Dielectric Filter_MONO TypeLow insertion loss for using high Q-value dielectric resonatorsSmall and light for using high dielectric constant ceramicsExcellent mechanical stability without vibratile st
The dielectric filter is designed and manufactured based on the characteristics of low loss, high dielectric constant, low frequency temperature coefficient and thermal expansion coefficient of dielectric ceramic material, and can bear high power. It is a microwave filter which adopts a dielectric resonator to achieve frequency selection through multistage coupling. After entering the 21st century, the dielectric filter has gradually moved from the laboratory to the production line after long-term accumulation in theory and practice. Due to its advantages of miniaturization, low loss and good temperature characteristics, the dielectric filter has been widely used in mobile communication and microwave communication systems. It is characterized by low insertion loss, good power resistance rate, and narrow band width. It is especially suitable for the level-directional coupling filtering of CT1, CT2, 900MHz, 1.8ghz, 2.4ghz, 5.8ghz, portable phone, car phone, wireless headset, wireless microphone, wireless radio, cordless phone and integrated transmitter-receiver diplexer. The surface of the dielectric filter is covered with a metal layer with zero tangential electric field. The electromagnetic wave is confined in the medium and forms a standing wave oscillation. Its geometric size is about half of the waveguide wavelength. Generally, ceramics with relative permittivity between 60 and 80 are used. In practice, the size of dielectric ceramic filter used in wireless communication is in the centimeter level. Its main advantages are large power capacity and low insertion loss, but there are two major disadvantages: first, the volume is large, in the order of centimetres, compared with the integrated circuit occupies a large volume of the system; Second, the dielectric filter is generally a discrete device, which cannot be integrated with the signal processing circuit. Besides, the filter to the signal processing chip needs to pass through a non-negligible transmission line, and impedance matching must be carried out, which not only has a complex structure but also causes certain signal attenuation. Our Dielectric Filter_MONO Type has lots of merits, like the low insertion loss for using high Q-value dielectric resonators, small and light for using high dielectric constant ceramics, excellent mechanical stability without vibratile structure, great temperature stability as well asSMD and reflow soldering available Mountable by automatic placement machine. The growth of user demand and the innovation of new technology promote the development of communication technology to higher requirements. The corresponding microwave communication equipment, in order to achieve a smaller volume and easy disassembly, has gradually abandoned the design structure of the traditional indoor all-in-one machine, and developed into the existing transceiver in the outdoor (ODU), modulation and demodulation and baseband interface in the indoor (IDU) split structure. The dielectric filter is formed by coupling several dielectric resonators. The main loss of the metal cavity resonator comes from the loss of the conductor. The dielectric filter replaces the metal conductor with a medium (such as microwave ceramic), which can limit the electromagnetic field to the resonator, so it has a high Q value. According to the propagation characteristics of the electromagnetic wave, when the electromagnetic wave enters the medium with low dielectric constant from the medium with high dielectric constant, it will emit and refract on the interface of the medium. When the incident Angle is greater than or equal to the critical Angle, total reflection of electromagnetic wave will occur. The higher the dielectric constant and the smaller the critical Angle of the medium, the more likely the phenomenon of total reflection will occur. It is also easier to form magnetic walls on the surface of the medium. A dielectric resonator is composed of a dielectric block enclosed by a magnetic wall. The electromagnetic field energy of this kind of microwave resonator, which is formed by high dielectric constant and low loss medium material, is basically concentrated in the resonator cavity, and the radiation loss is very small. The loss of the medium itself determines the Q value of the resonator, that is, Q=1/tan. The loss Angle tangent value of some common media materials is usually 0.0001 ~ 0.0002, and its Q value can reach 500 ~ 10,000. It is precisely because of the high quality factor of the medium that most of the electromagnetic energy is concentrated in the dielectric resonator, so the electromagnetic oscillation is easy to maintain. Therefore, the dielectric resonator can be used as a filter. At present, the relative dielectric constant of ceramic dielectric materials is about 39, and the maximum can be above 90. Therefore, using the dielectric material as the resonator can greatly reduce the volume and mass of the filter without reducing the performance of the filter. With the development of modern wireless communication technology, the filter ODM industry is facing new opportunities and challenges. As a result of the