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POWER DIVIDER
Objective: To find the characteristics of the microstipline power divider.
Equipment: VCO, Power meter, DC power supply, Matched terminations.
Theory: The basic function of the power divider is that it divides the input power at the
output ports. In power divider the input line impedance Zo is divided into two lines, each
of them are of impedance Z. It worksuch that, if input power is ‘p’ then out put power at
two output terminals are ‘p/2’ each. And the two output ports are isolated. The three ports
are not simultaneously matched.
2
1
3
Figure 1 : Power Divider
The important feature of power divider is that the output ports are isolated that is
input power into one of the output ports is not seen at the other output port. The power
divider which is used in this experiment is a ring type power divider. The ring shape
decreases the total area of the circuit for larger range of frequencies.This power divider is
based on the design proposed by E.J Wilkinson. The Wilkinson power divider is a threeport device and it has two types namely narrow band type and broadband type. The
narrow band design is as shown above and the broadband power divider is constructed by
just cascading similar sections.
This power divider is designed at –3dB coupling and operating frequency range of
2-8GHz.
Isolating resistor is the important part of the power divider, as it isolates the
two out put ports, such that the image of one of the port is not seen on the other port.
The device that is designed in this project work is the four-section power
divider. And the characteristic impedance of microstrip line in each section is given by -
Z = √ (Z1 Z2)
Where Z1 and Z2 are characteristic impedance of strip.
Procedure:
1.
Apply the voltages Vd and Vt to the VCO and set the power meter frequency
at 0.05 GHz
2.
Connect the VCO to the sensor of the power meter and measure the power
output from the VCO.
3.
Now connect the port 1 of power divider to the VCO and measure the power
output at the ports 2 and 3 of the power divider. Note down the readings
4.
Now change the frequency in power meter in steps of 0.5 GHz and measure
the input and output power of power divier.
5.
Tabulate the above readings.