“6G Era Accelerator” reconfigurable antenna model, what kind of black technology is this?

Produced by: Science Popularization China

Author: Li Rui (Semiconductor Engineer)

Producer: China Science Expo

At present, my country's 5G construction is developing rapidly. Looking back at the evolution of communication network systems, there are many black technologies involved. In future communication network systems (such as 6G), there is a black technology that will become an indispensable component, that is, reconfigurable antennas.

(Image source: Reference 1)

Reconfigurable antennas may be a concept that is very unfamiliar to all of us. In fact, in the field of modern communications, they are a very important device. After reading this article, I believe you will know what reconfigurable antennas are, where they can be used, and what are the latest developments in this field.

Transformers in the antenna world - reconfigurable antennas

Do you remember the earliest "big brother" and "PhS" or the radio at home? They have one thing in common - an antenna on top. The structure of the mobile phones we use now is greatly simplified, and most of them are in the shape of a rectangular block. But did you know that the antenna has not disappeared, but has changed from external to internal. When we use mobile phones or other wireless devices, we need to use antennas to receive and send wireless signals.

As the name suggests, reconfigurable antennas must have parameters that can be changed. Yes, a reconfigurable antenna is a device that can change its antenna structure or parameters during operation as needed.

Internal antenna

(Photo source: veer)

It can adapt to different wireless communication needs by changing its own configuration, such as different signal frequencies, different signal directions, etc. Compared with traditional fixed structure antennas, reconfigurable antennas have higher flexibility and adaptability, which can help us better cope with different communication needs.

To give an example, the reconfigurable antenna is like a Swiss Army knife, with multiple functions and uses, and can play different roles in different application scenarios, such as improving communication quality, enhancing anti-interference capabilities, and expanding coverage.

It seems that devices equipped with reconfigurable antennas will adjust according to different environments, and the signal will definitely not be bad.

In a vehicle navigation system using a reconfigurable antenna, when the vehicle travels to different cities and regions, the reconfigurable antenna can dynamically adjust its direction and polarization (we will introduce the concept of polarization later) according to local weather, terrain, buildings and other factors to ensure the signal quality and stability of the vehicle navigation.

Car Navigation System

(Photo source: veer)

So, the materials and technologies used in a reconfigurable antenna that can achieve such powerful functions must be quite sophisticated, right? In fact, some of these technologies and materials may look familiar to you.

Reconfigurable antennas can use a variety of technologies and materials to achieve their adjustability. The following are some common reconfigurable antenna technologies and materials:

Tunable inductors and capacitors: The frequency response and directivity of an antenna can be changed by varying its inductance or capacitance value.

PIN diodes and field-effect transistors (FETs): They can act as RF switches, controlling the current or voltage on the antenna, thereby changing its characteristics, such as adjusting frequency, polarization, or directionality.

Liquid crystal material: Its refractive index and polarization characteristics can be controlled by electric field, thereby achieving polarization adjustment of the antenna.

Piezoelectric materials: can change their shape by applying voltage, thus changing the structure and characteristics of the antenna.

Artificial electromagnetic materials (metamaterials): Materials with special electromagnetic properties can be realized through microstructure design, such as negative refractive index, metamaterials, etc. These materials can be used to design reconfigurable antennas and realize some non-traditional characteristics, such as ultra-wideband, polarization rotation, and electromagnetic wave focusing.

These techniques and materials can be used in combination to achieve more flexible and controllable reconfigurable antennas.

The application areas of reconfigurable antennas are beyond your imagination

Reconfigurable antennas have such powerful functions and their application fields are also very wide. You may not realize that there are already many reconfigurable antennas in our daily lives. Reconfigurable antennas have been widely used in mobile communications, radars, satellite communications and other fields.

In the field of mobile communications, reconfigurable antennas can help us realize multi-band, broadband and multi-antenna systems to improve communication quality and capacity. For example, reconfigurable antennas can adaptively adjust their antenna direction according to network load and signal strength to maximize signal reception and transmission efficiency. In addition, reconfigurable antennas can also be used to improve signal quality in scenarios such as vehicle communications and smart homes.

In radar systems, reconfigurable antennas can improve the resolution, detection range, and anti-interference performance of radar systems. For example, reconfigurable antennas can reduce multipath interference and reflections by adjusting their polarization or directivity, thereby improving the clarity and stability of radar signals.

