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Ultra-Wideband Radar Receivers
Published in James D. Taylor, Introduction to Ultra-Wideband Radar Systems, 2020
James D. Taylor, Elizabeth C. Kisenwether
For narrowband systems and receivers, the signal bandwidth is typically on the order of several kilohertz to tens of megahertz. These bandwidths are narrow enough that the signal components at the low frequency bound of the signal are not significantly distorted compared to the signal components at the upper frequency bound of the signal. Frequency-dependent dispersive effects are usually of little or no concern in narrowband receiver design, because the characteristics of receiver elements are essentially flat over small bandwidths. Additionally, if the absolute size of a relative bandwidth signal is small, then the frequency-dependent effects will not have as strong an influence on receiver design. The UWB signals, with wide relative bandwidths, present a different scenario; signal components at the low and high bounds of signal bandwidth will likely be processed with different fidelity, dispersion, and loss.
Temporal and spatial frequency domain representation. Interpretation of the temporal transform
Published in Edward J. Rothwell, Michael J. Cloud, Electromagnetics, 2018
Edward J. Rothwell, Michael J. Cloud
Time-harmonic electromagnetic waves have been studied in great detail. Narrowband waves are widely used for signal transmission, heating, power transfer, and radar. They share many of the properties of more general transient waves, and the discussions of § 2.10.1 are applicable. Here we shall investigate some of the unique properties of time-harmonic waves and introduce such fundamental quantities as wavelength, the phase and group velocities, and polarization.
Temporal and spatial frequency domain representation
Published in Edward J. Rothwell, Michael J. Cloud, Electromagnetics, 2018
Edward J. Rothwell, Michael J. Cloud
Time-harmonic electromagnetic waves have been studied in great detail. Narrowband waves are widely used for signal transmission, heating, power transfer, and radar. They share many of the properties of more general transient waves, and the discussions of § 2.10.1 are applicable. Here we shall investigate some of the unique properties of time-harmonic waves and introduce such fundamental quantities as wavelength, phase and group velocity, and polarization.
Compact ultrawideband filter with reconfigurable band notch characteristics
Published in International Journal of Electronics Letters, 2023
Dharmendra Kumar Jhariya, Akhilesh Mohan
Ultrawideband (UWB) technology attracted researchers from academia and industry due to its various salient features, such as low cost, compact size and high performance (Hsieh & Chang, 2003). An UWB bandpass filter (BPF) is an important component of an ultrawideband communication system. Several UWB filters using multimode resonator (Gao et al., 2006; Zhu et al., 2005), ring resonators (Ishida & Araki, 2004), stub loaded resonators (Chu et al., 2011; Han et al., 2009; Lin et al., 2014), multilayer aperture coupled patches (Abbosh, 2007), etc., have been reported in the literature. On the other hand, there exists some narrow band signals such as WiMAX (Worldwide Interoperability for Microwave Access), WLAN (Wireless Local Area Network), which may interfere with the FCC (Federal Communication commission) specified UWB spectrum. The interference from the narrow band signals may cause the signal distortion, which results in poor system performance. To overcome this problem, several single-band notched and multiple-band notched UWB filter are proposed in the literature (Chun et al., 2008; Song & Xue, 2010). For modern communication systems, tunable microwave filter with multi-functionality are required to effectively utilise the increasing crowded frequency spectrum. Recently, some attention has been paid to realise UWB filters with switchable or reconfigurable notch bands (Feng et al., 2015; Kurra et al., 2014; Quevedo-Teruel et al., 2013; Shaman & Hong, 2007; Thirumalaivasan & Nakkeeran, 2012; Wei et al., 2011). However, the size of these filters is quite large. Therefore, it is true challenge to design a compact filter with electronically switch ON/OFF a notch band that lies the frequency spectrum of UWB passband.
A Survey of National Disaster Communication Systems and Spectrum Allocation - an Indian Perspective
Published in IETE Technical Review, 2020
Shrayan Das, Kirtan Gopal Panda, Debarati Sen, Wasim Arif
Narrow-band technology mainly delivers voice and low-speed data communication services. Most of the present PPDR infrastructure in India supports narrow-band communication, along with occasional wide-band technologies in special scenarios. Narrow-band communication provides data rates of up to few tens of kilobytes per second, operating in frequency channels of up to 25 KHz [10]. TETRA, TETRAPOL [24] etc. are some of the commonly used narrow-band wide area coverage networks currently deployed in Europe. They are commonly referred to as professional or private mobile radio (PMR) and are also used in military communications besides PPDR applications.
Design and Implementation of an Enterprise Credit Risk Assessment Model Based on Improved Fuzzy Neural Network
Published in Applied Artificial Intelligence, 2023
Narrowband noise interference refers to the interference signal whose bandwidth is much smaller than the bandwidth of the target communication system. The transmission of corporate financial credit data has an inhibitory effect on narrowband interference.