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Design of Double-Layer Transmitarray Antenna based on 3D Printing Technology

Ahmed H. Abdelrahman and Hao Xin

Department of Electrical and Computer Engineering, University of Arizona, USA

Transmitarray antennas have received considerable attention in the area of high gain antennas. They

combine the advantages of the microstrip antenna arrays and the lens antennas, leading to the light weight

and low profile designs. A transmitarray antenna consists of multiple layers of planar array elements and

an illuminating feed source. The transmission phase of each element is designed independently to convert

the spherical phase front from the feed source into a planar phase front and focus the radiation beam with

a high gain. However, a full transmission phase range of 360° cannot be achieved by a single layer of

array elements, and therefore a design of multiple layers is required.

3D printing technology has recently attracted a growing interest in the microwave field as a novel

manufacturing technique. This technology allows the rapid prototyping of 3D arbitrary structures at low

cost. The goal of this work is to decrease the number of conductor layers using the 3D printing

technology, thereby reducing the complexity and cost of designing transmitarray antennas. The design

methodology is based on using two groups of unit cells. Each unit-cell group is composed of two layers

of printed elements separated by a dielectric material. The two groups have the same dielectric thickness

but different relative permittivities, such that the transmission coefficient phase range of each unit cell

group is different from the phase range of the other group. When combining the two phase ranges, a full

transmission coefficient phase range of 360° is obtained.

A polymer-jetting 3D printing technology will be used to fabricate the proposed transmitarray aperture,

which includes a mix of two different dielectric properties. As an example, Fig. 1 presents a parametric

analysis of the two double-layer unit cells using an arbitrary conductor element. The two unit cells have

the same substrate thicknesses equal to 0.4 wavelength, but different relative dielectric permittivity equal

to 1 and 2.8, respectively. It can be noticed that a full transmission phase range of 360° is achieved with

transmission magnitude better than -2 dB. These simulations were carried out using the commercial

software ANSYS HFSS.

Keywords: Transmitarray antenna, multilayer, transmission phase range, 3D printing.

(a) (b)

Fig. 1. Transmission coefficient versus element dimensions at 10 GHz, (a) magnitude, and (b) phase.

References: [1] A. H. Abdelrahman, A. Z. Elsherbeni, and F. Yang, “Transmission phase limit of multilayer frequency selective surfaces

for transmitarray designs,” IEEE Transactions on Antennas and Propagation, vol. 62, no. 2, pp. 690-697, February 2014.

[2] M. Liang, and H. Xin, "Three-dimensionally printed/additive manufactured antennas." In Handbook of Antenna

Technologies, pp. 1-30. Springer Singapore, 2015.

9 10 11 12-5

-4

-3

-2

-1

0

Element Dimensions (mm)

|S2

1| (d

B)

r = 1

r = 2.8

9 10 11 12-180

-90

0

90

180

Element Dimensions (mm)

S

21 (

degre

es)

r = 1

r = 2.8

Forum for Electromagnetic Research Methods and Applications Technologies (FERMAT)

*This use of this work is restricted solely for academic purposes. The author of this work owns the copyright and no reproduction in any form is permitted without written permission by the author. *

Ahmed H. Abdelrahman, (S’13–M’15) received the B.S. and M.S. degrees in Electrical

Engineering, Electronics and Communications from Ain Shams University, Cairo, Egypt, in

2001 and 2010, respectively. He received the Ph.D. degree in Engineering Sciences from The

University of Mississippi, University, MS, USA, in 2014. Dr. Abdelrahman is currently a

Postdoctoral Research Associate in The Electrical and Computer Engineering Department at

The University of Arizona, Tucson, AZ, USA. His research interests include

Transmitarray/Reflectarray Antennas, Mobile Antennas, 3D Printed Antennas, and

Thermoacoustic and Millimeter-Wave Imaging.

Dr. Abdelrahman has received several prestigious awards, including the third place winner

student paper competition award at the 2013 ACES annual conference, and the honorable mention student paper

competition at the 2014 IEEE AP-S International Symposium on Antennas and Propagation. Dr. Abdelrahman also

possess over eight years of experience in Satellite Communications industry. He worked as RF Design Engineer and

Communication System Engineer in building the low earth orbit satellite Egyptsat-1.

