UAT-978-1090

The UAT-978-1090 is a high-performance, Dual-Band Omnidirectional L-Band Antenna engineered for modern aircraft surveillance and navigation systems. Operating across the 960–1220 MHz range, this ruggedized coaxial dipole is fully compliant with UAT (978 MHz) and ADS-B (1090 MHz) protocols. Additionally, it supports ATC Mode-S (1030–1090 MHz) and DME (976–1213 MHz) applications. Designed for fuselage mounting with an extended stub to minimize airframe interference, the UAT-978-1090 ensures critical situational awareness and navigational integrity for both general aviation and commercial aircraft.

Design: Optimized Aviation Surveillance

The UAT-978-1090 features an advanced broadband coaxial dipole design that provides a true omnidirectional horizontal pattern. A key engineering highlight is the extended stub architecture, which strategically positions the radiating element away from the aircraft fuselage. This distance significantly reduces RF interference and pattern shielding caused by the aircraft body, ensuring 360-degree visibility for NextGen surveillance systems. With a wide 76-degree vertical beamwidth, the antenna maintains a stable link even during aggressive aircraft maneuvers and varying bank angles.

Construction: Aero-Ruggedized & Maintenance-Free

Built to survive the harsh environment of external aircraft mounting, the UAT-978-1090 is constructed from 6063T6 ultra-corrosion-resistant aluminum alloy and high-grade brass. The internal radiating elements are completely protected within a high-tech fiberglass/ABS radome that is aerodynamically profiled to handle airspeeds up to 300 Knots TAS. The antenna is ground-plane independent, meaning it provides a perfect radiation pattern whether installed on metallic airframes or non-metallic composite surfaces, eliminating the need for a counterpoise.

Reliability: High-Altitude Technical Excellence

This antenna is engineered for mission-critical reliability, handling up to 150 Watts of RF power and functioning at altitudes up to 35,000 feet. It is designed without internal junctions to prevent RF inter-modulation, ensuring the highest possible signal purity for digital data links. Installation is simplified via a 16mm bulkhead N-Female connector, supplied with a high-quality rubber "O" gasket and mounting hardware to ensure a pressurized, weather-tight seal against the aircraft chassis.

Technical Features

• Comprehensive L-Band Coverage: Supports UAT (978MHz), ADS-B (1090MHz), Mode-S (1030-1090MHz), and DME (976-1213MHz).
• Extended Stub Design: Minimizes airframe interference by offsetting the radiator from the aircraft body.
• Aerodynamic 300-Knot Rating: Designed for high-speed True Air Speed (TAS) environments with minimal drag.
• 35,000 Feet Operating Ceiling: Reliable performance throughout the general aviation and commercial flight envelopes.
• Ground-Plane Independent: Delivers a true omnidirectional pattern on both metallic and composite (non-metallic) surfaces.
• Ruggedized 30G Vibration Rating: Built to withstand the intense mechanical stresses and vibrations of aircraft operation.
• Center-Fed Coaxial Dipole: Provides a smooth VSWR (better than 2:1) and constant 2.14 dBi gain across the entire bandwidth.
• Ultra-Corrosion Resistant: 6063T6 aluminum and fiberglass construction prevents degradation from salt spray and acid rain.
• Simplified Bulkhead Mounting: Requires only a single 16mm hole for secure, streamlined installation.
• No Field Tuning Required: Arrives factory-calibrated for immediate integration into the aircraft’s avionics suite.

Avionics Integration Guide: Signal Integrity with the UAT-978-1090

For NextGen surveillance systems like ADS-B (Automatic Dependent Surveillance-Broadcast) and UAT (Universal Access Transceiver), "shadowing" is the primary cause of dropped data packets. The UAT-978-1090 is specifically engineered to mitigate these airframe-related interference issues through its unique physical architecture.

1. The Extended Stub: Combating Airframe Shadowing

When an antenna is mounted flush against a large metallic fuselage, the aircraft body acts as a massive ground shield. During banked turns or steep climbs, the fuselage can physically block the "line-of-sight" between the antenna and the ground station or other aircraft.

• Offset Radiation: The extended stub on the UAT-978-1090 moves the actual radiating element away from the aircraft's skin.
• Bank Angle Persistence: This offset allows the signal to "peek" around the curvature of the fuselage. Even during a 30-degree bank, the antenna maintains a clearer view of the horizon compared to low-profile "blade" antennas, ensuring your ADS-B "Out" signal remains consistent for Air Traffic Control.

2. 76-Degree Vertical Aperture for Tactical Maneuvers

In the 960–1220 MHz L-band, the vertical radiation pattern determines how well you stay connected during altitude changes.

• Wide Vertical Window: With a 76-degree vertical beamwidth, the UAT-978-1090 provides a very "forgiving" signal. Whether the aircraft is in a high-rate climb or a steep descent, the broad vertical lobe ensures that the ADS-B and UAT data links remain active.
• Ground Station Connectivity: This wide aperture is particularly effective for receiving ADS-R (Rebroadcast) and TIS-B (Traffic Information Service) data from ground stations located directly below the aircraft's flight path.

3. Ground-Plane Independence for Composite Aircraft

Modern aircraft are increasingly built using carbon fiber or fiberglass composites, which do not provide the electrical "mirror" (ground plane) that traditional aluminum airframes offer.

• Consistent Performance: The UAT-978-1090 is a coaxial dipole, meaning it carries its own internal electrical reference.
• Pattern Integrity: It delivers a true 2.14 dBi omni-directional pattern regardless of the mounting surface. This eliminates the need for heavy internal ground plates in composite fuselages and ensures the VSWR remains stable (better than 2:1) across the entire L-band.

4. High-Altitude Reliability (35,000 ft & 300 Knots)

Operating at the edge of the flight envelope subjects avionics to extreme vibration and pressure changes.

• No-Junction Construction: By eliminating internal mechanical junctions, the UAT-978-1090 is immune to Passive Inter-Modulation (PIM). This ensures that the high-speed digital pulses used in Mode-S and ADS-B are not distorted by the 30G vibrations typical of turboprop or light jet operations.
• Pressurized Seal: The 16mm bulkhead mount and supplied "O" gasket are designed to maintain the aircraft's pressure vessel integrity while providing a low-drag, low-profile external footprint.

Avionics Installation Checklist

• Mounting Location: Ideally, the UAT-978-1090 should be mounted on the bottom of the fuselage for maximum ground-station visibility. If the aircraft frequently operates at high altitudes far from ground stations, a top-and-bottom "diversity" setup may be required.
• Skin Surface Prep: Ensure the area around the 16mm mounting hole is clean. While the antenna is ground-plane independent, a solid mechanical fit is essential for withstanding 300-knot TAS wind loads.
• Coaxial Cable Selection: At 1090 MHz, cable attenuation is significant. Use high-quality, double-shielded cables like RG-400 or low-loss LMR-240-LL to ensure the full 150W pulse power reaches the antenna.
• O-Ring Sealing: Do not over-tighten the mounting nut. The rubber "O" gasket should be compressed enough to create a moisture seal without being deformed, preventing corrosion between the antenna base and the aircraft skin.