AC6-390

The AC6-390 is a professional-grade, high-performance Fiberglass Omni-Directional TETRA Band Collinear Antenna specifically engineered for the 380–400 MHz frequency range. Delivering a consistent 6.8 dBi gain, this ruggedized antenna is designed for mission-critical communication hubs where a perfect balance of regional reach and vertical aperture is required. Constructed with 6063T6 architectural aluminum and high-class brass alloys, the AC6-390 provides a persistent, "set-and-forget" solution for public safety, military, and industrial trunked radio networks operating in demanding environmental conditions.

Design: Precision Radiation for Urban & Rural Links

The AC6-390 utilizes a sophisticated center-fed design, a critical engineering choice that eliminates radiation pattern distortion and ensures a true 360-degree horizontal signal profile. By vertically stacking large-diameter brass radiating elements and feeding them in phase, the antenna achieves a highly stable 30-degree vertical beamwidth. This optimized concentration of RF energy along the horizon provides a constant 6.8 dBi gain, allowing the TETRA signal to penetrate dense urban areas or provide reliable coverage in varying terrain without "pattern squint" across the 20 MHz bandwidth.

Construction: Ruggedized Tactical Engineering

Built for ultimate survivability, the AC6-390 features fully welded junctions to prevent RF inter-modulation and maintain long-term signal purity. The radiating structure is completely protected within a high-tech heavy-duty fiberglass radome that offers excellent RF transparency and mechanical strength to withstand wind speeds up to 200 Km/Hr (125 MPH). Supplied in a tactical olive green finish, the antenna’s compact 1.8-meter profile is optimized for easy handling and shipping while delivering the substantial aperture required for elite high-gain performance.

Reliability: MIL-SPEC Certified Durability

The AC6-390 is an all-weather model engineered for persistent deployment in the harshest global environments, meeting rigorous MIL-STD-810G specifications for shock, vibration, salt fog, and fungus resistance. All mounting hardware is constructed from Type 316 marine-grade stainless steel, and the antenna handles a robust 250 Watts of RF power. With the N-Female termination enclosed at the bottom for total weather protection, this antenna is the definitive choice for coastal base stations, tactical masts, and critical infrastructure where communication failure is not an option.

Technical Features

• Optimized 380–400 MHz TETRA Coverage: Purpose-built for peak performance in international public safety and military UHF bands.
• High-Intensity 6.8 dBi Gain: Focused 30-degree vertical beam delivers superior signal reach and penetration for regional base stations.
• True Omni-Directional Pattern: Center-fed architecture ensures symmetrical 360° horizontal coverage without pattern distortion.
• MIL-STD-810G Compliant: Tested for high/low temperature, humidity, shock, vibration, rain, fungus, and salt fog.
• Heavy-Duty Fiberglass Radome: High-strength, 45mm diameter enclosure protects internal elements from extreme weather and UV radiation.
• Fully Welded Internal Junctions: Eliminates passive inter-modulation (PIM) for cleaner, noise-free signal transmission and reception.
• Marine Grade 316 Stainless Steel: Supplied with high-quality hardware for maximum resistance to rust and salt fog in coastal zones.
• 250W Power Capacity: Robust electrical design supports high-power transmission for high-traffic network hubs.
• Internal Weather Shielding: N-Female input termination is housed at the base for ultimate protection against moisture and icing.
• Maintenance-Free Readiness: Arrives factory-tuned and factory-calibrated with no field adjustments required for rapid deployment.

TETRA Network Optimization Guide: Balancing Range and Vertical Aperture with the AC6-390

In the 380–400 MHz UHF band, achieving a reliable link requires a strategic balance between gain (distance) and beamwidth (vertical coverage). The AC6-390 is engineered to provide a high 6.8 dBi gain while maintaining a generous 30-degree vertical beamwidth, making it the ideal "all-rounder" for complex geographical environments.

1. The Versatility of the 30-Degree Vertical Beam

High-gain antennas (9 dBi+) focus energy into very thin "disks" that can overshoot users in hilly terrain or at the base of tall buildings.

• The "Sweet Spot" Gain: The AC6-390’s 30-degree beam provides a wider vertical "window." This ensures that mobile units located in deep valleys or on the lower floors of urban canyons stay within the antenna's primary radiation pattern.
• Stable Connectivity: For moving vehicles, a wider vertical beam is more forgiving. As a vehicle tilts or moves over uneven ground, the 30-degree aperture ensures the signal remains locked, preventing the "picket-fencing" effect (rapid signal flickering) common with narrower beams.

2. Center-Fed Design: Zero Pattern Squint

In mission-critical TETRA networks, "blind spots" are a major safety risk. Many antennas are end-fed, which causes the radiation beam to "squint" (tilt) upward or downward as the frequency changes within the 20 MHz band.

• Symmetrical 360° Coverage: The AC6-390 is Center-Fed, which mechanically and electrically locks the beam at the 0-degree horizon across the entire 380–400 MHz range. This guarantees that users in all directions receive the same signal quality, regardless of their position relative to the base station.

3. Fully Welded Junctions & PIM Mitigation

Modern TETRA base stations often run multiple high-power channels simultaneously. If an antenna has internal mechanical joints, these signals can "mix" and create Passive Inter-Modulation (PIM) interference.

• Lower Noise Floor: PIM manifests as background noise that can drown out weak signals from distant handhelds. By using fully welded internal brass junctions, the AC6-390 eliminates this source of noise. This allows the base station to "hear" low-power radios from greater distances, effectively expanding your usable coverage footprint without increasing transmitter power.

4. Resilience in Extreme Environments

Deployments in coastal or industrial regions face unique challenges like salt fog, high humidity, and high UV exposure.

• Tactical Hardening: The AC6-390’s heavy-duty fiberglass radome and 6063T6 aluminum support pipe are designed to survive these stressors. The cylindrical shape not only provides a low wind profile but also minimizes ice formation in cold climates, ensuring the antenna remains within its electrical specifications regardless of the weather.

Tactical Deployment Checklist

• Optimized Mounting Height: For maximum regional coverage, mount the AC6-390 as high as possible. However, due to its 30-degree beam, it is also highly effective when mounted at moderate heights on rooftops to serve an immediate urban radius.
• Coaxial Cable Quality: At 400 MHz, cable loss is a critical factor. For tower runs over 15 meters, use LDF4-50A (1/2" Heliax). Using lower-quality cable for long runs can waste a significant portion of your 6.8 dBi gain before the signal reaches the antenna.
• Static and Lightning Safety: Ensure the 6063T6 aluminum support pipe is integrated into the site's grounding system. This drains static electricity buildup from wind and protects the 250W base station equipment from electrostatic discharge.
• Environmental Sealing: The N-Female termination is weather-shielded at the base. However, for permanent installations, always use a professional weatherproofing kit (butyl rubber and vinyl tape) to prevent moisture from wicking into the connector, which would otherwise lead to high VSWR and permanent damage.