lò vi sóng rf
Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P1)
Ngày tải lên :
24/10/2013, 16:15
... spectrum is the visible optical spectrum,
the ultraviolet spectrum, and x-rays. Below the microwave frequency spectrum is
the radio frequency (RF) spectrum. The frequency boundary between RF and mi-
crowaves ... that specific frequency range. Therefore, by extension, the
RF/ microwave applications can be referred to as communications, radar, navigation,
radio astronomy, sensing, medical instrumentation, ... some of these frequency spectrums are further divided into
many frequency bands as indicated in Figure 1.1.
Filters play important roles in many RF/ microwave applications. They are used to
separate...
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Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P2)
Ngày tải lên :
24/10/2013, 16:15
... halves with respect to its symmetrical interface.
When an even excitation is applied to the network, as indicated in Figure 2.4(a), the
symmetrical interface is open-circuited, and the two network ... building elements in many areas of RF/ microwave en-
gineering. Such networks are used to select/reject or separate/combine signals at
different frequencies in a host of RF/ microwave systems and equipment. ... chapter to describe various network concepts and provide
equations that are useful for the analysis of filter networks.
2.1 NETWORK VARIABLES
Most RF/ microwave filters and filter components can be...
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Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P3)
Ngày tải lên :
28/10/2013, 23:15
... the same 3 pole
Butterworth lowpass prototype as that used previously in Section 3.3.1, Figure
3.15(b) illustrates a bandpass having a passband from 1 to 2 GHz obtained using the
element transformation.
3.3.4 ... = 1 to n (3.24)
g
n+1
= 1.0
For convenience, Table 3.1 gives element values for such filters having n = 1 to 9.
As can be seen, the two-port Butterworth filters considered here are always sym-
metrical ... be chosen.
3.2.2 Chebyshev Lowpass Prototype Filters
For Chebyshev lowpass prototype filters having a transfer function given in (3.9)
with a passband ripple L
Ar
dB and the cutoff frequency...
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Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P4)
Ngày tải lên :
28/10/2013, 23:15
... account by using full-wave EM simulation.
4.1.11 Surface Waves and Higher-Order Modes
A surface wave is a propagating mode guided by the air–dielectric surface for a di-
electric substrate on the conductor ... previous expressions for
re
are
obtained based on the quasi-TEM or quasistatic approximation, and therefore are
rigorous only with DC. At low microwave frequencies, these expressions provide ... expressions also provide accuracy better than one percent. If more accurate
values are needed, an iterative or optimization process based on the more accurate
analysis models described previously can...
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Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P5)
Ngày tải lên :
07/11/2013, 21:15
... Semilumped Lowpass Filters Having Finite-Frequency
Attenuation Poles
The previous two types of microstrip lowpass filter realize the lowpass prototype
filters having their frequencies of infinite ... difference lies in the stopband behaviors. The microstrip
filter (Design 1) that uses the narrower inductive lines (W
L
= 0.1 mm) has a better
matched stopband performance. This is because that the ... EM
simulated performance of the filter.
(a)
(b)
Z
0
= 50 ohm C
1
= C
7
= 3.7596 pF
L
2
= L
6
= 11.322 nH C
3
= C
5
= 6.6737 pF
L
4
= 12.52 nH
The microstrip filter design uses a substrate having a relative...
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Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P6)
Ngày tải lên :
07/11/2013, 21:15
... active RF components in such a way that the RF be-
havior is not affected at all by the dc connection. Referring to Figure 6.15(a), the
connection of the bandstop filter should not affect the RF ... lowpass
prototype.
(a)
(b)
performances in Figure 6.13(b) and Figure 6.14(b), the optimum design demon-
strates substantially improved performance with a steeper stopband response.
6.2.4 Bandstop Filters for RF Chokes
A ... desired
stopband for RF choke. A quarter-wavelength inductive line at the input of a band-
stop filter is necessary for transforming an RF short circuit resulting from a radial
stub into an RF open circuit...
