RU2075801C1 - Device for integration of incoherent signals - Google Patents

Abstract

FIELD: radio engineering for ultra-high and microwave frequency, antennas and instruments. SUBSTANCE: standard phase-shift method involves modification of phase synchronization circuit by means of part of dispersion phasing line to Y-circulation unit with intermediate arm which is connected to high-quality refection resonator. In addition another circuit contains same Y-circulation unit which intermediate arm is connected to moving short circuit jumper in order to balance amplitude of constituents in signals of parallel channels. Central rejection frequency of resonator which is calculated as average of carrier frequencies of signals depends on size and position of tuning capacitance screw. This results in possibility to tune different between signals which depends on resonator bandwidth for 3 dB level, in other words on its connection to external circuits. This dependency is varied by setting different transmission elements which are shaped as diaphragm. Short circuit jumper provides possibility to set central rejection frequency and to locate signal spectrum on frequency axis. Device operations depend on phase-frequency characteristic of resonator circuit which adds constant intermediate differential phase shift which is equal to two right angles for corresponding frequencies greater or lesser than resonant one. This shift is required for signal combination. Y- circulation units are used for generation of directed reflection. EFFECT: possibility to add signals of different bands and carriers to single output circuit; signals can be changed arbitrarily with respect to other signals and difference between carrier frequencies is arbitrary. 2 tbl, 4 dwg

Description

 The invention relates to radio engineering of the high and microwave ranges, can be used in antenna-waveguide and measuring equipment.

 Known schemes for combining the signals of two or more transmitters (Handbook of satellite communications and broadcasting. / Under the editorship of L.Ya. Kantor. M. Radio and communications, p. 1983-288), which are used in cases where the separation between their carriers frequencies does not allow to implement the frequency-selective principle of AFT compaction. Selective multiplexing is unacceptable if the signal spectra are located close (it is impossible to build bandpass filters with sufficient frequency response and low loss) or overlap, as well as in the absence of fixation of the carrier transmitters (the position of the signals on the frequency axis varies over time, depends on the frequency schedule, adaptive transmission is used with random carriers), which translates into unrealistic requirements for the characteristics of tunable filters over the dynamic range while maintaining the passband niya and the complexity of the control scheme.

 In the presence of these conditions, multiplexers are created on the basis of bridge devices, taking into account the characteristics of the frequency response of the used guide systems. This is how the phase-difference and amplitude-difference schemes for combining different frequencies into a common AFT work the above. The phase-difference device is based on the dispersion of the phase constant of wave propagation in the transmission line and can be implemented before the separation of the signals of the transmitters, which is at least 1% of the average frequency of their carriers.

The amplitude-difference device is based on the law of constant differential phase shift of reflected and transmitted waves in a symmetrical reciprocal reactive node without losses and sources: the phase difference between the wave reflected from the reactive heterogeneity of the guide system and transmitted through it is always 90 ^o (N. Semenov Technical electrodynamics. Textbook for high schools. M. Communication, S. 1973-480). This scheme can be implemented before the separation of the signals of the transmitters, which is no more than 1% of the average frequency of their carriers, because with large spacings and broadband signals usually used for this, difficulties are created for the synthesis of a semi-reflective structure, which must retain certain frequency response and phase response for all frequencies of the signal spectrum. The disadvantages of the amplitude-difference method of combining include the complexity of calculating and adjusting or tuning these devices, and we note that this is compounded due to the appearance of a large number of pairs of inhomogeneities in the transmission line in the area of the semi-reflecting structure with a decrease in separation, which also leads to an increase losses. A detailed description of this scheme can be found in the literature.

 From this it should be concluded: in cases where the separation between the carrier frequencies of the signals is any, it is necessary to have both difference combining devices (depending on the separation, either one or the other circuit is used) or their combination, when more than two transmitters are connected to a common AFT. This method of AFT compaction is technologically disadvantageous and inconvenient, because requires the presence of additional switching devices in the path or significantly complicates the reconstruction of the combinational circuit without the condition of fixing the carrier frequencies, given that the techniques for reconfiguring phase-difference and amplitude-difference devices are somewhat different.

