Learn the basics of millimeter wave cables | Explaining their features and benefits

As next-generation communication systems evolve, millimeter wave cables are becoming increasingly important. In particular, they are attracting attention as key devices for achieving stable signal transmission in high-frequency bands in 5G/6G communication systems.

This article provides a comprehensive explanation of millimeter wave cables, from their basic characteristics to their development background, structure, and actual usage scenarios. It also explains points to consider when selecting a product, such as high frequency characteristics and durability, so please use it as a reference.

What is a millimeter wave cable?

Millimeter wave cables are cables with a special structure and materials developed for stable signal transmission in high frequency bands above 30 GHz.

They are indispensable in fields that require ultra-high speed wireless communication and precise radar measurement, such as 5G and the in-vehicle radar used in autonomous driving.

Characteristics of millimeter wave cables

The biggest feature of millimeter wave cables is that they minimize loss even at high frequencies and are less likely to degrade the signal.

With conventional coaxial cables, attenuation tends to increase as the frequency increases, making them unsuitable for long-distance transmission or high-precision communications.

However, by combining special conductors and insulators, millimeter wave cables enable stable data transmission even in bands of several tens of GHz.

There are also products that combine ease of handling with high frequency characteristics by devising the outer diameter and bending radius. In many cases, structures that are easy to use in limited spaces, such as sensor wiring inside a vehicle or connecting antennas at a base station, are selected.

Background of the development of millimeter wave cables

The emergence of millimeter wave cables is due to the rapid progress of higher frequencies in communications and radar technology.

In the fifth generation mobile communication system (5G), which has been rapidly spreading in recent years, the bandwidth is insufficient in the conventional frequency bands, and it is necessary to use a higher range of several tens of GHz. Since existing coaxial cables cannot efficiently transmit radio waves at such high frequencies, the development of a new cable became an urgent task.

One example is the field of autonomous driving, where the use of millimeter wave bands is becoming mainstream in order to improve the detection capabilities of on-board radar.

By considering the 24 GHz band in addition to the conventional 77 GHz band, it is possible to improve the accuracy of obstacle detection and create a safer system.

These technological innovations required a large number of cables with excellent high-frequency transmission capabilities, and as a result, millimeter wave cables were developed and became widespread.

Materials and Construction of Millimeter Wave Cables

Millimeter wave cables are made with the aim of achieving low loss, and careful consideration is given to everything from material selection to structural design.

Copper alloys or silver-plated copper are often used for the internal conductor to reduce electrical resistance.

In addition, polytetrafluoroethylene (PTFE) and special resins with low dielectric constants are used for the insulators, and efforts are made to minimize dielectric loss.

External shielding is extremely important for blocking external noise. Typical designs use multi-layer shielding, such as multiple layers of metal foil or braided shielding, or a metal tube structure, to provide a high level of shielding effect.

By combining these materials and shielding designs, a mechanism has been established that can minimize loss even in signal transmissions of several tens of GHz while also suppressing external interference.

Advantages of mmWave Cables

A major advantage of millimeter wave cables is that they easily achieve low insertion loss even at high frequencies.

As frequencies become higher, even slight differences in conductor characteristics and dielectric constant of insulators have a significant effect on communication quality. Therefore, by using a millimeter wave cable designed to reduce loss, the necessary bandwidth can be used without waste.

In addition, products are now available that reduce the outer diameter and bending radius of the cable itself, making them suitable for wiring in tight spaces.

This makes it possible to move to higher frequencies without making major modifications to existing facilities. In addition, the robust external shielding has the added benefit of reducing the effects of noise from adjacent equipment and cables.

As 5G base stations are installed, beamforming technology is introduced, and in-vehicle radar becomes more multi-channel, there will likely be an increasing number of situations in which the performance of these millimeter wave cables will be essential.

Applications of mmWave Cables

Millimeter wave cables have a wide range of applications, but a typical example is the wiring around the antennas of wireless base stations.

Antennas that use high frequencies have the risk that even the smallest loss can directly lead to large losses. Therefore, by using millimeter wave cables that minimize losses, the frequency range for communications can be used more efficiently.

Millimeter wave radio waves are now being used in automotive radar to prevent collisions and improve the accuracy of autonomous driving. By using millimeter wave cables, high quality connections can be made between sensors and control devices inside the vehicle, improving the detection accuracy of the radar.

They are also frequently used in measurement environments such as laboratories and factories as cables connecting measuring instruments in the tens of GHz band to the object under test.

In this way, it will be useful in all areas where communication and sensor technology advances, and it is likely that the scope of its use will continue to expand in the future.

Millimeter Wave Cable Challenges

Millimeter wave cables, which are useful for achieving high frequency transmission, also have some challenges.

One of the biggest hurdles is the high cost of production.

Since it requires advanced processes such as precise conductor processing, special resins, and multiple shielding layers, production costs tend to rise.

It is also important to be careful when handling it. Strict quality control is required to avoid impairing the high-frequency characteristics, such as limiting the bending radius and taking care when attaching connectors.

Especially in the tens of GHz band, even slight mechanical deformation or poor contact can significantly degrade measurement values ​​and communication quality.

Another issue is minimizing variation during mass production. Since high-frequency performance can be affected even by a small change in the conductor cross section, a rigorous inspection process is essential to maintain stable quality.

Summary

Millimeter wave cables are cutting edge cable technology that offer low loss and high shielding even at high frequencies.

Although it requires more stringent processing precision and material selection than conventional coaxial cables, it offers great benefits in advanced communications and detection fields such as 5G and radar for autonomous driving.

As technological development progresses to overcome these challenges, the range of applications for millimeter wave cables will likely expand even further.