FR2676878A1 - DEVICE FOR COUPLING, IN DECAMETRIC WAVES, BETWEEN TWO DISSYMETRIC LINES AND A SYMMETRIC LINE AND EMISSION STATION COMPRISING AT LEAST ONE SUCH DEVICE. - Google Patents

Abstract

The invention relates to a coupling device which makes it possible to couple, as desired, one or two asymmetrical lines to a same symmetrical line in order, generally, to connect, as desired, one or two transmitters to the same antenna. The device uses baluns (S1, S2) and switches (K1, K2) mounted so that the simultaneous coupling of the two unbalanced lines (1-L2, 2) to the same symmetrical line (3), is done by the electrical series connection of the two asymmetric lines at one end of a balun (S2), the other end of which is connected to the symmetrical line (3). Application, in particular, to HF radioemission.

Description

i HF coupling device between two lines

  asymmetrical and a symmetrical line

  and transmitting station comprising at least one such device.

  The present invention relates to coupling devices

  in the HF range to couple two dissymmetrical lines

  metrics to a symmetrical line with the possibility of

  that one of the two asymmetrical lines at the symmetrical line

  The invention also relates to transmitting stations

  comprising at least one such device.

  Such devices are used, for example, to cut

  two transmitters to the same radiating element, with the possibility of

  remove the coupling between one of the emitters and the radiating element; the two issuers that are usually

  identical, provide the same signal; when, for example,

  hours of the day, the power provided by a single transmitter

  is considered sufficient, the other issuer does not

  not; it will only consume energy at other times of the day, when all of the radiated power is needed.

  The devices known to perform this kind of cou-

  range with transmitters of several tens of kilowatts, or even 250 k W and more, are made in the form of 3-decibel couplers, magic rings or diplexers, and each transmitter is connected to the common radiating element by a circuit Rehabilitation followed by a frequency blocking circuit

issued by the other issuer.

  These known coupling devices are selective and neces-

  sive switching devices to cover a large

  frequency bandwidth In addition to the devices of cou-

  range with blocking circuit are not suitable for coupling

  two transmitters operating at the same frequency.

  The present invention aims to avoid or, for the

  least, to reduce these disadvantages.

  This is achieved, in particular, by the use of a balun in the common channel to the two transmitters when

  supply the same radiating element, which makes it possible

  this balun in the vicinity of the local transmitters, to have then only one power line, and not two, for

  go to the foot of the antenna which includes the

considered.

  According to the invention there is provided a device for

  range, in HF, to couple, as desired, a first asymmetrical line or the first and second asymmetrical lines to a symmetrical line, characterized in that the first asymmetrical line is connected to the symmetrical line

  according to a first path comprising, in series, a first

  controller, a first output of the first switch, a first asymmetrical line section a first balun, a

  first input of a second switch, the second switch

  symmetrical line, and in a second path comprising, in series, the first switch, a second output of the first switch, a second section of asymmetrical line, a second balun, a second input of the second switch and that the second asymmetrical line is connected to the symmetrical line by the part of the second path starting at the second balun and, for this, is electrically in series,

  at the level of the second balun, with the second section.

  The present invention will be better understood and others

  characteristics will appear from the description below.

  FIG. 1 is a diagrammatic view showing how a radiating element can be powered, according to the invention, by one or two of the emitters of a group of N transmitters, FIG. a more detailed view of a portion of Figure 1, Figures 3a, 3b diagrams showing how to be

  placed a measuring element of Figure 2.

  In the different figures, the corresponding elements

  are designated by the same symbols.

  Figure 1 is a partial diagram of a broadcasting station

  HF transmission according to the invention This station

  has a building part of which has been represented by a wall M

  In the interior of the building there are N emitters, El to EN, with N being at least 2, intended to be connected to antennas located outside the building.

  only one, A, of these antennas is shown in FIG.

  To allow the connection between a satellite antenna

  such as A, and the transmitters El to EN, a grid of

  G, arranged inside the building, has N inputs respectively connected by N asymmetric lines C1 to CN to

  outputs of the N transmitters and has several outputs so each

  one is connected to one of the antennas of the station; this is how the first and second outputs of the grid are connected to the antenna A.

  It should be noted that the lines and sections of dissociated lines

  metrics are coaxial cables in the example described.

  The second output of the gate G is connected to the antenna A by a path which comprises in series a coaxial line 2, a balun 52, a second access of a two-position switch K 2, this switch and a symmetrical line 3 In this connection between the second output of the gate G and the antenna A, the inner conductor of the line 2 is connected to the second

  entrance of the quadrupole formed by the balun 52.

  The first output of the gate G is connected to the antenna A by two paths: a first path which comprises in series a coaxial line 1, a coaxial switch with two positions, K1, a first output of the switch Ki, a line segment coaxial, Li, which is part of a balun Si, this balun Si up to its two outputs which are connected to a first access of the switch K 2, and the symmetrical line 3; and a second path which comprises in series the coaxial line 1, the coaxial switch K1, a second output of the switch K1, a coaxial line section, L 2, whose inner conductor is connected to the first input of the quadrupole constituted by the

  balun 52, the second access of the switch K 2, this switching

  and the symmetrical line 3 The external conductors of the

  coaxial line 2 and the coaxial line section L 2 are in con-

  electrical contact with each other, in the vicinity of their junction with the balun 52, with two solder points Pl and P 2. In the example described the symmetriers Si and 52 are of the type of baluns according to the French patent 2,556,508 filed December 13, 1983; they are baluns made using a symmetrical line of length L, whose impedance varies from

  continuously from a value Zd to a value Zs according to a function

  Z = f (x) where Z is the impedance at a point on the line dis-

  both of a length x (with O Qx <L) of the impedance end Zd and f a given function, such as the representative curve of Z = f (x) in plane rectilinear coordinates, intersects the segment which joins the ends of the curve a little above the middle of the segment and that the curve has a continuously increasing slope of the point for x = 0 at the point of intersection

  curve and the segment and continuously decreasing from the point of in-

  point tersection for x = L. Since the characteristic impedance of the unsymmetrical lines and line sections used in the arrangement according to FIG. 1 is 50 ohms and the characteristic impedance of the symmetrical line 3 is 300 ohms, the values Zd and Zs referred to above are respectively 50 ohms and 300 ohms for the balun Si and 100 ohms and 300 ohms for the

balun 52.

