“Transmitarrays, reflectarrays and Antenna Theory Course 12th May 2017 2 Outline 1. Introduction to Transmitarray and Reflectarray structures 2. Passive Transmitarrays 3. Passive

“Transmitarrays, reflectarrays and

phase shifters for wireless

communication systems”

Pablo Padilla de la Torre

Universidad de Granada

2 EI3204 Antenna Theory Course 12th May 2017

Outline

1. Introduction to Transmitarray and Reflectarray structures

2. Passive Transmitarrays

3. Passive Reflectarrays

4. Reconfigurability: Phase shifters

5. Reconfigurable devices: Example


1. Introduction to Transmitarray and Reflectarray structures


Txarray and Rxarray structures

Transmitarrays Equivalent to artificial lenses

Reflectarrays Equivalent to reflector-based antennas Reception and pattern rearrangement. Planar Architecture.

Fundamental Aim: Configure a new radiation pattern (passive devices). Reconfigure the radiation pattern (active devices). Different receivers for different signals, depending on DoA

Lens

Directions of arrival

Receiver 1

Receiver k

Lens

Directions of arrival

Receiver 1

Receiver k


Transmitarray concept:

2. Radiation pattern modification

Transmitarray structures

1. Phase error correction


Reflectarray concept:

1. Phase error correction 2. Radiation pattern modification

Reflectarray structures


Reflectarray Configuration:

Array distribution:

Without phase correction:

With phase correction:

Reflectarray structures


2. Passive Transmitarrays


Transmitarray configuration:

Passive Transmitarrays

Geometry Applied: Two different geometries analyzed and applied:

Design 1: Multilayer Planar Geometry

•Working frequency: 12 GHz.

•Band width: >0.7 GHz

•Linear polarization.

Particular Specifications:

Design 2: Planar Geometry with plane change


Design of one half of Transmitarray cell:

•Radiating element. •Stripline. •Coaxial to stripline transmission line.

Passive Transmitarray: Design 1

Transmitarray design:

Transmitarray Cell Design:

•5x5 element array.

•Array separation between elements: 0.8λ0.

•Radiation pattern reconfiguration: 10º tilt in one of the main axes.


Transmitarray configuration:


For measurements in the center of cell TRL calibration Kit

Design and Prototypes for Subsystems:

Phase delay line:

Prototype:

Measurement results:

•Coaxial to stripline transmission. •Stripline.

Half transmitarray cell prototype:

dB

Frequency (GHz) 9 10 11 12 13

0

-10

-20

-30

-40

dB

9 10 11 12 13 Frequency (GHz)

0

-10

-20

-30

-40



Design and Prototypes for Subsystems:

Delay line integration

•Coaxial to stripline transmission. •Stripline.

Transmission lines

Vias

Line detail

Complete soldered structure

Patch

array

Patch array integration

Feeding Horn and hanging elements Complete Prototype



Prototype Measurement

•Spherical acquisition chamber •Near field to far field conversion

Theoretical and measured radiation pattern

Phase error correction and 10º tilt in one axis.

Measured Gain: 15.4 dBi. Reduction due to spillover (accepted horn power 42%=-3.7 dB) and circuit losses (1.9dB).

Measuring scheme Copolar



Transmitarray design:

• 10x10 element array. • Stacked patches. • Array separation between

elements: 0.6λ0. • Radiation pattern

reconfiguration: 10º tilt in one of the main axes.


Transmitarray cell design:

Upper Patch

εr=2.17, h=1.575 mm

εr=1.07, h=2 mm

Lower Patch

εr=2.17, h=1.575 mm

Ground Plane

Upper Patch

εr=2.17, h=1.575 mm

εr=1.07, h=2 mm

Lower Patch

εr=2.17, h=1.575 mm

Ground Plane

14


Design of one half of Transmitarray cell: •Stacked patch Radiating element. •Coaxial to microstrip transmission line. •90º change in reference plane. •Microstrip lines


|S11|,

dB

Frequency (GHz)

Patch prototypes:

Prototypes of Subsystems :

Single patch measurement results:

Patch embedded in array:

90º Transition:

|S11|,

dB

Frequency (GHz)

Half transmitarray cell measurement:

Patch + 90º transition+ transmission line:

10 11 12 13 14

8 10 12 14 16

-10

-20

-30

-40

-50

0

-10

-20

-30

-40

-50

8 10 12 14 16

0

-10

-20

-30



Up

per

Lo

wer

Lay

er

• Two radiating interfaces. • 10x10 array. • 100 soldered

transmission lines • 200 metallic vias. • 50x50cm ground plane. • 800 soldering points.

