This report describes the design and simulation of a Wilkinson power divider. It begins with an ideal transmission line model and examines the reflection coefficient and power division. Microstrip implementations are then explored, with and without discontinuities. Adding resistors is shown to compensate for reflections at other ports. The report concludes by discussing further optimization of the microstrip design by adding curved sections and potential next steps of physically constructing the circuit.

1. Kaveh Dehno ELEC 453 project report
Wilkinson power divider 1
Table of Contents
OBJECTIVES ..................................................2
INTRODUCTION............................................2
WILKINSON POWER DIVIDER..........................2
IDEAL TRANSMISSION LINE............................2
MICROSTRIPS .................................................2
PRECEDURE AND RESULTS......................2
IDEAL DESIGN ................................................2
MICROSTRIP WITHOUT DISCONTINUITIES ......3
MICROSTRIPS WITH DISCONTINUITIES ...........4
CASE 5 IMPORTED DATA ................................5
DISCUSSION ...................................................5
CONCLUSION.................................................6
REFERENCES.................................................6
Table of figures
Figure 1: Wilkinson power divider [1].......................2
Figure 2: Ideal transmission line schematic...............2
Figure 3: Ideal transmission line reflection at port 1 .2
Figure 4: Reflection coefficient at all other ports ......2
Figure 5: Reflection coefficient at all other ports ......3
Figure 6: Microstrip design without discontinuities
schematic....................................................................3
Figure 7: Reflection of microstrip without
discontinuities at port 1 ..............................................3
Figure 8: Microstrip power division ..........................3
Figure 9: Microstrip without discontinuities reflection
at port 2 ......................................................................3
Figure 10: Microstrips with discontinuities schematic
....................................................................................4
Figure 11: Mircostrip with discontinuities reflection
at port 1 ......................................................................4
Figure 12: Microstrip with discontinuities power
division at port 1.........................................................4
Figure 13: Microstrip with discontinuities power
division from port 2....................................................4
Figure 14: Microstrip with discontinuity reflection at
port 2 ..........................................................................4
Figure 15: Case 5 and 6 schematic for importing data
....................................................................................5
Figure 16: Reflection coefficient for case 5...............5
Figure 17: Case 6 reflection coefficient.....................5
Figure 18: design with curves ....................................5
Figure 19: Design with curve reflection.....................5

2. Kaveh Dehno ELEC 453 project report
Wilkinson power divider 2
OBJECTIVES
• The be able to design a Wilkinson power
divider
• To practice the use of ADS program
• To examine the ideal and realistic design
differences
INTRODUCTION
Wilkinson power divider
Wilkinson power divider is a microwave circuit that
divides the power equally to matched loads and is
lossless. A picture of a Wilkinson power divider is
shown in Figure 1.
Figure 1: Wilkinson power divider [1]
Ideal Transmission line
Ideal transmission line is a representation of
transmission line without considering any losses due
to junctions and discontinuities.
Microstrips
Microstrips are a type of transmission lines that are
etched on dielectric materials. They occupy very little
space and are inexpensive to manufacture compared
with other types of transmission lines.
PRECEDURE AND RESULTS
Ideal design
At first an ideal transmission line simulation
was done to be able to see the behavior of the circuit.
The schematic of the ideal transmission line is shown
in Figure 2, the reflection coefficient at port 1 in
Error! Reference source not found. , the power
division from port 1 to all other ports in Figure 4.
Figure 2: Ideal transmission line schematic
Figure 3: Ideal transmission line reflection at port 1
The reflection coefficient at the desired frequency,
which is 5.8 GHz is about 31.0623e-6. This means
that almost no power is reflected if the input is port 1.
Figure 4: Reflection coefficient at all other ports
The power division simulation shows that the power
is equally divided between all ports, which is
0.25 = -6 dB. The reflection coefficient at all other
ports is shown in Figure 5.

