Internal and external antennas and internal antenna technical requirements

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Internal and external antennas and internal antenna technical requirements [Copy link]

Internal and external antennas and internal antenna technical requirements Antennas are divided into internal and external. External antennas mainly use spiral or PCB. Spiral antennas generally have better bandwidth and are more commonly used. PCB antennas are easier to adjust the frequency and are easy to design, but Ericsson has two important patents, so few other manufacturers use them in the European and American markets. There is also a fake internal antenna, which is actually the internal antenna of the external antenna. The performance is relatively poor and is generally not recommended. For internal antennas, they are mainly PIFA and MONOPOLE antennas. The structure of PIFA includes slot antennna, G antennna, etc., and G antenna is generally used. The efficiency of monopole antenna is extremely high. Samsung mobile phones often use this design, but the SAR value is more problematic. However, Samsung has more folding phones, and the antenna can be far away from the human brain, so the SAR has less impact on the human brain. Antenna design is a relatively narrow field. General RF engineers can design it, but it is very difficult to make a good antenna, which requires a long time of accumulation. Therefore, even NOKIA outsources the antenna to famous antenna design companies such as Feichuang. Slot antennna Medium, high and low frequencies are generally generated by parastic. Since the antenna actually requires 1/4 wavelength, in this structure, the slot length between the radiators is close to 1/4 wavelength, thus generating a resonance point. The G antenna is generally divided into two pieces, which are basically independent, one side generates low frequency and the other side generates high frequency. The frequency can be changed by controlling the length of the radiator. Sometimes it is suspected that both methods may exist in the two structures, because each antenna has the most sensitive area, and it may just be that one of them is stronger. The SAR value of monopole antenna, if it is a straight-screen phone, is generally above 2.0, which greatly exceeds the European and American standards. Generally, domestic mobile phones do not consider the SAR value, as long as the efficiency is good, so if you are using this kind of crappy phone, you can basically throw it away. Technical requirements for built-in antennas: The materials of built-in antennas are beryllium copper, stainless steel and other materials, and the specific support depends on the structure. The RF performance of beryllium copper (gold-plated on the outside) antenna is better, but the price is slightly higher than that of stainless steel. The performance of the built-in antenna requires strict structural requirements. The basic requirements are as follows. Otherwise, the antenna performance will be greatly affected. The specific degree of impact depends on the type of antenna. It is generally believed that PIFA antennas are large in size and have good performance; slider phones must use this type of antenna for design. The specific requirements are as follows: 1. The height of PIFA should not be less than 6.5mm; 2. The LCM connector should be arranged on the keyboard surface of the motherboard; 3. The width of the antenna should not be less than 20mm; 4. The impedance of the lead from the RF test port to the antenna feed point should be maintained at 50 ohms; 5. The components near the PIFA antenna should be shielded as much as possible; 6. The pad of the feed point should not be less than 2mm*3mm; 7. The pad of the feed point should be at the top and close to the edge; 8. If the layout of the test socket is difficult, it can also be placed in the antenna area; 9. Some positioning holes can be opened in the antenna area. 10. There should be no motor, speaker, receiver or other large metal objects within seven millimeters around the built-in antenna. The MONOPOLAR antenna is slightly smaller in size and has poorer performance, so it is generally not recommended. The specific requirements are as follows: 1. There should be no motor, speaker, receiver or other large metal objects within seven millimeters around the built-in antenna. 2. The width of the antenna should be no less than 15 meters; 3. Do not spray conductive paint or other conductive materials on the structural parts (surfaces) near the built-in antenna. 4. Do not perform electroplating processes near the mobile phone antenna area and avoid designing metal decorative parts. 5. There should be no overlap with the FPC above and below the built-in antenna, and the distance between the edges should be more than seven millimeters. 6. The distance between the built-in antenna and the mobile phone battery should be more than 5mm. In fact, for the MONOPOLE antenna, as long as there is enough space, its performance can still be relatively good. The efficiency of the one I made can reach more than 70%. The key issue is that there can be no ground under the antenna. If there is ground, its performance will be greatly reduced. Some mobile phone manufacturers do not want to add matching circuits to the current PIFA and MONO antennas. They do not want to modify their BOM list, so this is also a challenge for mobile phone designers. It is particularly difficult for DUAL-BAND and TRI-BAN. In the design of PIFA, the speaker and oscillator can be placed directly under the antenna. For the speaker, the shorter the height, the better, and the smaller the diameter, the better. Shrapnel contact is better than wire contact. In addition, when designing the shape of the antenna, the coupling between the antenna and the speaker can be minimized, and the impact on the antenna performance can basically be achieved without too much impact. At present, there are many products that make 3-band antennas, whether PIFA or FMA. It should be mainly determined by the design of the mobile phone itself and the size of the antenna, as well as the design of the antenna. Under the normal size, it is difficult to judge at once whether this project can be made into 3-band or not. The size requirements for 3-band antennas are generally required to be as large as possible. In the past, many examples can achieve 3-band, but some customers require 3-band or even 4-band, but can only do dual-band or 3-band, which seems to be closely related to the mobile phone. The things in this technical requirement should be the requirements under ideal conditions. Generally speaking, it is difficult for mobile phone manufacturers to really follow this standard, otherwise it will be relatively easier for antenna manufacturers to do it. For successful mobile phone antenna projects: 1. The efficiency of antennas with a height of 4-6mm can be more than 20%, which can also be used for some special projects. 2. The antenna width can be around 10mm, which can be achieved by PIFA and FMA. 3. The feed pad is in the middle of the PCB, and the distance between it and the ground feed point is close or far, with a short distance of 1mm and a long distance of 6 or 7mm. 4. There are many things that interfere with the built-in antenna below, which increases the difficulty of antenna design. In addition, it is not recommended to use a single-feed point antenna. Currently, many mobile phones on the market use this type of antenna. The antenna has a small area and low height requirements. The performance should be generally slightly better than PIFA. The SAR problem that is worried about should also meet the standards. It should be recommended for use. Some shortcomings may be that there can be no reference ground below the antenna, which reduces the utilization area of the mobile phone PCB board a lot.

povos

Haha, when I was reading your post, I actually dug up a gold coin. I’ll be happy for a while, and then I’ll look at it again.

kango

:)Ha ha

chuchuda

Thanks, I read it again