A basic method of calculation in dB for wireless applications

How to create level diagram of a wireless applicat ion using anechoic box

Application

In recent years, even circuit design and digital design engi neers should learn radio technologies with the increase of wireless applications. Some of those engineers may not be good at analyzing in dB. This paper presents a way how to create level diagram of a wireless application using an echoic box.

Solution

A basic of calculation in dB

1[mW]：10 x log(1)=0[dBm], 10[mW]：10 x log(10)=10[dBm], 20[mW]：10 x log(20)=13[dBm], 100[mW]：10 x log(100)=20[dBm]

Calculation in dB for creating level diagrams of wireless applications

A test system with an anechoic box to evaluate communic ation properties in wireless applications is shown in below figure.

As shown above, the transmission power and the received po wer is related in a simple algebraic sum. Accordingly, and when inserting a power amplifier between the transmitte r and the transmitting antenna,or inserting a low noise amplifier between the receiving antenna and the receiver, l evel diagram can be created by simply adding their amplification degree [dB] in the above equation.

System configuration

Signal analyzer [MSA538]	x 1
Electromagnetic anechoic box
Antenna
Jigs to mount antenna and EUT
Others(PC, I/F modules, cables, etc)

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