CN108808186B - Reconfigurable microwave quadruplex device - Google Patents
Reconfigurable microwave quadruplex device Download PDFInfo
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- CN108808186B CN108808186B CN201810916670.6A CN201810916670A CN108808186B CN 108808186 B CN108808186 B CN 108808186B CN 201810916670 A CN201810916670 A CN 201810916670A CN 108808186 B CN108808186 B CN 108808186B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
- H01P1/20—Frequency-selective devices, e.g. filters
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- H—ELECTRICITY
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- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P1/00—Auxiliary devices
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- H01P1/213—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies
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Abstract
The invention discloses a reconfigurable microwave quadruplex device, wherein each channel of the quadruplex device adopts a second-order folded loaded capacitive resonator, and all the channels are coupled together by a distributed coupling technology, so that a matching circuit is not needed, and good matching characteristics and adjustable characteristics can be kept. The second-order resonator of the invention has electric coupling and magnetic coupling, which is beneficial to generating transmission zero outside the band and improving the selectivity of the stop band. Secondly, the folded resonator has weak loading effect on an input feeder line, improves the isolation between output ports and has good matching performance. The characteristics of a wide stop band and effective suppression of a high-order mode of the slow-wave resonator are utilized, the slow-wave folded resonator is adopted in the lowest pass band to reduce the influence on other characteristics, particularly the characteristics of the highest frequency channel, and the size of the reconfigurable quadruplex device is further reduced.
Description
Technical Field
The invention relates to the technical field of microwave devices, in particular to a reconfigurable microwave quadruplex device.
Background
The multiplexer is capable of dividing a broadband signal into a plurality of frequency channel signals, and plays an important role in a mobile communication system. The conventional multiplexer basically adopts a cavity structure with the characteristics of high Q value and low loss, but generally occupies a larger volume and is inconvenient to apply to a reconfigurable system. With the rapid development of the current communication system, people gradually make researches on reconfigurable multiplexers, but only a small number of reconfigurable duplexers based on a microstrip structure are available at present, the reconfigurable duplexers can only be adjusted according to two simple channels, cannot be applied to wider communication scenes, and the researches on multi-channel reconfigurable multiplexers are very few.
Disclosure of Invention
In view of the above-mentioned shortcomings and drawbacks of the prior art, an object of the present invention is to provide a four-channel reconfigurable multiplexer, in which a second-order folded loaded capacitive resonator is used for each channel, and the channels are coupled together by a distributed coupling technique, so that a matching circuit is not required and good matching and tuning characteristics can be maintained. The reconfigurable quadruplex device provided by the invention solves the loading effect of multiple channels by a simple and efficient method, keeps good matching characteristics, and plays a certain guiding role in the research of other reconfigurable multiplexers.
The invention is realized by the following technical scheme:
a reconfigurable microwave quadruplex multiplexer comprises 1 input feeder port, a first output feeder port, a second output feeder port, a third output feeder port, a fourth output feeder port, a first adjustable filter, a second adjustable filter, a third adjustable filter and a fourth adjustable filter; a first frequency channel is formed by the first input feeder port, the first adjustable filter and the first output feeder port, a second frequency channel is formed by the second input feeder port, the second adjustable filter and the second output feeder port, a third frequency channel is formed by the third input feeder port, the third adjustable filter and the third output feeder port, and a fourth frequency channel is formed by the fourth input feeder port, the fourth adjustable filter and the fourth output feeder port; the four tunable filters are second-order folded loading variable capacitance resonators, and the second-order resonators are coupled in a symmetrical structure; the first tunable filter adopts a step-type impedance resonator, and the second tunable filter to the fourth tunable filter adopts a uniform impedance resonator.
The invention adopts the second-order folded loading variable capacitance resonator, couples all channels together by the distributed coupling technology without designing any matching circuit, effectively realizes the impedance matching of the total port and all channels, only needs to properly adjust the coupling distance of the input port and each channel, and further reduces the size of the quadruplex; the first channel adopts the step-type impedance resonator, so that the high-order resonance mode of the first channel can be effectively inhibited, and the stop band is widened.
Preferably, the input feeder port is a long microstrip line, the first adjustable filter and the fourth adjustable filter are connected to the input feeder port in a slot capacitive coupling manner, the first adjustable filter and the second adjustable filter are located on the same side in the length direction of the microstrip line, and the third adjustable filter and the fourth adjustable filter are located on the other side in the length direction of the microstrip line. The design can achieve the required external quality factor by simply adjusting the coupling distance with the input feeder line port, and does not need any matching circuit, so that the design complexity is further reduced, and the occupied size is reduced.
