In radio equipment, the device used to radiate and receive radio waves is called an antenna. Antennas are the converter of electromagnetic waves between free-space and transmission lines. It is an important tool for conveying information.
Accurate antenna measurements ensure prime signal propagation and reception. Through antenna measurement, we can evaluate the performance and efficiency of antennas used in various applications, which helps ensure that the antennas work as expected. Especially in high-frequency uses, subtle deviations can impact system functionality.
Thus, accurate antenna measurement helps utilize the antenna’s potential and raises advancements in wireless communication, satellite transmission, and radar systems.
Basic Knowledge Related to Antenna Measurement
This section will introduce you to antenna measurement and phased array antennas. And you will have a general understanding of them after reading.
1. About Antenna Measurement
Antenna measurement evaluates the performance and characteristics and validates the design of an antenna system. The OTA testing can reflect the radiation performance of the antenna. It can be divided into indoor testing and outdoor testing according to the testing site. According to testing methods, it can also be divided into far-field measurement, near-field measurement, and compact-field measurement. According to the shape of the scanning surface, it can be divided into plane near-field measurement, cylindrical near-field measurement, and spherical near-field measurement.
Indoor testing refers to test in a microwave anechoic chamber, with less external interference and higher measurement accuracy compared to outdoor testing. Therefore, the vast majority of antenna measurements are conducted using indoor testing. We will mainly introduce indoor testing in the upcoming section.
The microwave anechoic chamber used for indoor testing is a spatial structure, which can be a building or a box. As shown in Figure 1, the microwave anechoic chamber is a shielding space that isolates external electromagnetic waves. The absorbing materials in the anechoic chamber can effectively absorb internal electromagnetic waves in the measured frequency range, simulating a pure infinite electromagnetic space without electromagnetic interference.
Figure 1. Microwave Anechoic Chamber
The radiation area of antennas can be divided into induction field (Fresnel zone), near field area, and far-field area (Fraunhofer zone) based on the distance of the radiation, as shown in Figure 2.
Figure 2. The Field Distribution of Antenna Measurement
Figure 3. The Electromagnetic Simulation Diagram of Antenna Near/Far Field
Conventional methods of antenna measurement include three types of testing fields: far field, near field, and compact field. Far-field testing requires achieving the shortest testing distance (R0=2D2/λ). It can be seen from the above equation that the testing distance is proportional to the frequency, meaning that higher frequency often requires a longer testing distance. Thus, far-field testing is limited by space.
2. Introduction to Phased Array Antennas
A phased array antenna system comprises multiple individual antenna elements to be controlled in phase and amplitude, automatically steering the beam direction. Instead of physically moving the antenna, beam direction adjustment is made by adjusting the relative phases of each element. This technology is widely used in radar tracking, satellite communications, and wireless systems.
This antenna system can form multiple beams simultaneously in diverse directions. With advantages such as rapid beam steering, electronic beam steering, good stealth, and low probability of intercept (LPI), a phased array antenna is crucial for tasks ranging from tracking objects in the sky to ensuring reliable wireless communication.
Sunyield Phased Array Antenna Testing Series
The traditional method for phased array antenna testing is far-field measurement. However, the open testing field and electromagnetic environment can greatly affect measurement accuracy. If using the indoor field, the far-field conditions require a large area and high investment, but the function of the field is single. Moreover, for antennas with low and ultra-low sidelobes and special beam coverage characteristics, this kind of indoor field has large errors and low efficiency.
Therefore, compared to the traditional far field, choosing the near field and compact field for phased array antenna measurement will be a more practical, cost-effective, and operable solution. Here, we introduce the Sunyield phased array antenna measurement or testing series.
1. Compact Range Calibration and Testing
The SYCR series developed by Sunyield is the mainstream millimeter wave compact range calibration and testing system in the market. Aiming at the characteristics of millimeter-wave radar frequency bandwidth and small size, this series of products are compact range testing systems with different sizes suitable for millimeter-wave detection. It is suitable for testing millimeter wave antennas, radars, and millimeter wave detection devices.
The SYCR series ensures the accurate performance of an antenna in a controlled environment. The series adopts an integral curling surface, saving more space than conventional saw-tooth reflectors. It is equipped with a multi-dimensional bearing turntable, and the test tooling and electric auxiliary shaft can be customized according to user requirements.
Moreover, it is paired with a fully shielded, non-reflective microwave chamber and a movable base for flexible placement and deployment. The series also has an adjustable feed fixture and the corresponding band ripple speaker feed.
Figure 4. The Compact Range Testing for Phased Array Antenna
2. Compact Range + Spherical Field
While marrying the strengths of compact range and spherical field methods, our compact range plus spherical field testing approach analyzes the antenna’s performance. A rotating probe and the antenna under test in conjunction allow for accurately mapping the antenna’s radiation pattern in a three-dimensional space.
Figure 5. Compact Range + Spherical Field for Phased Array Antenna
This technology is typically applied in industrial and research fields, such as aerospace, telecommunications, and automotive, for testing communication, radar, and vehicle antennas. Accurate electromagnetic measurement is crucial in these applications and industries. Sunyield’s products in this testing plan include the SY series and Micro-chamber.
3. Far Field Test
Our far-field test, a traditional antenna measurement method, measures an antenna’s radiation pattern at a substantial distance from it. The far-field data obtained after measurement does not require calculation or post-processing. It can directly obtain the directional pattern.
At this range, spherical wavefronts from the antenna become almost planar. The advantage is a true representation of the antenna’s performance in its intended operational environment, meaning that its measurement results will be more accurate. This measurement scheme is widely used in radar cross-section (RCS) measurements, wireless communication, aerospace and defense.
4. Plane Field Test
The plane field test is an electromagnetic measurement or testing technique used to evaluate the characteristics and performance of antennas or electromagnetic equipment in their near-field region. This testing plan of Sunyield has three products, including SCR-5000, SPR-3000, and SPR-Scanner.
SPR-Scanner is suitable for testing antennas with strong directivity. It has an ultra-high precision electrical motion control system and mechanical drive system. SPR-3000 can achieve a three-dimensional holographic scanning of the forward radiation performance of the directional antenna and rapid diagnosis of antenna mass production. Moreover, SCR-5000 has the advantage of fast test speed, cost-effective system, and over-sampling technology, making it stand out among similar products.
Figure 6. Plane Field Test for Phased Array Antenna
Advantages of Sunyield’s Antenna Testing Equipment
Sunyield’s antenna measurement systems, especially the phased array antenna testing series, are excellent solutions in the market. Based on internationally advanced technology and R&D achievements, Sunyield has rich experience in this industry. Notably, we were the first to achieve real-time active TRP and TIS measurements.
Our antenna measurement system provides accurate results through precise positioning and data acquisition technology. Through flexible testing configurations and user-friendly interfaces, our system can provide users with the best experience.
We also have the added advantage of a short delivery time and the flexibility of ODM services for individual needs. Moreover, Sunyield’s promise to provide dedicated, professional, and concentrated service ensures good after-sales support. Besides the state-of-the-art capabilities of our equipment, we also offer high cost-effectiveness, rendering our solutions technically superior and economically viable.
Antennas are an important part of communication systems, and antenna measurement is crucial for the correct and effective operation of antennas. As an antenna system, phased array antennas are crucial in various industries. So, in order to test the most accurate antenna performance and ensure the smooth progress of the expected work, contact us to obtain an exclusive solution for you.