Consider the operation of the phase-difference scheme of combining frequencies (Fig. 1). We will do this using the example of a waveguide path. It consists of waveguide bridges 1 '(in this case, VSCH I and II), interconnected by two unequal segments of the waveguide transmission line 3'. The length of any of them is selected so that the phase difference between its input and output at the frequency of one of the combined signals is 0 ^o , and at the frequency of the second signal 180 ^o , when phasing the signals at the input and output of the other. The transmitters are connected to the shoulders of the first bridge (1 and 2 for I). One of the shoulders of the second bridge (3 for II) is connected to a common path. His other shoulder (4 for II) is loaded on the coordinated ballast load 4 '. Based on the properties of bridge devices, we obtain the following. The signals at frequencies f ₁ and f ₂ arriving at different inputs (1 and 2) of bridge I are divided between its outputs 3 and 4 into two components of equal amplitude. Moreover, if the phase shift along the input arms 1 and 2 of the next bridge II between the components of the signal f ₁ , passed from one of the input arms (1) of the previous bridge I, is equal to Ф (in this case with VSCH Ф = 90 ^o ), then the phase shift between the components of the signal f ₂ passed from the second input arm 2 of the previous bridge I, is Ф + 180 ^o . This shift is compensated by the phase shift obtained due to the different lengths of the segments 3 'between the pairs (3-1 and 4-2) of the outputs and inputs of the bridges I and II.

Thus, in the second bridge (II), the phase ratio of the components of both signals is the same, and they both go to the same arm 3 of bridge II, to which a common waveguide AFT is connected. However, the different lengths of the waveguide lines connecting both bridges I and II provide phase synchronization (differential inter-frequency shift at the input of one of the arms (2 for II) equal to 180 ^o ) only at the middle frequencies of the multiplexed signals. When deviating from these frequencies, the phase incursion becomes different from 180 ^o . Therefore, within the working bands of the transmitters, part of the signal power enters the ballast load 4 '. To this it is necessary to add losses due to the attenuation of energy in the walls of the waveguide.

 To combine several transmitters in the common signal path, multi-stage phase difference schemes are constructed.

 The third VSCM (III) with movable short circuits 2 'serves in the circuit depicted in FIG. 1, to select the center frequencies of the combined signals and adjust the separation between them. The bias of the short circuit leads to a change in the length of the phase-compensating segment, which regulates the spacing between the carrier frequencies.

 Phase-difference devices, as well as amplitude-difference ones, are widely used for BC waveguide paths by signals of several powerful transmitters in domestic satellite communication stations and belong to the class of resonator-free circuits for combining signals of different frequencies. They have high electric strength, low losses, low distortion of the phase response and high coordination with the AFT or the outputs of the transmitters. Depending on the number of transmitted signals, the separation between the carrier frequencies and the bandwidth of each, one of the difference schemes or their combination is used to combine them.

 The disadvantage of the phase-difference method of summing incoherent signals is the difficulties that arise when combining transmitters close in operating frequencies. Calculations show that with incoherent addition, for example, in the 6 GHz band, with a frequency spacing Δf = 100 MHz, the length of the compensating segment of the waveguide between the hybrid joints (HMI) is about 1.08 m, if Δf ≈ 25 MHz, then the length is ≈4.5 m, respectively, at Δf ≲ 10 MHz, it should be approximately 10 m or more. Natural with such a large size of the device is the presence of losses due to attenuation in the phasing waveguide, which in turn leads to the appearance of an amplitude imbalance between the half signal components at the input of the final hybrid connection and an unacceptable increase in the part of the signal power released at the ballast load.

 Phase difference schemes provide acceptable frequency response for incoherent signal addition with a frequency spacing of up to 100 MHz. When combining signals with a smaller separation, for example, 50 MHz, the losses at the edges of the working band of the transmitters (± 17 MHz) will be an unacceptably large value (1.4 dB). Therefore, in such cases, devices made according to the amplitude-difference scheme are used.

 However, the amplitude-difference principle of summing incoherent frequencies, like the phase-difference principle in the form in which it is usually realized, does not allow the combination of closely spaced signals with the corresponding spacing bands, the distance between the center frequencies of which is less than 0.2% of the average frequency of their carriers. The reason for this is the impossibility of synthesizing in practice a complex semi-reflective structure, which serves as the main node of the amplitude-difference scheme. With a small separation of signals to ensure the required forms of frequency response and phase response of this node, it is necessary that it includes a large number of pairs of heterogeneities. With an increase in the number of inhomogeneities, the dimensions of the device and attenuation significantly increase. In addition, this causes a strong sensitivity of the circuit to the accuracy of their installation in the waveguide and criticality to the distance between them, which translates into the possibility of accumulating phase errors that distort the phase response, and hence the frequency response, and the difficulty of tuning.

