Radar far-field measurement system：RT-FFS-100A
一、Far Field Design Principle
For the far-field measurement field, the distance between the antenna and the probe must be long enough to satisfy the antenna radiation in the plane wave region. This distance is related to the aperture of the antenna and the wavelength of the measured frequency. The formula is accepted by the industry.：
L：Distance measurement in far field
D：Measuring the aperture size of antenna
λ：Wavelength corresponding to measurement frequency
Figure: Diagram of antenna measurement distance
From the above formulas, we can see that far-field measurement technology often needs long enough measurement distance because of large aperture antenna measurement.
The formula of the test moment deviation from the far-field phase condition measured by RCS of antenna and target is as follows：
D：Interface dimensions of antennas or targets
λ：wavelength
f：frequency
c：Light speed
The wavefront phase difference incident on the antenna/target interface under this moment departure is as follows：
，The farther the moment is, the smaller the phase difference is. It is generally believed that the test moment distance is satisfied.
Under these conditions, the antenna test error is acceptable.
Calculate the far-field conditions below according to the user's product parameters：
Test Moment Departure Satisfying Far Field Conditions（m） | Test frequency（GHz） |
24GHz | 76GHz | 81GHz |
Antenna aperture size（cm） | 5cm | 0.40m | 1.27m | 1.35m |
8cm | 1.02m | 3.24m | 3.46m |
10cm | 1.60m | 5.07m | 5.40m |
二、Characteristics of Far Field System
Far-field system testing is intuitive, simple and convenient；
More suitable for radar target simulation scene testing；
Despite the large size of darkroom, the far-field system has a high overall cost performance ratio.
三、System Turntable
According to the specific test requirements of users, a special turntable for millimeter wave radar test can be provided；
四、Radio Frequency Link
The RF link of this system is designed with Keysight brand test instrument as the core, the passive antenna measurement is based on PNA network analyzer, and the millimeter wave radar product RF link is based on signal generator, spectrum analyzer and radar target simulator. At the same time, it supports user-defined instrument upgrade.
Figure：KeysightNetwork analyzer and radar target simulator
五、Systems software
The system provides perfect testing software for passive/radar product system：
Passive antenna test software: support 2D/3D pattern, gain, sidelobe level, efficiency, beam width, and other parameters measurement；
Radar product measurement: Tx transmitting 2D/3D pattern, gain, bandwidth, phase noise, modulation linearity, etc；
Rx receives 2D/3D pattern, frequency, sensitivity, etc.
The software supports user-defined development of DUT communication protocol, automation system and user-formatted test report generation；
