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This is part 36 of the LoRa/LoRaWAN tutorial.
In this video series different topics will be explained which will help you to understand LoRa/LoRaWAN.
It is recommended to watch each video sequentially as I may refer to certain LoRa/LoRaWAN topics explained earlier.
In this tutorial I will explain what the velocity factor is.
This will be a very short video.
It is important that you know what the velocity factor is because it will be used in other tutorials.
An antenna is made of a conductive material, such as copper or aluminium.
Electric current can easily flow through copper which allows the RF signal to propagate through the antenna.
Some conductive materials slows down the signal in the antenna compared to others.
The Velocity Factor (VF) is calculated as follows:
VF = Speed of a signal through a medium / Speed of a light in vacuum
The Velocity Factor will vary from material to material.
For example copper has a VF=0.95, it means copper slows down the propagation of RF signals to 95% of the speed of light.
If the antenna is covered by an insulating material this also impacts the RF signal when propagating out the antenna.
If f = 868 MHz and λ = 345.38 mm, l = 0.25 x 345.38 = 86.345 mm
If the antenna is made of bare copper: l = 86.345 x 0.95 = 82.028 mm
If the antenna is made of insulated copper: l = 86.345 x 0.95 (VF of copper) x 0.98 (VF of insulated material) = 80.387 mm
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