Complete Prototype

Transmitarray assembly:

Patch layers

Lines soldering detail

Complete passive transmitarray for the second design

Delay line layers



Prototype Measurement:

Theoretical radiation pattern Measured Radiation pattern

For Design 2: Phase error correction and 10º tilt in one main axis

3D measured radiation pattern 2D measured radiation pattern

Measured Gain: 22.5 dBi. Reduction due to spillover (accepted horn power 75%=-1.25 dB) and transmission line losses (1.05 dB) •Spherical acquisition chamber

•Near field to far field conversion

-90 -80 -70 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90-40

-35

-30

-25

-20

-15

-10

-5

0

dB

Theta (deg)



3. Passive Reflectarrays


Reflectarray Configuration:

Circularly polarized Reflectarray: geometry:

Arr

ay d

istr

ibu

tio

n:

• 13x13 cell array. • Multilayered square patches. • Cell separation: 0.55λ0. • Re-alignement of the radiation pattern towards the broadside direction.

• ~70% of available power coming from the feeder (spillover efficiency).

Reflectarray specifications:

Parameter Value Units

Frequency bands 11.5-12.5 GHz

Polarization LHCP/RHCP - Axial ratio < 2.5 dB

3dB beamwidth 7 º Side lobe level < -16 dB

Cross polarization < -25 dB

Gain > 25.5 dBi Directivity 27 dBi Radiation efficiency > 65 %

VSWR 1.4:1 (-15.6dB) - Size (planar structure) 240x240x3.524 mm

Array separation 0.55λ mm

Focal distance 210 mm

Ground plane

Shifting circuit layer

Lower patchlayer

Upper patchlayerRxLHCP/RHCP

TxLHCP/RHCP

x

z

y

Passive Reflectarray


Subsystem prototypes: multilayered patches and phase shifters

Isolated cell: Embedded patch in array: Phase shifters:



Up

per

laye

r

low

er la

yer

Prototyping: Reflectarray assembly

Patch layers:

Complete assembled prototype:

Phase shifting layer:



Prototype Measurements: Radiation Patterns (at 12GHz):

3D Pattern: 2D Pattern:

Gain: 26.5 dBi directivity: 28.1 dBi

Efficiency: ~68%

-80 -60 -40 -20 0 20 40 60 80-40

-30

-20

-10

0

phase [º]

[dB

]

measured CP

simulated CP

measured XP

-80 -60 -40 -20 0 20 40 60 80-40

-30

-20

-10

0

phase [º]

[dB

]

measured CP

simulated CP

measured XP

φ=

0º

(x a

xis)

φ

=90º

(y

axi

s)



Prototype Measurements: Radiation Patterns (11.5-12-12.5 GHz):

Axial Ratio (steering direction):

Gain: 26.5 dBi directivity: 28.1 dBi

Efficiency: ~68%

φ=0º (x axis)

-80 -60 -40 -20 0 20 40 60 80-40

-30

-20

-10

0

phase [º]

[dB

]

12GHz

11.5GHz

12.5GHz

11,5 11,75 12 12,25 12,50

1

2

freq. [GHz]

[dB

]



4. Reconfigurability: Phase shifters


1- Mechanical variation: feeder movement

Towards reconfigurability

B- Electronically reconfigurable phase shifters:

Advantages: • Technologically feasible. • Discrete (bits) control.

Withdraws: • Costs.

• Number of elements. • Control circuit.

A- Electronically reconfigurable radiating elements:

Advantages: • Costs.

• Tinny space necessary.

Withdraws: • Control circuit.

• Crosspolar levels.

For reconfigurability:

2- Electronic variation: phase variation at the Txarray or Rxarray

Some disadvantages: • Reduced steering variation. • Mechanical controlling


A. Active radiating elements

Basic equivalent Circuit.

Active Patch Scheme: Expected Behavior:

Variation in patch equivalent impedance changes in working frequency changes in the phase behaviour of S parameters.

