FR2606936A1 - APPARATUS FOR COMBINING CERAMIC TRANSMITTERS PROVIDED WITH A VARIABLE ELECTRICAL LENGTH SECTION AND INTERFACE WITH COUPLING LOOPS - Google Patents

Abstract

THE COMBINATION APPARATUS OF THE INVENTION INCLUDES A SET OF 100 TEMPERATURE COMPENSATED RF FILTERS THAT ARE PAIRED TO A MICROBAND COMBINATION DEVICE 300 TO COMBINE A SET OF INPUT RF SIGNALS TO BE APPLIED TO A COMMON ANTENNA. THE SIGNALS RECEIVED BY AN INPUT COUPLING LOOP 122 FROM EACH FILTER 100 ARE FILTERED AND SENT TO COMBINATION DEVICE 300 THROUGH OUTPUT COUPLING LOOP 311. THE COMBINATION DEVICE INCLUDES A CIRCUIT PLATE 310 WITH A SET OF LINES ABOVE. OF TRANSMISSION AND A LINE OF TRANSMISSION OF TUNING IN SHORT-CIRCUIT, IN MICROBANDS, ALL CONNECTED TO A CENTRAL JUNCTION AND IT IS TUNED BY A VARIABLE IMPEDANCE PRODUCED BY VARIING THE POSITION OF A DIELECTRIC PLATE OF TUNING ON THE LINE OF TRANSMISSION OF AGREEMENT.

Description

The present invention relates generally to arrangements

  radio frequency (RF) combination or multiplex tifs coupling a

  set of RF transmitters with a single antenna and, more particularly-

  ment, to a variable electrical length tuning device and coupling a loop interface for a combination device

ceramic emitters.

  In order to combine a number of RF transmitters,

  isolate RF signals from each transmitter from those of another

  to prevent intermodulation and possible deterioration of the transmitters. RF filters of the cavity type can be used

  filled with air to insulate between RF transmitters.

  Each cavity filter is tuned to pass only the RF signal from the transmitter to which it is connected, each RF transmitter producing an RF signal of different frequency. The output signals from each filter can be combined and sent to a common antenna by a combination device of the type indicated and described in the U.S. Patent. No. 4,375,622. Each filter is coupled to this combination device by exactly equal lengths of a coaxial cable. The combination device is tuned

  by means of transmission lines or regulated tuning sections

  manually, which are identically coupled to the

  combination by coaxial cable. However, these communication devices

  not only difficult to tune, but also

  expensive and they require an excessive amount of pre-

heavens.

  A classic device used to compensate for temperature

  these cavity filters are described in the U.S. Patent.

  NO 4,024,481. However, these air filled cavity filters are both expensive and relatively large, so that these cavity filters take up an excessive amount of valuable space at remote antenna locations located in

high of buildings and mountains.

  The dimensions of these RF filters can be reduced by using a ceramic resonator. Such a filter implementing a

  ceramic resonator is described in the U.S. patent.

2 2606936

  NI 4 241 322. Although providing a more compact filter, the reso-

  The ceramic element contained in this filter can have large shifts in the resonant frequency since it is not compensated for variations in ambient temperature and induced by dissipation of RF energy. Another filter described in the

  U.S. patent N 4 019 161 implements standard devices

  to compensate in temperature a ceramic resonator mounted on a micro-integrated circuit substrate, but it does not provide

  no heat dissipation in the ceramic resonator.

  It is therefore an object of the present invention to provide

  provide an advanced ceramic resonator that is compensated for both room temperature variations and variations

induced by dissipation.

  Another object of the present invention is to provide a thread

  tre compact and economical RF comprising a ceramic resonator sandwiched between temperature compensation discs

  and electromagnetic screens and enclosed in a metal housing

  lique. Yet another object of the present invention is to provide an improved RF filter comprising a ceramic resonator thermally coupled by compensating discs to a metal housing to minimize a temperature increase

  due to energy dissipation in the ceramic resonator.

  Another object of the present invention is to provide a circuit

  improved combination device tuning that produces an input impedance that can vary within a centered interval

  roughly at a predetermined input impedance.

  Yet another object of the present invention is to provide a compact and economical RF signal combining device

  which includes a single variable reactance tuning circuit.

  Yet another object of the present invention is to provide an improved RF signal combining device which

  operates a unique coupling interface between a communication device

  microstrip hoeing and two or more ceramic filters.

  Briefly described, the present invention encompasses an RF filter comprising a ceramic resonator placed sandwiched between

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  first and second temperature compensation discs and

  first and second protection plates. The resonator, the first

  The first protection plate and the first compensating disc can have concentrically aligned holes in which a tuning core is inserted to adjust the resonant frequency of the ceramic resonator. The resonator, the first and second

  compensation discs, the first and second protective plates

  tion and the tuning nucleus are surrounded and maintained in spa-

  tial between them by a metal housing. Input and output signals can be sent to the RF filter by means of respective input and output coupling loops which can be placed

  at any suitable location on the metal housing.

  Briefly described, the present invention encompasses an apparatus

  RF signal combining board including a coupling interface

  single age between a microstrip combination device and two

  ceramic filters or more. The micro- combination device

  band further includes a single tuning circuit and a wafer

  of a substrate circuit comprising a set of transmission lines

  sion in microstrips and coupler circuit boards

  each plant a ceramic filter corresponding to a junction.

