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As we all know, 5G will have low frequency band and two millimeter wave frequency bands, and the wavelength of the millimeter wave is very short and very expensive. So in 5G communication, we must solve this problem.
The first solution is a substrate integrated antenna (SIA).
This type of antenna is mainly based on two techniques: When the empty waveguide transmits, the loss caused by the medium is very small, so the empty waveguide can be used for feed transmission. However, there are several problems. Because it is an air waveguide, which is very large in size and cannot be integrated with other circuits, it is suitable for high-power, large-volume application scenarios. The other is the microstrip line technology, which can be mass-produced, but It is a loss in itself as a transmission medium and it is difficult to construct a large-scale antenna array.
Substrate-integrated waveguide technology can be produced based on these two techniques. This technique was first proposed by the Japanese industrial community. In 1998, they published the first paper on the waveguide structure of dielectric integration. They mentioned that a waveguide is implemented on a very thin dielectric substrate and a small pillar is used to block electromagnetic waves and avoid Both sides expand. It is easy to understand that when the two small pillars are separated by a quarter of a wavelength of fish, energy will not leak out. This can result in high efficiency, high gain, low profile, low cost, easy integration, and low loss. Antenna.
The lower right of the figure above is a 60GHz antenna made using this technique on the LTCC, with a gain of 25dB and a size of 8x8 cells.
This scheme is suitable for millimeter wave applications at the base station and there is another scheme on the mobile terminal.
The second solution is to design the antenna in a package integrated antenna (PIA).
Because the biggest problem of the antenna on the chip is that the loss is too large, and the size of the chip itself is very small, the antenna design will increase the cost, so it can hardly get large-scale application in engineering. If the antenna is designed using a package (larger than the chip size) as a carrier, not only a single antenna but also an antenna array can be designed. This avoids the limitation of volume, loss, and cost of the antenna directly on the silicon.
In fact, the antenna can not only be inside the package, but also at the top, bottom, and around the package.
Another point that needs attention is whether you can use the PCB board as an antenna. The answer is yes.
The key bottleneck is not the material itself, but the material design problems and processing problems. However, the PCB is only suitable for frequencies below 60GHz. LTCC is recommended after 60GHz, but after 200GHz, there is a bottleneck in LTCC.