In the field of satellite communications, reconfigurable antennas can improve the frequency coverage and power efficiency of satellite antennas. For example, reconfigurable antennas can dynamically adjust their direction and polarization during satellite signal transmission to adapt to different users and different transmission requirements, thereby improving the efficiency and reliability of satellite communications.

The giant antennas of the Atacama Large Millimeter/submillimeter Array

(Image source: Wikipedia)

When talking about antennas, we have to talk about the polarization of antennas.

When we introduced the application of reconfigurable antennas, we mentioned a word repeatedly: polarization. Many friends may have questions, what exactly is the polarization of the antenna?

The polarization of an antenna refers to the vibration direction of an electromagnetic wave during its propagation in space. Specifically, it can be divided into horizontal polarization, vertical polarization, and tilted polarization. When an electromagnetic wave vibrates in a plane perpendicular to its propagation direction, it is called horizontal polarization; when an electromagnetic wave vibrates in a straight line along its propagation direction, it is called vertical polarization; when an electromagnetic wave vibrates in a plane that is neither perpendicular to nor in the propagation direction, it is called tilted polarization.

The concept of polarization can also be understood using the following vivid example.

Imagine you are holding a rope with a ball at the end. In wireless communications, the antenna and electromagnetic waves we use are similar to the relationship between the rope and the ball. The vibration direction of the antenna is the polarization direction.

When you shake the rope left and right with your hand, the ball will also shake left and right. At this time, we can imagine that the ball vibrates in the left and right direction, which is horizontal polarization. If we let the ball vibrate in the front and back direction, it is vertical polarization. If the ball vibrates not only in the front and back direction, but also in the left and right direction, this is tilt polarization.

Therefore, choosing an antenna with appropriate polarization can help us better receive and send wireless signals, thereby improving communication effects.

(Photo source: veer)

It is important to note that the polarization direction of an antenna is not exactly the same as the direction the antenna is pointing, but the two concepts are related.

During the operation of the antenna, the vibration direction of the electromagnetic wave it transmits or receives is the polarization direction of the antenna, and the direction in which the antenna points is its radiation or reception direction.

For example, when the polarization direction of an antenna is vertical polarization, the vibration direction of the electromagnetic wave emitted or received by the antenna is perpendicular to the direction of the antenna. When the antenna points to the east, it will emit or receive electromagnetic waves from the east.

Therefore, the polarization direction and pointing direction of the antenna are two related but different physical quantities, and they are both important concepts in antenna work. We need to choose the appropriate antenna polarization direction and pointing direction according to the actual situation to meet the communication requirements.

Huge road-based radar and mobile radar vehicle

(Image source: Wikipedia)

What’s new about the new reconfigurable antenna?

Many current reconfigurable antenna designs have some flaws, such as not working properly in high or low temperature environments, having power limitations or requiring regular maintenance. To address these issues, researchers at Pennsylvania State University combined electromagnets and compliant mechanisms to propose a proof-of-concept for a reconfigurable patch antenna.

The research team used commercial electromagnetic simulation software to draw and design a prototype of a circular iris patch antenna. They then used 3D printing technology to put it into practice and tested a series of material and antenna parameters such as fatigue failure, frequency and radiation pattern fidelity in an anechoic chamber.

This reconfigurable antenna in the shape of a circular iris patch is only slightly larger than a human hand. It is designed to demonstrate frequency-specific applications and can be adjusted accordingly for different frequencies. For high-frequency applications, this technology can be scaled to the integrated circuit level; for low-frequency applications, its size can be expanded.

The researchers said that this achievement uses flexible mechanisms as a new design paradigm in the field of electromagnetism, which may be a completely new branch of the design field that will bring exciting applications to people.

Conclusion

In fact, the concept of reconfigurable antennas was proposed in the 1960s. Due to the characteristics of reconfigurable antennas, there is no need to consider the complex signal formation and processing processes at the transmitter and receiver during the research process. However, at the same time, the requirements for structural design have also been greatly increased.

This new achievement, combining 3D printing and flexible structures, undoubtedly provides new inspiration for the research of reconfigurable antennas. I believe that with the continued research of scientists, the 6G era will come soon.

Editor: Guo Yaxin