  The single tuning circuit includes a substrate circuit board having a first side and a second side, the second

  side being covered with a metallic layer; a transmission line

  tuning channel with an input coupled to the junction of the device

  microstrip combination signal, having a predetermined length, placed on the first side of the substrate circuit board and being terminated by a predetermined termination impedance;

  a dielectric plate having a dielectric constant predeter-

  mined to cover the chord transmission line, the impedance

  input of the tuning circuit having a predetermined input impedance-

  mined when the dielectric plate covers half of the tuning transmission line; and a device for adjusting the quantity

  whose dielectric plate covers the transmission line

  cord to vary the input impedance of the tuning circuit

  in an interval centered approximately at the pre-input impedance

determined.

  Other features and advantages of the present in-

  vention will be highlighted in the following description,

  born by way of nonlimiting example, with reference to the drawings an-

  attached in which: Figure 1 is an exploded perspective view of the preferred embodiment of the RF filter of the present invention; Figure 2 is a block diagram of a combination device advantageously using RF filters such

  as shown in Figure 1 to send RF signals

  respective RF devices to a combination device for an application

cation to a common antenna;

  Figure 3 is a top view of a combi device

  micro band and RF filter shown in Figure 1; Figure 4 is a top view of a circuit board

  coupling loop implemented in the combi device

  microstrip house shown in Figure 3; Figure 5 is a bottom view of the circuit board shown in Figure 4; Figure 6 is a top view of the microstrip circuit board used in the microstrip combining device shown in Figure 3;

  Figure 7 shows the tuning circuit used for ac-

  string the microstrip combination device shown in Figure 3; Figure 8 is an exploded view of the tuning circuit and a device used to tune the microstrip combining device shown in Figure 3; and Figure 9 is a bottom view of the combination device

  with microstrip shown in Figure 3.

  In Figure 1, there is shown an exploded view of a filter

  RF 100 which is particularly suitable for use in the appliance

  Figure 2 antenna combination module to combine two or more RF transmitters operating in the frequency range of 870-896 mHz. The nominal value Q not loaded of the filter 100 is equal

  to around 14000. The frequency offset of filter 100 in the inter-

  Valley of ambient temperatures from - 30 C to + 6GO C is at the maximum

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  oe 55 kHz with respect to the nominal frequency at am-

  The nominal dimensions of the lO0 filter are 14 cm in diameter and a length of 7.6 cm, compared to the diameter of 15.2 cm and

  the 33 cm length of a conventional air filled cavity filter.

  In addition to being much smaller than an equivalent air-filled cavity filter, filter 100 represents a cost saving of

  60% materials on the cavity filter filled with equivalent air.

  In FIG. 1, the filter 100 comprises a ceramic resonator 116 which is sandwiched between a first disc of

  compensation 114 and a second compensation disk 120. The resonance

  tor 116 is preferably made of a ceramic compound having a dielectric constant of at least thirty-six. Commercially available ceramic compounds such as those including preselected amounts of barium oxide, titanium oxide, zirconium oxide, zinc oxide, lanthanum oxide and / or oxide tin can be used. For example, compounds of

  Suitable ceramics are described in the U.S. Patent.

  No. 3,938,064 and in an article by G.H. Jonker and W. Kwestroo,

  entitled "The Ternary Systems BaO-TiO2-SnO2 and BaO-TiO2-ZrO2", pu-

  blié in the journal Journal of American Ceramic Society, Volume 41,

  NO 10, October 1958, pages 390-394 (incorporated here for reference).

  Among the ceramic compounds described in the article by 3onker, the compound Ba2Ti9020 from Table VI, having the composition of 18.5% of molecules of BaO, 77.0% of molecules of TiO2 and 4.5% of molecules of ZrO2 and having a dielectric constant of forty, can be

  used for resonator 116. Many other cereal compounds

  can be similarly used in Jonker's article

  read. The compensation discs 114 and 120 are preferably

  made of alumina (A1203), because alumina has a low per-

  dielectric, high thermal conductivity compared to

  ceramic resonator 116 and a dielectric temperature coefficient

  positive plate with respect to that of the ceramic resonator 116.

  According to an important characteristic of the filter 100, the coefficient

  negative dielectric temperature of the ceramic resonator

  mique 116 can be essentially compensated by the positive dielectric temperature coefficient of the compensation discs in

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  alumina 114 and 120. That is to say that the dielectric temperature coefficient of - 36 millionths / C of the ceramic resonator 116 can be appreciably offset by the dielectric temperature coefficient of + 113 millionths / C of the compensation discs in alumina 114 and 120. As is known in the art, the dielectric temperature coefficient of a dielectric material

  is proportional to the physical dimensions. Therefore, we

  holds the desired compensation by choosing the thickness of the alumina compensation discs 114 and 120 so that their dielectric temperature coefficient is essentially the same magnitude but

  of opposite sign with respect to the dielectric temperature coefficient

resonator plate 116.

