4 research outputs found
Novel and Compact Reconfigurable Antennas for Future Wireless Applications
Get PDFPhDThe development of reconfigurable antennas is considered to be very promising in modern and future communication systems. Reconfigurable antennas
have made use of many reconfiguration techniques that are centred upon
switching mechanisms such as p-i-n diodes or MEMS. Other techniques such
as optical switches, mechanical structure changing or the ability to change
the permeability or permittivity of smart substrate materials have also been
used. Reconfigurable antennas have created new horizons for many types of
applications especially in Cognitive Radio, Multiple Input Multiple Output
Systems, personal communication systems, satellites and many other applications.
Cognitive Radio is one of the potential wireless applications that may
place severe demands on RF systems designers and particularly antenna
designers, when it comes to providing
exible radio front-ends capable of
achieving the set objectives of the technology. The aim of this work is to
investigate possible roles that different categories of reconfigurable antenna
can play in cognitive and smart radio. Hence, the research described in this
thesis focuses on investigating some novel methods to frequency-reconfigure
compact ultra-wideband antennas to work in different bands; this will offer
additional filtering to the radio front-end. In the ultra-wideband mode, the
antenna senses the spectrum for available bands with less congestion and
interference and hence decides on the most suitable part to be reconfigured
to, allowing reliable and efficient communication links between the radio
devices. Ultra-wideband antenna with reconfigurable integrated notch capability is also demonstrated to provide further enhancement to interference
rejection and improve the overall communication link. Furthermore, the design of novel pattern and polarisation reconfigurable antennas will be also
investigated to assist Cognitive Radio through spatial rather than frequency
means.
An ultimate target for this research is to combine different degrees of reconfiguration into one compact, state of the art antenna design that meets
the growing demand of cognitive and smart radio devices for more intelligent and multi-functional wireless devices within the personal area network
domains and beyond
Reconfigured and Notched Tapered Slot UWB Antenna for Cognitive Radio Applications
No full textA compact reconfigurable and notched ultra-wideband (UWB) tapered slot antenna (TSA) is presented. The antenna reconfiguration operation principle relies on 2 mechanisms: in the first mechanism a resonator parasitic microstrip line electrically coupled to the TSA is used to notch the TSA at a specific frequency and the second mechanism relies on changing the input impedance matching of the antenna by means of changing the length of a stub line extended from an additional tiny partial ground on the back side of the antenna. The reflection coefficient, radiation patterns, and gain simulations and measurements for the proposed antenna are presented to verify the design concepts featuring a very satisfactory performance. Total efficiency simulations and measurements are also presented to highlight the filtering performance of the reconfigured antenna. When the antenna was reconfigured from the UWB to work into multiple frequency bands, the radiation patterns were still the same and the total peak gain has slightly improved compared to the UWB case. In addition, when the antenna operated in the notched mode, the gain has significantly dropped at the notch frequency. The simplicity and flexibility of the proposed multimode antenna make it a good candidate for future cognitive radio front ends
