Our mini class project.

1. Design of Equal
Split Wilkinson
Power Divider
Submitted by
Bhanwar Singh, ECE 4th Year, En. No. 08116009
J.Muralidhara Chary, ECE 4th Year, En. No. 08116019
Under the guidance of
Dr. M. V. Kartikeyan

2. DEPARTMENT OF ELECTRONICS AND COMPUTER ENGINEERING
INDIAN INSTITUTE OF TECHNOLOGY ROORKEE
ROORKEE – 247667
Acknowledgement
With deep sense of gratitude, we express our humble thanks unto our
esteemed supervisor, Dr. M.V. Kartikeyan (Professor, Department of Electronics
and Computer Engineering), for assigning us this project and hence helping us
to learn. His valuable guidance helped us to carry out this work under his
effective supervision.
We also express our heartiest gratitude to our friends for their invaluable advice
and
encouragement.
J.Muralidhara Chary
Bhanwar Singh Place:
IIT Roorkee

3. Table of Contents
1. Introduction
……………………….….……..……………………….….…..……..…………..………… 5

4. 2. Problem Statement……………….…
...…………………………………………………………………5
3. Theory
...……….………..………………………………………………………….….…..……...…...… 6
4. Calculation and Simulation
…….….………..………..…………...………..…………………………..... 8
5.
Results……………………………………………………………………………………………………9
5. Conclusion
...…………………………………………………………………………….…..…………. 10

5. Abstract
Power dividers (also power splitters and, when used in reverse, power
combiners) are passive devices used in the field of radio technology. They
couple a defined amount of the electromagnetic power in a transmission line to
another port where it can be used in another circuit. Directional couplers and
power dividers have many applications, these include; providing a signal
sample for measurement or monitoring, feedback, combining feeds to and from
antennas, antenna beam forming, providing taps for cable distributed systems
such as cable TV, and separating transmitted and received signals on telephone
lines. The Wilkinson divider splitter / Wilkinson combiner is a form of power
splitter / power combiner that is often used in microwave applications. It uses
quarter wave transformers, which are easily fabricated as quarter wave lines on
printed circuit boards and as a result it offers the possibility of proving a very
cheap and simple splitter / divider / combiner while still providing high levels
of performance.

6. Introduction

7. With The Rapid Development in wireless/wireline communications, their functions are
further enhanced, and the applications are also broadened. For industrial systems,
however, circuits/devices with much more stringent requirements are suffering from
the system cost, compactness, stability, reliability, and other specifications , as
compared with those systems like consumer electronics. It is known that any wireless /
wireline (RF) system is generally composed of passive and active circuits . Among
various RF passive circuits, Wilkinson power divider is a basic and important
component in application to RF power amplifiers, mixers, phased-array antennas, and
many kinds of equipment.
Problem Statement
Design of Equal -Split Wilkinson power divider of Frequency 2.4 GHz.
Specifications are:
1. Source Impedance = 50 ohms.
2. Load Impedance = 50 ohms
3. Substrate permittivity = 3.38
4. Thickness of substrate = 1.524 mm
5. Thickness of conductor = 0.15 mm
Simulate the circuit of Equal -Split Wilkinson power divider and plot the graphs of
various
S parameters.

8. Theory
The mostly used one is the three port network equal two way divider. It is
also called 3 dB power divider.
In this type of dividers, there are four different sections.
1-) Input port
2-) Quarter-wave transformers
3-) Isolation resistors
4-) Output ports
Input and output ports are identical and the value of the impedances of
them are Zo. Quarterwave transformer parts are called as quarter-wave
transformer because of the length of these parts. The length of these parts
are equal to the one fourth of the wavelength of the electromagnetic wave,
which is propagating in this three port network. This length is also related to
the operation frequency.
Wavelength * Frequency = Phase velocity (Usually the speed of light)

9. Why the quarter-wave transformers are used in the circuit? The reason for
this leads us to understand the matching conditions for this network.
Matching of the output ports is necessary for the better power transfer from
input to output, because if the output ports are matched, the reflected
power from the network when we input some amount of power is zero. This
means, there is no reflection from the outputs and all of the power is
transmitted to the output ports. Consider the case of inputing power at port
1 and terminate the ports 2 and 3 with the reference loads. Then the
reflected power for inputing power at port-1 is zero ( S11 = 0 ). All the
power is transferred at that frequency. The quarter-wave transformer part
leads to the matched ports. Isolation resistor is to isolate the output ports. If
there is a coupling effect between output ports or in other words, the power
comes from one output port has an effect on other output port, the perfect
division of the power cannot be possible. This isolation resistor avoids the
coupling
effects of the output ports. Output ports are the ports that divided power
comes to. These ports have the same impedance value with the input port's
impedance.
To analyze the Wilkinson power divider, even-odd mode analysis method is
used. In even-odd mode analysis the aim is finding the S-parameters of the
divider. S-parameters give all voltage and power information about the
network we consider. To find S-parameters, from the definition of them, we
should input power at a port and measure the contributions of that power to
the other ports. In even-odd mode analysis, the superposition of the two
modes is inputing power at port-2 and finding the effects at all ports. First
of all our circuit becomes symmetric, made symmetric with respect to the
axis at the middle. This symmetricity makes the analyze easy. An ideal half-
split power divider would divide incident power at port 1 equally between
ports 2 and 3. The S-matrix for the ideal Wilkinson divider is given below:

10. This ideal Wilkinson power divider would have perfect matching at all ports (S11
= 0, S22 = 0,
S33=0). Also, there would be perfect isolation between ports 2 and 3 (S23 = 0).
The insertion loss between ports 1 and 2 should be 1/√2 , and the insertion
loss between ports 1 and 3 should be 1/√2 (|S12| = |S13| = 1/√2 ). Even-odd
mode analysis can be used to derive the proper three-port circuit to use to
create the ideal Wilkinson power divider. The results are shown below, in Figure
1.
For this project, Z0 is 50 Ω and f = 2.4 GHz. This results in the following group
of ideal
values at λ/4, presented in Table 1:

11. Calculation and Simulation
These values were used as the first-cut microstrip design in ADS . These
values were then
converted to microstrip line values using LINECALC. These resulting
microstrip widths and
lengths were used in generating the layout for the circuit. After several
rounds of tweaking
the circuit, the following schematic was generated.
1.Calculation of Width and Length of Microstrip
Based on the specification given in the problem statement, width and length of
the microstrip
lines are calculated. According to it –
Zo = 50 Ohm, Frequency, fo = 2.4 GHz
Substrate Permittivity, ɛ r = 3.38
Thickness of Substrate, d = 1.524 mm
Thickness of Conductor = 0.15 mm

12. ADS provides a LineCalc utility to calculate the width, w and length, l in mils according
to your specifications. Using LineCalc:
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
2.Schematic Design
Figure 2 : Simulation Circuit
This schematic was then converted into a layout, and the final layout is
presented below, in
Figure 3.

13. Figure 3 : Layout
Results
The circuit’s three main S-parameters were plotted S11 ,S12,S23 and S31.
These indicate
matching, power division, and port isolation, respectively.
m1
freq= 2.466GHz
dB(S(2,1))=-3.042
0
m1
-5
dB(S(3,1))
dB(S(2,1))
dB(S(1,1))
-10
-15
-20
-25
1.0 1.5 2.0 2.5 3.0 3.5 4.0
freq, GHz

14. Conclusion:
The schematic of equal split Wilkinson power divider was drawn and the layout
was generated.
The results of the project were in agreement to the theoretical available results
,so the various S parameters were plotted as shown above.