lò vi sóng samsung gw73b 20l đt

Ngày tải lên: 28/08/2013, 10:23

Ngày tải lên: 28/08/2013, 18:19

... - 10:06 AM Lò nấu vi sóng Lò Vi sóng (Microwave oven - sóng cực ngắn) hiện nay đã ngự trị trong bếp của nhiều gia đình cũng như tại công sở, trường học…. Dân giầu có thì sắm một lò gắn vào tường ... fries) trong lò vì chất béo quá nóng gây cháy. - Tránh mọi hư hao cho cửa lò như đè lên cửa hoặc nhấc lò lên bằng cánh cửa lò. - Vài năm kiểm tra lò một lần coi có bị thất thoát sóng ra ngoài. - ... cần lưu ý là lò vi sóng hiện nay rất an toàn cho người mang máy điều hòa nhịp tim (pacemaker) vì các y cụ này đều được che chở chống phóng xạ hoặc vi sóng. © Copyright 2000-2003 Vinacomm, all...

Ngày tải lên: 17/09/2013, 20:10

... wavelengths between 1 ␮m (10 –6 m) and 1 mm. Beyond the infrared spectrum is the visible optical spectrum, the ultraviolet spectrum, and x-rays. Below the microwave frequency spectrum is the radio ... tuning. Here the costs for the design and tuning can be reduced greatly by using CAD, which can provide more accurate design with less design iterations, leading to first-pass or tuneless filters. ... developments in this area are cer- tainly being stimulated by increasing computer power. Another driving force for the developments is the requirement of CAD for low-cost and high-volume production. In...

Ngày tải lên: 24/10/2013, 16:15

... ports of the network NЈЈ ; and all the S submatrices con- tain the corresponding S parameters. Obviously, p + c = M 1 and q + c = M 2 . It is [aЉ] q [aЉ] c [SЉ] qc [SЉ] cc [SЉ] qq [SЉ] cq [bЉ] q [bЉ] c [aЈ] p [aЈ] c [SЈ] pc [SЈ] cc [SЈ] pp [SЈ] cp [bЈ] p [bЈ] c b i ᎏ a j a 1 a 2 Ӈ a M S 1M S 2M Ӈ S MM ... at port 2 of the network NЈ and port 1 of the network N Љ when SЈ mn and SЉ mn are evaluated individually. 2.8 NETWORK PARAMETER CONVERSIONS From the above discussions it can be seen that for ... composite network is given simply by the sum of the short-circuit admittance matrices of the individual networks. Analogously, the networks of Figure 2.3(b) are connected in series at both their input...

Ngày tải lên: 24/10/2013, 16:15

... 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...

Ngày tải lên: 28/10/2013, 23:15

... 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 ... 4.10(h). These microstrip patch resonators can be analyzed as waveguide cavities with mag- netic walls on the sides. The fields within the cavities can be expanded by the TM Z nm0 modes, where z is perpendicular...

Ngày tải lên: 28/10/2013, 23:15

... 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 ... (b) can only be electrically equivalent to the combline filter in the vicinity of the mid- band frequency, and its stopband behavior is different from that of the combline fil- ter. Similar to the ... inductances L 1 , L 3 , and L 5 block transmission by having infinite series reactance, whereas the capacitance C 6 shorts out transmission by having infinite shunt susceptance. A microstrip filter...

Ngày tải lên: 07/11/2013, 21:15

... design this type of filter, let us consider the design of an op- timum distributed highpass filter having a cutoff frequency f c = 1.5 GHz and a 0.1 dB ripple passband up to 6.5 GHz. Referring to Figure ... = 1 to n where b i are the susceptance slope parameters of series parallel resonators. It is obvious that for a chosen lowpass prototype, with known element values, the desired reactance/susceptance ... relative dielectric constant of 10.8 and a thickness of 1.27 mm. The bandstop filter is designed to provide an RF rejection better than 40 dB over an operating frequency band from 3.5 GHz to 5.5 GHz....

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 ... ability to effectively improve filter selectivity. Therefore, it does not constitute a particularly attractive choice for achieving frequency selectivity. Never- theless, it may be of interest ... production. The change in permittivity as a func- tion of electric field is the key to a wide range of applications. Frequency-agile filters are among many other device applications of ferro- electrics....

Ngày tải lên: 07/11/2013, 21:15

... 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 ... 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 ... resonator Y in = j ␻ C + = j ␻ 0 C ΂ – ΃ (8.74) Note that ␻ 0 = 1/͙L ෆ C ෆ is the resonant frequency. In the vicinity of resonance, say, ␻ = ␻ 0 + ⌬ ␻ , (8.74) may be simplified as Y in = j ␻ 0 C· (8.75) where...

Ngày tải lên: 15/12/2013, 06:15

... filter synthesis by optimization is a three-pole cross-cou- pled resonator filter having asymmetrical frequency selectivity. The desired filter response will exhibit a single finite frequency attenuation ... are violated. 9.3 OPTIMIZATION 287 minimize ⌬⌽,⌬⌰ Ή R b (⌽ + ⌬⌽, ⌬⌰) – R a (⌽)Ή where ⌬⌽ denotes the modifications to the physical design parameters for compensating the characteristic deviation ... the initial decomposition design, the filter is decomposed into individual cascaded sections, where reference planes of each individual section are represented by circuit nodes and the discontinuities...

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 ... rejection bandwidths are 100 MHz and 120 MHz, respectively, which obviously does not meet the rejection require- ments. Having determined the design parameters, the nest step is to find the physical ... communications systems, flat group delay of a bandpass fil- ter is demanded in addition to its selectivity. In order to achieve a flat group delay characteristic, two approaches are commonly used. The...

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 ... “New high temperature superconductive microstrip lines and resonators,” Applied Supercon- ductivity, Inst. Phys. Conf. Ser. 148, 1995, 1995, 1195–1198. [7] J S. Hong and M. J. Lancaster, “Novel ... is associated with the necessity of using low-value characteristic impedance lines ț High sensitivity to small variations in physical dimensions ț Excitation of higher-order modes ț Difficulty...

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 ... Nevertheless, the full-wave simulated re- sponse did verify the design approach. 12.3.3 Sensitivity Analysis Sensitivity analysis is very important for filter design, particularly for filter tuning, mainly ... specification. It is estimated the Q that can be attained is 50,000. Therefore, provided the required rejection and selectivity can be met, a filter with as low a number of poles as possible should be...

Ngày tải lên: 15/12/2013, 06:15

... 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

Ngày tải lên: 15/12/2013, 11:15

Ngày tải lên: 15/12/2013, 11:15

Ngày tải lên: 15/12/2013, 11:15