Preferably, each channel is a second-order resonator, and the synchronization is adjustable, so that the coupling coefficient and the external quality factor of each channel are determined by the following formula:
in the formula, M12For the coupling coefficient between the second order resonators, FBW is the relative width of the filter, Qe1And Qe2External quality factors, g, of the input and output ports of the filter, respectively0、g1、g2The low pass prototype component value corresponding to the selected filter type. And performing preliminary synthesis according to the performance index of the given filter to obtain the coupling coefficient between the resonators and the external quality factor of the input/output port, and adjusting the coupling distance between the resonators and the distance from the resonators to the input/output port to achieve the required parameter value.
Preferably, the first tunable filter is a slow-wave resonator formed by symmetrically coupling second-order stepped impedance resonators, and the second-fourth tunable filter is a half-wavelength resonator formed by symmetrically coupling second-order uniform impedance resonators. A slow-wave structure resonator is employed to widen the stop band and reduce the adverse effects of its higher order resonant modes on other channels.
Preferably, in the first channel and the fourth channel, the second-order resonators are folded into two U-shaped structures symmetrically arranged, one end of the first U-shaped structure is grounded through a variable capacitor, the end where the variable capacitor is located is coupled with a corresponding output feeder port, the other end of the first U-shaped structure is coupled with one end of the second U-shaped structure, and the other end of the second U-shaped structure is grounded through a variable capacitor and coupled with an input feeder port. The design enables the second-order resonators to be coupled in a symmetrical structure, the middle of the second-order resonators is electrically coupled, the variable capacitor grounding parts loaded on the two resonators are magnetically coupled, the required coupling coefficient can be achieved by selecting a proper coupling distance, and transmission zero points exist outside the band to improve the selectivity.
Preferably, the ends of the first U-shaped structure coupled with the second U-shaped structure are grounded through an inductor and a capacitor.
Preferably, the variable capacitor is a varactor diode. The varactor with a large varactor ratio is selected to achieve a wide frequency tunable range, and a high-frequency substrate material with low loss should be selected.
The invention has the following advantages and beneficial effects:
the four-way adjustable filter is connected with the input feeder port in a weak gap coupling mode by adopting a distributed coupling technology, and by adopting the method, any matching circuit is not required to be designed, so that the design is fast, and the size of the quadruplex is reduced. Each channel is a second-order folded loading variable capacitance resonator, and the second-order resonators are electrically coupled and magnetically coupled, so that transmission zero points can be generated outside the band, and the selectivity of a stop band can be improved. The reconfigurable characteristic of the quadruplex device is realized by changing the capacitance value of the variable capacitor loaded on each channel resonator. Secondly, the folded resonator has weak loading effect on an input feeder line, improves the isolation degree between output ports, has good matching performance and has high practical application value. The characteristics of a wide stop band and effective suppression of a high-order mode of the slow-wave resonator are utilized, the slow-wave folded resonator is adopted in the lowest pass band to reduce the influence on other characteristics, particularly the characteristics of the highest frequency channel, and the size of the reconfigurable quadruplex device is further reduced. By selecting the variable capacitance diode with large variable capacitance ratio, the reconfigurable range of each channel is wider.
Drawings
The accompanying drawings, which are included to provide a further understanding of the embodiments of the invention and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the invention and together with the description serve to explain the principles of the invention. In the drawings:
fig. 1 is a schematic plan view of the reconfigurable microwave quadroplexer of the present invention.
FIG. 2 is a schematic structural diagram of the reconfigurable microwave quadroplexer.
Fig. 3 shows the initial result of the reconfigurable microwave quadroplexer of the present invention.
Fig. 4 shows the return loss and insertion loss of the quadruplex of the invention during the adjustment of only the first channel.
Fig. 5 shows the isolation of the quadruplex of the invention during the adjustment of only the first pass.
Fig. 6 shows the return loss and insertion loss of the quadruplex of the invention during the adjustment of only the second channel.
Fig. 7 shows the isolation of the quadruplex of the invention during the adjustment of only the second channel.
Fig. 8 shows the return loss and insertion loss of the quadruplex of the invention during adjustment of only the third channel.
Fig. 9 illustrates the isolation of the inventive quadroplexer during adjustment of only the third channel.