scarcity of spectrum resources, the frequency allocation of the communication system is becoming more and more intensive. The requirement of energy saving and emission reduction in wireless system requires more strict power consumption control. Under this condition, the filter unit must meet the high suppression condition and achieve better in-band difference loss index at the same time. The evolution of the upper tower and the outdoor station and the trend of the miniaturization and portability of the system require the filter unit to realize the required performance indexes in a smaller space. Dielectric resonator filter has many advantages in common: first, high Q value; Secondly, by controlling the temperature coefficient of the dielectric material, the resonance frequency can be precisely controlled, so as to achieve extremely stable full temperature characteristics. These two characteristics guarantee the improvement of filter performance. At the same time, we can not ignore the media filter in product development, manufacturing, especially the realization of large-scale production of many challenges, the main problem is two, one: high order model product complex parasitic coupling has a great impact on the main mode, greatly improve the complexity of simulation, especially debugging. This requires that the high order mode must be treated with its inherent characteristics, to reduce the negative impact, strengthen the effective use (such as multi-mode media filter). Second: complex tunable coupling structure. At present,TE - mode and TM - mode dielectric filters have high commercial development value. Compared with the air cavity, TE mode can greatly improve the Q value (more than 200%). However, in the frequency band below 1.5g, due to its disadvantages in weight and volume and many reliability problems, it has little market prospect in the multi-cavity application field of this frequency band. However, for frequency bands above 1.5g and higher, the advantages of TE01 mode begin to emerge gradually: under the requirement of such a high frequency band, most applications can no longer improve the effective Q value by increasing the volume of air chamber, but at this time, the volume required to realize TE mode is equivalent to or even superior to the air chamber, and the weight is within the controllable range. Becomes the ultra high suppression, the low insertion loss application the second choice. The TM mode can increase the Q value by 40% on the basis of the volume of the same metal coaxial resonator, or the space utilization can be improved under the condition of the same Q value. Although these are only limited performance improvements, they undoubtedly provide a valuable resource for system design. Its applications include: 1: series of station type seamless integration,TM mode filter for a series of station type equivalent volume filter planning provides a more high-performance option. For equipment product planning, it is possible for high frequency band to be compatible with low frequency band and special performance to be compatible with conventional performance. 2. Miniaturization of RRH station type and subsequent micro-base station type. Due to the improvement of system efficiency, a smaller overall structure can be adopted to reduce installation and maintenance costs. At present, the biggest obstacle to the application of TM module is the production bottleneck caused by its own structural complexity. Filters were developed during world war ii to meet the needs of radar and electronic countermeasures, but civil applications, such as those in microwave links, were soon discovered. Many postwar developments were related to reducing the size and weight of these filters, first through the use of new analytical techniques that eliminated unnecessary components, and then through innovations in new materials such as dual-mode cavities and ceramic resonators. The specific characteristics of filter design are related to the transmission mode. The line based on the system and similar techniques have only one mode of transmission. In a waveguide system, any number of modes is possible. This may be a disadvantage, as spurious modes often cause problems, or it may be an advantage, as a dual-mode design may be much smaller than an equivalent waveguide single-mode design. The main advantage of waveguide filters over other technologies is their ability to handle high power and low loss. Compared with microstrip filter, the main disadvantage is the large size and high cost. There are various types of filters. Many of them by some coupling of resonators can be modeled as a chain of trapezoidal networks of LC circuits. One of the most common types is composed of many coupled resonators. Even within this type, there are many subtypes, most of which are distinguished by coupling. These coupling types include aperture, [w] iris, [x], and column. Other waveguide filter types include dielectric resonator filters, insertion filters, fin line filters, corrugated waveguide filters, and stub filters. Many waveguide components have filter theory applied to their designs, but their purpose is not just to filter signals. Such devices include impedance matching components, directional couplers, and diplexers. These devices are often at least partly in the form of filters.
