How to calculation of antenna gain Expected to finish reading in 10 minutes Gain refers to the ratio of the power density of the signal generated by the actual antenna and the ideal radiating unit at the same point in space under the condition of equal input power. It quantitatively describes the degree to which an antenna concentrates input power to radiate. The gain is obviously closely related to the antenna pattern. The narrower the main lobe of the pattern, the smaller the side lobe, and the higher the gain. The physical meaning of gain can be understood in this way ------ To generate a signal of a certain size at a certain point over a certain distance, if an ideal non-directional point source is used as the transmitting antenna, 100W input power is required, and When a directional antenna with a gain of G = 13 dB = 20 is used as the transmitting antenna, the input power only needs 100/20 = 5W. In other words, the gain of an antenna, in terms of its radiation effect in the direction of maximum radiation, is a multiple of the input power compared with an ideal non-directional point source. The gain of the half-wave symmetric oscillator is G = 2.15dBi. The four half-wave symmetrical oscillators are arranged up and down along the vertical line to form a vertical quaternary array with a gain of approximately G = 8.15dBi (the unit of dBi indicates that the comparison object is an ideal point source with uniform radiation in all directions). If a half-wave symmetrical oscillator is used as the comparison object, the unit of the gain is dBd. The gain of the half-wave symmetric oscillator is G = 0dBd (because it is compared with itself, the ratio is 1 and the logarithm is zero.) The vertical quaternary array has a gain of about G = 8.15-2.15 = 6dBd. Several calculation formulas of antenna gain 1) The narrower the antenna main lobe width, the higher the gain. For a general antenna, the gain can be estimated using the following formula: G (dBi) = 10Lg {32000 / (2θ3dB, E × 2θ3dB, H)} In the formula, 2θ3dB, E and 2θ3dB, H are the lobe widths of the antenna on the two main planes; 32000 is statistical experience data. 2) For a parabolic antenna, the gain can be approximated by the following formula: G (dBi) = 10Lg {4.5 × (D / λ0) 2} Where D is the diameter of the paraboloid; λ0 is the central working wavelength; 4.5 is statistical experience data. 3) For upright omnidirectional antennas, there are approximate calculation formulas G (dBi) = 10Lg {2L/ λ0} Where L is the length of the antenna; λ0 is the central working wavelength; About db, dBi, dBd and other units of the antenna Some friends tend to confuse these units more easily. The dB values are based on logarithmic values. (1) dB, which is simply a relative value, that is, the logarithm of the value of A over B. It is often used to say how much dB A is higher or lower than B, but it is unreasonable to say how much A's gain is dB, because we don't know what B is. It is just that many of our fellows so...

Uncovering large scale MIMO technology: key factor of 5g super high speed rate Expected to finish reading in 5 minutes In 5 gera, even if the signal is only one or two boxes, we can download files, video chat or watch online movies without any scruple. In most cases, these are as smooth as listening to music online. 5g large-scale MIMO (multiple input and multiple output) technology is one of the keys to open these5guser experiences. What is large scale MIMO? MIMO system has been widely used in wireless communication - mobile devices and networks generally use multiple antennas to enhance connectivity, improve network speed and user experience. Now, with the design of the new5gNR network, MIMO technology has a new look. By deploying a large number of antennas on the base station, large-scale MIMO can bring far more performance than traditional systems. Uncover large scale MIMO technology There are three key concepts in the construction of MIMO system: spatial diversity, spatial multiplexing and beamforming Spatial diversity and spatial reuse Spatial diversity is one of the main advantages of MIMO technology. In short, diversity aims at improving the reliability of the system by simultaneous interpreting the same data on different propagation paths or paths. Spatial multiplexing Spatial diversity has gradually evolved into a more complex concept, namely "spatial reuse". Its significance is not only to improve the performance through the diversity of air channels, but also to transmit multiple messages at the same time, and in the process of transmission, each way does not interfere with each other. We can imagine that there is a data transmission pipeline between the base station and the mobile phone in the mobile network, and there is an antenna on the base station and the mobile phone, and the data that the pipeline can transmit is very limited. If more antennas can be deployed on the base station and mobile phone, and appropriate space separation can be carried out, multiple virtual channels can be established between the mobile phone and the base station, so as to achieve a large number of data transmission. Beamforming Another key wireless technology is beamforming. Through advanced antenna technology on mobile devices and network base stations, it can gather wireless signals in a specific direction, rather than spread to a wide area. Just like the difference between a flashlight and a laser pen, the former can illuminate the whole room, while the latter can continuously point or track individual users. 3D beamforming With the increase of the number of antennas in MIMO system, beamforming becomes "3D beamforming". 3D beamforming technology can generate user oriented horizontal and vertical beams, so as to improve the data transmission rate and capacity of all users, including users on the top floor of high-rise buildings. With the feedback of mobile terminal, the beam can find any point in the space. Therefore, whether users are moving in the...