  In addition, the alumina compensation discs 114 and 120 not only provide room temperature compensation, but also minimize the temperature increase due to energy dissipation RF from the ceramic resonator 116 by providing low thermal resistance between the resonator ceramic 116 and the upper and lower covers 112 and 128 of the

  filter housing, and minimize overall RF loss

  ble of the filter by supporting the resonator 116 far from the covers

  of aluminum 112 and 128 inducing a loss. Since alumina con-

  dissipates heat much better than air, 114 alumina discs

  and 120 efficiently conduct the heat from the resonator 116 to the layers

  112 and 128 and housing 124, which minimizes the temperature increase in the resonator 116. A force of

  compression exerted by springs 144-147 of a protective plate

  tion 142 maintains good thermal contact between the resonator 116

  and covers 112 and 128, so that the thermal resistance

  between the resonator 116 and the covers 112 and 128 is inferior

  less than 1 C / W (i.e. 0.68 C / W predicted by study analysis). Consequently, according to another characteristic of the filter, it is possible to couple high power transmitters to the filter 100.

  since the increase in temperature due to dissipation of energy

  gie in the ceramic resonator 116 is minimized by the relatively low thermal resistance between the resonator in

  ceramic 116 and the upper and lower covers 112 and 128.

  For example, when the energy RF dissipated in the filter 100 is equal

  at twelve watts, the temperature of the ceramic resonator 116 does not increase

  only 8 C above room temperature and the

  quence of filter 100 shifts approximately 8 kHz

  sound of RF energy dissipation.

  Referring again to Figure 1, we see that the

  ment intended for the filter 100 comprises an upper cover 112, a housing 124 and a lower cover 128 which are preferably molded from an aluminum alloy (for example, aluminum alloy No. 380). The top cover 112 includes a cap

  upper 132 in which a threaded sleeve 133 consisting of preferably

  The rence of brass is fixed by pressure. The upper cover 112 also includes a hollow part for receiving a protective plate 142. The protective plate 142 comprises three lugs 160, 161 and 162 for positioning the disc 114. Likewise, the lower cover 128 comprises a hollow zone intended to receive a protective plate protection 148 and part of the disc 120. The degree

  high 121 of the disc 120 fits into the hole formed in the reson-

  teur 116. The pins 160, 161 and 162 of the protective plate 142,

  the high degree 121 of the disc 120 and the hollow zone of the cover

  128 keep the resonator 116 in an appropriate spatial relationship with the disks 114 and 120. The upper cover 112 is fixed to the housing 124 by means of four screws which are inserted in four holes, for example, 107 and 108 at the periphery of the cover 112 and housing 124. A 0.150-shaped ring constitutes a moisture seal and, if impregnated or covered with a conductive material, an electromagnetic seal between

  the upper cover 112 and the housing 124. The lower cover

  laughter 128 is preferably molded with the housing 124, but, in other embodiments of the filter 100, one can separate the lower cover 128 from the housing 124 and fix it to the

screw means.

  In order to produce a high Q filter, we make the logemer: RF filters typically from a very conductive material

  such as copper or its inner surfaces are covered with it

  this. For detailed information on filter design,

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  refer to the following two articles: "Design of Cylindrical Dielectric Resonators in Inhomogeneous Media", by René R. Bonetti

  and Ali E. Atia, IEEE Transactions on Microwave Theory and Techni-

  ques, Volume MTT-29, N 4, pp. 323-326, April 1981; and "Microwave Bandpass Filters Containing High-Q dielectric Resonators", by Seymour B. Cohn, IEEE Transactions on Microwave Theory and Techniques, Volume MTT-16, NO 4, pp. 218-227, April 1968. Although aluminum

  is not as good a conductor as copper, aluminum is costly

  lable and less expensive than copper. In the preferred embodiment of the filter 100, the housing parts 112, 124 and 128 are made of aluminum alloy No. 380. However, due

  of the lower conductivity of aluminum, the housing parts

  112, 124 and 128 dissipate a certain part of the external field

  of the resonator 116, which decreases the value of Q of the filter

100 to nine percent (9%).

  According to another characteristic of the filter 100, the decrease

  of the Q value of the filter 100 due to the aluminum housing parts

  minimum 112, 124 and 128 is essentially avoided by using a highly conductive protective plate 142 between the disc 114 and the

  upper cover 112 and another very protective cover

  conductive 148 between the disc 120 and the lower cover 128. A third highly conductive protective plate 140 is also placed on the upper surface of the tuning core 118. The plates

  140, 142 and 148 are preferably made of leather

  vre (silver or gold are also appropriate) to obtain the

  min at low losses wanted for the external field on the surface

  of the tuning core 118, to the upper surface of the disc 114, and to the lower surface of the disc 120, respectively. In other exemplary embodiments, the plates could be produced

  protective 140, 142 and 148 with non-conductive material and

  covered with copper, silver or gold, these all having a conduct-

  tivity greater than 1.3 x 107 mhos / m which is the conductivity of aluminum alloy no 380. Using the protective copper plates 140, 142 and 148, the housing parts 112, 124 and 128

  may be made of aluminum or other metallic materials

  low conductivity which are much cheaper than

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  copper or copper coated materials without decreasing the

  their of Q of filter 100. Therefore, filter 100 is relative-

  economic while at the same time having a relative Q value

high.

