The University of Delaware has developed complex beamforming passive antenna lenses for 5G communications through XJet’s ceramic 3D printing technology.
Xjet CEO Dror Danai introduces ceramic 5G antenna 3D printing technology
Reduce energy loss and improve beam control capability
MIMO technology
5G is the abbreviation of the fifth generation mobile communication technology. 5G communication means that the communication frequency is increased to the range of 5 GHz. 5G will provide higher spectrum and energy efficiency while minimizing system delay.
Unlike previous technologies, 5G includes several different frequency bands. Among them, the population using lower frequency bands below 6 GHz is large and the available bandwidth is limited. Therefore, in order to meet the requirements of 5G, many countries have approved several frequency bands for millimeter waves, including: 24 GHz to 29.5 GHz, 37 GHz to 42.5 GHz, 47.2 GHz to 48.2 GHz and 64 to 71 GHz. my country's 5G initial intermediate frequency band is 3.3-3.6GHz and 4.8-5GHz two bands, 24.75-27.5GHz, 37-42.5GHz high-frequency bands are being developed; and 28GHz is mainly used for international trials.
The biggest advantage of millimeter wave is the fast propagation speed, and the biggest disadvantage that comes with it is poor penetration and large attenuation. Establishing a reliable communication link for cellular applications in the millimeter wave band provides huge opportunities. The millimeter wave band can provide wider bandwidth, compact antenna size and smaller size. But millimeter wave band technology also has many challenges, such as high atmospheric signal attenuation, shadows, and high cost of system components.
The attenuation of the millimeter wave signal mainly depends on the propagation distance, weather conditions and operating frequency. Shadows are another important source of signal loss. These losses pose challenges to the development of antennas, as well as the need to develop highly efficient, steerable, and high-gain antennas to overcome these losses and establish high-quality communication links at millimeter wave frequencies.
Array-based multiple-input multiple-output (MIMO) technology has multiplied the number of base station antennas, far exceeding the antennas used by mobile terminals, thereby greatly improving the communication spectrum efficiency. MIMO technology is a relatively important technology in 5G communication. According to the relevant requirements of the mino technology, the antenna of 5G mobile communication should have technical characteristics such as high gain, miniaturization, wide frequency band and high isolation to meet the high transmission rate of 5G communication. Beam intelligent shaping, beam energy gathering and other functions.
Due to the high cost of components such as phase shifters used in system design, it is very complicated and expensive to develop 5G millimeter wave base station antennas and RF front-end solutions capable of high gain and beam control. In the manufacture of 5G millimeter wave antennas, a cost-effective way to produce antenna base stations is needed. Moving from active phased arrays with mechanically controllable technologies to passive devices will reduce the production cost of antenna technology and subsequently reduce maintenance requirements.
5G beam shaping lens
3D printing 5G beamforming passive antenna lens
Researchers at the University of Delaware tried XJet's ceramic nanojet 3D printing technology and developed a new passive lens antenna. The lens antenna can be mounted on top of a series of small antenna feeds. The antenna feed array is connected to the beam switching circuit.
The challenge in the development of this new beamforming lens is the ability to scatter millimeter waves at any angle with minimal energy loss. The design result achieved by the researchers through 3D printing technology is that the 3D printed spherical ball (blue part) can provide multiple beams on almost the entire hemisphere (-90°<<90°), while supporting from Sub-6GHz to 110GHz The wide frequency bandwidth is suitable for base stations (with the new 5G frequency band) and high-capacity millimeter wave backhaul links (E-band-up to 110GHz).
The spherical sphere contains many cavities, each of which is located on top of the antenna feed and serves as a waveguide at the correct angle in the hemisphere, which can support simultaneous multiple beams.
Find the ideal material
In addition to completing the design of the lens antenna, another challenge is to find the best material that can minimize interference and energy loss.
After examining several materials, the researchers chose zirconia (ZrO2) because its dielectric constant Dk = 32.2 is almost flat, and the loss is small over the entire spectral range. They conducted some measurements and simulations on zirconia and PBG. The results showed that the transmittance of zirconia is between 0 and -10dB, while the transmittance displayed by PBG materials is inconsistent between 0 and -44dB.
After sintering, zirconia shows another important characteristic with its excellent durability, wear resistance, hardness and toughness: this material has been used on the top of the beam antenna for many years without any maintenance.
After the design and material selection is completed, the next step is the test of manufacturing technology. Manufacturing technology needs to be able to fulfill the following requirements:
• Hollow cavity and holes-used to create millimeter wave waveguides; • Relatively small and lightweight-able to withstand the mechanical forces that may be emitted on the installed antenna, reducing the footprint, but still achieving higher durability and reducing the base station Maintenance; • Monolithic structure-no moving parts; • Excellent durability, wear resistance, hardness and toughness; • High precision and fine detail; • Excellent clarity – any uneven surface will scatter waves inside Into the waveguide, so sharp, smooth inside and outside surfaces are essential. The research team of the University of Delaware met the above requirements through XJet's ceramic nanojet 3D printing technology. The test result is:
•High precision and fine detail – construct internal cavity or waveguide at the same time;
• Excellent clarity-can reduce energy loss or internal absorption;
• Up to 99.9% density-resulting in flat homogeneous dielectric properties (Dk = 32.2);
• High productivity that can handle multiple custom parts of different frequencies-spend the same time on the same pallet to produce different The antenna size meets different frequency requirements.
The 5G construction puts forward higher requirements for antenna design, energy saving, and high-frequency devices. The emergence of 5G innovative technologies such as Massive MIMO has promoted the development of optical fiber and other industries to high-value-added industries.