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Ngày tải lên: 21/02/2014, 16:20

... the appendices. Chapter 2 provides an overview of wireless communication systems and their characteristics. 8 INTRODUCTION TABLE 1.4 Selected Applications of Microwave Solid-State Devices Devices Applications ... carry the video information as well. Table 1.1 shows the frequency bands used for commercial radio and television broadcasts. In the case of digital transmission, a standard monochrome television ... terrestrial communication system. Figures 1.3 and 1.4 list selected devices used at RF and microwave frequencies. Solid-state devices as well as vacuum tubes are used as active elements in RF and microwave...

Ngày tải lên: 15/12/2013, 11:15

... illustrated in Figure 2.7. A microwave signal generated by the oscillator is split into two parts via the power divider. The circulator feeds one part of this power to the antenna that illuminates a target ... Doppler frequency if the target is moving. Note that the signal travels twice over the same distance and, therefore, the Doppler frequency shift in this case will be twice that found via (2.4.33). Mathematically, o o  ... on-board electronics before transmitting it back. The gravitational force needs to be balanced somehow if this object is to stay in position. An orbital motion provides this balancing force. If a satellite...

Ngày tải lên: 15/12/2013, 11:15

... converted to corresponding impedance by moving to a point on the diametrically opposite side of the VSWR circle. It shows a normalized load impedance as 2  j2. Moving from this point by 3.15 l toward ... transformer is also presented along with a few examples to match resistive loads. Impedance measurement via the voltage standing wave ratio is then discussed. Finally, the Smith chart is introduced to ... Solutions to the transmission line equation are then constructed in order to understand the behavior of the propagating signal. This is followed by the concepts of sending end impedance, re¯ection...

Ngày tải lên: 15/12/2013, 11:15

... 3417,respectively. Substituting these into (4.5.5), Q of this cavity is found to be 2106. Circular Cylindrical Cavities Figure 4.20 shows the geometry of a circular cylindrical cavity of radius r and height h. It is ®lled ... CIRCUITS If the cavity is made of a perfect conductor and ®lled with a perfect dielectric then it will have in®nite Q. However,it is not possible in practice. In the case of cavity walls having a ®nite ... ac 3   m r e r r 4:5:2 Permittivity and permeability of the dielectric ®lling are given by e and m, respectively; o is angular frequency; and R s is the surface resistivity of walls which is related...

Ngày tải lên: 15/12/2013, 11:15

... re¯ection coef®cient of 0.2 is acceptable, circuits (iii) and (iv) can provide much wider bandwidth in comparison with those of the previous example. This concept can be used to shape the re¯ection coef®cient ... between them. This device can be inserted at a convenient point before the load. The impedance is matched by adjusting the lengths of the two stubs. Of course, it does not provide a universal solution. ... 36:6269 O ; C s  4:3453 pF and, X p  91:29009 O A C p  1:7434 pF Example 5.10: Reconsider the previous example where Y L  8 À j12 mS is to be matched with a 50-ohm line. Complete or verify the...

Ngày tải lên: 15/12/2013, 11:15

... characteristic impedance versus normalized length of the taper. This design can be achieved by moving the zeros at u Æ1 and Æ4 into the points Æ2 and Æ3, respectively. Hence, QuCu 2 À 2 2  2 u 2 À ... Hence, G in   L 0 dG in  1 2  L 0 e Àj2bz d dz ln  Zdz 6:7:3 Therefore, G in can be determined from (6.7.3) provided that  Zz is given. However, the synthesis problem is a bit complex because, in that case,  Zz ... meet such requirements. The chapter begins with the single-section impedance transformer that provides perfect matching at a single frequency. Matching bandwidth can be increased at the cost of...

