Bhanwar Singh

J Muralidhara Chary

Power divider divides input power into two

or more signals of lesser power.

Passive circuits

E.g. T junction power divider, resistive

divider, Wilkinson divider.

Providing a signal sample for

measurement or monitoring.

In feedback circuits.

In combining feeds to and from antennae

Providing taps for cable distributed

systems such as cable TV.

Separating transmitted and received

signals on telephone lines.

Can be used to split power in any ratio.

Lossless when the output ports are

matched i.e. only reflected power gets

dissipated.

3-dB power divider makes use of quarter

wave transformers.

Easily fabricated, cheap and high

performing.

Design of Equal -Split Wilkinson power

divider with specifications :

f = 2.4 GHz.

Source Impedance = 50 ohms.

Load Impedance = 50 ohms

Substrate permittivity = 3.38

Thickness of substrate = 1.524 mm

Thickness of conductor = 0.15 mm

For matching port 2 for even mode excitation,we have to make

We obtain:

We can obtain using transmission line

equations.

Looking into port 2 we see a impedance of r/2.

For port 2 to be matched for odd mode excitation we select r=2.

Thus we obtain :

With the above calculated Z and r values

we can find the input impedance at port 1

as

In summary we can establish the following

S-parameters for the wilkinson divider:

Z0 √2 Z0 (Charteristic

Impedance of quarter

wave transformer)

2Z0 (Shunt Resistor)

50 Ω 70.71 Ω 100 Ω

Then we used LINECALC to calculate length and width of microstrip lines –

For Zo=50 Ohm, at λ/4 W=3.37 mm, L= 19.19mm

For Z= √2Zo=70.71 Ohm at λ/4 W= 1.56mm, L=19.86 mm

1.5 2.0 2.5 3.0 3.51.0 4.0

-20

-15

-10

-5

-25

0

freq, GHz

dB(S

(1,1

))dB

(S(2

,1))

Readout

m1

dB(S

(3,1

))

m1freq=dB(S(2,1))=-3.042

2.466GHz

Thank you for your kind attention !!