Communication includes microwave communication, mobile communication, optical communication and so on. Microwave communication and mobile communication make full use of the wide range of frequency resources to realize the transmission of various information, while optical communication USES light to realize the transmission of information. The common point is not only to send the information completely, reliably and timely, but also to receive the required information completely and timely. The completion of receiving, sending signal function is dependent on a variety of machine equipment, but there is a device (or components) is also indispensable, this is the filter, it is the complete machine to complete the transceiver function of the key components. Due to its small size, high frequency, high quality factor and stable temperature characteristics, medium devices are widely used in rf circuits. In particular, it has irreplaceable advantages in the field of aerospace and microwave communication. The Dielectric Filter_MONO Type can be mainly used in communication systems,such as Base Station & Repeater, PCS system, CDMA system, GSM DCS system, WCDMA system, WLL system, TRS system, TD-SCDMA system and MMDS system. The frequency range is 400~6000MHz. Compared with the empty valley precision vibrator filter, the medium filter can realize miniaturization. In the 1970s, the dielectric filter was used in the field of microwave communication. After the 1980s, with the advent of cellular phones, the dielectric filter was also used in mobile communication systems. Nowadays, as a miniaturized high frequency, dielectric filter is indispensable in microwave and mobile communication. The dielectric filter made of ceramic materials with high dielectric constant (relative dielectric constant greater than 30) has a volume only a fraction of that of the cavity precision oscillator filter. More importantly, with the development of ceramic materials, the resonant frequency of the dielectric filter can be controlled in a small range with the change of temperature. The dielectric filter can be used not only as a bandpass filter in microwave relay lines and mobile communication systems, but also as a clock signal extraction filter for optical communication applications. Now in the market of medium filter according to the structure can be divided into two categories, one kind is with TE01 delta mode resonance ceramic filter medium, the filtering principle is first input of the electromagnetic energy into dielectric resonator at the input, through the resonance from the adjacent dielectric resonator, and after the output dielectric resonator output electromagnetic wave, in the process of this chain of resonance, the only allowed near the resonance frequency of the electromagnetic wave through the frequency components, so as to play to the role of the bandpass filter. The second type is TEM mode dielectric resonator filter. The filtering principle is basically the same as the first type dielectric filter: electromagnetic wave passes through the input coupling capacitor and is injected into the dielectric resonator. Causing electromagnetic resonance also allows only the frequency component near the resonant frequency to pass through, acting as a bandpass filter. Dielectric filter is also an indispensable electronic device in optical communication. The clock extract filter is a dielectric filter. As you can see, the optical cable transmission of optical signals must pass through optical receiver can be converted into communication equipment can receive signals, first of all, through fiber optic cable transmission of optical signals by photoelectric diode is converted into electrical signals, then the signals after two multiplier spare filter input to the clock pulse, the clock pulse signal and amplify electrical signals together into the "1" "0" judging circuit, the final output data signal. In optical communication, the input and output waveform of each part of the functional circuit is usually transmitted by NRZ(non-return to zero) encoding method, which is equivalent to the information of data signal directly compiled, excluding how to use timing method to distinguish "1" or "0" synchronous signal. Therefore, when receiving NRZ signals, a clock pulse extraction circuit that can produce synchronous signals from the input NRZ signals is needed. In this process, the narrow-band dielectric filter can perform its best to extract the synchronous signal components from NRZ signals. There's a sync signal. The distorted NRZ signal can be transformed into the regular data signal by the way of selective pass. The optical signal receivers using the above methods are mainly used for the communication backbone network transmitting signals over long distances. Like the transmission line filter, the waveguide filter always has multiple passbands and is a copy of the lumped element prototype. In most designs, only the lowest frequency passband is useful (in the case of a band-stop filter, the lowest is two), and the rest is considered to be unwanted parasitic artifacts. This is an inherent feature of the technology, and although the design can control the frequency position of the stray