In addition to the well-known 5G millimeter wave application of millimeter wave technology on mobile phones, another potential emerging application is 60-GHz millimeter wave motion (such as gestures or head movements) recognition radar. The display is an extremely important and dominant feature of mobile phones. With the full-screen trend that began in 2017, for today’s mainstream mobile phones, the design of large screens or high screen-to-body ratios has long become the standard basic Configuration. However, for most of the user’s mobile phone wireless control movements, especially gestures or head movements, the detection direction is often toward the front of the display screen, which implies that the radiation pattern of the radar antenna should be out of the screen and face the user. Direction. The current mainstream design is to open an antenna window without metal obstruction (such as notch notch) on the display screen, and place a 60-GHz millimeter wave AiP (antenna-in-package) solution under this window (or directly adopt a non-high The screen-to-body ratio is designed to be able to install a 60-GHz millimeter-wave AiP module in the non-screen area); in this way, the radar beam can better radiate out of the screen and face the user to help the user’s wireless control experience . However, this design often affects and even hinders the high-screen-to-body ratio or full-screen design of the mobile phone, and the look and feel of the display screen is often the top priority of the mobile phone as mentioned above. Therefore, how to be compatible with full-screen and 60-GHz millimeter wave motion recognition radar on mobile phones has become a new hot topic in mobile phone antenna research and design.
Recently, a research article submitted by the antenna pre-research team of vivo mobile communication company last year based on AiAiP [1]–[3] mobile phone millimeter wave antenna innovative design to be compatible with mobile phone full screen and 60-GHz millimeter wave antenna [4] Published online at this year’s EuCAP (European Antenna and Propagation Conference), this innovative design will not only contribute to the expansion of new ideas for the compatible design of future mobile phone full screens, 60-GHz millimeter wave antennas and LTE antennas, but also this design. It incorporates the coverage of the millimeter wave antenna by the screen glass of the mobile phone and glass adhesive, so it has more practical design guidance function.

The author of the article stated: “The main framework and ideas of this research originated in the second half of 2018. The relevant patent application was filed before the submission of the article in 2019, and this design concept inherits the AiA proposed by the antenna pre-research team. [5]–[6] and AiAiP [1]–[3] thinking, that is, transforming the metal frame that was unfavorable or restrictive to the antenna design into an antenna carrier that is beneficial and helpful to the antenna design, so as to break through the original It is compatible with the full screen design, and achieves the purpose of effective radiation and more competitive products. Because the radiation direction of the millimeter wave antenna based on the metal frame design needs to go out of the screen and face the user, but it is limited The thickness of the metal frame and the limited stacking space in the machine, the general form of antenna design scheme [7]–[10] is often difficult to meet the requirements of product and radiation at the same time, so the scheme here is to design embedded on the metal frame. The H-plane sectoral horn antenna uses a narrow metal frame as the boundary metal of the horn antenna (because the H-plane sectoral horn antenna is parallel to (not orthogonal to) the metal frame) Long-side opening, so there is no need to increase the thickness of the metal frame, that is, it does not affect the active area of ​​the full screen (that is, the proportion of the AA area) and can obtain the desired output screen and the radiation direction toward the user Figure, and this 60-GHz millimeter wave antenna is further embedded and integrated with the metal frame LTE antenna, so the two types of antennas can share the metal structure to achieve a more compact design that overcomes metal shielding; in addition, if the whole If the machine conditions permit, this design can also be placed in multiple layouts to achieve a better wireless control experience for users. I would like to give some thoughts to teachers, scholars and experts, and friends to advance and give guidance to Kuang Axe.”

The following are mainly excerpts selected from the aforementioned published articles (except for detailed dimensions and parameters) to share relevant design ideas. This design and simulation is based on the electromagnetic simulation software Dassault System Simulia CST 2018, and as shown in Figure 1 below, the appearance of this mobile phone has a metal frame and both front and back sides are covered with 100% glass (the front and back sides are the same) and are Typical actual size model. In the picture, the yellow part is metal, the blue part is the screen glass, and the brown part is the dielectric encapsulation. Figure 2 is a front view of the inside of the mobile phone with the screen glass removed. Figure 2 shows that four 60-GHz millimeter wave antennas (one of which is a transmitting antenna and three are receiving antennas) are embedded and integrated in metal In the frame, and this metal frame also serves as an LTE low and high frequency antenna, the visible area of ​​the screen (ie AA area) accounts for more than 91.7% of the entire front of the phone. Figure 3 is an internal view with the back cover glass removed. There are two T-shaped slits (narrow outside and wide inside) on the top and bottom metal frames to facilitate the design of the LTE antenna. The dimensions in Figures 1–3 are all millimeters (mm).