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Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P7)
Ngày tải lên :
07/11/2013, 21:15
... (MEMS) provide a class of new devices and com-
ponents which display superior high-frequency performance and enable new system
capabilities. For a general definition, a MEMS is a miniature device ... this point, it is worthwhile comparing the surface resistance of HTS with that
of normal conductors. For a normal conductor, the surface resistance and surface re-
actance are equal and are given ... finite thickness of thin film tends to increase both
the surface resistance and the surface reactance of thin film. Figure 7.4 plots the
surface resistance of the thin film as a function of t/
,...
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Tài liệu Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P8) doc
Ngày tải lên :
15/12/2013, 06:15
... of S
11
in (8.76)
is always equal to 1. This is because in the vicinity of resonance, the parallel res-
onator of Figure 8.11 behavior likes an open circuit. However, the phase response of
S
11
changes ... effect if their signs are opposite. Obviously, the direct evaluation of the cou-
pling coefficient from (8.31) requires knowledge of the field distributions and
performance of the space integrals. ... of
Kirchhoff’s two circuit laws and states that the algebraic sum of the currents leaving
a node in a network is zero, with a driving or external current of i
s
the node equa-
tions for the circuit of Figure...
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Tài liệu Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P9) doc
Ngày tải lên :
15/12/2013, 06:15
... all the numerical methods, is due to the fi-
nite cell or mesh sizes. These EM simulators divide a RF/ microwave filter structure
into subsections or cells with 2D or 3D meshing, and then solve ... superconductors can give better performance of filters, but is
normally more expensive. This may then be evaluated by a cost-effective factor in
terms of the performance. Labor costs include those ... 9.22 Performance of the filter in Figure 9.21. (a) Computed. (b) Measured.
(a)
(b)
9.2.3 Artificial Neural Network Modeling
Artificial neural network (ANN) modeling has emerged as a powerful CAD...
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Tài liệu Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P10) pptx
Ngày tải lên :
15/12/2013, 06:15
... the
improvement in selectivity over the Chebyshev filter is evident. The closer the atten-
uation poles to the cut-off frequency (⍀ = 1), the sharper the filter skirt and the
higher the selectivity.
⍀
a
FBW ... constant of 10.8. (b) Measured performance of the mi-
crostrip CQ filter.
(a)
(b)
loss L
R
= 20 log|S
11
| in dB, and n is the degree of the filter. It is obvious that ⍀ =
±⍀
a
(⍀
a
> 1) are ... [17].
10.5 LINEAR PHASE FILTERS
In many RF/ microwave communications systems, flat group delay of a bandpass fil-
ter is demanded in addition to its selectivity. In order to achieve a flat group...
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Tài liệu Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P11) ppt
Ngày tải lên :
15/12/2013, 06:15
... even without the via hole grounding. Thus, it would seem that the voltage
and current distributions would not change much in the vicinity of the midband fre-
quency, even though the via holes are ... the electromag-
netic energy efficiently as far as its occupied surface area is concerned. This is be-
379
Microstrip Filters for RF/ Microwave Applications. Jia-Sheng Hong, M. J. Lancaster
Copyright ... designed on
a RT/Duroid substrate having a thickness of 1.27 mm and a relative dielectric con-
stant of 10.8. Figure 11.9 illustrates the layout and the EM simulated performance
of the filter. This...
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Tài liệu Microstrip bộ lọc cho các ứng dụng lò vi sóng RF (P12) pptx
Ngày tải lên :
15/12/2013, 06:15
... stations
vary but may focus on increasing sensitivity and selectivity:
ț Sensitivity—The benefits of increasing sensitivity in rural areas is obvious
since the number of mobile base stations and ... other
side of the RF module. The RF module for three channel HTS microstrip duplexers
is shown in Figure 12.3. The diameter of the RF modules is only about 150 mm. The
designs and performances of ... Microstrip
Duplexer
Non-HTS
Microstrip
Circuit
FIGURE 12.3 RF module with three channels of HTS microstrip duplexers.
Compressor
Encapsulated
RF Modules
FIGURE 12.4 Encapsulated RF modules on the Stirling cooler with...
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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, ... to cable television, and the end of the Cold War has made many military
technologies available to civilian applications. The global positioning systems
(GPSs), RF identi®cation (RFID) systems, ... in the United States, including televisions,
radios, satellite communications, cellular phones, police radar, burglar alarms, and
navigation beacons. The performance of each application is strongly...
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