  The copper protection plate 142 also includes three lugs 160, 161 and 162 for positioning the disc 114, and it further includes raised parts 144, 145, 146 and 147 to produce an elastic force when the cover 112 and the housing 124 are assembled. Thus, the housing parts 112, 124 and 128 completely enclose the sandwiched ceramic resonator 116 and compress the raised parts 144, 145, 146 and 147 of the plate 142 to produce an elastic force in order to maintain the spatial relationship between the ceramic resonator 116 and the discs

  of alumina 114 and 120. In addition, the rel-

  ves 144, 145, 146 and 147 of the copper protection plate 142

  are made large enough to conduct cha-

  from disc 114 to top cover 112 to minimize

  mum the increase in temperature of the resonator 116 due to dissipation

  energy pation. In other embodiments, the resonance

  ceramic ceramic 116 and the alumina compensating disks 114 and 120 can be maintained in spatial relationship with one another by bonding them together with a suitable adhesive such as sintered glass or

a layer of solder.

  The resonant frequency of the ceramic resonator 116 can be adjusted by means of the threaded tuning shaft 102 and the dielectric tuning core 118 fixed thereto. The resonant frequency of the resonator 116 decreases when the tuning core 118 is inserted into essentially concentric holes formed in the plate

  142, the disc 114 and the resonator 116. In the example

  ple of preferred embodiment, the disc 120 does not include a hole for the tuning core 118 since it is not necessary to insert the tuning core 118 into the disc 120 in order to obtain the tuning range wanted. In other exemplary embodiments, the disc

  may also have a hole concentric with the holes

  més in the disc 114 and in the resonator 116. The tuning core 118 is preferably made of a ceramic material with low

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  losses, such as, for example, the same ceramic material used for the resonator 116. The tuning core 118 not only varies the resonance frequency, but also eliminates certain parasitic resonance modes (keeping the overall dimensions constant of the housing when the frequency of the resonator 116 is tuned), minimizes the decrease in Q of the resonator (because it uses a ceramic material with low losses), and allows to have a good thermal contact between the discs 114 and 120

  and the resonator 116 on all of its upper and lower surfaces

  re. Although the resonator 116 is preferably tuned by means

  of the tuning core 118, another arrangement can also be used

appropriate classic chord.

  The tuning shaft 102 is threaded and is in correspondence with the correspondingly threaded brass sleeve 133, which is

  press fit into the top cap 132 of the top cover

  laughing 112. The position of the shaft 102 can be fixedly maintained by tightening a nut 104 and a washer 106. The tuning shaft 102, the housing 124 and the covers 112 and 128 are preferably made of aluminum . Since aluminum is non-ferrous, the tree

  102, housing 124 and covers 112 and 128 present

  try to decrease Q less when they are subjected to

  external magnetic fields if they are made of more aluminum

  sooner than steel or other ferrous materials.

  The tuning shaft 102, the tuning core 118, the sleeve 133, the compensation discs 114 and 116 and the housing parts

  112, 124 and 128 can also be made of pre-

  selected each with different coefficients of expansion

  to compensate for variations in the resonance frequency of the reso-

  116 at room temperature. For example, we can compensate

  partially the displacement of the chord nucleus 118 at temperatures

  ambient by means of the sleeve 133 and the height of the hat

  132 of the upper cover 112. That is to say that the com-

  thought of desired temperature is achieved by the difference in the coefficient of expansion between, and the respective dimensions, the / of the sleeve 133, the / of the tuning shaft 102, the / of the upper cap 132 and the / of the core d 118. This arrangement can compensate for a variation of 1.1 millionths / C of the temperature coefficient

  in the worst case of frequency of filter 100.

  The dimensions of the different elements of an example of a

  filter 100 for operation at frequencies

  taken between 865 and 902 MHz are listed below in Table I. In this embodiment, the resonator 116 and the tuning core 118 consist of the ceramic compound, the disks 114 and 120 of alumina, the sleeve 133 of brass, the tuning shaft 102 of aluminum and the housing parts 112, 124 and 128 of aluminum alloy no 380. The exact dimensions of the elements of an exemplary embodiment of the filter 100 vary depending on the desired operating frequency and the materials chosen for

each of the elements.

  Table I - Dimensions of the filter in centimeters Upper element tr Length Resonator 116 6.81 3.20 1.96 Disc 114 7.11 3.20 2.90 Disc 120 7.11 - 2.87 Core 118 3.05 - 3 , 48 Shaft 102 0.97 - 5.84 Housing 124 14.27 13.97 7.62 Top cover 112 14.27 3.81 2.29

Bottom cover 128 14.27 - -

  Referring next to Figure 2, we see that we have represented

  felt an antenna combination device to couple transmitters

  RF sensors 201-205 having different signal frequencies at one year

  common valve 231. Filters 211-215 are preferably fil-

  very 100 implementing the present invention. The disposi-

  combination device 221 is preferably the combination device

  microstrip sound 300 shown in FIG. 3. The combination device 221 can also be a suitable conventional antenna combination device as indicated and described in

  the U.S. patent NO 4,375,622, which is cited for reference.