Figure 4 shows the oblique rear view layout of a single H-plane sectoral horn antenna, which is embedded in the semi-transparent middle metal frame in the figure (this metal frame is also an LTE low and high frequency antenna) , And the metal frames at the left and right ends can be used as LTE intermediate frequency and non-cellular antennas (such as GNSS or WiFi antennas). And Figure 5 is a perspective and enlarged view of this embedded H-face sector horn antenna. The gray horn antenna is filled with dielectric material, and the pink color is the adhesive tape along the metal frame and the glass. Figure 6 Shows the feeding pin of the horn antenna and its position. In addition, due to the self-shielding effect of the boundary metal of the horn antenna, the designed antenna is less sensitive to the overall system stacking and layout inside the metal frame, so it can have a more stable antenna performance, which can increase the system stacking and layout design. flexibility.

Figure 7 is a stacking diagram of the y-z plane based on the centerline of the horn antenna in the x-direction of Figure 4. It can be seen that this design takes into account the related practical factors of multiple mobile phone stacking in the environment near the millimeter wave antenna, such as screen glass, glass adhesive, The display body, the main board, and the glue filling in the T-shaped slit and the system. And based on the AiAiP design, as the low and high frequency LTE antenna, the inside of the metal frame also integrates the package from AiP et al. [11]–[15] as the feeding part to reduce the feeding part of the millimeter wave. The radiating part (radiating part) is based on AiA’s integrated embedded design; therefore, AiAiP = AiA (radiating part) + AiP package (feeding part). Figure 8 shows the LTE antenna design. Because the full screen squeezes the keep-out area of ​​the antenna, in order to achieve better antenna performance, this design uses an antenna carrier, which combines part of the LTE antenna. Lift up off the ground [16].

Figure 9 is a perspective view of the layout of four equally spaced and identical embedded horn antennas based on the single horn antenna of Figures 4-6 as the building block. P1’–P4′ correspond to the four horn antennas respectively Feeding port, Figure 10 shows the internal side view of the carrier board with packaged IC (such as RFIC and PMIC) and LTE antenna bracket, while P1–P4 on the IC carrier board (at this viewing angle, the position of P4 is blocked by the LTE antenna bracket ) Respectively correspond to 4 radio frequency ports (from the traces fanned out by 4 RFICs). These 4 radio frequency ports are connected to the feed ports P1’–P4′ of the 4 horn antennas on the aforementioned metal frame. Transmission of radio frequency energy. And Figure 11 is the inside side view with the shield and the connector (the LTE antenna bracket is hidden at this time for easy viewing). The exploded view of the overall mockup is shown in Figure 12.

Figure 13 is the simulation |Snn| performance comparison diagram of the two scenes of the single horn antenna of Figure 4 with and without glass and glass glue. It can be seen that glass and glass glue have a significant impact on the reflection performance of the antenna port. Of course, the real mobile phone design is a scene with glass and glass glue. For real scenes (with glass and glue), the bandwidth (|Snn| ≤–6 dB) is 56.84 GHz–65.18 GHz, so it can cover the commonly used 60-GHz motion recognition frequency band (57.0 GHz–64.0 GHz) . Figure 14 is the performance comparison diagram of the total efficiency of the simulated antenna and the simulated peak real gain (realized gain) of the single horn antenna in Figure 4 with and without glass and glass glue. For the real scene (that is, with glass and glass glue) In terms of viscose), the antenna efficiency in the entire band is higher than –2.90 dB, and the highest antenna efficiency value is –1.59 dB; the peak actual gain in the band is higher than 3.0 dBi, and the highest peak actual gain value is 5.61 dB.

Figure 15 shows the single horn antenna (hiding half of the horn antenna structure) in Figure 4 when there is glass and glass glue at φ = 90° at the three frequency points of 57.0 GHz, 60.0 GHz, and 64.0 GHz (low and medium) , High-frequency point) electric field distribution diagram, it can be seen that as the frequency increases, the reverse behavior of the electric field increases. Figure 16 shows the single horn antenna in Figure 4 at 57.0 GHz, 60.0 GHz, and 64.0 GHz in two scenes with and without glass and glass glue. The three frequency points of φ = 90° and θ = 90° are 2D. Parallel polarization (co-pol.) and cross polarization (x-pol.) simulated actual gain patterns (realized gain patterns). Figure 17 shows a single horn antenna with glass and adhesive coverage and Figure 18 shows a single horn antenna without glass and adhesive coverage. Simulated 3D actual gain radiation at the same three frequencies and the same scale. Directional map. Figure 16-18 shows that in the scene with glass and glass glue, the radiation pattern becomes more dispersed as the frequency increases; but in the scene without glass and glass glue, the shape trend of the radiation pattern is not Disperse as the frequency increases, so the coverage of glass and glass adhesive has a significant impact on the performance of the antenna.

