With the advent of new high data rate wireless applications, as well as growth of existing wireless services, demand for additional bandwidth is rapidly increasing. Existing spectrum allocation policies of the Federal Communications Commission (FCC) prohibits unlicensed access to licensed spectrum, constraining them instead to several heavily populated, interference-prone frequency bands, which...

Sensor arrays have been used widely in applications including radar, sonar, seismology, biomedicine, communications, geophysical exploration, astronomy, and imaging. A very popular type of sensor array is circular array. It has several advantages such as the fact that it can perform 360 scan around its center very conveniently and during the scan the array pattern can be kept almost invariant. ...

Compressed sensing (CS) has been receiving a lot of interest because it provides possibilities to reconstruct signals or images from significantly fewer samples than were traditionally thought necessary. In this paper, we apply this technique to circular SAR (CSAR) and use wavelet transform matrix to improve efficiency and accuracy. The method is demonstrated with simulations. It is well known ...

A new type of cascaded series feed beamforming networks (BFNs) is introduced. The network architecture is based on a dualseries Nolen matrix topology. It is able to produce tapered output amplitude distributions from N × N configurations. The general concept, analysis and systematic design of the BFNs are given. The networks are designed and intended to be used mainly for low Sidelobe Level (SL...

This paper deals with diagonal variable loading recursive least squares (VLRLS) array beamforming based on a generalized sidelobe canceller. In conjunction with a subweight partition approach, the VLRLS-based beamformer demonstrates the advantages of fast convergence speed, insensitivity to dynamic estimate modeling error, less computational load, and more robust to against pointing errors and ...

Ultrasound imaging is an important diagnostic tool in clinical medicine. It displays images in real time and is considered safe, noninvasive and less costly than other cross-sectional imaging modalities, e.g., X-ray CT, MRI and PET. In modern ultrasound machines, digital beamforming (focusing) is widely used. It is essential for attaining good image quality by increasing signal-tonoise ratio (S...

For hands-free acoustical human/machine interfaces, e. g. for automatic speech recognition or teleconferencing systems, microphone arrays using robust Generalized Sidelobe Cancellers (GSCs) in conjunction with acoustic echo cancellation (AEC) can be efficiently applied for optimum communication. This contribution devises a new structure for combining AEC and GSC. It reduces the computational co...

Abstract— One of the important applications of Radar is to track and search the target in interfering environment. Which requires design of an array antenna with the most important property is, the ability to form precisely located deep pattern null for angle tracking. In this paper an attempt is made to analyze difference patterns for some of the odd symmetric excitation amplitude functions. T...

Recently, millimeter wave applications are rapidly growing in modern high-speed and broadband wireless systems such as uncompressed HD-TV transmission, home link and radar for the collision prevention. In this paper, a NRD guide [1] fed dielectric lens antenna with high gain and low sidelobe characteristics is proposed for millimeter wave applications. The proposed antenna is designed on the ba...