The invention pursues the following objectives:
1. Creating a device for combining incoherent signals, which with the same success summarizes them with any (small or large) spacing.

 2. Development on the basis of such a universal scheme of a device for summing very close frequencies into the common path (spacing less than 0.2% of the average frequency of the carrier transmitters), which would allow incoherent signals with corresponding spacing bands to be added with reasonable losses.

 The goals are achieved by the fact that in the phase-difference device, the portion of the dispersion phasing line 3 'between the output 4 and input 2 of the hybrid compounds I and II (bridges 1') (Fig. 1) is removed and replaced by a cavity resonator 4 ', acting as a reactive load of one from the shoulders (3 - intermediate) of the Y-circulator II (3 '), included by means of arms 1 and 2 instead of this section in the resulting gap (4-2) the output-input of these bridges (figure 2). To amplitude-balance this circuit and set the correct initial phases (without a resonator with a shorted arm 3 of circulator II) of two equal signal components to another adjacent gap (3-1), the output-input of hybrid compounds 1 'is also set to Y-circulator (I), but loaded on a moving short circuit 2 '(Fig. 2).

The position of the short circuit is selected so that when the intermediate arm of the circulator II is shorted out, the signals of half power of both combined frequencies are present at the outputs 3 and 4 of the last bridge II. Moreover, in the input arms 1 and 2 of the indicated hybrid connection, the frequency components f ₁ are in phase, and the frequency components f _{2 are} out of phase (or vice versa). In this case (figure 2), if you load this F-circulator with a notch resonator 4 'with a resonant frequency f ₀ (f ₁ + f ₂ ) / 2, both signals will go to one of the output arms of the VSCM (3 for II), connected to the general AFT. As you know, any circuit (resonator) with sufficient accuracy in a certain frequency band before resonance is physically equivalent to one of the integral elements (capacitance or inductance) included in it, and to another in a certain band after resonance. Hence, when a signal with a carrier frequency f ₁ <f _{0 is} reflected from the resonator, it receives an additional phase shift of 90 ^o +180 ^o , and a signal with a carrier f ₂ > f ₀ acquires a phase shift of 90 ^o (or vice versa). The differential phase difference between the signals in the synchronization channel is equal to 180 ^o , it is this condition that must be met to combine them in one of the output arms of the last VCHM. Y-circulator II is needed to set the direction of signal propagation, because from the point of view of the resonator, the reflected waves move towards the incident ones.

 The difference between the added incoherent frequencies depends on the notch band of the resonator, which in turn is determined by the intrinsic and loaded Q factors. The larger the intrinsic Q factor of the resonator and the weaker the connection with the transmission line, the greater its loaded Q factor. An increase in the Q factor loading causes a narrowing of the notch band, which makes it possible to maintain the phasing channel frequency response and frequency response required for incoherent summation at very small frequency spacings without introducing significant amplitude asymmetry due to the non-uniform attenuation in the paths connecting the bridges.

 If the average frequency of the carrier signals is constant, and it is the center frequency of the notch band of the resonator, then the minimum distance between the combined frequencies is determined by the largest physically realized intrinsic Q factor of the resonator and the smallest coupling at which it is still capable of normal excitation. The maximum distance between the combined frequencies at a constant initial loaded Q factor is determined by such a coupling value at which the resonator can still be considered a resonator, i.e. he is still able to perform the function of notch.

In order for the device to be universal, it is necessary to use a resonator with the highest intrinsic Q factor. In this case, the H _III mode half-wave cavity is used, made as a section of a short-circuited circular waveguide limited by a thin diaphragm. It is quite technologically advanced to manufacture, easy to set up, and at the same time has a significant quality of its own. The methodology for calculating such resonators is well known and described, for example, in the book by Matteya D.L. Young L. Jones E.M. T. Microwave Filters, Matching and Communication Circuits ", v. 1, 1971. (Translated from English under the editorship of L.V. Alekseev and F.V. Kushnir). The higher the loaded Q factor, the less is the separation between by combined signals and already frequency bands in which the amplitude-phase relations necessary for incoherent addition are fulfilled.However, it is clear that closely spaced signals also have narrow spectra, therefore, the attenuation requirements at the edges of the bands they occupy are satisfied.

