TACAN Shore Based Antenna Group Specification_20260317.pdf

This document is a Performance Specification for the TACAN Shore Based Antenna Group, establishing technical requirements for a tactical air navigation antenna system designed to interface with existing AN/URN-32 TACAN Transponders at shore stations.

The antenna system must operate within the 960-1215 MHz frequency band and provide vertically polarized signals with omnidirectional horizontal coverage and specific vertical radiation patterns. Key performance requirements include: a minimum antenna gain of 8.0 dBi with horizontal polarized signals at least 26 dB less than vertical; main lobe vertical coverage of 5.0 degrees width at half-power points, positioned 2.0-7.0 degrees above the horizon; and gain specifications below and above the horizon (minimum 2 dBi on horizon, less than -16 dB at 6-50 degrees below, greater than -15 dB at 6-20 degrees above, and greater than -25 dB at 20-50 degrees above). The system must modulate the 15 Hz and 135 Hz TACAN components according to specified formulas with defined tolerances for frequency, azimuth deviation, phase deviation, and modulation percentages. Reference bearing signals must include north trigger pulses and eight auxiliary trigger pulses at 40-degree increments, with trigger pulses meeting specific shape, rise/fall time, width, and amplitude parameters. Physical specifications require the antenna assembly to be enclosed in a radome painted Insignia White (FED-STD-595 chip 17925), measure no more than six feet in diameter and eleven feet in height, weigh no more than 900 pounds, and mount on a steel support ring with corrosion mitigation. The system must achieve an Availability (AA) greater than or equal to 0.99, with Mean Time Between Maintenance (MTBM) and Mean Maintenance Time (MMT) not exceeding 3 hours. Environmental operating conditions include temperatures of -46°C to 49°C outdoor and -18°C to 38°C indoor; wind resistance to 150 mph; ice loading tolerance of ½ inch; humidity from 5-100 percent relative; and altitude range of 700-1025 millibars. The antenna system must handle ground transponder peak power outputs of 4000W at 5 percent duty cycle, maintain 1.8:1 VSWR or less, generate harmonic content not exceeding 25 percent, include azimuth accuracy monitoring with hard alarm reporting within 10 seconds of fault detection, support remote maintenance monitoring through an IP-enabled RMM port, and comply with military standards including MIL-STD-291C for TACAN signals, MIL-STD-461G for EMI, MIL-STD-810H for environmental testing, and MIL-HDBK-1857 for grounding and bonding practices.