lò vi sóng electrolux emm1908w có tốt không
Tài liệu Lò vi sóng RF và hệ thống không dây P1 docx
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),...
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Tài liệu Lò vi sóng RF và hệ thống không dây P2 docx
Ngày tải lên :
24/12/2013, 17:15
... real axis.
The Smith chart can be used to đnd (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 chart ... 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
, đnding 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
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 ... ịẳ
1
2
Reẵ
~
EE
~
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
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...
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Tài liệu Lò vi sóng RF và hệ thống không dây P5 pdf
Ngày tải lên :
24/12/2013, 17:15
... 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
Ngày tải lên :
21/01/2014, 23:20
... 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 resona-
tors, or superconducting resonators=cavities); (2) temperature compensation circuits;
or (3) phase-locked...
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Tài liệu Lò vi sóng RF và hệ thống không dây P7 ppt
Ngày tải lên :
21/01/2014, 23:20
... receiving. A duplexer
is used to separate the transmitting and receiving signals. A circulator is shown in
Fig. 7.2 as a duplexer. A switch can also be used, since transmitting and receiving ... f
d
7:34ị
FIGURE 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 moving
toward radar.
7.7 FREQUENCY-MODULATED ... introduction and overview of radar systems are given.
7.2 RADAR EQUATION
The radar equation gives the range in terms of the characteristics of the transmitter,
receiver, antenna, target, and environment...
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Tài liệu Lò vi sóng RF và hệ thống không dây P8 ppt
Ngày tải lên :
21/01/2014, 23:20
... À1dB
Space loss
dB
Atmospheric loss À2dB
Polarization loss À1dB
Receiving feed loss À2dB
Receiving antenna gain 35 dB
Receiving antenna pointing error
ỵị 1dB
REFERENCES
1. E. A. Wolff and R. Kaul, ... picture of this vision [8]. The
WLAN is for wireless indoor radio communication services or high-data-rate
communications. The system employs a central microcell hub (base station) that
services cordless ... À1dB
Space loss
dB
Atmospheric loss À2dB
Polarization loss À0:5dB
Receiving feed loss 1dB
Receiving antenna gain 20 dB
Receiving antenna pointing error
ỵị 1dB
8.8 A microwave link is set up to...
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Tài liệu Lò vi sóng RF và hệ thống không dây P9 docx
Ngày tải lên :
21/01/2014, 23:20
... time-sharing transmission is called time division
multiplexing.
3. The message is represented by a coded group of digital pulses. The effects of
random noise can be virtually eliminated.
TABLE 9.1 Modulation ... Japanese
digital cellular time division multiple access (TDMA) radio standard; it has high
power efficiency and spectral efficiency. In power-efficient, nonlinearly amplified
(NLA) environments, where fully ... 2pf
m
tịt9:7ị
The maximum frequency swing occurs when sin 2pf
m
t ẳặ1. Here Df is the
frequency deviation, which is the maximum change in frequency the modulated
signal undergoes. The amplitude...
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Tài liệu Đã có cách làm brownie bằng lò vi sóng rồi đây! doc
Ngày tải lên :
21/01/2014, 00:20
...
Còn nếu không thích thì măm măm luôn thôi!
Đã có cách làm brownie bằng lò vi sóng rồi đây!
Một loại bánh với hương thơm thật quyến rũ của chocolate… và chỉ mất 6’ cho vi c
nướng...
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