FR2688944A1 - SINGLE POINT RECEIVING ANTENNA FOR MULTIPLE SATELLITES OF DIFFERENT ORBITAL POSITIONS. - Google Patents

Abstract

The single-point receiving antenna, for several satellites of different orbital positions, comprises a multi-sector reflector comprising a central sector (2) and at least one outer sector (1) in a ring around the central sector. The sectors of the reflector are formed from portions of paraboloids with different axes defining the directions of reception (D1, D2) corresponding to the different orbital positions, the sectors focusing the radiations they receive in the same focusing zone (F) . A multipolarization broadband source (S) is placed in the zone (F), the source being coupled to an electronic processing wheel for the selection of the useful signals. The invention applies, in particular, to satellite reception in individual stations.

Description

Single point receiving antenna for multiple satellites

  The invention relates to satellite reception equipment available as individual reception stations and more particularly to a single-point reception antenna for several satellites of different orbital positions. When several satellites placed at different orbital positions must be received at the same location, the following minimum requirements must be present:

  an antenna equipped with a motor equatorial mount

  a broadband source associated with one or more low-noise demodulators,

  a control device and a memory device

  the coordinates of the selected satellites.

  The passage from the reception of a satellite on a first orbital position to the reception of a satellite on another orbital position requires several seconds or even tens of seconds. When, moreover, several satellites thus placed on different orbital positions must be received simultaneously for reasons of service, the problem becomes much more complex. An obvious solution is to target the

  satellites by as many antennas as there are orbital positions.

  Several reasons make this solution inapplicable on a large scale First of all there are reasons of economic order: the cost of the installation is multiplied by the number of antennas and the installation is complex and expensive There are also reasons for aesthetic order: besides the clutter of a field of two or three parables, a set of parables hardly integrates into the rectilinear architectures of current constructions Finally there are also regulatory reasons because, in many countries, only one parable is tolerated per building; moreover the windy

  Antennas can be a source of insecurity, not tolerated.

  A new need therefore appears for a single antenna

  to receive simultaneously or sequentially several

  satellites at different orbital positions, without changing the pointing of the antenna so as to avoid motorized equipment and corresponding controls, and to save time by minimizing downtime during

Changes.

  It is known from French Patent Application No. 89 14287

  filed on 31 October 1989 in the name of the Claimants

  Multifocal reception pole with single pointing direction

  for several satellites located on the same orbital position.

  For this reason the reflector is multi-sectors, the different sectors of the reflector focusing the radiation that they receive from the targeted direction towards sources placed in positions

  different from households in different sectors.

  With the antenna described in this application, the reception can therefore take place on several satellites of predefined orbital position, either simultaneously or sequentially according to the equipment of the antenna (one or more microwave heads); but the satellites received are always located on the same orbital position, and their selection is effected by a choice of polarization and frequency, because of a spatial separation of the polarizations,

the antenna being multifocal.

  The object of the invention is to meet the need of one year

  tenne capable of receiving simultaneously or sequentially several satellites located on different orbital positions by a single pointing, and a single electronic assembly For this the reflector of the antenna is multi-sectors, each sector being adapted to the reception of a satellite, and these sectors have spatially coincident foci; a broadband and multipolarization source transmits the various signals received to

  the electronic unit that separates them.

  According to the invention, a reception antenna pointing

  for several satellites of different orbital positions.

  annuities, comprising a multi-sector reflector comprising a

  central sector and at least one outer ring sector beyond

  central sector tower, is characterized in that the sectors of the reflector are formed from portions of paraboloids

  different axes defining the reception directions corresponding to

  at the different orbital positions, the focal sectors

  the radiation they receive in the same focus area, and that a multipolar broadband source is placed in the area, the source being coupled to a channel of

  electronic processing for the selection of useful signals.

  The invention will be better understood and other characteristics

  will appear with the following description in reference

  in the appended figures: FIG. 1 illustrates, in section, a receiving antenna

  single point for several satellites located on

  different orbital states in a first embodiment; FIG. 2 illustrates a second embodiment in section of the antenna according to the invention having a "flat" shape, for the reception of two satellites;

  FIG. 3 represents in section another embodiment of

  of a flat antenna according to the invention, for the reception of

three satellites.

  FIG. 4 shows in plan a third mode of

realization of the antenna.

  According to the invention, the antennas comprise sectors of paraboloids whose characteristics are such that they focus at the same point on radiation coming from directions

different.

  Figure 1 schematically illustrates the principle of the

  according to the invention for the reception of two satellites: two sectors of paraboloids 1 and 2 connected by a truncated cone

  3, focus the radiation from the directions

  The two sectors 1 and 2 therefore have different axes, Fx 1 and Fx 2 angularly offset from the difference between the orbital positions of the two satellites to be aimed at. The shape of the reflector with its two sectors 1 and 2 as illustrated in Figure 1 is usable But there is an advantage to use a reflector producing the same result,

  but whose size is reduced.

