AC3-840

The AC3-840 is a professional-grade, compact TETRA Band Omni-Directional Collinear Antenna specifically engineered for the 806–870 MHz frequency range. Delivering a consistent 3 dBd (5.15 dBi) gain, this ruggedized antenna is designed for tactical and base station applications where a balance of performance and low-profile aesthetics is required. Built with 6063T6 architectural aluminum and high-class brass alloys, the AC3-840 is a "set-and-forget" solution for public safety, military, and industrial networks, ensuring mission-critical communication in the most demanding environmental conditions.

Design: Optimized Radiation & Pattern Purity

The AC3-840 utilizes a sophisticated center-fed design, a critical engineering choice that eliminates the radiation pattern distortion common in end-fed antennas. By vertically stacking large-diameter brass radiating elements and feeding them in phase, the antenna achieves a true 360-degree horizontal pattern with a stable 38-degree vertical beamwidth. This ensures consistent signal propagation across the entire TETRA band without the need for field tuning. Specialized stub matching provides a smooth VSWR of less than 1.5:1, maximizing the efficiency of 800 MHz radio equipment.

Construction: Rugged Tactical Engineering

Built for ultimate survivability, the AC3-840 features fully welded junctions to prevent RF inter-modulation and maintain signal integrity. The radiating structure is completely protected within a high-tech, UV-resistant ABS radome that offers excellent RF transparency and mechanical strength. Finished in a tactical olive green military color, the antenna is designed for low-visibility deployment. Its compact 0.65-meter length makes it easy to handle and ship, while its 200 Km/Hr wind rating ensures it remains operational during severe weather events.

Reliability: Marine-Grade Durability

The AC3-840 is an all-weather model engineered for long-term deployment in high-salinity and corrosive environments. All mounting hardware is constructed from Type 316 marine-grade stainless steel, ensuring the antenna remains securely fastened to masts up to 50mm in diameter. With an operating temperature range of -30°C to +70°C and complete weather protection for the N-Female termination, the AC3-840 is a robust choice for coastal base stations, tactical masts, and critical infrastructure where communication failure is not an option.

Technical Features

• Optimized 806–870 MHz TETRA Coverage: Purpose-built for peak performance in international public safety and trunking bands.
• Balanced 3 dBd (5.15 dBi) Gain: Provides a wide 38-degree vertical beam for reliable communication in both flat and hilly terrain.
• True Omni-Directional Pattern: Center-fed architecture ensures 360° horizontal coverage without pattern squint or distortion.
• Fully Welded Internal Junctions: Eliminates the risk of passive inter-modulation (PIM) for cleaner signal transmission.
• UV-Resistant ABS Radome: High-strength enclosure protects internal elements from solar radiation and impact.
• Marine Grade 316 Stainless Steel: Supplied with high-grade hardware for maximum resistance to rust and corrosion.
• Compact Tactical Profile: 0.65-meter overall length allows for discreet installation and simplified logistics.
• 150W Power Capacity: Handles high-traffic radio signals for multi-channel TETRA network hubs.
• Internal Weather Shielding: The N-Female input termination is housed at the base for ultimate protection against moisture.
• Maintenance-Free Deployment: Factory-calibrated for immediate "plug-and-play" operation with no field adjustments required.

TETRA Network Optimization Guide: Urban Reliability with the AC3-840

In dense urban environments and undulating terrain, the AC3-840 serves as a high-reliability communication node. While high-gain antennas (9–12 dBi) are excellent for long-distance flat-land links, the 38-degree vertical beamwidth of the AC3-840 is specifically optimized for "filling the gaps" in complex RF environments.

1. The Advantage of a Wide 38° Vertical Beam

High-gain antennas focus their energy into a very thin "disk" (7–8 degrees). In a city with tall buildings or a region with rolling hills, this thin beam can actually "overshoot" users who are located at steep angles relative to the antenna.

• The Urban Solution: The AC3-840 provides a much broader 38-degree vertical beam. This ensures that users on the street level, as well as those on the upper floors of skyscrapers, remain within the antenna’s effective radiation pattern.
• Terrain Coverage: In hilly or mountainous areas, the wider beam allows the TETRA signal to "spill" into valleys and over ridges, maintaining connectivity where a narrower beam would be blocked by the landscape.

2. Center-Fed Design for Pattern Stability

In critical public safety networks, "null zones" (dead spots) can be life-threatening. Many compact antennas are end-fed, which causes the signal to "tilt" or distort as you move across the 806–870 MHz band.

• Symmetrical 360° Coverage: The AC3-840 is Center-Fed, ensuring that the RF energy is distributed with 100% horizontal symmetry. This means that a police officer or emergency responder will receive the same high-quality signal regardless of which side of the antenna they are standing on.

3. Fully Welded Junctions & PIM Mitigation

TETRA systems often use "Trunking," where multiple voice and data channels are transmitted simultaneously. If an antenna has poor internal connections, these signals can mix to create Passive Inter-Modulation (PIM), which creates "noise" that drowns out weak signals from handheld radios.

• Cleaner Reception: By using fully welded internal junctions, the AC3-840 eliminates the mechanical friction that causes PIM. This results in a much lower "noise floor" at the base station, allowing the receiver to pick up clear audio from low-power handheld units even in high-interference urban areas.

4. Low-Profile Tactical Signature

At only 0.65 meters (approx. 25 inches) in length, the AC3-840 is significantly less visible than 3-meter or 4-meter high-gain towers.

• Stealth and Aesthetics: This compact size is ideal for "stealth" deployments on rooftop chimneys, utility poles, or inside a tactical "Quick Deploy" kit. The olive green military finish further reduces the visual signature, making it a preferred choice for covert or rapid-response security details.

Tactical Deployment Checklist

• Mounting Height: For urban coverage, mount the AC3-840 high enough to clear immediate obstructions, but avoid extreme heights if the goal is to serve users directly below the building. Its wide beam is designed to "look down" effectively.
• Grounding for Static: Even a small antenna can build up a significant static charge in high winds. Ensure the 6063T6 aluminum support pipe is securely grounded to protect the connected TETRA base station from electrostatic discharge (ESD).
• Connector Integrity: The N-Female termination is weather-shielded at the base. However, for permanent installations, always use a weatherproofing kit (butyl and electrical tape) to prevent "moisture wicking" into the coaxial cable, which can increase VSWR and reduce your 150W power efficiency.
• Cable Selection: While loss is lower at 0.65 meters, 800 MHz still requires high-quality cable. For runs under 10 meters, LMR-400 is sufficient; for longer runs, upgrade to 1/2" Heliax to ensure the full 5.15 dBi gain reaches the radiating elements.