Classifications

• • 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
  • H01P1/213—Frequency-selective devices, e.g. filters combining or separating two or more different frequencies

Definitions

• the present invention relates to a device for separating broadband microwave bands.
• Microwave band splitters are devices used in particular in broadband microwave receivers. These receivers receive multichannel signals with adjacent channels that the splitters are responsible for separating individually. The performance of these wideband microwave receivers is limited by the following points: • the head amplifier (the one immediately following the receiving antenna) has non-linearities causing the generation of harmonic frequencies;
• the bandpass filters currently used at microwave frequencies are generally of the type with rectilinear coupled lines or folded in a "U" shape. Such filters have insufficient stiffness of the sides of their frequency / attenuation characteristic and insertion losses.
• Document US Pat. No. 5,838,675 discloses a microwave channel separator with a “manifold” type structure and including amplifier-limiters, which makes it complex to produce.
• the present invention relates to a separator device for wideband microwave receiver of the aforementioned type, this separator device does not have the aforementioned drawbacks of the devices of the prior art.
• the separator device comprises a set of pairs of bandpass and lowpass filters, and in each pair of filters relating to a frequency band Fb n -Fh n to be separated from a set of bands, the band pass filter has a pass band between Fb n and Fh n (with Fb n ⁇ Fh n ), while the low pass filter has a cutoff frequency located at Fh n . ⁇ , all the filters being made of superconductive material cooled in operation to a temperature below the critical temperature of this material, each pair of filters being produced on the same individual strip and having a common inlet to which these filters are directly connected.
• FIG. 1 is a block diagram of a separator device according to the invention
• FIG. 2 is a plan view of a pair of filters forming part of a separator device according to the invention
• FIG. 3 is a plan view of a preferred embodiment of a bandpass filter forming part of the pair of filters of Figure 2; and - Figure 4 is an enlarged detail view of the filter of Figure 1.
• the separator device 1 shown diagrammatically in FIG. 1 comprises several pairs of filters, each pair of filters consisting of a band pass filter and a low pass filter.
• the separator device comprises five pairs of filters, respectively referenced 2.1 to 2.5, but it is understood that the number of pairs of filters of the separator device of the invention may be different, depending on the number of channels contained in the signal received by the microwave receiver of which this separator device is a part.
• the first pair of filters 2.1 connected just after input 3 is that relating to the highest frequency channel (channel 1 in the example), the second pair, 2.2; connected just downstream of the first pair, relates to the channel (channel 2) at frequencies just lower than those of channel 1, and so on up to the pair of filters 2.5 (channel 5).
• channels 1 to 5 respectively have the following frequency bands (in GHz): 16-18, 12-16, 8-12, 4-8 and 2-4, but it is understood that these values may be different in other applications.
• Each pair of filters 2.1 to 2.5 (2.1 to 2.n in the most general case) is produced on the same strip of individual support substrate, as described below with reference to FIG. 2.
• the different strips of the separator 1 are fixed in a box with separate boxes 4, parallel to each other, and decoupled from each other by electromagnetic shields 5.1 to 5.4 formed on the partitions of the boxes of box 4.
• Input 3 is connected to point 5 which is the common input of the filters of the pair 2.1.
• the output 6 of the pair of filters 2.1 to the next pair 2.2 is the output of the low-pass filter of the pair 2.1 (opposite to its input 5).
• This output 6 is connected to the input 7 of the pair 2.2 which is the common input of the filters of the pair 2.2 and so on up to the pair 2.5 (outputs 8, 10, 12 connected respectively to the inputs 9, 11 , 13).
• the output 14 of the low-pass filter of the pair 2.5 is connected either to a suitable dummy load (in order to absorb residues of the incident signal) or, for example, to a spectrum analyzer.
• the signals from channels 1 to 5 are collected, and only these signals (without harmonics or extreme parts of the contiguous channels).
• FIG. 2 shows one of the bars of the separator 1, for example the bar 2.1. Its bandpass filter is produced as follows. The bandpass filter described here has a bandwidth of 2 or 4
• the bandpass filter 20 shown in Figures 2 to 4 of the drawing comprises, for the present example, twelve lines of electrical length ⁇ / 2 coupled together and referenced L1 to L12, but it is understood that the number of lines d 'a filter can be different, advantageously between 12 and 16.
• the stiffness of the flanks of the frequency / attenuation characteristic being a direct function of the number of lines, it may be necessary to seek a compromise between a great stiffness and a large bulk (general, the devices comprising such filters should include a large number of them to improve their characteristics, while their size must be limited, for example when these devices are airborne).
• Lines L1 and L12 are "folded" lines with a general "V" shape.
• the two branches of this "V" instead of being rectilinear, are each in the form of a "stair step" having, at mid-height, a landing perpendicular to the 'axis of symmetry of the' V 'at each end of which is connected a' post 'parallel to the axis of symmetry of the' V '.
• the successive lines are arranged head to tail, so as to be optimally coupled and to reduce the size of the filter.
• the free end of line L12 is directly connected to a metallized block E formed on a support strip 21 and constituting the input terminal of the filter 20.
• the free end of line L1 is directly connected to a metallized block S formed on the substrate 21 and constituting the output terminal of the filter 20.