  Using the RF 100 filter for filters 211-215, you can

  significantly reduce the overall requirements on the dimensions

  sions and the space of the combination device shown in Figure 2. Since space takes precedence at locations 12 zbos

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  antenna located remotely, substantial savings can be made

using the filter 100.

  In Figure 3, there is shown a top view of the wire-

  tre 100 and the microstrip combining device 300 implementing the present invention. The upper cover 112 of the filter

  is removed to more clearly indicate the neck loops

* range 122 and 311. Two screws are inserted in holes 139 for

  mount each of the five filters 100 on a suitable mounting panel

  prayed. Four screws are inserted into holes 108 to mount the

  upper cover 112 on the housing 124.

  RF signals are sent to filter 100 in Figure 3 to

  by means of the coupling loop 122 of a connector 136 and the plug

  coupling key 311 on a circuit board 301. In the example

  In the preferred embodiment of the filter 100, the coupling loops 122 and 311 are placed essentially in the same plane as the center of the resonator 116 and are arranged about 120 from one another as shown in Figure 3. Since the exact location of the coupling loop 122 is not critical for the operation of the filter 100, it is also possible to place the coupling loop 122 on the housing 124 at any suitable location in the plane of the center of the resonator 116, as long as that the coupling loop 122 and the coupling loop 311 are sufficiently separated to avoid

undesirable direct coupling.

  The combiner 300 of Figure 3 comprises a substrate circuit board 310 (see also Figure 6), a metal housing 320 and five coupling circuit boards 301-305 (see also Figures 4 and 5). An output connector 902 (see Figure 9) is soldered to the center of the substrate circuit board 310 and extends out from below the metal housing 320. The board 310 is preferably made of a material

  dielectric suitable for microstrip transmission lines.

  In the preferred embodiment of the combination device

  300, the substrate circuit board 310 is made of aluminum

  mine. The coupling circuit boards 301-305 are fixed to the housing 320 with a screw. A strip 314 is welded between a coupling loop 312 and the mass on the wafer 310, and a

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  strip 313 is welded between the coupling loop 312 and a line

  in corresponding microstrip located on the plate 310. Bars-

  similar rettes are used to couple the plates 301, 303, 304 and 305 to the plate 310. The housing 320 is fixed by two screws to a plate 154 located on each filter 100. Once fixed to each of the five filters 100, the housing 320 is enclosed by fixing an upper metal plate 330 by means of screws (see

Figure 8).

  Each coupling circuit board 301-305 is inserted into corresponding openings 152 formed in the housing 124 of the filter 100, and each of them is made moisture-proof by means of a rubber casing, for example, 340. A transmitter signal from a transmitter, for example 201, is applied

  to connector 136 and sent to resonator 116 through the loop

  track 122. The filtered transmitter signal is detected by the coupling loop 311 located on the circuit board 301. The microstrip circuit located on the board 310 combines the five signals

  transmitters and sends them to an output connector 902 (see Fig.

gure 9).

  We will now refer to Figures 4 and 5 where we have represented

  felt in more detail the coupling circuit board 301 and the coupling loop 301. The coupling loop 311 is covered with a metal layer, preferably a layer of copper, on the upper surface of the board 301, preferably in a material called PTFE with unevenly distributed fibers having a constant

  nominal dielectric equal to 2.1. The plate 301 is fixed to the lo-

  320 of the combination device 300 by means of a screw which is inserted into a hole 402. The plate 301 contains a line of

  fifty-ohm 411 microstrip transmission, the neck loop

  range 311 and a ground pad 413. As shown in Figure 5, only

  the part 502 of the lower surface of the wafer 301 is

  covered with copper. Part 502 is opposite the line of trans-

  fifty-ohm microstrip mission 411 and ground stud 413.

  That is, the bottom surface of the wafer 301 is not

  covered opposite the coupling loop 311.

  We will now refer to Figure 6 where we have represented

  in more detail the substrate circuit board 310. The board-

  te 310 is coated with copper on its underside and includes

  five transmission lines in microbands of fifty ohms 601-

  605 of equal lengths on its upper side to send si-

  gnals of filtered transmitters corresponding to a junction 620. The junction 620 has a hole in its center to introduce the central conductor of the output connector 902 (see Figure 9). The

  plate 310 also includes a transmission line in ser-

  pentin 610 for the junction of agreement 620.

  We will now refer to Figure 7 where we have represented

  a single tuning circuit with variable reactance of the present in-

  vention including the 610 serpentine transmission line and a

  dielectric tuning plate 630 for tuning the com

  microstrip binning 300 of FIG. 3. Line 610 is a short-circuit transmission line with a length of 3L / 4, having

  an infinite input reactance when half of its physical length

  that L is covered with the dielectric tuning plate 630. The

  line 610 can have the shape of a serpentine as we have shown

  or it can be simply straight or have any other shape imposed by a proposed application of it. The

  line 610 and the tuning plate 630 together constitute an impe

  dance whose reactance can be changed from an inductive state to a capacitive state simply by moving the plate 630 relative to the line 610, for example from a position B to a position C. The only tuning circuit to variable reactance of Figure 7

  has an input impedance ZI = jX, where the value of the reactan-

  this input X is changed by moving the plate 630 relative to the line 610. According to the present invention, the variation value of the input reactance X is determined by the length of the line

