Construction of Slotted Line
As shown in the below diagram, the slatted line consists of minimum λ/2 piece having a slot in its longitude and a circular shape internally. The test probe is kept inside the slot in such a way that it is parallel to the electric field and the transmission line. The output of the probe is provided to standing wave indicator in order to measure the voltage standing wave ratio. The transmission lie is kept inside the slotted line for measurement of values of maximum voltage point and minimum voltage location.
Working of Slotted Line
Whenever we want to measure the voltage standing wave ratio of the transmission line, we are to place the conducting wire of the line inside the slotted line through the slot provided in that device. We are to adjust the probe should not touch the conducting wire of transmission line. It should only be electrically coupled with the energy passing through the transmission line.
For measuring of voltage standing wave ratio we take the maximum and minimum reading of voltage along the transmission line by moving the probe right and left and locating at the SWR indicator.
To measure the frequency of the transmitter with the help of slotted line, the scale is provided at the device. We mark the point for maximum and minimum voltage reading. The distance between those two points provides us the wave length equal quarter λ frame which we can calculate the operating frequency using the formula
λ/4 = v/uF
Where V stand for velocity of electromagnetic waves in free space equal to 3 X 108 ms.
Uses of Slotted Line
The slotted line is used to measure the voltage standing wave ratio of the transmission line upto the frequency in GHz.