How to enhance the signal of walkie talkie? ① Increase the launching height: outdoor players who often play with the handsets have such experience. When the signal is not good, stand higher. In fact, with the increase of the transmitting height, the coverage of the radio transmitting signal increases, which can greatly improve the communication effect. ② Improve the communication sensitivity: when the general hand-held walkie talkie leaves the factory, the sensitivity has been adjusted to the best state according to the relevant technical requirements, so it is not allowed to adjust the receiving sensitivity of the walkie talkie without the guidance of professional instruments and technicians. If you want to further improve the communication sensitivity, you can use a high gain antenna, but pay attention to ensure that the antenna is in the same frequency band. ③ Choose a wide communication environment and direction: when the radio wave of the walkie talkie is in the open area without obstacles, the loss of radio wave propagation is the minimum. The reinforced concrete buildings in the city absorb the electric wave seriously, and the outdoor use should avoid the block of the surrounding tall buildings or trees. ④ Increase the antenna length: Generally speaking, the special extended hand table antenna is better than the original hand table antenna; the vehicle antenna is better than the small whip antenna; the rod antenna is better than the vehicle antenna; the multi unit unidirectional antenna is better than the rod antenna. ⑤ Enhance the transmitting power: the transmitting power of the hand station is related to the voltage and capacity of the battery. When the hand station is fully charged, the transmitting power is high, otherwise it is small. The interphone with large capacity battery can effectively improve the transmission power. For example, Beifeng 511uv walkie talkie has three transmit power options: high (5W), medium (3w) and low (1W). When it is convenient to use, it can be adjusted according to distance, environment and other factors.

What determines the communication distance of the wireless module? Selection is very important for antenna 2020-2-18whwireless The communication distance of wireless module is an important index. How to maximize the effective communication distance has always been a puzzle for customers. In this paper, according to the debugging experience, the selection and use of the antenna are explained, hoping to help engineers quickly debug the communication distance. The primary parameter affecting the communication distance of the wireless module is the transmission power. The transmission power of the wireless module and the corresponding ideal transmission distance can be found in the manual. On the premise that the transmission power meets the requirements, the selection of the antenna and the directionality of the antenna are considered. The first is the selection of antenna: The main specifications of the antenna include the following: frequency range, SWR or VSWR, antenna gain, polarization mode and impedance. The frequency range should be selected as required; the VSWR should be less than 1.5; the antenna gain also affects the transmission distance; the polarization mode can be divided into linear polarization and circular polarization; the impedance needs to match the output impedance of the wireless module, generally 50 ohms. Pay special attention to VSWR parameters here. It is better to test SWR with network analyzer after purchasing antenna. The comparison table of SWR, return loss and transmission power is shown in Table 1. It can be seen from the above table that when VSWR = 1.5, the theoretical transmission power is 96%. When VSWR = 2, the transmission power is only 88.9%. Some antenna VSWR indexes are less than 2. When selecting an antenna, the best VSWR is less than 1.5, which can get higher transmission power. Secondly, antenna directionality: Antenna has directionality, which means that antenna has different radiation or receiving ability in different directions of space. The antenna directionality is usually measured by using a pattern. Figure 1 shows a pattern of an antenna with a frequency range from 2400mhz to 2500mhz. When the antenna is placed vertically, the direction with the deepest red color is the direction with the strongest radiation or receiving ability of the antenna. Therefore, when installing the antenna, install the antenna in the direction with the red color as much as possible, so as to ensure good signal quality. In addition, the metal plate has a shielding effect on the signal, so there should be no metal plane in the direction of transmitting and receiving. There are also some antenna directions shown in the manual, which are represented by two-dimensional drawings, including H-plane and E-plane, as shown in Figure 2. When testing the communication between wireless modules, the directionality of the antenna must be considered. When the communication space is not blocked and the direction of the antenna corresponds ...