Fig. 10 shows the return loss and insertion loss of the quadruplex of the invention during the adjustment of only the fourth channel.
Fig. 11 shows the isolation of the quadruplex of the invention during the adjustment of only the fourth channel.
Fig. 12 shows the return loss and insertion loss of the four channels of the inventive quadplexer in case 1.
Fig. 13 shows the return loss and insertion loss of the four channels of the inventive quad-plexer in case 2.
Reference numbers and corresponding device names in the drawings:
1-an input feeder port, 2-a first output feeder port, 3-a second output feeder port, 4-a third output feeder port, 5-a fourth output feeder port, 6-a first frequency channel, 7-a second frequency channel, 8-a third frequency channel, 9-a fourth frequency channel, 10-a variable capacitor, 11-an inductor, 12-a capacitor, 13-a ground terminal, 14-an air cavity, 15-a metal ground layer.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail below with reference to examples and accompanying drawings, and the exemplary embodiments and descriptions thereof are only used for explaining the present invention and are not meant to limit the present invention.
Examples
The reconfigurable microwave quadruplex device adopts the distributed coupling technology to connect the four-path adjustable filter with the input feeder line port in a weak gap coupling mode, and by adopting the method, any matching circuit does not need to be designed, so that the design is fast, and the size of the quadruplex device is reduced. Each channel is a second-order folded loading variable capacitance resonator, and the second-order resonators are electrically coupled and magnetically coupled, so that transmission zero points can be generated outside the band, and the selectivity of a stop band can be improved. Secondly, the folded resonator has weak loading effect on an input feeder line, improves the isolation degree between output ports, has good matching performance and has high practical application value. The characteristics of a wide stop band and effective suppression of a high-order mode of the slow-wave resonator are utilized, the slow-wave folded resonator is adopted in the lowest pass band to reduce the influence on other characteristics, particularly the characteristics of the highest frequency channel, and the size of the reconfigurable quadruplex device is further reduced. By selecting the variable capacitance diode with large variable capacitance ratio, the reconfigurable range of each channel is wider.
As shown in fig. 1-2, the quadplexer of the present embodiment includes 1 input feeder port 1, a first output feeder port 2, a second output feeder port 3, a third output feeder port 4, a fourth output feeder port 5, a first tunable filter, a second tunable filter, a third tunable filter, and a fourth tunable filter; a first frequency channel 6 is formed by the first input feeder port, the first tunable filter and the first output feeder port, a second frequency channel 7 is formed by the second input feeder port, the second tunable filter and the second output feeder port, a third frequency channel 8 is formed by the third input feeder port, the third tunable filter and the third output feeder port, and a fourth frequency channel 9 is formed by the fourth input feeder port, the fourth tunable filter and the fourth output feeder port; the four tunable filters are second-order folded loading variable capacitance resonators, and the second-order resonators are coupled in a symmetrical structure; the first tunable filter adopts a step-type impedance resonator, and the second tunable filter, the third tunable filter and the fourth tunable filter adopt uniform impedance resonators.
The first tunable filter adopts a slow-wave structure resonator formed by symmetrical coupling of second-order stepped impedance resonators, the first tunable filter adopts a stepped impedance resonator, and the second tunable filter, the third tunable filter and the fourth tunable filter adopt a half-wavelength structure resonator formed by symmetrical coupling of second-order uniform impedance resonators.
In the first frequency channel, the second frequency channel, the third frequency channel and the fourth frequency channel, the second-order resonator is folded into two symmetrically-arranged U-shaped structures, one end part of the first U-shaped structure is grounded through a variable capacitor 10, the end where the variable capacitor is located is coupled with an output feeder port of the corresponding channel, the other end of the first U-shaped structure is coupled with one end of the second U-shaped structure, and the other end of the second U-shaped structure is grounded through the variable capacitor and is coupled with an input feeder port. The ends of the first U-shaped structure coupled with the second U-shaped structure are grounded through an inductor 11 and a capacitor 12.
The slow wave structure adopts a step-type impedance resonator, and the slow wave structure can effectively restrain a high-order resonance mode of the slow wave structure. And the resonator has the characteristics of wide stop band and easy construction of ultra-narrow band filter.
In the distributed coupling technology, the input port is a long microstrip line, and each adjustable filter is designed and then indirectly connected with the input port in a slot capacitive coupling mode. On the one hand, the required external quality factor can be achieved by simply adjusting the coupling distance with the input port. On the other hand, any matching circuit is not needed, and the design complexity is further reduced while the occupied size is reduced.