  610 and the dielectric constant of the tuning plate 630. In aug-

  lying about the length of the line 610 or the dielectric constant of the plate 630, the interval of reactance tuning is increased and

  vice versa. The center of the reactance tuning interval is

  terminated by end of line impedance 610 and line length 610. In general, the input impedance ZI can be calculated by the equation:

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  _ZT / ZO + jtg (> L) 1 (1) Z EZ, o I 0 - 1 + (ZT / Zo) jtg (PL) o = L = 2 (f / c) (L1 / Erl + L2 / Er2) ; f is the frequency; c is the speed of light; Z0 is the characteristic impedance of line 630; ZT is the end of line impedance 630; line 630 has a physical length L = L1 + L2; and Erl and cr2 are the effective dielectric constants of

  covered and uncovered parts L1 and L2, respectively.

  In the preferred embodiment of the single circuit

  according to variable reactance of Figure 7, the transmission line

  ion of agreement 610 ends in a short circuit, that is to say that

  ZT = 0. When it ends in a short circuit, the equation

  above for the input impedance ZI of line 610 is reduced to:

(2) ZI = jZ0 tg (OL).

  According to the present invention, the center of the reactance tuning interval (i.e., when plate 630 covers half of line 610 or when L1 = L2 = L / 2) can be chosen for each specific application of the single variable reactance tuning circuit in Figure 7. For the preferred embodiment of the combination device 300, the center of the reactance interval has been chosen so that there is a infinite reactance, so that the input reactance X of the input impedance ZI can be shifted between capacitive and inductive reactances. Since one

  infinite reactance has no effect on the functioning of the device

  Combination device 300, the combination device 300 is tuned by shifting the input reactance X from infinity to increasing values of capacitive or inductive reactance to obtain the characteristics of the desired combination device. For any specific termination impedance ZT, the input impedance ZI of the single variable reactance tuning circuit of Figure 7 is shifted in an interval given by equation (1) above and

  centered approximately at the predetermined input impedance which is pro-

  pick when the plow 630 covers half of the trans-

  agreement mission 610 (i.e. L1 = L2 = L / 2).

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  When used in combination with the combination device 300, the single tuning circuit 610 and 630 in FIG. 7 provides variable compensation for the reactance associated with the discontinuity of the microstrip at the junction 620 of the five transmission lines in microstrip 601 -605. I1 follows that the device

  300 has a higher transmission efficiency

  over a wider bandwidth than you might get

  hold without the unique tuning circuit of the present invention.

  Furthermore, the unique tuning circuit of the present invention can

  be advantageously used in any application ap-

  property in which one wishes to have an inductive agreement and / or

variable capacitive.

  In Figure 8, there is shown an exploded view of the single tuning circuit in strip lines and the device of this

  invention used to tune the micro combination device

  strip 300 shown in Figure 3. The upper plate 330 is

  fixed to the housing 320 by means of screws. Plate 330 also includes

  a hole 350 to access the transmission line in service

  pentin 610. The dielectric tuning plate 630 is bonded to a block 806 by means of an appropriate adhesive. Block 806 has three holes, one for inserting a spring 804 and the other two for terminals 808 and 809. A cover plate 802 includes terminals 808 and 809 and slot-shaped holes 810 and 811. Screws '' insert into the holes 810 and 811 to fix the plate

  cover 802 to the upper plate 330 of the combination device

  its 300. The terminals 808 and 809 of the plate 802 position the block 806 and the dielectric tuning plate 630 on the line of

  serpentine transmission 610. Spring 804 forces the actuating plate

  dielectric cord 630 against the serpentine transmission line

  610. During the tuning of the combination device 300,1

  The plate 802 is loosened and the plate 802 is slid back and then forward in the direction of the slot-shaped holes 810 and 811 to tune the combination device 300. When

  the desired agreement is obtained, the screws retaining the plate 802 are tightened

  rees. The unique tuning device and the above-mentioned method of the present invention make it possible to quickly tune and

17 2606936

  precisely the combination device 300.

  In Figure 9, a bottom view of the device is shown.

  The microstrip combining device 300 shown in Figure 3. The output connector 902 extends from the bottom of the housing 320 and provides the combined output signal from the combining device 300.

  connector 902 is fixed to housing 320 by means of a nut 904.

  In summary, there has been described an apparatus for combining

  new RF channels that include a micro-combination device

  band coupled to ceramic filters by coupling loops

  unique and tuned by a variable variable reactance tuning circuit

  than. New tuning circuit includes tuning transmission line and dielectric tuning plate, tuning interval

  of this being determined by the length of the transmission line-

  tuning ion and the dielectric constant of the tuning plate.

  If the chord transmission line is terminated by a short-

  baked, the input reactance of the new tuning circuit can be changed between inductive and capacitive reactances simply by adjusting the amount by which the dielectric tuning plate covers the tuning transmission line. The unique tuning circuit of the present invention can advantageously be used in any suitable application o a variable input reactance

is necessary.

