Technical Background
Tiantong-1 satellite is a high-orbit (GEO) synchronous satellite, which means that it is located at a fixed position about 36,000 kilometers above the earth's equator, synchronized with the earth's rotation, and therefore always located above the same area. Since Tiantong-1 satellite is a high-orbit satellite, its signal coverage is large and can provide a wider range of communication services. A single high-orbit satellite can cover more than 40% of the earth's surface, which is very beneficial for providing services in a fixed area. Within the coverage area, 24-hour uninterrupted communication can be achieved, and the service stability is high. "In addition, the construction of a high-orbit satellite system is relatively simple. For example, only three synchronous earth satellites are needed to cover most areas except the poles, which means that the system has a small number of satellites, and the cost-effectiveness of operation and on-orbit maintenance is relatively high." At present, Tiantong-1 satellite mainly covers China and its surrounding areas.
China's Beidou satellite also has communication functions. The Beidou satellite system consists of medium-orbit satellites in the earth's orbit. Its main functions are navigation and positioning. Its short message communication function is suitable for sending short messages and emergency assistance. The Tiantong satellite service focuses more on providing a communication experience similar to that of traditional mobile phones, including clear voice calls and flexible text message exchanges.
However, most of the traditional Tiantong equipment is used in Tiantong functional handsets, vehicle-mounted aftermarket and other fields, and the reliability cannot meet the requirements of vehicle-mounted pre-installation.
Technical description
This external Tiantong antenna technical solution aims to solve at least one of the technical problems existing in the existing technology. Compared with the existing technology, this solution has the following characteristics:
① Meet the requirements of vehicle-mounted pre-installation
② Solve the problem of vehicle-mounted satellite phone communication, structurally adapt the installation environment of the car through the support plate, and use a metal symmetrical array plus a feeding network to improve the radiation efficiency and gain of the antenna to ensure the effect of satellite calls (refer to Figures 1-2)
③ This external Tiantong antenna adopts a symmetrical array structure, and feeds equal amplitude and 90° phase difference excitation through the feeding plate, so that the external Tiantong antenna works in a left-hand circular polarization state. Compared with the traditional microstrip antenna, the present invention has a higher overall efficiency and enhanced antenna radiation capability because the antenna radiation part adopts an all-metal design and has no dielectric loss. Since the external Tiantong antenna is used in the front of the vehicle, the metal fence is used to increase the equivalent metal coverage area of the antenna to offset the interference of the surrounding environment. The external Tiantong antenna changes the structural parameters of the antenna so that the antenna's directional pattern gain in the low-profile direction can also be guaranteed. This external Tiantong antenna is usually installed on consumer cars and is used in the field of satellite communications.
Figure 1
Figure 2
Implementation Data
| Frequency (MHz) | Left-hand circular polarization gain dBi |
| theta 0° | theta 35° | theta 45° | theta 60° | theta 70°
|
| max | min | max | min | max | min | max | min |
| 1980 | 6.11 | 4.37 | 4.06 | 3.08 | 2.67 | 1.17 | 0.49 | -0.74 | -1.55 |
| 1995 | 6.54 | 4.32 | 4.03 | 3.18 | 2.61 | 1.41 | 0.61 | -0.64 | -1.44 |
| 2010 | 6.6 | 4.45 | 4.11 | 3.31 | 2.73 | 1.51 | 0.77 | -0.56 | -1.27 |
| 2170 | 6.42 | 4.36 | 3.97 | 3.13 | 2.58 | 1.28 | 0.56 | -0.73 | -1.54 |
| 2185 | 6.45 | 4.38 | 3.98 | 3.17 | 2.59 | 1.31 | 0.57 | -0.75 | -1.51 |
| 2200 | 6.29 | 4.31 | 3.92 | 3.07 | 2.59 | 1.21 | 0.51 | -0.77 | -1.56 |
Installation requirements
① There is no metal obstruction directly above the external Tiantong antenna and within the 25° side tilt range.
② It is best not to place the side of the external Tiantong antenna around a transmitting antenna with overlapping frequencies (such as a 4G antenna, etc.).
This technical solution realizes the application of the Tiantong external antenna in the front-mounted vehicle for the first time. Compared with the traditional handheld antenna, this external Tiantong antenna has higher efficiency and wider lobe width, which can meet the call effect in complex environments. Compared with the traditional microstrip antenna, the antenna has higher efficiency and wider lobe width, which can meet the call effect in complex environments; through the all-metal symmetrical array structure, plus the feed plate excitation equal amplitude phase difference of 90° signal, circular polarization radiation is achieved, and the antenna efficiency is guaranteed.
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