Antenna pattern automatic test system based on MSP430 single chip microcomputer

Single chip microcomputer STM32L151CCU6

RF cable can be customized for other specifications

1206RGB (single)

Test - lowercase jpg

Kaixin micro test

The antenna pattern is an important indicator of the antenna. The purpose of the antenna test is to verify the radiation characteristics of the antenna. Early antenna testing relied mainly on manual, with large errors and low efficiency. With the development of computer application technology, an automatic control system for antenna testing has emerged, which has effectively improved test accuracy and work efficiency. However, the systems developed in the past are mainly used in the commercial field, with high cost and long development cycle. In order to test the actual requirements of the antenna test system for experimental research, teaching practice and small antenna engineering test, an automatic test system for antenna pattern based on MSP430 is proposed and designed, which can accurately test the antenna.

1 Directional diagram automatic test system theory and scheme design

According to the principle of antenna reciprocity, the rotating antenna method is adopted. The fixed radiation antenna emits electromagnetic waves as a transmitting antenna, rotates the antenna under test to receive, and detects the signal level at different angles within the measured range, so that the direction of the antenna to be tested can be obtained. In the actual measurement, it is not necessary to study each point of the space carefully. It is only necessary to measure two mutually perpendicular patterns of the E plane and the H plane including the maximum radiation direction. This system is a research object for the antennas erected on the ground, taking parallel and ground horizontal directions, and drawing on the liquid crystal in a Cartesian coordinate system.

The test system mainly includes the following parts: a wireless signal transmission module, a signal acquisition control module, a data processing, a display and a storage module. The principle block diagram is shown in Figure 1.

2 pattern automatic test system design

The design requirements of this system are mainly as follows: 1) Using MSP430 to control the antenna turntable to rotate according to the test requirements; 2) Collecting and storing the antenna signals; 3) Drawing the direction map according to the collected data. Based on the above requirements, the whole circuit is designed with the principles of stable system, comprehensive functions, convenient control and cost saving. The system hardware structure is shown in Figure 2.

2.1 Test system automatic control module implementation

The automatic control in the antenna pattern automatic test system mainly refers to the control of the antenna turntable by the MSP430. During the measurement process, the determinant non-coded keyboard is attached to the P1 port of the MSP430 with interrupt function to interrupt the query operation mode, and the relevant control command parameters (including start, stop, automatic and single-step operation) are sent to the MSP430. The MSP430 converts it into an electrical pulse to drive the turntable to rotate smoothly. The antenna turret operates at 24 V AC, with a rated load of 18 kG and a horizontal speed of 6° per second. Through experiments, the speed is accurate within the rated load. Since the drawing direction only needs the amount of change of the angle, the timer TA module in the MSP430 can be used to generate a fixed angle by interrupt timing, so that the antenna can be rotated according to the test requirements.