Purpose of passive repeaters in the microwave transmission Questions 2022

The digital microwave radio system shown in Fig 1 below operates in the 18GHz radio frequency band and provides 2x2 Mbps transmission capacity between two sites. The system deploys a passive repeater. Calculate the nominal Receive Signal Level (RSL) at the input of the receiver in dBm assuming free space conditions. (7 marks) Briefly discuss the purpose of the passive repeater in this system? (3 marks)

Running head: ELECTRONICS 1
Electronics
Name of Student
Institution Affiliation

ELECTRONICS 2
Solution
In Unfaded conditions: the link budget is determined by the formula
PRX= PTX-LTX-FLTX+ATX-FSL+ARX-FLRX- LRX (Raychaudhuri & Gerla,
2011).
Where PRX= Unfaded Nominal Receiver Level in dBm
PTX = output of transmitter power in dBm
LTX =branching loses in the transmitter
FLTX = transmitter feeder loses of the waveguide or cable in dB
ATX = the antennae gains in dBi
FSL = the free space loses
ARX = the antenna gains in dBi
FLRX =receiver feeder loses of the waveguide or cable in dB
LRX =receiver branching loses
The provided parameters are
PTX = + 23 dBm
LTX = 3dB
FLTX = 1.5dB
ATX = 39.5dBi
FSL =?
ARX = 39.5 dBi
FLRX = 1.5dB
LRX = 4dB
Other Loses= 1dB

ELECTRONICS 3
f = 18GHz= (18 * 10^9) Hz
D= (4.5 + 0.5) Km
= 5km
Determination of the FSL value.
FSL= ?
FSL= 20 log 10{¿)} (Raychaudhuri & Gerla, 2011).
Where d= 5km
= 5 * 10^3
f= 18*10^9
c= 3*10^8
Substituting back to the equation
FSL= 20 log 10{¿)}
=20 log 10{¿)}
=20 log 10{4 π (3∗103)}
=20 log 10{3769911.184}
But log 10{3769911.184}= 6.57633
= 20 * 6.57633
= 131.52dB
Substituting:
PRX= PTX-LTX-FLTX+ATX-FSL+ARX-FLRX- LRX
= + 23 dBm - 3dB -1.5dB+39.5dBi -131.52Db+39.5 dBi-1.5dB -4dB- 1dB
= -40.52 dBm.

ELECTRONICS 4
Q2: Purpose of passive repeaters in the microwave transmission
The whole system comprises, of a repeater, for instance: receiver, amplifier, isolator, and
the antennae. For this system, the passive repeaters are meant to redirect the signals which have
been obstructed by any obstacle after transmission. The perceive repeater do not require any
power and this makes its maintenance to be virtual (Dar, Bakhouya, Gaber, Wack & Lorenz,
2010).

ELECTRONICS 5
References
Dar, K., Bakhouya, M., Gaber, J., Wack, M., & Lorenz, P. (2010). Wireless communication
technologies for ITS applications [Topics in Automotive Networking]. IEEE
Communications Magazine, 48(5), 156-162.
Raychaudhuri, D., & Gerla, M. (Eds.). (2011). Emerging wireless technologies and the future
mobile internet. Cambridge University Press.