• a metallized block S formed on the substrate 21 and constituting the output terminal of the filter 20.
• the shapes and dimensions of the terminals E and S are determined so as to give them an adequate impedance. It is also understood that, if only the bandpass filter 20 is used, the filter can enter the line L1 side, and exit it from the L12 line side.
• the bar 21 has for example a rectangular shape, and the lines L1 to Ln follow one another in a direction 22 parallel to a long side of the bar 21. These lines have a general shape of "V" and the axes of symmetry of these " V "are all parallel to a direction 23 which is perpendicular to direction 22, the openings of the" V "being alternately directed in direction otherwise.
• the common “height” of all the lines L1 to Ln is referenced h (dimension of the lines measured parallel to the direction 23).
• all the lines are produced as follows, as explained below for the line Lm, identical to all other lines, only the orientation of the lines alternating from one line to the next.
• the axis of symmetry of the line Lm is referenced 24, and only half of this line is described here (to the left of the axis 24, as seen in FIG. 4), the other half is deducing the symmetry with respect to the axis 24.
• the line Lm comprises a first rectilinear section 25 extending over practically half the height h. This section is parallel to axis 24 and is about h / 2 away from it. The section 25 is followed by a section 26 which is perpendicular to it and goes towards the axis 24 without however reaching it. The section 26 is extended by a section 27 parallel to the axis 24, which itself extends by a section 28 perpendicular to the axis 24 and arriving up to the axis 24.
• the other half of the line Lm consists of sections 25a to 28a, respectively symmetrical of sections 25 to 28 with respect to axis 24.
• D be the distance between sections 25 and 25a.
• the sum of the lengths of the sections 28 and 28a is substantially equal to D / 3, and it follows that the lengths of the sections 26 and 26a are practically each equal to D / 3.
• Successive lines L1 to Ln are very close to each other, in order to ensure optimum coupling between them.
• the distance d between two adjacent lines is advantageously a few tens of micrometers and preferably less than 100 ⁇ m for filter lines capable of operating at frequencies between 2 and 20 GHz, for example.
• the low-pass filter 29 of the strip 2.1 is produced in a manner known per se with regard to its topology, the important difference compared to the known low-pass filters operating at similar frequencies residing in the fact that the conductive elements of the low-pass filter of the invention are, not conventional metallic layers (Cu, Au, etc.) but are composed of thin superconductive layers deposited on the same strip of substrate 21 as that carrying the band-pass filter described here - above. For this reason, the low-pass filter 29 will only be described here briefly.
• This filter 29 comprises several LC cells, for example nine cells 30.1 to 30.9.
• Each of these cells 30.1 to 30.9 consists of a narrow line, possibly folded in meanders and acting as an inductor (referenced 31.3 for cell 30.3 only, to simplify the drawing) and a rectangular plate (referenced 32.3 for the cell 30.3) acting as a capacitor with the metallization of the other face of the substrate 21 (not visible in the drawing).
• the electrodes of the capacitors of cells 30.1 to 30.8 are of the same dimensions, while that of cell 30.9 is of smaller dimensions.
• the inductances of cells 30.2 to 30.8 are identical, while those of cells 30.1 and 30.9 are smaller.
• the capacitor of the last cell 30.9 is connected to a small block S1 constituting the output terminal to the next pair (or to the termination for the pair 2.5).
• the relative dimensions of the inductors and the capacitors of the various cells of the low-pass filter are determined as a function of the relative impedances of the filter and of the elements connected to its input and to its output, the impedance adaptation being able to be taken into account. charge by the first and last cells, or else be progressive and affect neighboring cells.
• the shapes and dimensions of the conductors connecting the filter cells to terminals 15 and 16 are such that these conductors provide part of the impedance matching.
• the inductor 30.1 is connected not directly to the input terminal E, but to the line L12 of the bandpass filter, almost in the middle, but it is understood that this connection could be carried out differently (inductor 30.1 connected directly to terminal E or at another location on line L12).
• inductor 30.1 connected directly to terminal E or at another location on line L12.
• the separator can be connected at the head, immediately behind the antenna. This separator is then followed by amplifiers, which very strongly eliminates or decreases the harmonics which would otherwise be produced by these amplifiers;

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• Control Of Motors That Do Not Use Commutators (AREA)
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• Aerials With Secondary Devices (AREA)
• Two-Way Televisions, Distribution Of Moving Picture Or The Like (AREA)
• Inorganic Insulating Materials (AREA)
• Surface Acoustic Wave Elements And Circuit Networks Thereof (AREA)

Applications Claiming Priority (3)

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• 2002
  • 2002-11-08 FR FR0214049A patent/FR2847079B1/fr not_active Expired - Fee Related
• 2003
  • 2003-11-03 EP EP03795990A patent/EP1568098B1/de not_active Expired - Lifetime
  • 2003-11-03 ES ES03795990T patent/ES2280834T3/es not_active Expired - Lifetime
  • 2003-11-03 AT AT03795990T patent/ATE352879T1/de not_active IP Right Cessation
  • 2003-11-03 DE DE60311520T patent/DE60311520T2/de not_active Expired - Lifetime
  • 2003-11-03 AU AU2003298265A patent/AU2003298265A1/en not_active Abandoned
  • 2003-11-03 WO PCT/EP2003/050780 patent/WO2004042863A1/fr active Search and Examination

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