Insertion loss is unavoidable, and it may be due to one of the following reasons:
Ohmic loss due to power dissipated in the conductor used to make the transmission line components, i.e., cables, connectors, etc.
Poor connection and field termination can also cause a significant loss in transmitted signal strength.
Dielectric loss due to the absorption of the signal by the dielectric material that forms the conductor insulation and cable jacket.
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