Reconfigurable Antenna Systems Enrico Tolin

Supervisor: Prof.ssa Francesca Vipiana

Submitted and published works • E. Tolin, A. Bahr, M. Geissler and F. Vipiana, "Flexible and cost effective reconfigurable UHF RFID antenna system," 11th

European Conference on Antennas and Propagation (EUCAP), Paris 2017.

• E. Tolin, O. Litschke, S. Bruni and F. Vipiana, "Innovative Rotman lens setup for extended scan range array antennas," IEEE-

APS Topical Conference on Antennas and Propagation in Wireless Communications (IEEE APWC), Verona 2017.

• E. Tolin, O. Litschke and F. Vipiana, " Phase shifters design for Rotman lens based beamforming network scan range

extension ", 2018 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting,

Boston 2018.

• E. Tolin, O. Litschke, S. Bruni and F. Vipiana, "Flexible and cost effective reconfigurable UHF RFID antenna system," 11th

European Conference on Antennas and Propagation (EUCAP), London 2018.

• E. Tolin, O. Litschke, S. Bruni and F. Vipiana, “Extended scan range radar system based on Rotman lens,“ in preparation

List of attended classes • 01MMRRV – Tecniche numeriche avanzate per l'analisi ed il progetto di antenne (26/5/2017, 4 credits)

• 01QFFRV – Tecniche innovative per l'ottimizzazione (11/9/2017, 4 credits)

• 01QFDRV – Photonics: a key enabling technology for engineering applications (11/9/2017, 5 credits)

• 01RZTRV – Il criterio di responsabilità nella ricerca e nell'innovazione - l'impatto sulle sfide sociali

(24/5/2017, 4 credits)

• 01RZURV – Il criterio di responsabilità nella ricerca e nell'innovazione - Il ruolo dell'ICT nell'era di internet

(30/5/2017, 4 credits)

• 01QTXRV – BIO/CMOS interfaces and co-design (18/10/2017, 3 credits )

• 01QRNRV – Electromagnetic dosimetry in MRI: computational and experimental methods (9/11/2017, 4

credits)

• ESoA Course – RADAR 2020, FUTURE RADAR SYSTEMS (7/5/2018, 3 ECTS credits)

• The frequency and polarization agile RFID antenna presents a new method to apply the

reconfigurability concept to an antenna: in fact the tuning element is not inserted directly in

the antenna but instead it is used in the matching network. For changing the polarization

(V, H and ±45°), 3 different concepts of reconfigurable feeding network has been

designed, employing switchable delay and metamaterials lines. A very compact solution

using reconfigurable rat-race coupler has been developed.

• The extended scan range applied to the Rotman Lens as beamformer allow to double the

scan range of the Rotman Lens. For the investigated case of a ±30° Rotman Lens design

a dedicated phase management unit has been designed. A highly integrated solution

employing a novel switchable microstrip-to-slot coupled phase inverter (using 4 PIN diodes

for selecting the desired Electric field orientation).

Novel contributions

Addressed research questions/problems

• Polarization agility is also added, allowing the patch to radiate in horizontal, vertical and

the combination of these two polarization (i.e. +45° and -45°). This approach ensures

better performance in terms of Polarization Loss Factor (PLF) compared to standard

circular polarization approach.

• Rotman lenses are key devices in many phased array applications because of good

performance and relatively simple development and low cost fabrication. Anyway, its use in

applications like automotive radars is limited by the drawback of having poor

performance level at wide scan angles, which leads to a bulky and sub-optimal designs.

Therefore, an innovative phase management has been developed for doubling the scan

range of an antenna array fed by a Rotman lens. It combines two effects called Complete

Beam Shifting and Beam Mirroring.

• The phase management unit employ a progressive phase shift for moving all the beams

toward positive/negative scan angles (90° for the examined case), while the Beam

Mirroring introduces a shift on the opposite side of the scan range (in the basic unit cell

only 2 phase inversion are needed in the case of Rotman lens designed for ±30° scan).

By combining these 2 effects a doubling scan range can be obtained (approximately 60°).

Research context and motivation • Traditionally wireless systems are designed for single predefined operations. To overcome

from limitations due to the standard approach reconfigurable antennas and systems are

employed for increase performance and to change the intrinsic characteristic of the

antenna to adapt to a pre-determined operative state (frequency, pattern, polarization).

Adopted methodologies • Due to the heterogeneous nature of this topic, different methodologies were exploited for

designing the reconfigurable antenna systems. Moreover, an important part of the research

concerned the investigation of new technology for applying this techniques in an industrial

Future work • Final measurements on the RFID antenna, showing effective frequency reconfigurability

and selectable polarization.

• Application to the extending scan range method to a 77GHz array with the use of new

technologies like tunable materials, preferably using waveguide technology for minimizing

losses.

PhD program in

Electrical, Electronics and

Communications Engineering

XXXII Cycle

Rotman Lens

Antenna array

Phase Management

Array side

outputs φD

φB

φC

φD

φA 90° 180° 270° 360°

-90° 180° -270° 360°

0° 30° -30 60° 0° 30° -30°

Complete Beam

Shifting

Mirror

Beam Mirroring 60° 0° 30° -30° -60°

Fixed phase shifting superimposed to Rotman

Lens

Phase inversion applied at every second antenna

array input

Beam Shift

Special case of Rotman

Lens with max scan range

angle of ±30° allows a

compact and efficient

phase management unit

• A frequency reconfigurable RFID reader´s

antenna aim to unify the radiating element

that has to be used in Europe and USA area

has been designed. In particular the

reconfigurability concept is applied to the

matching network, by using a high power

CMOS switch, and taking advantage of wide

band radiation capability of patch antennas.

environment. In particular the combination of

circuit simulation and EM modeling was the key

element for the creation and verification of the

proposed solutions.

• The interaction between active components and

EM structures leads to an accurate modelling of

the switches and co-simulation of the complete

system with a full wave simulator.

Frequency Agility Polarization Agility

PIN Diodes

Pol V

Pol H

Input

Polarization control

Frequency control

-60° -30° 30° 60°

Extended Scan Range

• Reconfigurable antennas are important in industrial

application because they allow to achieve a better

integration, less costs and maximize connectivity.

• Automotive Radar technology is growing exponentially

in recent years, with great efforts for the development of

the Advanced Driver Assistant System (ADAS), following

the goal of fully automated driving by the year 2025.