3. Kaveh Dehno ELEC 453 project report
Wilkinson power divider 3
Figure 5: Reflection coefficient at all other ports
This graph shows that if the input is at ports other
than port 1, then there is some power reflected. To
compensate for this three resistors are added to the
design which is shown in the next step.
Microstrip without discontinuities
In this step the design was implemented
using microstrips. For this specific design RO3035
substrate was chosen from Roger Corporation. It has
a dielectric constant of 3.5 loss tangent of 0.0015, a
thickness of 0.13 mm, and the copper cladding is 0.35
um. The microstrip design is shown in Figure 6, and
the port 1 reflection coefficient in Figure 7.
Figure 6: Microstrip design without discontinuities
schematic
Figure 7: Reflection of microstrip without discontinuities at
port 1
The reflection coefficient at port 1 shows almost zero
reflection at port 1, which is what is expected. The
power division is shown in Figure 8.
Figure 8: Microstrip power division
The power division graph in Figure 8 shows that the
power division is close to the ideal case, but there is
0.5 power loss. This could be due to the loss in
junctions or the material. The reflection at port 2 is
shown in Figure 9.
Figure 9: Microstrip without discontinuities reflection at
port 2

4. Kaveh Dehno ELEC 453 project report
Wilkinson power divider 4
The reflection at port 2 shows that there is some
power reflected when the input is port 2. To
compensate for this issue, three resistors are added to
the design.
Microstrips with discontinuities
In this design the junctions are added to the
microstrip design as well as three resistors for
reflection at other ports. The schematic with
discontinuities id shown in Figure 10.
Figure 10: Microstrips with discontinuities schematic
The reflection coefficient at port 1 of this design is
shown in Figure 11. It shows that even having the
microstrips and junction, the reflection is very close
to zero at port 1.
Figure 11: Mircostrip with discontinuities reflection at port
1
Figure 12: Microstrip with discontinuities power division
at port 1
The power division from port 1 is shown in Figure
12. It shows that discontinuities do not have that
much effect on the power division and the power is
almost divided equally.
Figure 13: Microstrip with discontinuities power division
from port 2
The power division at port 2 in Figure 13 shows that
the power is divided evenly even if the input is port 2.
This is due to the addition of the resistors.
Figure 14: Microstrip with discontinuity reflection at port 2

5. Kaveh Dehno ELEC 453 project report
Wilkinson power divider 5
Figure 14 shows the reflection at port 2, which is
almost zero at 5.8 GHz. This is also due to the
addition of the three resistors to the design.
Case 5 imported data
The schematic of case 5 and 6 for importing s
parameters is shown in Figure 15.
Figure 15: Case 5 and 6 schematic for importing data
The reflection coefficient for case 5 is shown in
Figure 16.
Figure 16: Reflection coefficient for case 5
Figure 16 shows that because the loads in case 5 are
not matched to 50 ohms we have some reflection at
5.8 GHz.
The reflection coefficient for case 5 is shown in
Figure 17.
Figure 17: Case 6 reflection coefficient
Figure 17 shows that the reflection is slightly better
for case 6.
DISCUSSION
One can continue with the microstrip design
and add curves for a better realization. I did some
part of it, but left it unfinished du to lack of time. The
schematic with curves is shown in Figure 18 and the
reflection Figure 19.
Figure 18: design with curves
Figure 19: Design with curve reflection

6. Kaveh Dehno ELEC 453 project report
Wilkinson power divider 6
In addition, the same circuit can be designed only
with curves and be compared with respect of size and
reflection coefficient.
CONCLUSION
In conclusion, a Wilkinson power divider is
a circuit that divides the power equally and is lossless
and matched at all ports. There should be resistors
added to the circuit to make sure that the reflection at
all ports is zero independent of the input port. A
designer should take into account the discontinuities
and curve for the ultimate design. I wish we had the
time and ability to physically build and test the
circuit, because usually the result of simulations and
reality are a bit different.
References
[1] P. M, Microwave engineering, Wiley, 2011.