  With the assembly according to Figure 1 it is possible to connect-

  only one of the N transmitters E1 to EN on the antenna A; it suffices to control the switching gate G so that the output signal of the chosen transmitter appears on the first output of the gate G and to control the switches K 1 and K 2 so that this output signal follows the path that has the

balancer Si.

  With the assembly according to Figure 1 it is also possible

  to connect two transmitters, from the N transmitters, to the antenna

  AT; for this, the gate G must be ordered so that the

  output of the two selected transmitters appear respectively

  on his first and second outings and the changes

  K1 and K2 must be controlled so that the output signals of the two selected transmitters follow paths including the balun 52. Thus, as required, the energy radiated by the antenna A can come from a single transmitter or from

two transmitters.

  But for the coupling of two transmitters to a single

  antenna is performed satisfactorily it is necessary to

  kill a control of the phase of the currents at the exit of the line-

  coaxial 2 and coaxial line section L 2 which are put in series on the electrical plane; there must be a phase opposition there and, if not, the difference

  phase between the two transmitters must be changed.

  Figure 2, which is an enlarged view of the part of

  the assembly according to FIG. 1 comprised between the commutation grid

  G and the symmetrical line 3, shows how to verify that there is a phase opposition between the two currents, that is to say that the values of the currents in the two drivers of the

  balun 52 are respectively I and -I.

  A first way of controlling this phase shift of 180 degrees is to introduce two current loops, 4 and 5, respectively in the coaxial line 2 and in the coaxial line section C 2, in the vicinity of their junction with the balun 52; a control circuit of which only the two measuring loops 4 and 5 have been represented in FIG. 2

  allows to control the phase shift between the two transmitters.

  coupled to the antenna A of Figure 1, so that the

  currents in the loops 4 and 5 are in phase opposition.

  A second way to control the phase shift of 180

  degrees consists in using a control circuit that does not

  gate only one current loop, 6, disposed in a plane parallel to the plane of the two conductors of the balun 52 and equidistant from these two conductors Figures 3 a and 3 b which are the same cross section, at the level of the loop 6, of the balun 52, show the two drivers of this

  baluns; these conductors are formed of conducting bars

  such as 7 and 8 interconnected by spacers con-

  9. When, as shown in Figure 3a, the currents are in phase in the two conductors of the balun, the resultant H of the electric field created by these two currents, at the loop level, is in the plane of the loop and therefore induces

no current in the loop 6.

  On the other hand, when currents in both

  are in phase opposition, as shown in Figure

  3b, the resultant H of the electric field created by these two

  The loop level is perpendicular to the plane of the loop, that is, it is arranged optimally to create a current in the loop 6. Thus, the phase difference between the two transmitters connected to the antenna A is adjusted. will do so

  that the current in the loop 6 is maximum.

  The invention is not limited to the example described, it is thus that the symmetrizers Si and 52 can be of any known type but that the baluns of the example described have been

  chosen because they had the best characteristics

  particular, from the point of view of reliability, being

  given that this type of balun does not use

tors.

Claims (4)

  1 coupling device, in HF, for coupling, as desired, a first asymmetrical line (1) or the first and second (2) asymmetrical line to a line   symmetrical (3), characterized in that the first asymmetrical line   is connected to the symmetrical line along a first path   having, in series, a first switch (K1), a first   first output of the first switch, a first section (Li)   of asymmetrical line a first balun (Si), a first   first input of a second switch (K 2), the second switch   symmetrical line, and in a second path comprising, in series, the first switch, a second output of the first switch, a second section (L 2) of asymmetrical line, a   second balun (52), a second input of the second   in that the second asymmetrical line is connected to the symmetrical line by the part of the second path starting at the second balun and, for this purpose, is electrically in series,   at the level of the second balun, with the second section.   Coupling device according to claim 1,   to allow the coupling of two transmitters (El-EN) to a single   radiating element (A), characterized in that it comprises a cir-   control furnace having measuring means (4, 5) for measuring   the phase difference of the currents flowing respectively in the second asymmetric line (2) and the second section (L 2), at the level of the second balun (52) so as to be able to control   the phase difference between the two transmitters.   3 coupling device according to claim 1, for coupling two transmitters (El-EN) to a same radiating element (A), characterized in that it comprises a control circuit having measuring means (6) for measuring the phase difference of the currents flowing in the second balun (52) so as to be able to control the phase difference between the two transmitters.   Coupling device according to claim 1, characterized   in that at least one of the symmetrizers (Si, 52) is a balun made with a symmetrical line of given length whose impedance varies continuously from a value Zd to a value Zs according to a function Z = f (x), where Z is the   dance at a point on the distant line of a length x of the ex-   impedance trough Zd, with x between zero and the given length and of is a given function, such that the representative curve of Z = f (x), in plane rectilinear coordinates, intersects the segment joining the ends of the curve a little above the middle of the segment and that the curve has a   continuously increasing slope of the point for x = 0 at the point of   tersection between the curve and the segment and continuously decreasing   health of the point of intersection at the point for x equal to the length given.   HF emission station, characterized in that it comprises at least one device according to one of the preceding claims.