AC12-840

The AC12-840 is an elite, ultra-high-gain TETRA Band Fiberglass Collinear Antenna engineered for maximum coverage in the 806–870 MHz frequency range. Delivering an exceptional 12 dBi gain, this professional-grade omni-directional antenna is designed for critical mission-critical communication hubs where long-distance signal penetration is a requirement. Constructed with 6063T6 architectural aluminum and high-class brass, and protected by a ruggedized fiberglass radome, the AC12-840 ensures persistent network reliability for public safety, military, and large-scale industrial trunking systems.

Design: Unmatched Range and Pattern Integrity

The AC12-840 is meticulously crafted using a center-fed design to eliminate radiation pattern distortion and ensure a true 360-degree horizontal coverage profile. By stacking large-diameter brass radiating elements vertically and feeding them in-phase, the antenna achieves a highly focused 7-degree vertical beamwidth. This extreme concentration of RF energy along the horizon provides a massive 12 dBi gain, effectively extending the communication "radio horizon" and ensuring stable links for distant handheld and mobile radios. The integration of specialized stub matching ensures a superior VSWR of better than 1.5:1 across the entire TETRA band.

Construction: Ruggedized MIL-SPEC Engineering

Built to survive the most punishing environmental conditions, the AC12-840 features a high-tech fiberglass radome and type 316 marine-grade stainless steel mounting hardware. To facilitate logistics, the antenna is supplied in two segments that thread together securely to prevent RF inter-modulation. Its 4-meter overall length is designed for side-mounting on towers and includes a non-metallic 1.2-meter horizontal arm. This specialized offset mount holds the antenna away from the metal tower structure, preventing pattern interference and ensuring the 12 dBi gain remains consistent in all directions.

Durability: Tactical Survival in Extreme Climates

The AC12-840 is an all-weather model rated for extreme wind loads up to 200 Km/Hr. The N-Female termination is fully enclosed at the bottom of the antenna, providing 100% weather protection against moisture ingress and salt fog. With an operating temperature range of -30°C to +70°C, this antenna is ideal for coastal zones, high-altitude mountain sites, and high-salinity industrial environments. Its robust mechanical build and center-fed architecture make it a "set-and-forget" solution for high-traffic TETRA networks requiring zero field tuning or maintenance.

Technical Features

• Ultra-High 12 dBi Gain: Focused 7-degree vertical beamwidth delivers maximum signal reach for mission-critical TETRA networks.
• Optimized 806–870 MHz Coverage: Purpose-built for peak performance in international public safety and trunking bands.
• True Omni-Directional Pattern: Center-fed architecture ensures 360° horizontal coverage without pattern squint or distortion.
• Two-Segment Modular Design: Threaded segments allow for easier handling and shipping while maintaining electrical integrity.
• Fiberglass Radome Protection: Ruggedized enclosure provides superior RF transparency and survives the harshest weather.
• Marine-Grade Hardware: Includes Type 316 stainless steel brackets and fasteners for maximum corrosion resistance.
• TETRA Tower Side-Mount Kit: Supplied with a 1.2-meter non-metallic arm to maintain pattern purity when mounted on steel structures.
• High-Power 200W Capacity: Handles high-density trunked radio traffic without thermal degradation.
• Internal Weather Shielding: N-Female termination is housed at the base for ultimate protection against rain and humidity.
• Superior VSWR Performance: Factory-calibrated for a VSWR better than 1.5:1, maximizing transmitter power efficiency.

TETRA Network Optimization Guide: Long-Range Links with the AC12-840

In wide-area TETRA (Terrestrial Trunked Radio) deployments, particularly in rural or coastal regions, the AC12-840 acts as a high-precision signal "blade." By focusing RF energy into an ultra-tight 7-degree vertical beam, this 12 dBi antenna pushes the boundaries of the traditional radio horizon, ensuring reliable communication for distant vessels, remote patrols, and isolated industrial sites.

1. The Power of the 7-Degree Vertical Beamwidth

Standard antennas scatter energy in a broad "donut" shape, wasting much of the transmitter's power by sending it toward the empty sky or the ground immediately surrounding the tower.

• The High-Gain Advantage: The AC12-840 compresses the vertical radiation into a razor-sharp 7-degree window. This concentrated disk of energy is directed almost entirely along the horizon.
• Extended Radio Horizon: This extreme focus allows the signal to travel significantly further before atmospheric attenuation or the earth's curvature breaks the link. In coastal applications, this 12 dBi gain is the difference between losing contact at the shoreline and maintaining a clear digital link 30+ miles out at sea.

2. Side-Mounting and the 1.2-Meter Offset Arm

When a high-gain antenna is mounted directly against a steel tower, the metal structure acts as a "reflector," distorting the 360-degree omni-directional pattern and creating "null zones" (dead spots) on the opposite side of the tower.

• The Non-Metallic Solution: The AC12-840 includes a 1.2-meter (4-foot) non-metallic horizontal arm. By holding the antenna nearly four feet away from the mast, the influence of the tower is minimized.
• Pattern Purity: This offset ensures that the 12 dBi gain remains uniform in all directions, providing true 360-degree coverage. This is vital for a central base station that must serve users scattered across a 100-kilometer radius.

3. Overcoming Multi-Path Fading in Coastal Environments

In coastal or flat rural areas, RF signals often reflect off the water or ground, reaching the receiver at slightly different times. This "multi-path interference" can cause digital TETRA signals to break up or drop entirely.

• Vertical Discrimination: The tight 7-degree beam of the AC12-840 naturally rejects many of these steep-angle reflections coming from the ground or water surface. By only "listening" and "talking" to the horizon, the antenna provides a much cleaner Signal-to-Interference-plus-Noise Ratio (SINR), ensuring crystal-clear voice and high-speed data even in reflective environments.

4. Center-Fed Architecture: Zero Pattern Squint

As frequency shifts within the 806–870 MHz band, many antennas experience "pattern squint," where the beam tilts upward or downward, missing the users on the ground.

• Stability at Range: The AC12-840 is Center-Fed, which mechanically and electrically locks the beam precisely at the 0-degree horizon across the entire bandwidth. For an antenna with a beam as narrow as 7 degrees, this stability is mandatory; a shift of just 4 degrees would send your 12 dBi of power into the clouds, leaving your ground units in total silence.

High-Gain Deployment Checklist

• Tower Verticality: Because the beam is only 7 degrees wide, the antenna must be perfectly vertical. A tilt of even 2 or 3 degrees will significantly degrade performance in one direction while shooting the signal into space in the other. Use a high-precision level during installation.
• Mechanical Stability: At 4 meters (13 feet) long, the AC12-840 acts as a large lever in high winds. Ensure the marine-grade stainless steel brackets are torqued to specification and the tower itself is rated for the additional wind load of a 45mm diameter radome.
• LDF Cable Requirement: To preserve the 12 dBi gain, you must minimize "Feeder Loss." At 850 MHz, use LDF5-50A (7/8" Heliax) or better for tower runs exceeding 40 meters. Using thin, high-loss cable can easily "erase" 3–4 dB of your antenna's gain before the signal ever reaches the radiator.
• Thread Sealing: When assembling the two threaded segments, ensure the joints are clean and tight to prevent moisture ingress. Although the N-Female base is protected, the mid-section joint is a critical point for maintaining the 200W power handling without arcing.