band, it cannot be designed. Therefore, in any given filter design, there is a high frequency beyond which the filter cannot perform its function. Therefore, true low-pass and high-pass filters cannot exist in waveguides. At some high frequencies, there are spurious passband or stopband interference filters that are intended to function. However, similar to the waveguide cutoff frequency, the filter can be designed so that the edge of the first stray band is much higher than any frequency of interest. The range of frequencies available for a filter depends largely on the desired waveguide size. At lower frequencies, the waveguide must be unrealistically large to keep the cutoff frequency below the operating frequency. On the other hand, filters that operate at frequencies so high that the wavelength is less than a millimeter cannot be made using conventional machining techniques. At such high frequencies, fiber optic technology is starting to become an option. A waveguide is a low-loss medium. The loss in the waveguide is mainly caused by the ohmic dissipation caused by the induced current in the waveguide wall. The loss of the rectangular waveguide is lower than that of the circular waveguide and is usually the preferred format, but the loss of the TE 01 circular mode is very low and can be used for long-distance communication. Loss can be reduced by polishing the inner surface of the waveguide wall. In applications requiring strict filtration, the walls are coated with a thin layer of gold or silver to improve the surface conductivity. An example of this type of requirement is satellite applications that require their filters to have low loss, high selectivity, and linear group delay. One of the main advantages of waveguide filter over TEM mode is the quality of its resonator. The quality of the resonator is characterized by a parameter called Q factor or Q. Q values of waveguide resonators are thousands of orders of magnitude higher than those of TEM mode resonators. The resistance of a conductor (especially a conductor in a wound inductor) limits the Q of a TEM resonator. The improved Q results in better performance of the filter in the waveguide and greater stopband suppression. The loss in Q's localized waveguide is mainly due to the ohmic loss of the wall described above, but the inner wall can double Q by silver plating. Waveguide has good power processing capability, which leads to the application of filter in radar.  despite the performance advantages of waveguide filters, microstrip is often the preferred technology due to its low cost. This is especially true for consumer goods and lower microwave frequencies. Microstrip circuits can be made using inexpensive printed circuit technology, and when integrated with other circuit modules on the same printed circuit board, they incur little additional cost. Due to its advantages of miniaturization, low loss and good temperature characteristics, the dielectric filter has been widely used in mobile communication and microwave communication systems. It is characterized by low insertion loss, good power resistance and narrow band width. It is especially suitable for the phase-to-phase coupling filtering of CT1, CT2, 900MHz, 1.8ghz, 2.4ghz, 5.8ghz, 5G, portable phone, car phone, wireless headset, wireless microphone, wireless radio, cordless phone and integrated transmitter-receiver duplex. The surface of the dielectric filter is covered with a metal layer with zero tangential electric field. The electromagnetic wave is confined in the medium and forms a standing wave oscillation. Its geometric size is about half of the waveguide wavelength. Generally, ceramics with relative permittivity between 60 and 80 are used. In practice, the size of dielectric ceramic filter used in wireless communication is in the centimeter level. The main advantages of the dielectric filter are large power capacity and low insertion loss, but there are two disadvantages. Second, the dielectric filter is generally a discrete device, which cannot be integrated with the signal processing circuit. Besides, the filter to the signal processing chip needs to pass through a non-negligible transmission line, and impedance matching must be carried out, which not only has a complex structure but also causes certain signal attenuation. The dielectric filter is formed by coupling several dielectric resonators. The main loss of the metal cavity resonator comes from the loss of the conductor. The dielectric filter replaces the metal conductor with a medium (such as microwave ceramic), which can limit the electromagnetic field to the resonator, so it has a high Q value. According to the propagation characteristics of the electromagnetic wave, when the electromagnetic wave enters the medium with low dielectric constant from the medium with high dielectric constant, it will emit and refract on the interface of the medium. When the incident Angle is greater than or equal to the critical Angle, total reflection of electromagnetic wave will occur. The higher the dielectric constant and the smaller the critical Angle of the medium, the more likely the phenomenon of total reflection will occur. It is also easier to form magnetic walls on the