Below we prove the correspondence of the proposed solution to the criterion of "significant differences":
1. Distinctive design features of the proposed technical solution are the use of a combining device (phase difference scheme, Fig. 1) to create in one of the arms the necessary phase compensation of a tunable cavity resonator 4 'with adjustable coupling with external circuits, connected in series through a ferrite Y-circulator II to create a unidirectional reflection, and in the other parallel arm for amplitude balancing of the component signals and setting their initial phases of the same Y-circulated RA 1, loaded on a movable short-circuit 2 '(figure 2).

 The bandwidth of the volume notch resonator at a level of 3 dB corresponds to the spacing of the center frequencies of the added signals. The bandwidth of the notch can be changed by restructuring the coupling of the resonator with the Y-circulator (in this case, it depends on the diameter of the hole in the diaphragm between the circulator and the resonator), and the resonant frequency is within a small range (≈5%) by a capacitive screw, and by a significant change in the length of the resonator (figure 2).

Since the frequencies of the summed incoherent signals are on different sides of the resonant frequency of the notch, between them there is a phase shift of 180 ^o . This shift is necessary for phase synchronization. All the distinctive design features, together with the known ones, represent a single set, the elements of which are interconnected, and the replacement of any element does not allow to obtain a positive effect by combining signals with any small or large spacing using one universal device with the simple possibility of tuning, tuning and simplicity of engineering design, or increases losses in the circuit. If it is necessary to sum the incoherent signals of more than two transmitters, a cascade connection of circuits is used when the outputs of the circuits of the previous cascade are inputs of subsequent cascades.

 The absence of any one of these new design differences leads to the loss of a positive effect.

 2. The applicant has reviewed the scientific and technical literature on cl. H 01 P and UDC 621.372 related to signal combining devices, volume resonators, semi-reflective structures, etc. As a result of the analysis of the above literature, the applicant did not find technical solutions that have a combination of distinctive features similar to the proposed one.

 An additional classification according to the hallmarks of the previously mentioned paragraph 1, a new implementation of the phasing arm is impossible, because the phasing path is part of a universal device for combining incoherent signals according to a phase difference scheme and is in the same class.

 3. In addition, the new principle of phase synchronization provided the proposed solution, in comparison with the prototype, with an additional new property: in the case of very large spacings between the carrier transmitters, when the use of the resonator is impossible (due to the need for strong coupling with external circuits, i.e. Y-circulator II, the resonator degenerates into a short-circuited line segment), the intermediate arm of the Y-circulator 3 in the phasing channel is shorted (the resonator 4 'is disconnected), and due to the presence in the parallel channel of the circulator 1 with a moving short circuit 2 ', the required dispersion phase incursions are realized, moreover, at a length half as small as in the standard phase difference scheme, because the waves go back and forth along the same section of the waveguide shorted at the end. This reduces the dimensions of the device.

In FIG. Figure 2 shows a diagram where the numbers indicate the arm numbers of the VSCH and FC, the numbers with a dash the functional units of the device, and the Roman numbers indicate the serial numbers of the unified elements of the circuit, a cylindrical screw-tuned resonator with oscillation H _{III is} used as a notch element, the diaphragm being replaced by communication elements.

The proposed scheme works as follows (similar to the phase-difference scheme). The combined signals from two transmitters with incoherent carriers t ₁ and t ₂ are received at inputs 1 and 2 of the first VMS. At its outputs 3 and 4, half-amplitude components of each signal with phase shifts relative to each other are obtained (see Table 1).

The values indicated in parentheses (see Table 1) were obtained as a result of a mathematical transformation in order to bring the components of incoherent frequencies in one of the arms (in this case, in the third) to the same initial phases. The lengths of the segments of the waveguides connecting the outputs of the first VMS with the next are the same. The only difference between the channel 3-Y-1 from 4-Y-2 is that the load of the intermediate arm 2 of the Y-circulator 1 in the path 3-Y-1 is a waveguide with a movable short circuit 2 ', and in the path 4-Y-2 resonator 4 'with communication with the circulator II through the hole in the diaphragm. The position of the short circuit is set so that when the channel 3-Y-1 passes, the signal components receive an additional phase incursion of 90 ^o . In this case, the phase ratio turns out to be such that with a shortened intermediate arm of the circulator 3 'in the channel 4-Y-2 (synchronization channel), i.e. in the absence of a resonator, at each of the outputs 3 and 4 of the last VHSM II there are signals of half power from both transmitters, since from inputs 1 and 2 of this bridge, the corresponding components with the carriers f ₁ and f ₂ are squared at outputs 3 and 4. If, however, a resonator is installed in the phasing path, the following result of the correspondence of the phases of the components is obtained (see Table 2).