Claims (19)

  1. Radio frequency (RF) filter, characterized in that it comprises: a resonator means (116) comprising upper surfaces   and lower and made of a ceramic material having a conduc- predetermined thermal activity;   first and second compensation means (114,120) comprising   each carrying upper and lower surfaces and arranged res-   pectively above and below the resonator means, the surface   lower of the first compensation means (114) and the upper surface   of the second compensation means (120) being respectively thermally coupled to the upper and lower surfaces of the resonator means, and the first and second compensation means being made of a dielectric material having a thermal conductivity greater than the thermal conductivity of the air ;   first and second protection means (142,148) consisting of   killed with metallic material and thermally coupled to and available   located respectively above and below the first and second compensation means, to produce a low loss electromagnetic path above and below the resonator means; housing means (112,124,128) made of a metallic material having an electrical conductivity lower than that of the metallic material of the first and second protective means and further including upper, lower and lateral surfaces;   an input coupling means (122,136) and a coupling means   output pads (311,152) disposed on the side surface of the housing means (124) opposite the resonator means and at a preselected distance from each other for transmitting the respective input signals and output signals the RF filter (100); and the housing means (112,124,128) enclosing and holding   essentially the resonator means (116) between the first and the second   cond compensation means (114,120) and the first and second protection means (142,148), the upper and lower surfaces of the housing means being respectively thermally coupled to the   first and second means of protection, a path with low resistance   this thermal thus being produced between the resonator means, the pre-   mier and second means of compensation, the first and second means of protection and the housing means for driving away from the resonator means the heat dissipated therein, thereby minimizing the increase in temperature of the means   resonator due to energy dissipation.   2. RF filter according to claim 1, characterized in that the resonator means (116), the first protection means (142) and the first compensation means (114) further comprise   respective holes essentially concentrically aligned in-   be them, the RF filter (l00) further comprising a tuning means (118, 102) made of a dielectric material and inserted in the   holes of the first compensation means, of the first protection means   resonator means to vary the resonant frequency of the resonator means.   3. RF filter according to claim 2, characterized in that the tuning means comprises a tuning shaft (102) and a core   tuning unit (118), the tuning core (118) being made of a material ceramic riau.   4. RF filter according to claim 3, characterized in that   that it further comprises a third means of protection (140) consisting   made of metallic material and placed above the tuning core   (118) to protect the resonator means (116) and the tuning core.   5. RF filter according to claim 3, characterized in that   the tuning shaft (102) is threaded and the housing means (112) includes   further takes a threaded sleeve (133) arranged to receive the shaft Okay.   6. RF filter according to claim 5, characterized in that the tuning shaft (102), the sleeve (133), the first and second compensation means (114,120) and the housing means (112,124, 128) are made of pre-selected materials with different coefficients of expansion with temperature to compensate for   variations in the resonant frequency of the resonator means in function tion of the temperature.   7. RF filter according to claim 1, characterized in that   the first and second compensation means (114,120) are constituted mostly killed with alumina. 2606936   8. RF filter according to claim 1, characterized in that   that one of the first and second means of protection (142,148) comprises   takes elastic means (144-147) to produce a force of   compression when held by the housing means.   9. Radio frequency (RF) filter, characterized in that it comprises: a resonator means (116) comprising upper surfaces   and lower and made of a ceramic material having a conduc-   predetermined thermal activity and a speed of variation of the predetermined resonant frequency as a function of the temperature;   first and second compensation means (114,120) available   placed respectively above and below the resonator means,   and each having upper and lower surfaces, the surface   underside of the first compensation means (114) and the surface   upper of the second compensation means (120) being respective   thermally coupled to the upper and lower surfaces of the resonator means, and the first and second compensation means   being made of a dielectric material having a velocity of   riation of the resonance frequency as a function of the polarity temperature opposite to that of the predetermined speed of variation,   and the dielectric material of the first and second compensating means   also having a thermal conductivity greater than the con- thermal ductivity of air;   first and second protection means (142,148) consisting of   killed with metallic material and thermally coupled to and available   located respectively above and below the first and second compensation means, to produce a low loss electromagnetic path above and below the resonator means; and housing means (112,124,128) made of a metallic material having an electrical conductivity lower than that of the metallic material of the first and second protective means and further including upper, lower and lateral surfaces;   an input coupling means (122,136) and a co means, -   output area (311,152) arranged on the lateral surface of the means   housing opposite the resonator means and at a pre-   selected from each other to transmit the input signals and the respective output signals of the RF filter (100); and the housing means (112,124,128) enclosing and holding   essentially the resonator means (116) between the first and the second   cond compensation means (114,120) and the first and second protection means (142,148), the upper and lower surfaces of the housing means being respectively thermally coupled to the first and second protection means, a path with low thermal resistance thus being product between the resonator means,   the first and second means of compensation, the first and second-   me means of protection and the means of housing to drive away   of the dissipating heat by the resonating means, thereby reducing to a minimum   mum the increase in temperature of the resonator means due to the dis- energy sipation.   