surface of the medium. A dielectric resonator is composed of a dielectric block enclosed by a magnetic wall. The electromagnetic field energy of this kind of microwave resonator, which is formed by high dielectric constant and low loss medium material, is basically concentrated in the resonator cavity, and the radiation loss is very small. The loss of the medium itself determines the Q value of the resonator, that is, Q=1/tan. The loss Angle tangent value of some common media materials is usually 0.0001 ~ 0.0002, and its Q value can reach 500 ~ 10,000. It is precisely because of the high quality factor of the medium that most of the electromagnetic energy is concentrated in the dielectric resonator, so the electromagnetic oscillation is easy to maintain. Therefore, the dielectric resonator can be used as a filter. At present, the relative dielectric constant of ceramic dielectric materials is about 39, and the maximum can be above 90. Therefore, using the dielectric material as the resonator can greatly reduce the volume and mass of the filter without reducing the performance of the filter. Dielectric resonator filter is a new development of microwave filter circuit technology, which can meet the requirements of small size and low insertion loss of microwave filter. Although the research of microwave millimeter wave filter has a long history, the traditional design and implementation of high quality technology, such as the use of traditional metal waveguide or the use of microstrip line filter implementation technology, is either expensive or difficult to achieve the required technical indicators. In order to realize high quality mobile communication, it is very important to control the communication channel of T disturbance signal. On the one hand, it is necessary to control the influence of the interference outside the communication channel on the communication channel. On the other hand, in the same communication system to control the communication channel in the mutual interference. In order to achieve this goal, high quality microwave filter must be set in the mobile communication base station. Whether the communication system is time division system or frequency division system, this kind of microwave filter is indispensable. The dielectric cavity filter introduced in this paper is applied to the mobile code division earth station and 8-channel digital microwave relay machine. The satellite earth needs to receive the communication signal and the beacon at the same time. In 6 GHZ, 7 GHZ, 8 GHZ frequencies band-pass filter implemented, such as the measured performance with the AD - TECH Micowave company reported data in mobile code points 1983 earth station transceiver attacking signal system and mixture falcon microstrip circuit, in addition to the high power with traveling wave, the effect of airport pipe 0 4 GHZ to choose machine and inverter output filter on 6 GHZ using dielectric resonator bandpass filter. In the 8-channel digital microwave relay machine, the microwave channel machine is fully field effect piped, adopting the microstrip mixed integrated circuit, the dielectric resonator stabilized oscillator as the local oscillator source, and the dielectric cavity bandpass filter for the front and rear preselected filter. Preliminary realization of the microwave machine integration, miniaturization. However, the cavity filter device composed of a dielectric resonator has obvious advantages. First, a single resonator has a high frequency and Q value, so it has good performance. In addition, it adopts the method of electromagnetic coupling, which is suitable for microwave communication, radar, electric confrontation, military, aerospace and other fields. It is a new device with a promising future. The ideal filter would be a two-port network that allows complete transmission of the microwave signal in the passband and complete transmission of the microwave signal in the stopband. However, we can only design a filter that is as close to the ideal filter characteristics as possible. Like other microwave devices, there are also two kinds of problems to be studied for microwave filters, one is analysis, the other is synthesis. It is an analytical problem to know the circuit structure and component parameters of the filter and calculate its working characteristics. On the contrary, it is a comprehensive problem to determine the circuit structure and component values of the filter based on the predetermined operating characteristics. In the actual work is encountered more is the comprehensive problem. The comprehensive design of the filter generally consists of four steps: according to the system requirements to determine the filter's working characteristics, select the appropriate mathematical expression of the approximation function to describe the above working characteristics, determine the lump-parameter network structure of the filter, and select the appropriate microwave structure to realize it.
|System||Part Number||Center Frequency||Bandwidth||Insertion Loss in BW||Ripple in BW||Return Loss in BW||Attenuation (dB)||Size|
(L x W x H)mm
SMD filter is called because of its package, surface mounted filter, distinguishing from Pin type package.