thiết bị dùng cho lò vi sóng

Ngày tải lên: 20/04/2014, 18:22

Ngày tải lên: 03/07/2014, 03:20

Ngày tải lên: 09/07/2014, 19:20

... 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. ... distributed highpass filters, narrow- band and wide-band bandstop filters, as well as filters for RF chokes. Design equa- tions, tables and examples are presented for easy references. The remaining...

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

... a 7-pole (n = 7) Butterworth prototype should 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 ... 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 ... Butterworth Lowpass Prototype Filters For Butterworth or maximally flat lowpass prototype filters having a transfer func- tion given in (3.7) with an insertion loss L Ar = 3.01 dB at the cutoff ⍀ c =...

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 ... coupling coefficients. For a given fractional bandwidth FBW, and a chosen ladder type of lowpass prototype (such as a Chebyshev one) having the lowpass parameters g i , which are given for a normalized ... (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...

Ngày tải lên: 07/11/2013, 21:15

... 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 ... circuit, as shown in Figure 6.15(a). To achieve a wider stopband and better RF choke, the width of inductive lines should be chosen to be as narrow as possible; in other words, the characteristic impedance ... ohms Z 2 = 44.9169 ohms A commercial substrate (RT/D 6006) having a relative dielectric constant of 6.15 and thickness of 1.27 mm is chosen for this microstrip filter realization. Using the microstrip...

Ngày tải lên: 07/11/2013, 21:15

... 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 ... (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 ... 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 ... = 2.0 mm. The opposite frequency shifts of f e or f m at these two coupling spacings are again evidence that the resultant coupling coefficients have the opposite signs. 8.5.2 Extracting k (Asynchronous...

Ngày tải lên: 15/12/2013, 06:15

... is a m × r matrix. Solving (9.29) for [A] results in [A] = [C]·[B] T ([B]·[B] T ) –1 (9.30) 296 CAD FOR LOW-COST AND HIGH-VOLUME PRODUCTION (n = m), then the set S a can be chosen as ⌽ a 1 = ⌽* b and ... 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...

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 ... ⍀ c are the element values and the cutoff frequency of a chosen low- pass prototype of the order n. For determining Cp 0 , C 0,1 , and Cp 1 , choose a trial capacitance Cx 0 . Then: C 0,1 = Ί ๶๶ Cp 0 = ... have the first spurious passband at 3f 0 , they require short-circuit (grounding) connections with via holes, which is not quite compatible with planar fabrication techniques. Lumped-element filters...

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

Ngày tải lên: 29/06/2014, 16:20

Ngày tải lên: 29/06/2014, 21:55

... gia nhiệt cho kim loại. Cho đến nay các lò trung tần dùng trong đốt nóng hoặc nấu chảy kim loại chủ yếu đợc xây dựng trên cơ sở nghịch lu cộng hởng thyristơ. ĐÃ có những mẫu thiết bị này đợc ... phải làm vi c tin cậy trong mọi trờng hợp nhiệt độ thay đổi. -Yêu cầu về lắp ráp vận hành: Sử dụng thiết bị dễ thay thế, dễ lắp ráp, điều chỉnh, thiết bị thay thế dễ dàng giữa các khối cho nhau ... lò cảm ứng 1.2.1. Lũ c m ng trung t n dựng mỏy phỏt i n cao t n Hình: Lò trung tần cấp nguồn từ máy phát cao tần Hai lò cảm ứng trung tần lò 1 và lò...

Ngày tải lên: 02/05/2013, 14:44

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 ... cũng như cách dùng lò sao cho hiệu quả và đúng hướng dẫn. Lịch sử lò vi sóng Nhiều phát minh khoa học là kết quả của nhận xét tình cờ. Kháng sinh Penicillin được tìm ra khi nhà vi trùng học ... đồ nấu bịt kín vì áp suất lên cao bình sẽ nổ. - Không chạy lò khi không có thực phẩm trong lò. - Luôn luôn có nước hoặc thực phẩm ướt khi dùng lò, để tránh cho ống magnetron khỏi bị hư hao....

Ngày tải lên: 17/09/2013, 20:10