Ngày tải lên: 15/12/2013, 11:15

... Z o2 Z 2  Z o2  b 2 a 2 7:6:22 Dividing (7.6.17) by a 1 and then using (7.6.21), we ®nd b 1 a 1  G 1  Z 1 À Z o1 Z 1  Z o1  S 11  S 12 a 2 a 1  7:6:23 Now, dividing (7.6.18) by a 2 and then ... jb, the network becomes lossless. In that case, S 11 S 12 S 21 S 22 !  0 e Àjb` e Àjb` 0 ! Obviously, it is a unitary matrix now. Example 7.19: Find scattering parameters of the two-port network ... illustration). 280 TWO-PORT NETWORKS Current through 0.1 S is I 1 À I N  0:0692V 1 . Using the current division rule, current I M through 0.2 S is found as follows: I M  0:2 0:2  0:025 0:0692V 1  0:0615V 1 A Hence,...

Ngày tải lên: 24/12/2013, 17:15

... devise some way to control its attenuation around the cutoff. Expression for the propagation constant of a T-section is listed in Table 8.1. In order to ®nd g of this T-section, we ®rst divide ... two-port network. Filters have been designed using active devices such as transistors and operational ampli®ers, as well as with only passive devices (inductors and capacitors only). Therefore, these ... the load and source resistances are at 75 O each. The low-pass ®lter designed in Example 8.7 provides the initial data for this high- pass ®lter. With m  3; g L  0:62425, and g C  0:9662, we...

Ngày tải lên: 24/12/2013, 17:15

... SIGNAL-FLOW GRAPH REPRESENTATION OF A PASSIVE SINGLE-PORT DEVICE Consider load impedance Z L as shown in Figure 9.18. It is a single-port device with port voltage and current V L and I L ,respectively. ...  Z S Z o  V ref S  E S À 1À Z S Z o  V in S or, V ref S  Z o Z o  Z S E S À Z o À Z S Z o  Z S V in S Dividing it by  2Z o p ,we ®nd that V ref S  2Z o p  Z o Z o  Z S E S  2Z o p À Z o À ...  Z L Z o  V ref L  Z L Z o À 1  V in L 9:3:1 or, V ref L  Z L À Z o Z L  Z o  V in L  À L V in L 9:3:2 After dividing it by  2Z o p ,we then use (7.6.15) and (7.6.16) to ®nd that b L  À L a L 9:3:3 where, b L  V ref L  2Z o p 9:3:4 a L  V in L  2Z o p 9:3:5 and, À L  Z L À...

Ngày tải lên: 24/12/2013, 17:15

... Since G o is approximately 14 dB, the remaining 2 dB can be set via G S and G L . If we design an input-matching network that provides G S as 1.22 dB then we need an output- matching network for ... values of load or source impedance) if one or both of these conditions are violated. It means that the transistor can provide stable operation for a restricted range of G S and G L . A simple procedure ... blocks of an electronic system. While vacuum tube devices are still used in high-power microwave circuits, transistorsÐ silicon bipolar junction devices, GaAs MESFET, heterojunction bipolar transistors (HBT),...

Ngày tải lên: 24/12/2013, 17:15

... nonlinear active device. In addition, since the device is producing RF power, it must have a negative resistance. The basic principle of an oscillator circuit can be explained via a linear feedback system ... the active device at the frequency of oscillation. These two conditions are complementary to each other; i.e., if condition (11.7.1) is satis®ed then (10.7.2) is also satis®ed, and vice versa. ... radians per second per volt. Mixer 1 Change of output phase equals change of input phase. Divider 1 N N is the division ratio. Phase detector K d K d is the slope of phase detector voltage to phase characteristic...

Ngày tải lên: 24/12/2013, 17:15

... 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),...

Ngày tải lên: 24/12/2013, 17:15

... 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...

Ngày tải lên: 24/12/2013, 17:15

... 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...

Ngày tải lên: 24/12/2013, 17:15

... 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...

Ngày tải lên: 24/12/2013, 17:15

Ngày tải lên: 24/12/2013, 17:15

Ngày tải lên: 21/01/2014, 23:20

Ngày tải lên: 21/01/2014, 23:20

Ngày tải lên: 21/01/2014, 23:20