307 research outputs found
Analysis and Life Cycle Assessment of Printed Antennas for Sustainable Wireless Systems
Siirretty Doriast
Reconfigurable Antennas
In this new book, we present a collection of the advanced developments in reconfigurable antennas and metasurfaces. It begins with a review of reconfigurability technologies, and proceeds to the presentation of a series of reconfigurable antennas, UWB MIMO antennas and reconfigurable arrays. Then, reconfigurable metasurfaces are introduced and the latest advances are presented and discussed
A 2.4 GHz CMOS class-F power amplifier with reconfigurable load-impedance matching
© 2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.A novel reconfigurable CMOS class-F power amplifier (PA) at 2.4 GHz is proposed in this paper. It is able to match the output load variations mainly due to the effect of hand and head on a mobile phone. The effect of load variation on power-added efficiency (PAE), output power, and distortion is compensated by reconfiguring the output network using an impedance tuner. The tuner controls the output matching at fundamental frequency without affecting the class-F harmonic tuning up to 3rd harmonic. To the best of our knowledge, this is the first design of a CMOS class-F PA addressed to compensate the effect of load variation. Measurement results for 50 ohm load impedance show a maximum PAE of 26% and maximum output power of 19.2 dBm. The measured total harmonic distortion is 4.9%. Measurement results for load values other than 50 ohm show that PAE increases from 6.5% (not-tuned PA) up to 19.9% (tuned PA) with the same output power (19.2 dBm). Tuning also reduces the adjacent-channel leakage ratio by 5 dB and the spectral regrowth of a Wi-Fi signal at the PA output. The size of the fabricated chip is 1.6 mm × 1.6 mm.Peer ReviewedPostprint (author's final draft
Passive Planar Microwave Devices
The aim of this book is to highlight some recent advances in microwave planar devices. The development of planar technologies still generates great interest because of their many applications in fields as diverse as wireless communications, medical instrumentation, remote sensing, etc. In this book, particular interest has been focused on an electronically controllable phase shifter, wireless sensing, a multiband textile antenna, a MIMO antenna in microstrip technology, a miniaturized spoof plasmonic antipodal Vivaldi antenna, a dual-band balanced bandpass filter, glide-symmetric structures, a transparent multiband antenna for vehicle communications, a multilayer bandpass filter with high selectivity, microwave planar cutoff probes, and a wideband transition from microstrip to ridge empty substrate integrated waveguide
Autonomous smart antenna systems for future mobile devices
Along with the current trend of wireless technology innovation, wideband, compact size,
low-profile, lightweight and multiple functional antenna and array designs are becoming more
attractive in many applications. Conventional wireless systems utilise omni-directional or
sectored antenna systems. The disadvantage of such antenna systems is that the
electromagnetic energy, required by a particular user located in a certain direction, is radiated
unnecessarily in every direction within the entire cell, hence causing interference to other
users in the system. In order to limit this source of interference and direct the energy to the
desired user, smart antenna systems have been investigated and developed. This thesis
presents the design, simulation, fabrication and full implementation of a novel smart antenna
system for future mobile applications.
The design and characterisation of a novel antenna structure and four-element liner array
geometry for smart antenna systems are proposed in the first stage of this study. Firstly, a
miniaturised microstrip-fed planar monopole antenna with Archimedean spiral slots to cover
WiFi/Bluetooth and LTE mobile applications has been demonstrated. The fundamental
structure of the proposed antenna element is a circular patch, which operates in high
frequency range, for the purpose of miniaturising the circuit dimension. In order to achieve a
multi-band performance, Archimedean spiral slots, acting as resonance paths, have been
etched on the circular patch antenna. Different shapes of Archimedean spiral slots have been
investigated and compared. The miniaturised and optimised antenna achieves a bandwidth of
2.2GHz to 2.9GHz covering WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile standards.
Then a four-element linear antenna array geometry utilising the planar monopole elements
with Archimedean spiral slots has been described. All the relevant parameters have been
studied and evaluated. Different phase shifts are excited for the array elements, and the main
beam scanning range has been simulated and analysed.
The second stage of the study presents several feeding network structures, which control
the amplitude and phase excitations of the smart antenna elements. Research begins with the
basic Wilkinson power divider configuration. Then this thesis presents a compact feeding
network for circular antenna array, reconfigurable feeding networks for tuning the operating
frequency and polarisations, a feeding network on high resistivity silicon (HRS), and an ultrawide-band
(UWB) feeding network covering from 0.5GHz to 10GHz. The UWB feeding
network is used to establish the smart antenna array system.
Different topologies of phase shifters are discussed in the third stage, including ferrite
phase shifters and planar phase shifters using switched delay line and loaded transmission line
technologies. Diodes, FETs, MMIC and MEMS are integrated into different configurations.
Based on the comparison, a low loss and high accurate Hittite MMIC analogue phase shifter
has been selected and fully evaluated for this implementation. For the purpose of impedance
matching and field matching, compact and ultra wideband CPW-to-Microstrip transitions are
utilised between the phase shifters, feeding network and antenna elements. Finally, the fully
integrated smart antenna array achieves a 10dB reflection coefficient from 2.25GHz to
2.8GHz, which covers WiFi/Bluetooth (2.45GHz) and LTE (2.6GHz) mobile applications. By
appropriately controlling the voltage on the phase shifters, the main beam of the antenna array
is steered ±50° and ±52°, for 2.45GHz and 2.6GHz, respectively. Furthermore, the smart
antenna array demonstrates a gain of 8.5dBi with 40° 3dB bandwidth in broadside direction,
and has more than 10dB side lobe level suppression across the scan.
The final stage of the study investigates hardware and software automatic control systems
for the smart antenna array. Two microcontrollers PIC18F4550 and LPC1768 are utilised to
build the control PCBs. Using the graphical user interfaces provided in this thesis, it is able to
configure the beam steering of the smart antenna array, which allows the user to analyse and
optimise the signal strength of the received WiFi signals around the mobile device.
The design strategies proposed in this thesis contribute to the realisation of adaptable and
autonomous smart phone systems
Design of a planar wideband patch antenna for UHF RFID tag
In this article, a planar wideband microstrip patch antenna for ultrahigh frequency (UHF) radio identification (RFID) tag is presented. By incorporating two resonating C-shape patches, two resonances are excited close to each other to create wide impedance bandwidth to cover the entire operating frequency of UHF RFID system between 860 and 960 MHz for universal mental mountable tag. For complex impedance matching between the antenna input terminal and the references microchip whose impedance is Zchip = (31-j212) Ω, a small rectangular loop feed structure was utilized where both of the resonating patches are magnetically coupled. The antenna design and simulation were carried out using finite element method based software, Ansoft HFSS v13. The simulated and measured radiation patterns at operating frequency of 915 MHz are in good agreement. the simulated and measured impedance bandwidth (Return Loss >_3 dB) of 159 and 155 MHz were obtained that are well above the required 100 MHz bandwidth
Antenna Designs for 5G/IoT and Space Applications
This book is intended to shed some light on recent advances in antenna design for these new emerging applications and identify further research areas in this exciting field of communications technologies. Considering the specificity of the operational environment, e.g., huge distance, moving support (satellite), huge temperature drift, small dimension with respect to the distance, etc, antennas, are the fundamental device allowing to maintain a constant interoperability between ground station and satellite, or different satellites. High gain, stable (in temperature, and time) performances, long lifecycle are some of the requirements that necessitates special attention with respect to standard designs. The chapters of this book discuss various aspects of the above-mentioned list presenting the view of the authors. Some of the contributors are working strictly in the field (space), so they have a very targeted view on the subjects, while others with a more academic background, proposes futuristic solutions. We hope that interested reader, will find a fertile source of information, that combined with their interest/background will allow efficiently exploiting the combination of these two perspectives
RECONFIGURABLE POWER AMPLIFIER WITH TUNABLE INTERSTAGE MATCHING NETWORK USING GaAs MMIC AND SURFACE-MOUNT TECHNOLOGY
As the demand of reconfigurable devices increases, the possibility of
exploiting the interstage matching network in a two-stage amplifier to provide center
frequency tuning capability is explored. While placement of tuning elements at the
input and/or output matching network has some disadvantages, placement of tuning
elements in the interstage absorbs the lossy components characteristics into useful
attributes. The circuit design methodology includes graphical method to determine
the bandpass topology that achieves high Q-contour on the Smith chart thus result in
narrow bandwidth. T-section and π-section topologies are used to match reactive
terminations provided by the first and second amplifier stages. The design
methodology also includes utilization of interstage mismatch loss that decreases as
increasing frequency to compensate for amplifier gain roll-off and equalize the gain
at different tuning states.
In prototype realization, three design configurations are discussed in this
thesis: 1) a discrete design for operation between 0.1 – 0.9 GHz with the total layout
area of 7.5 mm x 12.5 mm, 2) a partial monolithic design (Quasi-MMIC) for
operation between 0.9 – 2.4 GHz that is 25 times smaller layout area compared to the
discrete design, and 3) a conceptual design of integrated monolithic reconfigurable
PA for operation between 0.9 – 2.4 GHz that is 130 times smaller layout area
compared to the discrete design. One variant of the fabricated reconfigurable PA
offers advantage of 4-states center frequency tuning from 1.37 GHz to 1.95 GHz
with gain of 21.5 dB (+ 0.7 dB).
The feasibility of interstage matching network as tuning elements in
reconfigurable power amplifier has been explored. The input and output matching
networks are fixed while the interstage impedances are varied using electronic
switching (discrete SP4T and GaAs FET switches). The discrete design is suited for
the operation at low frequency (fo < 1GHz), while monolithic implementation of the
tunable interstage matching network is required for higher frequency operation due
to size limitation and parasitic effects. The reconfigurable PA using MMIC tuner was
designed at higher frequency to possibly cover GSM, CDMA, Bluetooth, and
WiMAX frequency (0.9 – 2.4 GHz)
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