Dr. Hao Xin, Professor of Electrical and Computer Engineering at the University of Arizona. He

is named an Arizona Engineering fellow in Aug. 2013. He also serves as the inaugural director

of the Cognitive Sensing Center of the ECE department at the University of Arizona. He joined

University of Arizona since August 2005 as an assistant professor. He was promoted to tenured

associate professor in 2009 and to full professor in 2012. From 2000 to 2003, he was a research

scientist with the Rockwell Scientific Company. He was a Sr. Principal Multidisciplinary

Engineer with Raytheon Company from 2003 to 2005. He received his PhD in Physics from

Massachusetts Institute of Technology in February 2001. He obtained his BS degree in Physics

and Mathematics from University of Massachusetts Dartmouth in May 1995.

His primary research interests are in the area of microwave / millimeter wave / THz antennas, devices, circuits and

their applications in wireless communication and sensing systems. His recent research activities have covered a

broad range of high frequency technologies, including applications of new technologies and materials in microwave

and millimeter wave circuits such as electromagnetic band gap crystals and other meta-materials, carbon nano-tubes

devices, solid state devices and circuits, active or semi-active antennas, and passive circuits. He has authored over

260 referred publications and 14 patents (13 issued and 1 pending) in the areas of microwave and millimeter-wave

technologies, random power harvesting based on ferro-fluidic nano-particles and carbon nanotube based devices. He

is a senior member of IEEE and chair of the joint chapter of IEEE AP/MTT/EMC/COMM in Tucson AZ. He is a

general co-chair of the 8th International Workshop on Antenna Technology. He also serves as an associate editor

for IEEE Antennas and Wireless Propagation Letters. hxin@ece.arizona.edu 520-626-6941

1

Ahmed H. Abdelrahman and Hao XinDept. of Electrical and Computer Engineering, University of Arizona, Tucson, AZ, USA

Design of Double-Layer Transmitarray Antenna using 3D

Printing Technology

AP-S/URSI 2016

June 26 – July 1, 2016, Fajardo, Puerto Rico

Outline

2

• Introduction

•3D Printing Technology

•Multilayer FSS Transmitarray

•Proposed Transmitarray Antenna

•Conclusion

Outline

3

• Introduction

•3D Printing Technology

•Multilayer FSS Transmitarray

•Proposed Transmitarray Antenna

•Conclusion

Transmitarray Antennas

4

Microstrip Array Antenna

https://www.cst.com/Content/Articles/a

rticle915/ArrayPhoto.png

Lens antenna

http://www.rozendalassociates.com/pro

ducts/microwave-lens-antenna/

A. H. Abdelrahman et al, “Bandwidth improvement methods of transmitarray

antennas,” IEEE Trans. Ant. Prop., vol. 63, no. 7., pp. 2946-2954, July 2015

Transmitarray Antenna Transmitarray antennas combine

the favorable features of the optic

theory and array technique.

ADVANTAGES:

Low profile and light weight.

High radiation efficiency.

Flexible radiation performance.

Transmitarray antenna consists of:

o An illuminating feed source.

o A flat transmitting surface.

Description of Transmitarray Antenna

5

Transmission coefficient of each element is

individually designed.

It converts the spherical phase to a planar phase.

Required element phase range ~ 360°

𝝍𝒊 = 𝒌(𝑹𝒊 − 𝒓𝒊. ො𝒓𝒐) + 𝝍𝟎

𝝍𝒊: Transmission phase of ith element

k: Propagation constant

Ri: Distance from the feed to ith element

𝒓𝒊: Position vector of ith element

ො𝒓𝒐: Mean-beam unit vector

𝝍𝟎: Phase constant

Transmitarray Antenna vs. Lens Antenna

6

Low profile, light weight, and

low fabrication cost

Individual element control

provides versatile functionalities

Transmitarray has a relatively

narrow bandwidth

Transmitarray AntennaLens Antenna

Transmitarray vs. Reflectarray

7

Free from source blockage

More tolerant to fabrication

errors

Transmitarray requires more

volumetric space

Transmitarray Antenna

Reflectarray Antenna

Outline

8

• Introduction

•3D Printing Technology

•Multilayer FSS Transmitarray

•Proposed Transmitarray Antenna

•Conclusion

Polymer Jetting Rapid Prototyping

9

Resolution: 42 μm*42 μm* 16 μm

Fast fabrication of polymer components

with arbitrary shapes and complexity

Fused Deposition Modeling (FDM)

