Solved Examples on dB, dBm, and dBi
Example 1: The ratio of two intensities of sounds is given as 3. Find the difference between the two sound levels.
Solution:
Let the intensity of two sound levels be a and b.
b/a = 3
As we all know decibel is used to measure the difference between sound levels. Let the two sound levels be named as x and y
y – x = 10log10( b/a)
=> y – x = 10 log(3)
=>y – x = 10×(0.477)
=>y – x = 4.77 dB
Example 2: Convert 4mW to dBm
Solution:
The power(P) given is 4mW
S(dBM) = 10 log P
= 10 log (4)
= 6.02 dBm
Example 3: Find the gain of an isotropic antenna provided the comparison gain is given by 5Watt
Solution:
G = 5W (given)
Using the formula
G(dBi) = 10 log(G)
=>G(dBi) = 10 log(5)
=>G(dBi) = 6.98 dBi
Example 4: Convert 10mW to dBm
Solution:
The power(P) given is 10mW
S(dBM) = 10 log P
= 10 log (10)
= 10 dBm
Difference between dB, dBM and dBi
Decibel is the unit of sound intensity. It is the ratio of two physical quantities and then the logarithm of the ratio is taken. It is also used in electricity to measure current, voltage, and power.
Table of Content
- What is Decibel
- Decibel Milliwatts (dBm)
- Decibel Relative to Isotropic Gain(dBi)
- Difference between dB, dBm, and dBi
- Solved Examples on dB, dBm, and dBi
- dB, dBm, and dBi- FAQs