The folded loading capacitor resonators enable the second-order resonators to be coupled in a symmetrical structure, the middle is electrically coupled, and the grounding parts of the two resonators loaded with the variable capacitors are magnetically coupled. The required coupling coefficient can be achieved by selecting the proper coupling distance, and the transmission zero point exists outside the band to improve the selectivity.
The first channel, namely the lowest frequency passband, adopts a second-order slow-wave structure resonator, so that the stopband is widened, and the adverse effect of the higher-order mode on other passbands is reduced. To reduce design complexity, the remaining channels all use half-wavelength-averaging loaded variable capacitance resonators, and the initial design center frequencies between the channels are spaced 400MHz apart. The varactor with a large varactor ratio is selected to achieve a wide frequency tunable range, while the high frequency substrate material with low loss should also be selected.
The working principle of the invention is as follows: the design of the multiplexers always needs to be integrated into the design of the filters per channel, as is the case for reconfigurable multiplexers. Firstly, by designing a proper reconfigurable filter, a single filter can have a wider adjustable range and a constant percentage bandwidth, so that a multiplexer can have good characteristics. Secondly, the key point for the design of the filter is the choice of resonator structure, the different forms being decisive for the filter characteristics. Generally, the resonators of the microstrip structure are mostly in the form of half-wavelength electrical length, and can be roughly divided into a Uniform Impedance Resonator (UIR) and a Stepped Impedance Resonator (SIR). The channels of the invention take the form of slow wave resonators formed by the SIR as soon as the channels are in the form of UIRs. After the resonator form is determined, it is necessary to design the filter per channel according to the coupled resonant circuit theory, including two main parameters: coupling coefficient and external quality factor.
The normalized impedance matrix is mainly composed of a coupling coefficient mijExternal quality factor qeiAnd a frequency conversion formula p. The impedance matrix can therefore be decomposed into:
[Z]＝[q]+p[U]-j[m]
wherein [ U ]]Is an n multiplied by n unit matrix; [ q ] of]Is also an n × n matrix, and divides by q11＝1/qe1And q isnn＝1/qenIn addition, the other values are all 0; [ m ] of]Is generally said toAnd is a reciprocal network, so it can be expressed as:
the coupling matrices listed above pertain to the case of synchronous tuning, i.e. the resonance frequency of each resonator is the same. Each channel of the reconfigurable quadruplex is a second-order resonator and is also synchronous and adjustable, and the coupling coefficient and the external quality factor of each channel can be determined by the following formulas (1) and (2):
in the formula, M12For the coupling coefficient between the second order resonators, FBW is the relative width of the filter, Qe1And Qe2External quality factors, g, of the input and output ports of the filter, respectively0、g1、g2The low pass prototype component value corresponding to the selected filter type.
The formulas (1) and (2) can be used for giving filter indexes to carry out preliminary synthesis to obtain the coupling coefficient and the external quality factor between the resonators, and then the required parameter value is achieved by adjusting the coupling distance between the resonators and the distance from the resonators to the input and output ports.
After the coupling coefficient and the external quality factor are obtained from the resonance circuit theory, the physical structure and size of the resonator need to be determined according to the actual design requirements. The center frequencies of four passbands of the initial design of the reconfigurable quadruplex device are set as follows: 1.1GHz, 1.5GHz, 1.9GHz and 2.3GHz with a spacing of 400 MHz. In order to ensure higher isolation between channels, the introduction of transmission zero is a necessary requirement of the invention. In general, a filter with an n-order resonator generates n-1 transmission zeros at most, and the design adopts a hybrid electromagnetic coupling mode, namely, the second-order resonators simultaneously have electric coupling and magnetic coupling, and the magnitude of the two types of coupling can be reasonably controlled to realize an out-of-band pair of transmission zeros so as to improve frequency selectivity. The resonator is defined as a folded U-like structure which can achieve the above requirements while reducing the size of the quadplexer.
When the tunable filter for each channel is designed, the key design point of the multiplexer is the way to combine the four paths together. In order to ensure that the quadruplex can have a wider frequency reconfigurable range, a distributed coupling technology is adopted, namely the four-way adjustable filter is connected with an input feeder line port in a capacitive coupling mode. This effectively realizes impedance matching of the total port and each path, and the coupling coefficient of the input port and each channel only needs to be adjusted properly, and simultaneously further reduces the size of the quadrupler.
