YD/T 3934-2021 in English

Standard Framework and Technology Evolution

As the core part of the Ka-band satellite communication earth station series standards, this standard is the first to establish technical specifications for the special needs of vehicle-mounted in-motion stations in mobile scenarios. Compared with the Ku-band standards such as YD/T 3254-2017, its technological breakthroughs are mainly reflected in:

Analysis of core performance indicators

Key technologies of antenna system

Moving communication antenna needs to meet dual mechanical properties: a rotation speed of 120°/s in azimuth and an acceleration of 200°/s² to ensure stable tracking at a speed of 120km/h on the highway. Typical parameter requirements:

• Efficiency ≥ 60%
• Cross-polarization isolation > 20dB
• Noise temperature ≤ 74K (30° elevation angle)

RF characteristic specifications

The transmitting system needs to strictly control the phase noise: 100Hz offset ≤ -60dBc/Hz, and at the same time meet the linearity requirement of third-order intermodulation ≤ -25dBc. An example of a spectrum template is as follows:

Implementation difficulties and solutions

Vehicle integration challenges

Car body modification must meet the following requirements:

1. Top load-bearing capacity ≥ 3 times the system weight
2. Total heat transfer coefficient ≤ 0.4W/m²·K
3. Equipped with lightning protection system (grounding resistance ≤ 0.02Ω)

Electromagnetic compatibility design

It is recommended to adopt a layered shielding strategy:

• Body level: in line with GB/T 22630-2008
• Equipment level: meet YD/T 1312.14
• Cable level: twisted pair + magnetic ring filter

Environmental adaptability verification

The standard divides the temperature into three categories. The most stringent Category III area requires an operating range of -40℃ ~ +55℃. Key verification points: