7 research outputs found
A Novel Ancient Coin-Like Fractal Multiband Antenna for Wireless Applications
This study proposes a novel square-circle structure fractal multibroadband planar antenna, similar to an ancient Chinese coin-like structure, for second generation (2G), third generation (3G), fourth generation (4G), WLAN, and navigation wireless applications. The device is based on the principles and structural features of conventional monopole antenna elements, combined with the advantages of microstrip antennas and fractal geometry. A fractal method was presented for circular nested square slotted structures, similar to an ancient Chinese copper coin. The proposed antenna adapted five iterations on a fractal structure radiator, which covers more than ten mobile applications in three broad frequency bands with a bandwidth of 70% (1.43–2.97 GHz) for DCS1800, TD-SCDMA, WCDMA, CDMA2000, LTE33-41, Bluetooth, GPS (Global Positioning System), BDS (BeiDou Navigation Satellite System), GLONSS (Global Navigation Satellite System), GALILEO (Galileo Satellite Navigation System), and WLAN frequency bands, 16.32% (3.32–3.91 GHz) for LTE42, LTE43, and WiMAX frequency bands, and 10.92% (4.85–5.41 GHz) for WLAN frequency band. The proposed antenna was fabricated on a 1.6 mm thick G10/FR4 substrate with a dielectric constant of 4.4 and a size of 88.5 × 60 mm2. The measurement results reveal that the omnidirectional radiation patterns achieve a gain of 1.16–3.75 dBi and an efficiency of 40–72%. The good agreement between the measurement results and simulation validates the proposed design approach and satisfies the requirements for various wireless applications
Detection of active mobile phone in exam hall
The use of mobile phone as a cheating tool in the examination hall among students have considerably increased a burden to invigilators to ensure integrity in examination hall. Many active mobile phone detection schemes had been proposed as the solution to this problem. However, the detection system function in a small detection range of 1.5 to 2 meters from the detection circuit and does not distinguish various frequency bands of radio frequency signals. In order to have diverse range of RF mobile phone signals detection for alerting the invigilators of their specified monitoring region, antenna is proposed to be used. This is done by antenna design simulation using Computer Simulation Technology (CST) software. Two types of antenna; single-dipole antenna and multi-band dipole antenna are simulated to know the characteristics of VSWR, gain and total efficiency. From the simulation results, multi-band dipole antenna shows acceptable VSWR value which are approximate to 2 V, gain is equal to 2.85 dB and total efficiency is equal to 2.484 dB for 2.4 GHz signal. The results imply positive event that multi-band antenna can be a preferable tool in elaborating accurate RF signal detection of active mobile phone in examination hall
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
The Largest Unethical Medical Experiment in Human History
This monograph describes the largest unethical medical experiment in human history: the implementation and operation of non-ionizing non-visible EMF radiation (hereafter called wireless radiation) infrastructure for communications, surveillance, weaponry, and other applications. It is unethical because it violates the key ethical medical experiment requirement for “informed consent” by the overwhelming majority of the participants.
The monograph provides background on unethical medical research/experimentation, and frames the implementation of wireless radiation within that context. The monograph then identifies a wide spectrum of adverse effects of wireless radiation as reported in the premier biomedical literature for over seven decades. Even though many of these reported adverse effects are extremely severe, the true extent of their severity has been grossly underestimated.
Most of the reported laboratory experiments that produced these effects are not reflective of the real-life environment in which wireless radiation operates. Many experiments do not include pulsing and modulation of the carrier signal, and most do not account for synergistic effects of other toxic stimuli acting in concert with the wireless radiation. These two additions greatly exacerbate the severity of the adverse effects from wireless radiation, and their neglect in current (and past) experimentation results in substantial under-estimation of the breadth and severity of adverse effects to be expected in a real-life situation. This lack of credible safety testing, combined with depriving the public of the opportunity to provide informed consent, contextualizes the wireless radiation infrastructure operation as an unethical medical experiment