Radio frequency (RF) power amplifiers are used in everyday life for many applica- tions including cellular phones, magnetic resonance imaging, semiconductor wafer processing for chip manufacturing, etc. Therefore, the design and performance of RF amplifiers carry great importance for the proper functionality of these devices. Furthermore, several industrial and military applications require low-profile yet high-powered and efficient power amplifiers.
标签： Introduction Amplifier Design Power to RF
上传时间： 2020-05-27
上传用户：shancjb
With the rapid expansion of wireless consumer products,there has been a con- siderable increase in the need for radio-frequency (RF) planning, link plan- ning, and propagation modeling.A network designer with no RF background may find himself/herself designing a wireless network. A wide array of RF planning software packages can provide some support, but there is no substi- tute for a fundamental understanding of the propagation process and the lim- itations of the models employed. Blind use of computer-aided design (CAD) programs with no understanding of the physical fundamentals underlying the process can be a recipe for disaster. Having witnessed the results of this approach, I hope to spare others this frustration.
标签： Introduction Propagation to RF
上传时间： 2020-05-27
上传用户：shancjb
Nature is seldom kind. One of the most appealing uses for radio- telephone systems—communication with people on the move—must over- come radio transmission problems so difficult they challenge the imagina- tion. A microwave radio signal transmitted between a fixed base station and a moving vehicle in a typical urban environment exhibits extreme variations in both amplitude and apparent frequency.
标签： Communications Microwave Mobile
上传时间： 2020-05-28
上传用户：shancjb
Multi-carrier modulation‚ Orthogonal Frequency Division Multi- plexing (OFDM) particularly‚ has been successfully applied to a wide variety of digital communications applications over the past several years. Although OFDM has been chosen as the physical layer standard for a diversity of important systems‚ the theory‚ algorithms‚ and implementation techniques remain subjects of current interest. This is clear from the high volume of papers appearing in technical journals and conferences.
标签： COMMUNICATIONS MULTI-CARRIER DIGITAL
上传时间： 2020-05-31
上传用户：shancjb
his research aims at creating broadband tunable, fully integrated filters for the application of cognitive radio and signal classification receivers. The approach under study is the N-path filter technique which is capable of translating a baseband impedance to a reference frequency creating a tunable filter. The traditional N-path filter suffers from fundamental architectural limitations, namely : a trade-off between insertion loss and out-of-band rejection, reference clock feed- through, and jammer power handling limitations. In the first approach, the fundamental trade- off of the traditional N-path filter between insertion loss and out-of-band rejection is improved by a transmission line (T-line) N-path filter technique.
上传时间： 2020-05-31
上传用户：shancjb
All wireless communication standards, existing and under development, adopt or consider adopting orthogonal FREQUENCY-division multiplexing (OFDM) as the modulation technique. It is clear that OFDM has become the definitive modulation scheme in current and future wireless communication systems.
标签： Baseband Receiver Design OFDM
上传时间： 2020-05-31
上传用户：shancjb
Before delving into the details of orthogonal frequency division multiplexing (OFDM), relevant background material must be presented first. The purpose of this chapter is to provide the necessary building blocks for the development of OFDM principles. Included in this chapter are reviews of stochastic and random process, discrete-time signals and systems, and the Discrete Fourier Transform (DFT). Tooled with the necessary mathematical foundation, we proceed with an overview of digital communication systems and OFDM communication systems. We conclude the chapter with summaries of the OFDM wireless LAN standards currently in existence and a high-level comparison of single carrier systems versus OFDM.
上传时间： 2020-05-31
上传用户：shancjb
Emerging technologies such as WiFi and WiMAX are profoundly changing the landscape of wireless broadband. As we evolve into future generation wireless networks, a primary challenge is the support of high data rate, integrated multi- media type traffic over a unified platform. Due to its inherent advantages in high-speed communication, orthogonal frequency division multiplexing (OFDM) has become the modem of choice for a number of high profile wireless systems (e.g., DVB-T, WiFi, WiMAX, Ultra-wideband).
标签： OFDM-Based Broadband Networks Wireless
上传时间： 2020-05-31
上传用户：shancjb
Radio propagation measurements and channel modelling continue to be of fundamental importance to radio system design. As new technology enables dynamic spectrum access and higher data rates, radio propagation effects such as shadowing, the presence of multipath and frequency dispersion are the limiting factors in the design of wireless communication systems. While there are several books covering the topic of radio propagation in various frequency bands, there appears to be no books on radio propagation measurements, which this book addresses at length.
标签： Propagation Measurement Radio
上传时间： 2020-06-01
上传用户：shancjb
One of the prerequisites for the development of telecommunication services is the understanding of the propagation of the waves, either acoustic, electromagnetic, radio or light waves, which are used for the transmission of information. In this work, we shall limit ourselves to the study of radio waves: this term apply to the electromagnetic waves used in radio communications. Their frequency spectrum is very broad, and is divided into the following frequency bands : ELF waves (f < 3 kHz), VLF (3-30 kHz), LF waves (30-300 kHz), MF waves (300-3000 kHz), HF (3-30 MHz), VHF waves (30-300 MHz), UHF waves (300-3000 MHz), SHF waves (3-30 GHz), EHF waves (30-300 GHz) and sub- EHF waves (300-3000 GHz).
标签： Propagation Radio Wave
上传时间： 2020-06-01
上传用户：shancjb
