1, DBM
DBM is a value of an absolute value of the test power, and the calculation formula is: 10LGP (power value / 1MW).
[Example 1] If the transmit power P is 1 mW, it is 0 dBm after the DBM is converted.
[Example 2] For the 40W power, the value after the DBM unit is converted to:
10LG (40W / 1MW) = 10Lg (40000) = 10LG4 10LG10 10LG1000 = 46dBm.
2, DBI and DBD
DBI and DBD are values (power gain) of the gain, both of which are relative values, but the reference reference is not the same. The reference reference reference reference reference for the DBI is a full-directional antenna, and the reference reference reference for DBD is a dipole, so the two are slightly different. It is generally believed that the same gain is generally indicated by DBI, which is more than 2.15, indicated by DBD.
[Example 3] For an antenna having a gain of 16 dBd, it is 18.15 dBi (generally ignored a small digit, 18dBi).
[Example 4] 0dBd = 2.15dbi.
[Example 5] The GSM900 antenna gain can be 13dBd (15dBi), and the GSM1800 antenna gain can be 15dBd (17dbi).
3, DB
DB is a value characterizing the corresponding value. When the power considering the power is larger than the two dimensions or small DB, the formula is calculated: 10LG (Arm A / Effic)
[Example 6] Arm A is doubled than the power rate, then 10LG (Arm A / EtOAc) = 10LG2 = 3dB. That is, the power ratio of the power ratio of the A is 3 dB.
[Example 7] The 100-meter transmission loss of 7/8 inch GSM900 feed is approximately 3.9 dB.
[Example 8] If the power of the armor is 46dBm, the power of B is 40 dBm, and it can be said that the armor is 6 dB.
[Example 9] If the Atenna is 12 dBd, the antenna is 14dBD, which can be said to be a small 2 db.
4, DBC
Sometimes the DBC will also be seen, it is also a unit that represents the relative value of the power, which is exactly the same as the calculation method of DB. In general, DBC is relative to the carrier power, in many cases, the relative value of the measurement and carrier power, such as used to measure interference (same frequency interference, intermodulation interference, interference interference, belt External interference, etc.) and relative magnitude of coupling, stray or the like. In principle, DB replacement can also be used in terms of using DBC. DBIL, DBIC is not very clear