Figure 19 is the simulation |Snn| performance comparison diagram of the four horn antennas in Figure 9 (in the actual scene, with glass and glass glue) and the single horn antenna in Figure 4. The reflection performance of the five antenna ports can be seen It is basically the same, and the bandwidth of |Snn| ≤-6 dB is 56.86 GHz-65.16 GHz, so it can cover the required 60-GHz frequency band. Figure 20 shows the isolation between the four horn antennas, and the worst in-band isolation is higher than 27.57 dB. Fig. 21 and Fig. 22 are simulation comparison diagrams of the antenna efficiency and peak actual gain of a 4-antenna horn antenna and a single horn antenna in a real scene (that is, covered with glass and glue). The antenna efficiency of the four horn antennas in the entire band is higher than –3.08 dB, and the highest antenna efficiency value is –1.59 dB; the peak actual gain in the band is higher than 3.29 dBi, and the highest peak actual gain value is 5.67 dBi.

Figure 23 below shows the actual gain pattern of the 2D parallel polarization and cross polarization simulation of the above four horn antennas at 57.0 GHz, 60.0 GHz, and 64.0 GHz on the two tangent planes of φ = 90° and θ = 90° . It can be seen from the figure that the radiation behavior of antenna #1 to antenna #3 is very similar, but the radiation behavior of antenna #4 is different from that of antenna #1–#3, mainly because antenna #4 is close to the aforementioned LTE antenna. Feeding structure, so the boundary conditions of antenna #4 are different from the other 3 antennas, but the radiation behavior within the 3-dB beam width of the main lobe is still close to the 4 antennas. Figure 24 shows the simulated 3D actual gain radiation pattern of antenna #1 to antenna #4 at 57.0 GHz, 60.0 GHz, and 64.0 GHz for a more intuitive understanding.

Figure 25 shows the simulated antenna efficiency and peak actual gain when antenna #1–antenna #3, the three antennas with similar performance, form a receiving linear antenna array while performing constant amplitude and phase feed at the same time. The antenna efficiency is higher than –2.99 dB, and the highest antenna efficiency value is –1.58 dB; the peak actual gain in the band is higher than 7.10 dBi, and the highest peak actual gain value is 10.27 dBi. Figure 26 shows the actual gain pattern of the linear array at 57.0 GHz, 60.0 GHz, and 64.0 GHz on the φ = 90° and θ = 90° two-section planes; Figure 27 shows the array at 57.0 GHz. , 60.0 GHz, and 64.0 GHz simulation 3D actual gain pattern.

Figure 28 shows the |Snn| and total antenna efficiency of LTE low and high frequency antennas. When |Snn| ≤ –6dB, the coverage bandwidth is 877 MHz–962 MHz and 2273 MHz–2753 MHz, so the LTE antenna can cover LTE Band 8 ( 880 MHz–960 MHz), Band 40 (2300 MHz–2400 MHz), and Band 41 (2496 MHz–2690 MHz), if you want to perform different low frequency bands (such as: LTE Band 17, Band 20, or Band 5, etc.) Overlay, tunable devices can be added. In the current LTE low-frequency (Band 8) and high-frequency (Band 40 and Band 41) bands, the lowest antenna efficiency is –3.83 dB and –1.73 dB, respectively, so it can perform wireless communication well. In addition, the isolation between the 4 millimeter wave horn antennas and the LTE antenna is higher than 24.86 dB.

Finally, in the conclusion part of this article forward-looking: “This design can be further integrated with the previously published 5G (fifth generation mobile communications) millimeter wave AiA [5] or AiAiP [2] solution, that is, the LTE antenna , 5G millimeter wave antenna array, and 60-GHz millimeter wave antenna are integrated in a three-in-one antenna design to be compatible with the product features of mobile phone metal frame and full screen and achieve a good user wireless communication and control interactive experience To achieve a more compact and competitive product design.”

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