A discussion of minimum possible antenna quality factor ( ) is first presented in the paper. Based on the spherical wave function theory, the maximum possible ratios of gain to for both directional antenna and omnidirectional antenna are examined and new upper limits for both cases have been obtained. Universally applicable numerical results and some related discussions are also included in the...

The need of ultrawideband (UWB) antennas with omni-directional coverage is increasing for both military and commercial applications (Wiesbeck et. al., 2009; Minin, 2010). The UWB radio technology promises high resolution radar applications, sensor networks with a large number of sensors for industrial or home surveillance as well as high data-rate communication over short range for personal are...

This paper considers synthetic aperture radar and other synthetic aperture imaging systems in which a backscattered wave is measured from a variety of locations. The paper begins with a (linearized) mathematical model, based on the wave equation, that includes the effects of limited bandwidth and the antenna beam pattern. The model includes antennas with poor directionality, such as are needed ...

The IEEE 802.15.3 is an ad hoc MAC layer suitable for multimedia WPAN applications and a PHY capable of data rates in excess of 20 Mbps. In 2.4 GHz unlicensed band, IEEE 802.15.3 specifies data rates up to 55 MBPS. It basically employs an ad hoc PAN topology, with roles for “master” and “slave” devices.In this work, it needs to determine the delay in discovering the devices by Pico Net Controll...

Imaging radar has become a keen research topic in recent years. UWB technology provides many advantages to imaging radar such as fine resolution and high power efficiency. The performance of a UWB imaging radar can be further improved by applying polarimetric diversity. The polarimetric signature of objects can be used to enhance the quality of target recognition. Like any other wireless system...

This master thesis has focused on the aspect of UWB antenna design for the impulse based UWB radar which is built on CMOS technology. The design of new UWB antenna faces some challenges. The antenna should be compact, preferably conformal, low cost for manufacture, and have good electrical performance, such as good matching, directional radiation performance over a wide band, good time response...

We concentrate on an ad hoc network model with nodes on integer lattice points over a 2D plane. We examine the limits of ad hoc network performance for systems with antenna arrays capable of allowing both spatial multiplexing and directional processing. Two cases are considered. In the first case, we consider “perfect” directional antenna arrays, in other words, each node can form beams of infi...

Three types of printed radio-frequency-identification (RFID) antennas with the characteristics of high gain, wide beam wave, and omnidirectional beam wave are constructed and evaluated in this study. The objective is to find out their best reading rates for providing effective wireless communications among RFID antenna readers during the library book inventory process. Three kinds of antenna re...

This paper is an effective method to search or a quick scan the easy spot for directional antenna beams, and it is used for high speed data transmission in millimeter wave. The present paper proposes a method using the Fuzzy Logic control system for giving maximum data rate transfer using directional antenna[1]. The methods of transmission is using TDD, and it sends the control instructions of ...

We study the benefits of electronically-switched directional antennas in low-power wireless networks. This antenna technology may improve energy efficiency by increasing the communication range and by alleviating contention in directions other than the destination, but in principle requires a dedicated network stack. Unlike most existing works, we start by characterizing a real-world antenna pr...