10

Potentially low cost

Convenient and faster fabrication process

Printed Precision = 0.4 mm

Fabrication of Metal

11

Ultrasonic / Thermal Wire Embedding

Embedded wires during the printing processUltrasonic wire embedding system

Smallest wire diameter = 50 μm

High Conductivity

Integration with FDM

Examples of 3D Printed Components

12

Luneburg Lens

THz waveguideTHz woodpile structure THz horn antenna

W-Band Reflectarrays

Examples of 3D Printed Components

13

Patch AntennaWilkinson Power Divider

Outline

14

• Introduction

•3D Printing Technology

•Multilayer FSS Transmitarray

•Proposed Transmitarray Antenna

•Conclusion

Overview of Multilayer FSS Transmitarray

15

30

210

60

240

90

270

120

300

150

330

180 0

Single layer with a conductor element

|S

21| vs. S

21

|S21

| = -1dB

|S21

| = -3dB

S21

=0S

21=90

S21

=27

S21

=45

A. H. Abdelrahman, A. Z. Elsherbeni, and F. Yang, “Transmission phase limit of multilayer frequency

selective surfaces for transmitarray designs,” IEEE Trans. Ant. Prop., vol. 62, no. 2, pp. 690-697, Feb. 2014.

Single Conductor Layer:

Phase range = 54° for |S21| < -1dB

Phase range = 90° for |S21| < -3dB

Double Conductor Layer:

Phase range = 170° for |S21| < -1dB

Phase range = 228.5° for |S21| < -3dB

Overview of Multilayer FSS Transmitarray

16

A. H. Abdelrahman, A. Z. Elsherbeni, and F. Yang, “Transmission phase limit of multilayer frequency

selective surfaces for transmitarray designs,” IEEE Trans. Ant. Prop., vol. 62, no. 2, pp. 690-697, Feb. 2014.

Triple Layer:

Phase range = 308° for |S21| < -1dB

Phase range = 360° for |S21| < -3dB

Quad Layer:

Phase range = 360° for |S21| < -1dB

Non-Identical Double Layer

17

Non-identical Layers:

Element shapes are different.

Element dimensions are different.

Non-identical double-Layer TA:

Two degrees of freedom.

Maximum phase range when the two

layers are identical.

Outline

18

• Introduction

•3D Printing Technology

•Multilayer FSS Transmitarray

•Proposed Transmitarray Antenna

•Conclusion

εr = 2.8

εr = 1

Proposed Double Layer Unit-Cell

19

(εr = 1) (εr = 2.8)

T = 12.17 mm at 10 GHz

Two-different double-layer unit-cells.

Unit-cells are different in substrate

permittivity.

Phase range = 360° for |S21| < -2dB.

Numerical Validation (Lossless Element)

20

(εr = 2.8)(εr = 1)

P = λ/2 = 15 mm, W = 0.5 mm, S = 1.75 mm

Both layers are identical

P = λ/2

L1

L2

W

W

S

Unit-Cell: Double Square Loop

Numerical Validation (Lossless Element)

21

HFSS Simulation Results

-180 -120 -60 0 60 120 180-20

-10

0

10

20

30

(degrees)

Gain

(dB

)

xz-plane

yz-plane

Transmitarray Modeling (Lossless Elements)

22

Circular aperture at 10 GHz

317 elements (Diameter = 315 mm = 10.5 λ0).

Focal length = 16 cm (F/D = 0.51).

Gain = 25 dB, SLL = -18.6 dB, BLL = -11.9 dB.

5 10 15 20

5

10

15

20

Permittivity Distribution

(εr = 2.8 & tanδ = 0.01)

Numerical Validation (Lossy Element)

23

P = λ/2 = 15 mm, W = 0.5 mm, S = 1.75 mm

Both layers are identical

P = λ/2

L1

L2

W

W

S

Unit-Cell: Double Square Loop(εr = 1)

Transmitarray Modeling (Lossy Elements)

24

Circular aperture at 10 GHz

317 elements (Diameter = 315 mm = 10.5 λ0).

Focal length = 16 cm (F/D = 0.51).

Gain = 24.8 dB, SLL = -18.7 dB, BLL = -12.5 dB.

-180 -120 -60 0 60 120 180-20

-10

0

10

20

30

(degrees)

Gain

(dB

)

xz-plane

yz-plane 5 10 15 20

5

10

15

20

Permittivity Distribution

Proposed 3D Printed Configuration

25

3D printed

3 Neighbor Elements

(εr = 2.8 & tanδ = 0.01)

0.5

1

30

210

60

240

90

270

120

300

150

330

180 0

HFSS

Analytical

(εr = 1)

3D Printed Unit-Cell

Outline

26

• Introduction

•3D Printing Technology

•Multilayer FSS Transmitarray

•Proposed Transmitarray Antenna

•Conclusion

3D Printing Technology.

Two Different Unit-Cell Structure.

Transmitarray Antenna Modeling.

Conclusion

27-180 -120 -60 0 60 120 180

-20

-10

0

10

20

30

(degrees)

Gain

(dB

)

xz-plane

yz-plane

28

Thank You