10. Apparatus for combining at least two radiofrequency signals   frequency (RF) having different predetermined frequencies and   generated by separate signal sources to produce a compound output signal, the RF signal combining apparatus (300) being characterized in that it comprises: substrate means (310) having a first side and a second side , the second side being covered with a metallic layer; junction means (620) placed on the first side of the substrate means and producing the compound output signal;   a set of transmission lines (601-605) coupled cha-   cune by means of junction and having an input coupled to receive a corresponding RF signal; and a tuning circuit (610,630) having a variable input impedance, comprising:   tuning transmission line means (610) having an input   cable coupled to the junction means, having a predetermined length, placed on the first side of the substrate means and being terminated by a predetermined termination impedance;   a dielectric plate (630) having a dielectric constant   predetermined electric and intended to cover the line of trans-   tuning mission, the input impedance of the tuning circuit having a   predetermined input impedance value when the dielectric plate   that covers half of the agreement transmission line; and 22 2606936   means (320,330,802) for adjusting the quantity of which the   dielectric plate (630) covers the transmission line   cord (610) to vary the input impedance of the circuit   agree in an interval centered roughly at the impedance of very predetermined.   11. Combination apparatus according to claim 10, ca-   characterized in that the agreement line transmission means comprises   takes a transmission line (610) having a serpentine shape and ended with a short circuit.   12. Combination apparatus according to claim 10, charac-   characterized in that the adjustment means comprise: a means of lo-   to enclose the combination apparatus (300); and cover plate means (330,802) coupled to the housing means for positioning the dielectric plate (630) and forcing the plate   dielectric against the tuning transmission line means (610).   13. Combination apparatus according to claim 12, charac-   characterized in that the cover plate (802) further comprises two terminals (808,809) extending therefrom, an elastic or spring means (804) and a block (806) having two holes for introducing the terminals and another hole for inserting the spring, the dielectric tuning plate (630) being fixedly connected boulder (806).   14. Apparatus for combining radio frequency (RF) signals, characterized in that it comprises: antenna means (231); a set of RF signal transmitters (201-205) each having a different predetermined frequency and producing an RF signal;   a set of filtering means (211-215; 100) coupled cha-   none for receiving a signal different from the RF signals and producing an output signal; and combining means (221; 300) comprising: substrate means (310) having a first side and a second side, the second side being covered with a metallic layer; joining means (620) placed on the first side of the substrate means and coupled to the antenna means;   a set of transmission lines (601-605) comprising 23 2606936   both an output coupled to the junction and comprising   an input coupled to a corresponding filtering means for receiving   see an output signal from it; and tuning transmission line means (610) having an input coupled to the junction means, having a variable input impedance, having a predetermined length, being placed on the first side of the substrate means (310) , and being terminated by a predetermined termination impedance;   a dielectric plate (630) having a dielectric constant   predetermined electric and intended to cover the line of trans-   tuning mission, the input impedance of the tuning transmission line having a predetermined input impedance when the plate   dielectric covers half of the transmission line   cord; and means (320,330,802) for adjusting the amount by which the dielectric plate covers the tuning transmission line   to vary the input impedance of the transmission line   tuning in an interval centered around the impedance predetermined entry.   15. RF signal combining apparatus as claimed   cation 14, characterized in that the tuning transmission line means comprises a transmission line (610) having the form   of a coil and being terminated by a short circuit.   16. RF signal combining apparatus as claimed   cation 14, characterized in that it further comprises a set   of coupling circuit boards (301-305) on each of which   is placed a coupling loop (311), each of the loops   coupling coupled to a corresponding line of transmission lines   and terminated by a short circuit to receive the output signal constituting a corresponding filtering means (100) of the filtering means.   17. RF signal combining apparatus according to the claim   tion 14, characterized in that the adjustment means (320,330,802) comprise: a housing means (320) for enclosing the means of   jumpsuit (300); and cover plate means (330,802) covered   folded by means of housing to position the dielectric plate   (630) and force the dielectric plate against the transmission line- I agree.   18. RF signal combining apparatus as claimed   cation 17, characterized in that the cover plate means (802) further comprises two terminals (808,809) extending therefrom, an elastic or spring means (804) and a block (806) comprising two holes to introduce the terminals and another hole to introduce the spring, the dielectric tuning plate (630)   being fixedly linked to the block (806).   19. Apparatus for combining at least two radiofrequency signals   quence (RF) having different predetermined frequencies and generates   fed by separate signal sources to produce a compound output signal, the RF signal combining apparatus (300) being characterized in that it comprises: substrate means (310) having a first side and a second side , the second side being covered with a metallic layer; junction means (620) placed on the first side of the substrate means and producing the compound output signal;   a set of transmission lines (601-605) coupled cha-   cune by means of junction and having an input coupled to receive a corresponding RF signal; and a tuning circuit (610,630) having a variable input reactance, comprising: tuning transmission line means (610) having   an input coupled to the junction means, having a predetermined length-   mined, placed on the first side of the substrate means and being finished undermined by a short circuit;   a dielectric plate (630) having a dielectric constant   predetermined electric and intended to cover the line of trans-   tuning mission, the input reactance of the tuning circuit having   an essentially infinite value when the dielectric plate re-   covers half of the tuning transmission line; and means (320,330,802) for adjusting the amount of which   the dielectric plate (630) covers the transmission line   cord (610) to vary the input reactance of the ac circuit   cord between a predetermined inductive reactance and a reactance predetermined capacitive.