The use of multiple antennas at the transmitter and the receiver is considered for the uplink of cellular communication systems. The achievable spectral efficiency in bits/s/Hz is used as the criterion for comparing various design choices. The focus is on wideband code-division multiple-access (CDMA) systems when the receiver uses the matched-filter or the minimum mean-squared error detector, f...

The microstrip antennas have been one of the most innovative fields of antenna techniques for the last three decades. Microstrip antennas have several advantages such as lightweight, smallvolume, and that they can be made conformal to the host surface. In addition, these antennas are manufactured using printed-circuit technology, so that mass production can be achieved at a low cost. Microstrip...

In this thesis micromachined antennas suitable for on-chip integration with silicon based active devices are treated. The emphasis is put on compact 24 GHz antennas, capable of being integrated in commercial SiliconGermanium (SiGe) processes using low temperature post processing micromachining techniques. Antenna types covered are the slot loop antenna, wire loop antenna, meandered dipole and t...

The purpose of optical antennas is to convert the energy of free propagating radiation to localized energy, and vice versa. Although this is similar to what radio wave and microwave antennas do, optical antennas exploit the unique properties of metal nanostructures, which behave as strongly coupled plasmas at optical frequencies. It is hoped that optical antennas can increase the efficiency of ...

Several diversity techniques employing multiple antennas in the base station have been developed for mobile communication systems. However, the performance of diversity methods strongly depends on the correlation between antenna elements. When multiple co-polarized antennas are used in base station, the practical factor limiting the number of diversity branches is the required antenna separatio...

Microstrip fed inset patch antennas embedded in planar and cylindrically curved surfaces are introduced to be used in Body Area Networks (BANs) presented. These antennas are designed as wearable antennas for industrial, scientific and medical (ISM) band wireless communication networking. The proposed antennas consist of 50 Ω microstrip line feeding inset patch printed on the front face of diele...

Ultra−WideBand (UWB) technology was approved by the Federal Communications Commission (FCC) in February 2002 (FCC, 2002). According to the FCC regulations, the frequency band from 3.1 to 10.6 GHz can be used for short−range and high speed wireless communications systems. This recent allocation of a very wide spectrum of frequencies for the devices uses, with effective isotropic radiated power (...

The use of directional antennas in wireless ad hoc networks can significantly improve global performance due to a high spatial channel reuse. Nevertheless, its introduction poses new location dependent problems related to the MAC protocol. In this paper, the Balanced Incomplete Block Design theory has been exploited to develop a new MAC protocol for wireless ad hoc networks using directional ant...

A set of hybrid microstrip patch and semi-circular cavity antennas is introduced. The semi-circular cavity is implemented using Half-mode Substrate Integrated Waveguide (HMSIW) technique. Different shapes of patch include rectangular, semi-circular and equilateral triangular are excited using proximity effect by the circular SIW cavity at its TM010 mode of operation. The whole structures have b...

It is shown that the throughput capacity of wireless ad hoc networks using omni-directional antennas (OMN networks) is significantly decreased with the increased number of nodes. One major reason lies in the interference caused by using omni-directional antennas, which just broadcast radio signal in all directions. Thus, a communication with multiple short-ranged hops is suggested in such netwo...