vswr, antenna (practical)

8/12/2019 VSWR, Antenna (Practical)

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Nepal Telecom, MSD 1

VSWR, Antenna (Practical)

Presented By:

Bhupendra JhaNT-RF Engineer

MSD, Sajha Bhaban, Hariharbhaban, Lalitpur


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GSM General architecture:


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Antenna

RF system components: Amplifier, Filter, Mixer, Antenna.

Antenna:

The purpose of antenna is to convert electricity into

electromagnetic waves and radiate those waves into a medium

(air or free space).

Antenna installation needs proper planning to ensure good

signal coverage, user mobility, and eliminate interference


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Antenna: Gain and Loss

-Understanding of RF Signal transmission involves knowing:

1. The strength or power with which the transmitter is sending the signal.2. The amount of reduction in signal strength caused by cables, connectors.

3. The transmission medium (air or free-space).

4. The minimum strength of the signal required by the receiver to be able to

properly recover the data sent by the transmitter.

- Gain:Strength in the signals power.

- Loss: Weakness in the signals power.

- Both gain and loss are relative concepts and they expressed in terms of

Decibel (dB). Gain = 3dB (+3dB)/ Loss = 3dB (-3dB).

- Decibel is a ratio between two signal levels

- Knowing how much gain or loss occurs in RF system composed of radio

transmitter, receivers, cables, connectors is necessary to assist the RF

engineers to select appropriate components and installation.


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Gain and Loss

-

IndB

inmilliWatt (mW)

inmilliWatt (mW)


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Different types of Antenna andUses:


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Antenna Radiation Patterns

- Antenna performance is a measure of how efficiently an antenna can radiate RF

signal.

- The design, installation, size, and shape of antenna can affect its performance.

-Antenna pattern indicates the direction, width, and shape of RF signal beam

coming from the antenna.

Antenna Patterns viewed from above


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Antenna Radiation Pattern

Antenna

Patterns viewed

from side


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Antenna Radiation Pattern

DifferentAntenna Radiation Patterns


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Details of Antenna ElectricalProperties:

Click herepage 60
http://localhost/var/www/apps/conversion/tmp/scratch_3/BSA_System_Prod_Sel_Guide.pdfhttp://localhost/var/www/apps/conversion/tmp/scratch_3/BSA_System_Prod_Sel_Guide.pdf


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SWR:

this is the ratio of the maximum tothe minimum voltage of a standingwave (which is the instantaneous sumof incident and reflected waves).


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SWR Alarm

Minor SWR alarm= 3.0 > VSWR >1.5

Major SWR alarm= VSWR > 3.0

Solution:

Check Feeder Connector.

Check RF connector Connection.


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Why VSWR Exists:

If the feed line has no loss, andmatches both the transmitter outputimpedance and the antenna inputimpedance, then - and only - thenwill maximum power be delivered tothe antenna. In this case the VSWR

will be 1:1 Anything differ from this Create

VSWR


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VSWR Practical Application:

Different SWR Alarm: click here

SWR alarm Sites: click here
http://localhost/var/www/apps/conversion/tmp/scratch_3/ZXG10-BSS+Standing+Wave+Alarm+Analysis.pdfhttp://localhost/var/www/apps/conversion/tmp/SWR%20alarm.xlshttp://localhost/var/www/apps/conversion/tmp/SWR%20alarm.xlshttp://localhost/var/www/apps/conversion/tmp/scratch_3/ZXG10-BSS+Standing+Wave+Alarm+Analysis.pdf


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VSWR of PA Alarm

Minor Alarm:

Cause: backward power over-high

due to open end output of PA orhigh resistance.

Effect: TRU out of operation or PA

damaged. Processing: check PA output and

see if the cable connection isfastened.


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VSWR of Combiner Alarm Major Alarm:

Cause: combiner output open-ended, high resistance or

interference is received by EAM. Effect: PA is closed for protection,

making the corresponding cell wont

operate normally. Processing:check EAM and

connectors involved.


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Thank You

vswr, antenna (practical)

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