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

... various services such as voice mail, email, video, messaging, data, and computer on-line services. The direct link between satellites and personal communication systems can provide voice, video, ... Chapter 2 reviews some fundamental principles of transmission lines and electromagnetic waves. Chapter 3 gives a brief overview of how antennas and antenna arrays work. Chapter 4 provides a discussion FIGURE ... (DBS) systems have offered an alternative to cable television, and the end of the Cold War has made many military technologies available to civilian applications. The global positioning systems (GPSs),...

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

... axis. The Smith chart can be used to ®nd (1) G L from Z L and vice-versa; (2)  Z in from  Z L and vice-versa; (3) Z from Y and vice-versa; (4) the VSWR; and (5) d min and d max . The Smith ... normalized values. 2. Moving away from the load (i.e., toward the generator) corresponds to moving in a clockwise direction. 3. A complete revolution around the chart is made by moving a distance l ... degree of accuracy, by dividing P 2 by P 1 , ®nding the logarithm of the result, and multiplying it by 10. FIGURE 2.11 Transmission line connected to an open load. 28 REVIEW OF WAVES AND TRANSMISSION...

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

... or microwave power. It is a reciprocal device, and the same antenna can serve as a receiving or transmitting device. Antennas are structures that provide transitions between guided and free-space ... the HPBW and SLLs. Also shown is FNBW, the first-null beamwidth. 3.5.5 Directivity, Gain, and Efficiency The directivity D max is defined as the value of the directive gain in the direction of its maximum ... Þ¼ 1 2 Re½ ~ EE Â ~ HH*. The directivity of an isotropic antenna equals to 1 by definition, and that of other antennas will be greater than 1. Thus, the directivity serves as a figure of merit relating...

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

... capacitances. Active ﬁlters can be built by using active devices such as MESFETs in microwave frequencies and CMOS in RF. 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, on the other hand, are small, fast, and inexpensive. The ferrite devices do have some advantages ... the comparison between ferrite and p i n diode control devices [1]. It should be mentioned that the use of FETs or transistors as control devices could provide gain instead of loss. Switches are widely...

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

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

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

... the reference frequency can also be divided before it is connected to the phase detector. This scheme is shown in Fig. 6.20. A ﬁxed frequency divider with division ratio of N 2 is introduced between ... to heating of a solid-state device. Some of these characteristics can be found in an example given in Table 6.1. 6.2 TRANSMITTER NOISE Since the oscillator is a nonlinear device, the noise voltages ... high-Q circuits to build the oscillators (examples are waveguide cavities, dielectric resonators, or superconducting resonators=cavities); (2) temperature compensation circuits; or (3) phase-locked...