AY-390

The AY-390 is a professional-grade UHF High Gain TETRA Band Directional Yagi Antenna engineered for peak performance in the 380–400 MHz spectrum. Delivering a potent 13 dBi (11 dBd) gain, this antenna is a critical component for TETRA base stations, point-to-point backbone links, and mission-critical public safety networks. Built from 6063T6 architectural aluminum and designed with an innovative feed system, the AY-390 ensures maximum signal efficiency and mechanical survivability for long-haul communication links.

Design: Innovative Modern RF Engineering

The AY-390 reflects a breakthrough in modern antenna construction, featuring a unique feed system that acts as an integrated matching device. This proprietary design eliminates the need for a traditional folded dipole, resulting in significantly lower VSWR (better than 1.5:1) and increased radiation efficiency. With a focused horizontal beamwidth of 50 degrees and a vertical beamwidth of 40 degrees, the AY-390 concentrates RF energy with surgical precision. This directional focus, combined with a 16 dB front-to-back ratio, effectively isolates the desired signal while suppressing unwanted interference from the rear.

Construction: Tactical Hardening & Mechanical Stability

Engineered for ultimate structural integrity, the AY-390 utilizes high-quality 6063T6 architectural anodized aluminum alloys for its radiating elements and 25.4mm square-tube support boom. The antenna arrives in a pre-assembled condition with elements permanently fixed to the boom, ensuring consistent electrical contact and long-term durability. The feed point radiator is protected within a specialized Nylon housing, designed to shield against severe environmental conditions while minimizing pattern distortion. Its aerodynamic profile minimizes wind resistance, conserving tower loading capacity in high-exposure areas.

Reliability: Marine-Grade Versatility

The AY-390 is a "field-ready" solution that comes factory-tuned for immediate deployment without the need for field adjustments. It is supplied with specialized mounting hardware made of Type 316 marine-grade stainless steel, allowing for secure installation on either vertical or horizontal members up to 52mm (2 inches) in diameter. This versatility enables operators to switch between Vertical or Horizontal polarization to match mission requirements. Rated for wind speeds up to 200 Km/Hr, the AY-390 provides a reliable, high-power (250 Watts) directional link for the most demanding UHF and TETRA infrastructure.

Technical Features

• High-Intensity 13 dBi Gain: Precision-engineered for long-range directional links and high-sensitivity signal interception.
• Optimized 380–400 MHz Bandwidth: Provides full-band coverage for international public safety, military, and trunked radio systems.
• Integrated Matching Feed: Unique design maintains low VSWR and higher efficiency without the use of a traditional folded dipole.
• Permanently Fixed Elements: Factory-secured elements ensure electrical stability and prevent passive inter-modulation (PIM).
• 6063T6 Aluminum Alloy Construction: Architectural-grade anodized aluminum provides superior strength and corrosion resistance.
• Marine Grade 316 Stainless Steel Hardware: High-quality fasteners and mounts prevent rust in saline coastal and industrial climates.
• Focused 50° Horizontal Beamwidth: Concentrates signal energy forward to maximize regional range and sector isolation.
• 250W Power Capacity: Robust electrical design supports high-power transmission for high-traffic TETRA base station hubs.
• Nylon Feed Protection: Ruggedized housing protects the radiator from environmental degradation and physical impact.
• Pre-Assembled Logistics: Factory-tuned and assembled for rapid "plug-and-play" deployment on tactical or fixed masts.

Directional Link Optimization Guide: UHF Range Extension with the AY-390

In the 380–400 MHz TETRA band, the AY-390 serves as a high-precision "signal force multiplier." By concentrating RF energy into a directional beam, this 13 dBi antenna can effectively triple the operational range of a base station compared to standard omni-directional dipoles, making it the definitive choice for point-to-point backbone links and "filling" coverage holes in remote sectors.

1. The Power of 13 dBi Gain: Overcoming Path Loss

In the RF world, a 6 dB increase in gain effectively doubles the distance of a usable signal in a line-of-sight environment.

• The High-Gain Advantage: Moving from a standard 2 dBi omni antenna to the AY-400’s 13 dBi gain provides an 11 dB improvement. This massive increase in the link budget allows UHF signals to penetrate deeper into buildings or reach remote tactical outposts that were previously in "dead zones."
• Signal Concentration: Because the AY-400 uses a specialized feed instead of a traditional folded dipole, it minimizes internal matching losses. Nearly 100% of your 250W transmitter power is converted into a focused beam, ensuring maximum signal-to-noise ratio (SNR) at the receiving end.

2. Interference Rejection & Front-to-Back Ratio

In high-density radio sites, "noise" from other transmitters can desensitize your TETRA receiver, causing dropped calls or data errors.

• The 18 dB Shield: The AY-400 features an 18 dB Front-to-Back ratio. This means the antenna is nearly 60 times less sensitive to signals coming from behind it than those in its primary forward lobe.
• Tactical Isolation: By aiming the AY-400 at your target and "turning its back" to a known interference source (like a nearby cellular tower or co-located transmitter), you effectively clean up the RF environment. This isolation is critical for maintaining high-speed data throughput in modern digital TETRA networks.

3. Polarization Agility: Vertical vs. Horizontal

The AY-400 is supplied with marine-grade 316 stainless steel hardware that allows for mounting in either Vertical or Horizontal polarization to suit the mission profile.

• Vertical Polarization: Standard for communicating with handheld TETRA units and mobile vehicle fleets. Using vertical polarization ensures maximum compatibility and signal alignment with field units.
• Horizontal Polarization: Often used for fixed point-to-point "backbone" links between two towers. Horizontal polarization typically suffers less from man-made electrical noise and certain types of ground reflections, providing a more stable high-speed data link over long, flat stretches of land.

4. Minimizing Tower Load and Wind Resistance

High-gain antennas can often be heavy and bulky, putting excessive stress on tactical masts or high-altitude towers.

• Aerodynamic Design: The AY-400 uses a 25.4mm square-tube aluminum boom and 12.7mm round-tube elements. This minimal surface area results in an extremely low "Wind Surface Area."
• Survivability: Rated for 200 Km/Hr (125 MPH) winds, this antenna is designed to stay aligned and functional during severe weather events, ensuring that emergency and mission-critical communications remain online when they are needed most.

Tactical Deployment Checklist

• Aiming Precision: With a 55-degree horizontal beamwidth, precise alignment is mandatory. A 20-degree error in aiming can result in a significant loss of signal. Use a compass or GPS-based alignment tool to "zero-in" on the remote station.
• Cable Loss at 400 MHz: At UHF frequencies, signal loss in the coaxial cable is a major "gain killer." Use high-quality LDF4-50A (1/2" Heliax) or LMR-400 cables. A long run of thin, low-quality cable can easily waste 50% of your antenna's 13 dBi gain before the signal ever reaches the elements.
• Environmental Protection: The AY-400 is coated with high-quality olive green epoxy powder. During installation, ensure the coating is not scratched to the bare metal, as this could lead to localized corrosion in salt-fog environments.
• Mounting Rigidity: Use the supplied stainless steel U-bolts to secure the antenna to a 52mm (2 inch) mast. Any "sway" or vibration in the mount will cause the narrow 45-degree vertical beam to "flutter," leading to intermittent signal drops during high winds.