Patch with surface Varactor:


Two ways of defining simulations:

1- Complete Simulation with general purpose simulation SW: CST, HFSS, SEMCAD, etc.

2- Simulation with connection of a variety of S parameter boxes, for the different active patch elements.


Simulation Model:


Simulation results with CST:

1st Model (Complete model) With Cmin (0.13 pF)

2nd Model (Boxes model)

With Cmin (0.13 pF)

With Cmax (2.0 pF)

With Cmax (2.0 pF)



Circuit layout

Varactor

Choke Inductance

Decoupling capacitor

Patch Prototype:

x10

Some active patch details:

x6

•Patch over substrate with εr= 2.17. •Unions with conductive epoxy. •Varactors for microwave purpose.

Measurement Schemes:

Reflection scheme: •S11 •The phase behaviour is assumed to be twice the phase behaviour considered in a transmission scheme.

Transmission scheme: •S12

•The phase behaviour of the patch is directly the measured one.



Laboratory Measurements

Reflection model:

With Cmax

With Cmin

Transmission model:

With Cmax

With Cmin



Crosspolar Level:

With the reflection model up to 200º could be achieved in a ‘go and return scheme’ (100º for each way).

With the transmission model, the phase variation decreases (up to 80º, for one way).

To avoid polarization rotation or parasitic polarization (high crosspolar), the connection of the active circuitry is performed in the symmetry axes of the patch.

Symmetry line

Patch Feeding

Active Circuitry

Radiation pattern for 4.5v polarization voltage:

Phase Range:



Phase Shifter Scheme:

Subsystem 1: Directional coupler:

Subsystem 2: Reflective circuit:

00 )(/)( ZVjXZVjX

B. Active phase shifters

Directio

nal

Co

up

ler 3

dB

- 90

º

Input

Output

Directio

nal

Co

up

ler 3

dB

- 90

º

Input/Output

For Txarray:

For Rxarray:


Phase Shifter Design: initial element design

4 port 3dB/90º coupler: Reflective LC circuits:



P1 (in) P2 (out 90º)

P3 (out 180º)P4 (isolated)

P(in/out)

L

C

L

C

L

C

Hybrid couplerReflective circuit

Reflective circuitReflective circuit

way 1way 2way 3way 4


working scheme

For Linearly Polarized Rxarrays:


Phase Shifter Design: LP integrated design

Amplitude: Phase:


printed Lprinted L

printed Lvaractor

varactorvaractor

hybridcoupler

reflectivecircuits

reflectivecircuit

via transition groundplane

substrate

coaxial feeding port(input/output)

11 11.2 11.4 11.6 11.8 12 12.2 12.4 12.6 12.8 13

-600

-400

-200

0

200

Freq [GHz]

S11 [

deg]

0.13pF

0.23pF

0.39pF

0.65pF

0.82pF

1.16pF

1.51pF

2.2pF

11 11.2 11.4 11.6 11.8 12 12.2 12.4 12.6 12.8 13-5

-4

-3

-2

-1

0

Freq [GHz]

S11 [

dB

]

0.13pF

0.23pF

0.39pF

0.65pF

0.82pF

1.16pF

1.51pF

2.2pF



LP prototype manufacturing details




Amplitude: Phase:

11 11.2 11.4 11.6 11.8 12 12.2 12.4 12.6 12.8 13-5

-4

-3

-2

-1

0

Freq [GHz]

S11 [

dB

]

0v

2v

4v

6v

8v

10v

12v

14v

16v

11 11.2 11.4 11.6 11.8 12 12.2 12.4 12.6 12.8 13-600

-500

-400

-300

-200

-100

0

Freq [GHz]

S11 [

deg]

0v

2v

4v

6v

8v

10v

12v

14v

16v

Phase Shifter: LP integrated prototype




For Circularly Polarized Rxarrays:

PA(in/out)L

C

P4 P3 (180º)

P2 (90º)P1

L

C

Hybrid coupler 2AReflective

circuits

way 1way 2way 3way 4

L

C

L

C

Reflectivecircuit

P1

P4

Hybrid coupler 1

P2 (90º)

L

C

P1 P2 (90º)

P3 (180º)P4

L

C

Hybrid coupler 2BReflective

circuits

PB(in/out)

PA PB:

Reflectivecircuit

P3 (180º)


working scheme


Amplitude:

Phase:

11.5 12 12.5 13 13.5-1000

-800

-600

-400

-200

S12 [deg]

Freq [GHz]

0.13pF

0.23pF

0.39pF

0.65pF

0.82pF

1.16pF

1.51pF

2.2pF

460º

11.5 12 12.5 13 13.5-5

-4

-3

-2

-1

0

S12 [dB

]

Freq [GHz]

0.13pF

0.23pF

0.39pF

0.65pF

0.82pF

1.16pF

1.51pF

2.2pF


Phase Shifter Design: CP integrated design




CP prototype manufacturing details



Amplitude: Phase:

11.5 12 12.5 13 13.5-1000

-800

-600

-400

-200

S12 [deg]

Freq [GHz]

0v 2v 4v 6v 8v 10v 12v 14v 16v

370º

0 4 8 12 16-800

-650

-500

-350

S12 [

deg]

Volts

12.5 GHz

11.5 12 12.5 13 13.5-5

-4

-3

-2

-1

0

S12 [dB

]

Freq [GHz]

0v 2v 4v 6v 8v 10v 12v 14v 16v

Phase Shifter: CP integrated prototype




For Linearly Polarized Txarrays:


working scheme


Amplitude: |SX1| behaviour versus polarization voltage:

Structure replication up to

3 times

Phase response for edge values (mask)

Phase Shifter integrated design:





Prototype manufacturing details



Varactor

Inductive Line

Control circuit connection

Output Port

Input Port Coax. to microstrip transition

Z0Ω Transmission Line

Hybrid Circuit

Holes to Ground Plane

GND Connection

S21 Phase:


Phase Shifter measuring results:


Amplitude: |SX1| behaviour versus polarization voltage:


5. Example of reconfigurable device: Electronically Reconfigurable

Transmitarray


Electronically Reconfigurable Txarray

Transmitarray Scheme: Geometry Applied:

Patch grouping by means of bidirectional distribution networks.

•12 GHz, BW >0.7 GHz, LP

•Feeding corrugated horn

•6x6 element array. 0,7λ0 grid.

•360º range phase shifters.

•2x2 patch groups.

Constituting elements:

Stacked patches: Phase shifters:

Distribution networks: 90º transitions:


• Average insertion losses: 3.7 dB

• Average Phase Shift: 379º

• Control voltage range: 0V to16V

Towards the complete assembly

Phase Shifters Verification and Calibration:

Pattern modifications in one of the main axes: Plane φ=0º, θ=0º Plane φ=0º, θ=-10º



Shifters integration Integration in ground plane

• Two radiating interfaces. • 72 radiating elements. •18 distribution networks. • 9 complete phase shifters.

Complete Prototype:

Transmitarray assembly:

Patch layers

Radiating interface

Detail of inner zone Distribution networks

Transmitarray core

Complete electronically reconfigurable Txarray assembled




•Pattern 1: only phase error correction (all with 0V control voltage). •Pattern 2: phase error correction and reconfiguration of radiation pattern in one of the main axes, applying a 9 degrees tilt.


For prototype validation, two configurations:

Pattern 1: only phase error correction (all shifters with 0V control voltage).


Measured Gain: 16.05 dBi. Reduction due to spillover (accepted horn power 60%=-2.2 dB) and shifter insertion losses (3dB mean value in this configuration.




•Pattern 1: only phase error correction •Pattern 2: phase error correction and reconfiguration of radiation pattern in one of the main axes, 9 degrees tilt.


For prototype validation, two configurations :

Pattern 2: Phase error correction and 9º tilt in one main axis


Measured Gain: 15.1 dBi. Reduction due to spillover (accepted horn power 60%=-2.2 dB) and shifter insertion losses (4dB mean value in this configuration).



Thanks for your attention!

I. MIMO antenna

performance parameters

EI3204 Antenna Theory Course 8-10 May 2017

“Transmitarrays, reflectarrays and

phase shifters for wireless

communication systems”

Pablo Padilla de la Torre

Universidad de Granada

Documents

“Transmitarrays, reflectarrays and Antenna Theory Course 12th May 2017 2 Outline 1. Introduction to Transmitarray and Reflectarray structures 2. Passive Transmitarrays 3. Passive