As shown in fig. 3 to 13, the simulation results obtained by simulating the reconfigurable microwave quadroplexer of the present embodiment show that: in the reconfigurable microwave quadruplex, the center frequency of each channel can be adjusted simultaneously or independently, and the initial design center frequency is as follows: 1.1GHz, 1.5GHz, 1.9GHz and 2.3GHz, and the adjustable frequency range of each passband is more than 350 MHz; as can be seen from fig. 3, each channel of the quadplexer of this embodiment has a transmission zero outside the band, and the first frequency channel has a wider stop band; fig. 4 to 11 show that the return loss, the insertion loss, and the isolation degree obtained by separately adjusting the first channel, the second channel, the third channel, and the fourth channel, respectively, are simulated, and when a certain channel is separately adjusted, the characteristics of other channels are hardly affected; FIGS. 12-13 are the return loss and insertion loss, isolation of each channel for both cases of simultaneous conditioning of all channels, maintaining good port matching and S11< -14dB throughout the conditioning process; therefore, the reconfigurable microwave quadroplexer of the embodiment has small mutual influence of the channels when being adjusted independently or simultaneously; and the insertion loss of the four channels can be kept less than 1.8dB in the whole adjusting process, and the isolation between the output ports is more than 30 dB.
The above-mentioned embodiments are intended to illustrate the objects, technical solutions and advantages of the present invention in further detail, and it should be understood that the above-mentioned embodiments are merely exemplary embodiments of the present invention, and are not intended to limit the scope of the present invention, and any modifications, equivalent substitutions, improvements and the like made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (6)
1. A reconfigurable microwave quadruplex multiplexer is characterized by comprising 1 input feeder port, a first output feeder port, a second output feeder port, a third output feeder port, a fourth output feeder port, a first adjustable filter, a second adjustable filter, a third adjustable filter and a fourth adjustable filter; the first frequency channel is formed by the input feeder port, the first adjustable filter and the first output feeder port, the second frequency channel is formed by the input feeder port, the second adjustable filter and the second output feeder port, the third frequency channel is formed by the input feeder port, the third adjustable filter and the third output feeder port, and the fourth frequency channel is formed by the input feeder port, the fourth adjustable filter and the fourth output feeder port; the four tunable filters are second-order folded loading variable capacitance resonators, and the second-order resonators are coupled in a symmetrical structure; the first tunable filter adopts a step-type impedance resonator, and the second tunable filter, the fourth tunable filter adopts a uniform impedance resonator; each frequency channel is a second-order resonator, and is synchronous and adjustable, so that the coupling coefficient and the external quality factor of each frequency channel are determined by the following formula:
in the formula, M12For the coupling coefficient between the second order resonators, FBW is the relative width of the filter, Qe1And Qe2External quality factors, g, of the input and output ports of the filter, respectively0、g1、g2The low pass prototype component value corresponding to the selected filter type.
2. The reconfigurable microwave quadroplexer of claim 1, wherein the input feed line port is a long microstrip line, the first tunable filter and the fourth tunable filter are connected to the input feed line port by slot capacitive coupling, the first tunable filter and the second tunable filter are located on the same side of the microstrip line in the length direction, and the third tunable filter and the fourth tunable filter are located on the other side of the microstrip line in the length direction.
3. A reconfigurable microwave quadplexer as claimed in any one of claims 1-2 wherein the first tunable filter employs a slow-wave structure resonator formed by symmetric coupling of second-order stepped impedance resonators, and the second-quadplexer employs a half-wavelength structure resonator formed by symmetric coupling of second-order uniform impedance resonators.
4. The reconfigurable microwave quadroplexer as claimed in claim 3, wherein the second-order resonators in the first-fourth frequency channels are folded into two symmetrically arranged U-shaped structures, one end of the first U-shaped structure is grounded through a variable capacitor, and the end of the first U-shaped structure where the variable capacitor is located is coupled with the corresponding output feeder port, the other end of the first U-shaped structure is coupled with one end of the second U-shaped structure, and the other end of the second U-shaped structure is grounded through the variable capacitor and coupled with the input feeder port.
5. The reconfigurable microwave quadroplexer of claim 4 wherein the ends of the first and second U-shaped structures that are coupled are grounded through an inductor and a capacitor.
6. The reconfigurable microwave quadplexer of claim 4 wherein the variable capacitance is a varactor.
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