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Tài liệu Lò vi sóng RF và hệ thống không dây P1 docx

... variousservices such as voice mail, email, video, messaging, data, and computer on-lineservices. The direct link between satellites and personal communication systems canprovide voice, video, ... Chapter 2 reviews some fundamentalprinciples of transmission lines and electromagnetic waves. Chapter 3 gives a briefoverview of how antennas and antenna arrays work. Chapter 4 provides a discussionFIGURE ... (DBS) systems have offered analternative to cable television, and the end of the Cold War has made many militarytechnologies available to civilian applications. The global positioning systems(GPSs),...

Tài liệu Lò vi sóng RF và hệ thống không dây P2 docx

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... real axis.The Smith chart can be used to đnd (1) GLfrom ZLand vice-versa; (2)ZinfromZLand vice-versa; (3) Z from Y and vice-versa; (4) the VSWR; and (5) dminanddmax. The Smith chart ... normalized values.2. Moving away from the load (i.e., toward the generator) corresponds tomoving in a clockwise direction.3. A complete revolution around the chart is made by moving a distancel ... degree ofaccuracy, by dividing P2by P1, đnding the logarithm of the result, and multiplying itby 10.FIGURE 2.11 Transmission line connected to an open load.28REVIEW OF WAVES AND TRANSMISSION...

Tài liệu Lò vi sóng RF và hệ thống không dây P3 pptx

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... or microwave power.It is a reciprocal device, and the same antenna can serve as a receiving ortransmitting device. Antennas are structures that provide transitions betweenguided and free-space ... the HPBWand SLLs. Also shown is FNBW, the ﬁrst-null beamwidth.3.5.5 Directivity, Gain, and EfﬁciencyThe directivity Dmaxis deﬁned as the value of the directive gain in the direction of itsmaximum ... ịẳ12Reẵ~EE ~HH*.The directivity of an isotropic antenna equals to 1 by deﬁnition, and that of otherantennas will be greater than 1. Thus, the directivity serves as a ﬁgure of meritrelating...

Tài liệu Lò vi sóng RF và hệ thống không dây P4 ppt

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... capacitances. Active ﬁlters can be builtby using active devices such as MESFETs in microwave frequencies and CMOS inRF. The active devices provide negative resistance and compensate for the losses ... biasing ﬁeld.Ferrite control devices are heavy, slow, and expensive. Solid-state control devices, onthe other hand, are small, fast, and inexpensive. The ferrite devices do have someadvantages ... thecomparison between ferrite and pi n diode control devices [1]. It should bementioned that the use of FETs or transistors as control devices could provide gaininstead of loss.Switches are widely...

Tài liệu Lò vi sóng RF và hệ thống không dây P5 pdf

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... dBmFIGURE 5.13 Third-order intermodulation.164RECEIVER SYSTEM PARAMETERS 2. Selectivity. Receiver selectivity is the ability to reject unwanted signals onadjacent channel frequencies. This ... sensitivity of the receiver. In order for a signal to be detected, it should havea strength much greater than the noise ﬂoor of the system. Noise sources inthermionic and solid-state devices ... the equivalent noisetemperature in kelvin, (d) the minimum detectable signal (MDS) in dBm atinput port, and (e) the input IP3 power level in dBm. The individualcomponent system parameters are...

Tài liệu Lò vi sóng RF và hệ thống không dây P6 ppt

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... the reference frequency can also be divided before it is connected to thephase detector. This scheme is shown in Fig. 6.20. A ﬁxed frequency divider withdivision ratio of N2is introduced between ... toheating of a solid-state device.Some of these characteristics can be found in an example given in Table 6.1.6.2 TRANSMITTER NOISESince the oscillator is a nonlinear device, the noise voltages ... high-Qcircuits to build the oscillators (examples are waveguide cavities, dielectric resona-tors, or superconducting resonators=cavities); (2) temperature compensation circuits;or (3) phase-locked...

Tài liệu Lò vi sóng RF và hệ thống không dây P7 ppt

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... receiving. A duplexeris used to separate the transmitting and receiving signals. A circulator is shown inFig. 7.2 as a duplexer. A switch can also be used, since transmitting and receiving ... fd7:34ịFIGURE 7.17 Waveform for a moving target: (a) stationary target waveform for compar-ison; (b) waveform for a target moving toward radar; (c) beat signal from a target movingtoward radar.7.7 FREQUENCY-MODULATED ... introduction and overview of radar systems are given.7.2 RADAR EQUATIONThe radar equation gives the range in terms of the characteristics of the transmitter,receiver, antenna, target, and environment...

Tài liệu Lò vi sóng RF và hệ thống không dây P8 ppt

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... À1dBSpace lossdBAtmospheric loss À2dBPolarization loss À1dBReceiving feed loss À2dBReceiving antenna gain 35 dBReceiving antenna pointing errorỵị 1dBREFERENCES1. E. A. Wolff and R. Kaul, ... picture of this vision [8]. TheWLAN is for wireless indoor radio communication services or high-data-ratecommunications. The system employs a central microcell hub (base station) thatservices cordless ... À1dBSpace lossdBAtmospheric loss À2dBPolarization loss À0:5dBReceiving feed loss 1dBReceiving antenna gain 20 dBReceiving antenna pointing errorỵị 1dB8.8 A microwave link is set up to...

Tài liệu Lò vi sóng RF và hệ thống không dây P9 docx

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... time-sharing transmission is called time divisionmultiplexing.3. The message is represented by a coded group of digital pulses. The effects ofrandom noise can be virtually eliminated.TABLE 9.1 Modulation ... Japanesedigital cellular time division multiple access (TDMA) radio standard; it has highpower efﬁciency and spectral efﬁciency. In power-efﬁcient, nonlinearly ampliﬁed(NLA) environments, where fully ... 2pfmtịt9:7ịThe maximum frequency swing occurs when sin 2pfmt ẳặ1. Here Df is thefrequency deviation, which is the maximum change in frequency the modulatedsignal undergoes. The amplitude...