SD9-128
VHF Stacked Dipole ATC Antenna
| Model | Product Description | Frequency | Gain | Download | Enquiry | |
|---|---|---|---|---|---|---|
| SD9-128 | VHF Stacked Dipole ATC Antenna | 118-137MHz | 9 dBd |  |  |  |
The SD9-128 is an ultra-high-performance VHF aviation band stacked folded dipole array designed for high-capacity radio sites requiring long-range coverage. Engineered for the 118–137 MHz civil aviation spectrum, this 12-meter array provides exceptional gain and pattern flexibility, making it the premier choice for regional ATC centers, repeaters, and multi-channel paging systems.
Strategic Gain and Pattern Control
The SD9-128 offers remarkable radiation flexibility. In its standard configuration, it delivers a 9 dBd omnidirectional gain (360° coverage). However, by adjusting the dipole positions in the field with common hand tools, it can be reconfigured to an Offset pattern, boosting the gain to 12 dBd over a 180° sector. This "high-haul" performance is driven by eight vertically stacked folded dipoles, precisely fed in phase by a specialized center-fed phasing harness. With a razor-thin 9-degree vertical beam-width, the antenna concentrates RF energy toward the horizon, ensuring maximum link distance and "null-fill" coverage for consistent signal reception.
Industrial-Grade Durability
Built using 6063T6 architectural-grade anodized aluminum, the SD9-128 is designed to withstand decades of exposure in harsh environments. The dipole ends and cable connections are sealed in high-grade epoxy at the boom ends to prevent moisture ingress and provide maximum structural rigidity. All fasteners are manufactured from marine-grade stainless steel, and the N-Female termination is further protected by flame-retardant heat-shrinking tubing for 100% waterproofing. Rated to survive wind speeds of 180 Km/Hr, this 12-meter system is a fortress against the elements.
Operational and Logistical Efficiency
Despite its massive 12-meter overall length, the SD9-128 is optimized for global logistics. The central mounting mast is shipped in four manageable 3-meter sections, allowing for cost-effective transport and easier on-site handling. Efficiency is further enhanced by its pre-adjusted factory stacking distances, ensuring peak performance immediately upon assembly. The system’s high power capacity (500 Watts) and low noise floor make it highly efficient for multi-carrier sites where signal interference and intermodulation must be kept to an absolute minimum.
Detailed Technical Features
- Dual Pattern Versatility: Field-configurable for 9 dBd Omni or 12 dBd Offset coverage.
- Extreme Elevation Directivity: Narrow 9° vertical beam-width maximizes long-range ground-to-air links.
- Low Noise Architecture: Folded dipole design offers inherently lower noise and better static dissipation than standard dipoles.
- Precision Phasing: Center-fed harness ensures all 8 dipoles receive equal, in-phase power for maximum array gain.
- Broad Multi-Channel Support: Maintains constant gain and a VSWR of < 1.5:1 over the full 10 MHz operating bandwidth.
- D.C. Grounded Protection: The entire structure acts as a low-resistance discharge path, shielding connected equipment from lightning transients.
Detailed Mechanical Features
- Array Composition: Eight heavy-duty folded dipoles mounted on a high-strength aluminum boom.
- Modular Mast Design: 12-meter central mast ships in 4 segments (3m each) for ease of transport.
- High-Purity Materials: 51mm O.D. aluminum support pipe and 12.7mm O.D. folded dipole elements.
- Weatherproof Sealing: Epoxy-encapsulated junctions and heat-shrunk RF terminations.
- Weight Profile: 50 Kgs (Total with mast) or 20 Kgs (Antenna array only).
Detailed Environmental Features
- Wide Operating Window: Rated for operation from -30°C to +70°C.
- High Humidity Tolerance: Performs reliably in 0 to 95% RH conditions.
- Storm Resilience: Specifically designed to survive 180 Km/Hr wind loads while maintaining structural alignment.
Key Advantages
- "Long-Haul" Reach: The high gain and narrow beam-width allow ATC centers to communicate with aircraft significantly further than standard dipoles.
- Field Adaptability: Allows technicians to change from 360° coverage to a directional offset pattern if the site's requirements shift over time.
- Lightning Hardened: The all-metal, D.C. grounded construction is essential for high-altitude mountain-top or coastal sites.
Primary Applications
- Regional Air Traffic Control: Serving as the primary omnidirectional high-gain link for aeronautical VHF communications.
- Multi-Channel Paging/Repeaters: Ideal for highly populated radio sites requiring high power handling and low noise.
- Coastal Surveillance: Providing long-distance signal coverage for oceanic information regions (OIC).
| Feature | Specification | Tactical Benefit |
|---|---|---|
| Gain | 9 dBd (Omni) / 12 dBd (Offset) | Tailorable coverage for specific site needs. |
| Vertical Beam | 9 Degrees | Maximum energy concentration toward the horizon. |
| Wind Survival | 180 Km/Hr | Reliability in severe weather and mountain sites. |
| Length | 12 Meters | High-aperture array for superior signal density. |
Design Features: The SD9-128 ultra high performance VHF aviation band stacked dipole array is designed for use with highly populated radio sites requiring long haul omni-directional coverage. The SD9-128 is heavy duty stacked dipole array features, wide bandwidth, high gain, high power handling capacity, low VSWR, low noise performance and null filling coverage with omni-directional characteristics. This stacked dipole array maintains constant gain and VSWR over its 20 MHz bandwidth, making it highly suitable as base station antennas for repeater, paging and any other multi-channel communication systems. The radiation pattern can be changed in the field by use of common hand tools. The Vertical stacking distance is factory adjusted for highest possible efficiency. Specially designed center fed phasing harness ensures equal and in phase signal distribution to all the eight dipoles. The SD9-128 High gain stacked dipole array operates at D.C. ground for protection against lightning.
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