Novel Varactor-Loaded Phasing Line for Reflectarray Unit Cell with Large Reconfigurability Frequency Range - New Contributions in Information Systems and Technologies - page 2

Novel Varactor-Loaded Phasing Line for Reflectarray
Unit Cell with Large Reconfigurability Frequency Range

Sandra Costanzo, Francesca Venneri, Antonio Raffo,
Giuseppe Di Massa, and Pasquale Corsonello

DIMES - University of Calabria
87036 Rende (CS), Italy
[e-mail]

Abstract. A novel phasing line is proposed to improve the reconfigurability
frequency range of an aperture-coupled reflectarray unit cell. A couple of
broadband radial stubs loaded by a single varactor diode is adopted to realize
the dynamic phase shift mechanism, extending the unit cell beam-scanning
and/or reshaping pattern capabilities within a broader frequency range. The
radiating structure is properly optimized at 11.5 GHz, obtaining a full phase
tuning range within a very large frequency span of about 1.35 GHz.

Keywords: Reflectarray, reconfigurable antennas, radiocommunications.

1 Introduction

Reconfigurable antenna systems are gaining growing interest in last decades, as
they meet multi-functionality and flexibility demands of modern radio-
communications. They offer many advantages, such as: ability to support multiple
standards (UMTS, WiFi, WiMAX) and instantaneous adaptability to different
coverage requirements. A very interesting alternative to standard mechanically moved
reflectors or conventional phased arrays, usually adopted in spatial communications
or in radar applications, is given by reconfigurable reflectarray antennas. As a matter
of fact, they can be properly designed to dynamically change their radiation patterns
offering additional benefits, such as low profile and scalability. Unlike mechanically
scanned antennas, reconfigurable reflectarrays can move the radar beam almost
instantaneously, without time delays and vibration due to mechanical systems.
Furthermore, with respect to phased arrays they are characterized by higher
efficiencies and simpler architectures. Recently, many different active reflectarray
configurations have been presented, based on the use of tunable components or
materials, such as MEMS, PIN/varactor diodes and liquid crystal substrates [1]-[7]. A
very successful configuration has been proposed by the authors in [4], which consists
of an aperture-coupled patch integrated with a single varactor diode. By changing the
varactor bias voltage, the element reflection phase is properly tuned, thus providing a
dynamic control of the antenna radiation features. The proposed configuration has
been experimentally validated in [8], demonstrating very good beam scanning
capabilities and the possibility to dynamically reshape the radiated pattern within -25°