIS - the signal radiates at a high angle towards the ionosphere and is refracted to return at a close to medium distance from the source.

[High Efficient] Radiates 10dB to 14dB more than a whip antenna, Equivalent to a 500W transmitter with a whip antenna[Simple Installation] Does not require welding or mounting plates, No separate antenna tuner to install, Fast & inexpensive installation, Easily moved between vehicles[Integrated Roof Rack] Conventional roof rack for storing tents, boxes, Additional storage w/o compromising performance Eliminates or minimizes skip zones, Virtually continuous HF coverage from 0~1000Km+ [Noise Reduction] Increased immunity to ignition & power line noise [Simple Design] Mechanically simple & robust folding mechanism, Low risk of failure [Covert] Easily disguised for covert applications, Not immediately recognizable as an antenna, No unwanted attention in areas of conflict

General Specifications

Frequency range	3.7MHz ~ 13MHz
Power rating	Up to 125W PEP
Power supply	12VDC (24VDC Option)
Radiation pattern	Omni directional at high radiation angles, NVIS optimized
VSWR	≤1.3:1@50Ohm
Tune control	Control signal from radio, Customizable to suit 3rd party radios
Tune time	Approximately 3 seconds
Tuning method	Continuously variable tuning capacitor
Drive method	Microprocessor controlled precision stepper motor
Tune point	Peak antenna current
Receive bandwidth	Variable from 40kHz at 3.7MHz to 280kHz at 13MHz
Gain	+8dB ~ +22dB @ 0-300Km distance (vs typical 1.8m mobile whip)
Dimension	1700 x 1256 x 795mm Folding: 1700 x 1256 x 140mm
Weight	45Kg (w/o mounting bracket)
Environmental	IP67 for outdoor and indoor modules, MIL-STD-461, MIL-STD-810F (Clauses 516.5 for shock, 514.f for vibration, 510.4 for dust
Operating Temperature	-40° C ~ +70° C
Humidity	95%

Continues coverage & no skip zone

Glocom’s GA-114A NVIS antenna is a technological breakthrough in vehicle based HF radio communications. It is without doubt the best type of antenna for vehicular NVIS operations and is effective in overcoming the skip zone common in whip based antenna systems. GA-114A is a magnetic half loop antenna which predominantly radiates RF energy towards the ionosphere, making it ideal for NVIS propagation, with the correct selection of frequency, is virtually continuous from 0 to 1000Km or more. Glocom’s GA-114A antenna system also provides highly

effective medium range communications, reducing the skip zone traditionally found between 30-150Km. The skip zone refers to the area where groundwave propagation ends and skywave propagation begins. Between these two points, HF coverage using a whip antenna is very limited or non existent. GA-114A overcomes this by using NVIS propagation, providing continuous coverage for up to 1000Km or more. Whip antennas, which are usually vertically polarized, radiate most of their RF signal radiates towards the horizon. As a result, very little signal radiates towards the zenith, which is required to facilitate NVIS propagation.