Since the cavity resonator is included in channel 4-Y-2 and the frequencies f ₁ and f ₂ are located on opposite sides of its resonant frequency, the components of the signals when passing through the Y-circulator II with this notch resonator acquire additional phase incursions (90 ^o or 90 ^o respectively). At the same time, the required differential phase shift at input 2 of the last VHSM II between them is realized, equal to 180 ^o , which is necessary to perform the correct phase ratio of half incoherent frequencies in the input arms of this bridge in order to combine them at output 3.

 Part of the power due to the amplitude asymmetry of the 3-Y-1 and 4-Y-2 waveguide lines, and also due to the phase imbalance of the phase-frequency characteristics of the circuit elements (bridges 1 ', circulators 3' and the resonator) in the frequency band of the signals is allocated at the output of 4 VHSM II at a ballast load of 5 '.

The universal device for combining incoherent signals of close frequencies to specific carriers f ₁ and f ₂ with a given separation Δf is configured as follows:
a) the movable short circuit 2 'in the path for setting the initial phases is set so that the signal with a frequency f ₀ (arithmetic average of f ₁ and f ₂ ) from both inputs (1 and 2 for 1 VHSM) of the circuit is divided into equal power parts by its outputs (3 and 4 for VSCM II) with a shortened intermediate arm 3 of circulator II in the synchronization path;
b) the Y-circulator 3 'in the phasing channel is loaded onto the notch volume resonator 4' with the required intrinsic Q factor and coupling, the resonant frequency of which is f ₀ , and the band is at the level of 3 dB-Δf;
c) tuning elements (resonator screw, selection of the communication diaphragm and position of the short-circuit switch 2 ') achieve the greatest power of signals with center frequencies f ₁ and f ₂ at the output of the circuit (3 for II HFM) connected to a common AFT.

To be able to change the spacing between incoherent signals, it is necessary to have an appropriate set of coupling diaphragms, which provide the necessary resonance rejection bands Δf. In the case of a change in the frequency schedule, there should be a set of resonators with the expected average notch frequencies f ₀ .

 Using non-reciprocal and bridge nodes of another technological design, it is possible to build similar devices in coaxial and flat versions. The reliability of the positive effect is confirmed by the results of experimental verification of the layout in the range of 6 GHz.

 Figure 3 shows the generalized dependence of the minimum loss and diameter of the hole in the communication diaphragm on the frequency spacing. In FIG. Figure 4 shows the frequency response of a circuit combining signals with carriers of 5.94 GHz and 6.02 GHz (80 MHz spacing), the diameter of the circular communication hole in the diaphragm is 18 mm. From the graph clearly follows the possibility of combining incoherent signals with the proposed modified phase-difference scheme.

 With a minimum frequency difference of 4 MHz, the loaded Q factor of the resonator was ≈1500 units. Signal attenuation was about 2.1 dB.

 The model used serial VSCMs, which have good strength, Y-circulators of the FCV-2-11 type, standard matched load 35 • 15 mm. The resonator was made of Invar, which provides good thermal stabilization of the notch band and the middle frequency. The inner surface of the resonator and the diaphragm are silver plated.

 The measurements were carried out on a device P2-59. In the industry laboratory solid-state microwave devices NEIS them. N.D. Psurtseva made prototypes of the claimed devices combining incoherent signals in a common AFT.

Claims (1)

 A universal device for combining incoherent signals, containing two hybrid compounds in the form of waveguide-gap bridges, in one of which one of the arms is loaded on a matched absorbing load and the adjacent arms of which are connected respectively by two lines of equal electric length, characterized in that the first line is ferrite The U-circulator, the intermediate arm of which is loaded on an adjustable short-circuit, and the second line is identical to the ferrite U-circulator, the intermediate arm of which agruzheno through the diaphragm due to bandstop resonator, wherein the width of the notch resonator bandwidth of 3 dB corresponds to the carrier spacing merged signal.

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