Field-strength diagram and choice of receiving antenna

The use of satellite signal field strength coverage maps to select the diameter of the receiving antenna is one of the topics of great concern to the majority of satellite TV enthusiasts.
In general, when carrying out the sub-work, the first thing is to understand the distribution of satellite signal coverage to be received, whether it is full beam coverage or fragmented beam coverage, and then according to the actual field strength EIRP value of the beam coverage at the receiving location And the difference is whether the collective receiving station or individual single receiving station chooses the size of the receiving antenna. If you are already familiar with the reception of Asia-1 satellite, it is the two beams of satellite signals covering the north and south. The central field strength of the north beam is 36 ~ 37dBW, mainly covering China, Mogu, Nepal, North and South Korea, etc. The central field strength of the south beam is 37dBW, covering Southeast Asia and other countries. When the 1.5M antenna is selected as an individual receiver, its north-beam satellite TV programs can be viewed normally in most areas of China, but it cannot receive normal south-beam satellite TV programs. Another example: Indonesia ’s C2 star at 113 degrees east longitude, although it is a high-power satellite, the central field strength of the C-band signal is as high as 40dBW. However, because the satellite signal mainly covers Southeast Asia, it cannot be used in most parts of China. 1.5M antenna for normal signal reception. There is also the "Zhongxin 1" satellite that was launched last year, and its KU band is divided into K1 Southeast Asian beams and K2 Central Asian beams. Among them, the K1 beam is divided into a high-power spot beam (52dBW) and a medium-power beam (49dBW). In our country, except for a few in the southeast coast, most provinces and regions are unlikely to receive the satellite's KU band signal.
For the satellite signal field strength EIRP value, the unit is "dBW", the larger the unit number, the stronger the satellite's transmit power. At present, the C-band field strength value is generally 32 to 40 dBW from the edge to the center beam, and the KU band field strength value is 42 to 60 dBW from the edge to the center beam. With the further improvement of satellite manufacturing technology, satellite transmission power is getting stronger and stronger, and the field strength value covered by satellite signals will also be broken, resulting in the increasingly narrower diameter of ground receiving antennas.
In terms of satellite reception, there are many domestic professional antenna manufacturers. Basically, they can produce antenna products with efficiency and gain that meet the standards strictly in accordance with the performance requirements of the national receiving antenna. The following is a list of antenna aperture and gain specifications based on the products of the two companies:
When the antenna diameter is specifically selected, if the C-band satellite signal field strength at the receiving location is within 36 to 37dBW, the single receiving station can use a 1.8M (or even 1.5M) antenna to defeat the normal viewing requirements. The collective receiving station selects 3M The antenna can also reach the level 4 image standard for normal viewing. The receiving station with a large number of users chooses a 4.5M antenna. As for the antenna aperture of the KU band, because the satellite signal field strength value is much higher than the C band, it can reach 60dBW. , Coupled with the characteristics of KU wavelength, the size of the KU-band dedicated bias feed antenna is greatly reduced, even as small as O.35M. According to the practice of reception: the area with a field strength value of 54dBW can be offset by 0.45M KU The antenna receives KU band digital programs. In areas where the field strength value reaches 52dBW, a 0.6M offset feed antenna can be used, while in areas where the field strength value is only 46dBW, using 1.2M KU offset feed antenna reception is not a problem. Like Asia-Pacific 2R, it is not an exaggeration to use a 0.35MKU antenna to receive digital programs when the signal field strength of its KU band reaches 58dBW and the effect of rain attenuation is not considered.
In addition, for those who do not have a dedicated partial-feed antenna for the time being, you need to use the original C-band antenna to receive KU programs. Of course, you can also determine the reception target according to the actual satellite signal field strength value. For example, a single receiving station in the KU band field strength of 50 to 52dBW can achieve the KU band digital program viewing effect with a standard 1.5M or 1.8MC band antenna, and a single receiving station in the KU field strength of 47dBW, a pair The 2.4MC band antenna will be fully competent.

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