# Analysis of Distributed Measurement Method for Array Antenna Position
## 1 Introduction  
The synthetic aperture radar (SAR) was first developed in the 1950s and used in the Earth observation system of airborne platforms [1]. The airborne high-resolution Earth observation system shown in Figure 1 is a comprehensive technology to obtain high-precision spatial information of the Earth's surface by using the moving imaging load. It is of great significance to the monitoring and early warning of major natural disasters and it can solve a series of major problems that humans face such as environmental degradation and disasters facing [2]. With the increasing requirement of high-resolution imaging in aerial remote sensing, load array measurement technology has gradually become an effective means to improve the imaging resolution. SAR based on array technology can perform three-dimensional high-precision stereo imaging, and it has been widely valued in recent years [3; 4].  
The aircraft wing is the carrier of array antenna, in which there is phased array radar. Due to the influence of aircraft flying environment, the aircraft wing will produce large deformation, which will lead to the deformation of the array antenna conformal with the wing. The deformation of the aircraft wing changes the phase center of the array antenna, which affects the measurement accuracy of the array antenna [5]. When the airborne platform flies, it will produce severe jitter, and the load antenna will deform and flutter along with the deflection of the wing. Therefore, the relative motion relationship between the sub-antennas cannot be accurately determined [6]. Distributed position and orientation system (POS) technology is mainly based on the airborne-distributed inertial measurement system. In the 1990s, researchers first proposed the concept of an integrated inertialnetwork. By sharing the information of flight control, attitude reference or navigation system on the carrier, several high-precision inertial measurement units (IMU) are arranged to form a complete set of airborne inertial navigation system networks. At present, the airborne distributed measurement technology is mainly used in initial attitude alignment of air-based missiles before launch and the relative motion information measurement of radar motion compensation. Airborne distributed measurement technology has the advantages of short measurement time, convergence and estimation of the filter. The airborne distributed system consists of the main inertial navigation system and the sub inertial navigation system. As a minimum distributed system including two sets of inertial navigation system (INS), the accuracy of sub-INS is guaranteed by fast transfer alignment technology. In order to improve the position and attitude accuracy of the subsystem, the transfer alignment method is used to constrain and calibrate the low-precision inertial navigation system. In order to obtain the phase center of the array antenna accurately, it is necessary to measure the deformation of the aircraft wing accurately. The paper presents measurement technology comprising the combination of airborne distributed POS technology and airborne optical fiber-sensing technology. The distributed POS technology and optical fiber-sensing technology are introduced, then the measurement process is analyzed, and finally the strength of the designed experimental model structure is checked to ensure the normal verification of the method.