SD9-250
UHF High Gain Stacked Dipole Array
| Model | Product Description | Frequency | Gain | Download | Enquiry | |
|---|---|---|---|---|---|---|
| SD9-250 | UHF High Gain Stacked Dipole Array | 220-290 MHz | 9 dBd. |  |  |  |
The SD9-250 is an ultra-high-performance VHF stacked dipole array designed for the 220–290 MHz frequency range. Featuring eight vertically stacked folded dipoles, this antenna is engineered for high-density radio sites that require long-range, omni-directional coverage. With its high power handling and "null-fill" characteristics, it serves as a robust backbone for repeaters, paging systems, and multi-channel communication networks.
Strategic Coverage and High Gain
The SD9-250 provides a consistent 9 dBd gain in an omni-directional configuration, offering 360 degrees coverage. For sites requiring focused energy in a specific direction, the radiation pattern can be adjusted in the field to provide a 12 dBd offset gain. The array utilizes a specialized center-fed phasing harness to ensure all eight dipoles receive equal, in-phase signal distribution. This results in a highly efficient vertical beam-width of 9 degrees, concentrating energy toward the horizon for maximum "long-haul" reach.
Tactical Mechanical Engineering
Constructed from 6063T6 architectural-grade anodized aluminum, the SD9-250 is built for permanent, heavy-duty installation. The eight folded dipoles are sealed in epoxy at their boom connections, ensuring internal components are shielded from moisture and vibration. To address logistical challenges, the 8-meter central mast is designed in three interlocking sections of 2.8 meters each, making it easy to ship and transport to remote or elevated sites.
Operational Resilience
This antenna is designed to thrive in high-interference environments. It features low noise performance and a wide 20 MHz bandwidth with a VSWR of better than 1.5:1. For environmental protection, the N-Female termination is sealed in flame-retardant heat-shrinking tubing for complete waterproofing. Furthermore, the entire array operates at direct D.C. ground, providing an integrated discharge path to protect sensitive base station equipment from lightning strikes.
Detailed Technical Features
- Dual-Mode Pattern: Switchable between 9 dBd Omni and 12 dBd Offset patterns using standard hand tools.
- High Power Capacity: Rated for continuous RF power handling of up to 500 Watts.
- Null-Fill Characteristics: Engineered to provide consistent signal strength even in the "null" areas typically found directly below high-gain antennas.
- Vertical Precision: 9-degree half-power vertical beam-width for superior long-distance propagation.
- Phasing Integrity: Center-fed harness ensures equal signal distribution across all 8 radiating elements.
Detailed Mechanical Features
- Reflector/Mast Length: Overall height of 8 meters, collapsible into 2.8-meter sections for shipping.
- High-Strength Build: 51 mm O.D. aluminum support pipe with 12.7 mm O.D. dipoles.
- Elite Fasteners: All mounting hardware and fasteners are manufactured from Marine Grade Stainless Steel.
- Weight Versatility: 16 Kgs (array only) or 30 Kgs (with central mast) for different tower loading requirements.
- Mounting Interface: Compatible with support masts up to 52 mm (2 inches) in diameter.
Detailed Environmental Features
- Wind Resilience: Rated for survival in winds up to 180 Km/Hr.
- Waterproofing: Epoxy-sealed dipole ends and heat-shrink protected RF terminations.
- Thermal Window: Operational from -30°C to +70°C.
- Humidity Tolerance: Certified for operation in 0 to 95% RH environments.
Key Advantages
- Field-Adjustable Patterns: Allows technicians to optimize coverage (Omni vs. Offset) without replacing the antenna.
- Heavy-Duty Reliability: The use of anodized 6063T6 aluminum ensures a long, maintenance-free service life in corrosive environments.
- Lightning Safety: Integrated low-resistance discharge path protects the entire radio system during stormy weather.
Primary Applications
- VHF Base Stations: High-gain backbone for repeaters and multi-channel communication hubs.
- Paging Systems: Reliable, high-power signal distribution for regional paging networks.
- Populated Radio Sites: Low-noise performance makes it ideal for sites with high RF density.
- Long-Haul Communication: Focused 9-degree vertical beam is perfect for bridging large geographical gaps.
| Feature | Specification | Tactical Benefit |
|---|---|---|
| Gain | 9 dBd (Omni) / 12 dBd (Offset) | Versatile coverage options for diverse site needs. |
| Power Handling | 500 Watts | Supports high-power multi-channel transmitters. |
| Overall Length | 8 Meters | High aperture for superior vertical focus. |
| Mounting | D.C. Ground | Inherent lightning protection for site safety. |
Design Features: The SD9-250 ultra high performance VHF band stacked dipole array is designed for use with highly populated radio sites requiring long haul omni-directional coverage. The SD9-250 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 9dBd 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 SD9-250 high gain stacked dipole array operates at D.C. ground for protection against lightning.
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