  For this, the second embodiment of the antenna shown in FIG. 2 is such that the outer paraboloid sector 1 is in fact constituted by several different paraboloid portions whose virtual vertices on the axis Fxi are shifted by one. integer half wavelength, and which are connected by truncated cones, each of these paraboloid portions focusing the received radiation in the same direction D 1 as before, the focus F This structure minimizes clutter and allows to obtain a quasi-planar structure formed, for the external sector, of a set of "rings" of paraboloids The central sector 2 whose dimension is relatively small if it is chosen for the reception of the satellite having the strongest apparent power

  radiates well into the antenna forming with the reflec-

  1 a quasi-flat structure for the receiver.

  The main advantage of the flatness of the antenna due to this ring group structure is to reduce the cost per unit of volume especially for everything relating to the pre-installation conditioning To further facilitate the pre-installation procedures. in particular the packaging for transport from the place of manufacture to the place of installation, the outer sector 1 in rings can be cut to form a rectangular or square structure that optimizes the receiving surface compared to traditional means This embodiment is shown in plan in FIG. 3. The central sector 2 'hatched is also in rings on its outer part, and is associated with the satellites with strong apparent radiated power (EIRP according to the English abbreviation). for example, TDF 1 for example, and the outside sector 1 'cut in square is associated with the more radiated power satellites For example, the sectors 1 'and 2' can rotate relative to one another to allow their relative positions to be adjusted. For this purpose, an axis of rotation Y 'Y makes it possible to define precisely

  the angle between the two pointing directions.

  Figure 4 illustrates a structure in which the reflec-

  It is possible to focus radiation from three different directions in the same focus F. For this purpose, the central part consists of a paraboloid portion focusing at F in the direction D 3; an intermediate portion is formed of concentric rings formed of sectors of paraboloids and truncated cones and focuses F radiation from the direction D 2 This middle portion is contiguous to the central portion inward and joined with a second structure in outer rings for always focusing in F the radiation from the direction D In the same way as described with reference to Figure 2 the rings of sectors 1 and 2 of the reflector are formed of paraboloid portions whose vertices are offset by an integer number of times the half wavelength of the received radiation, on the axes Fx 1 and Fx 2 respectively, the axis Fx 3 parallel to D being

the axis of the central sector 3.

  All of these embodiments allow without moving

  the reflector, so with a single pointing direction, to receive in the various predetermined directions at the location point F is placed a multipolarization source and multiband or broadband This source receives the signals of different satellites, for example signals from telecommunications satellites, FSS band, 10.7 to 11.7 GHz or 12.5 to 12, 75 GHz, or signals from public broadcasting satellites in the BSS band,

  12.5 GHz These satellites are at different orbital positions

  rents and emit at different frequencies in the bands mentioned in different polarizations (circular right, circular left, horizontal or vertical) The multipolarization source can be a multipolarization printed network

  plan equipped with electronic switching means for

  The source can be made in particular according to the structures described by M. DUBOST in an article entitled "Dual polarized flat folded dipoles application to an array in KU Band" published in "Asia-Pacifie Microwave conference ( AGMC 1990), TOKYO After the source it is of course necessary to provide a separator or polarization switch to select

the required signal (s).

  FIGS. 5 and 6 illustrate the necessary channels in the electronic assembly associated with the antenna so that satellites emitting in directions D 1 and D 2 can be received. FIG. 5 illustrates the case where it is not desired to receive the radiation. from two satellites that

  sequentially A single microwave head 10 is required

  It is preceded by a polarization switch (or separator) 11 adapted to the selection of one of the four types of polarization mentioned (circular right, circular left, horizontal and vertical) whose input is connected to the wide source. multipolarization band S. Figure 6 illustrates the case where one wishes to receive

  simultaneously radiation from two satellites.

  Two microwave heads 20 and 30 are then required.

  each have a low-noise amplifier and a converter

  Each of these microwave heads or "LNB" (for "Low Noise Block" according to the English terminology) is preceded by a bias switch, respectively 21 and 31 If the microwave heads 20 and 30 are assigned to the processing of signals transmitted respectively in circular polarization and in linear polarization, the polarization switch 21 selects the polarized radiation circular right or left and the polarization switch 31 selects the linearly polarized radiation either vertically or horizontally The inputs of the switches are connected to these structures have a large number of advantages, the reception set has its cost decreasing because of the

  presence of a single reflector, a single source and a set of

  common electronic circuits for the reception of

  Even if the electronic circuits must provide, as indicated above, switching and separation means, the set obtained is of course less expensive than a juxtaposition of specialized systems for receiving data.

different satellites.

  Another advantage of such a structure is the simplicity of its installation since by a single adjustment of the position of the antenna reflector several reception directions are obtained. In addition, the system is versatile since it is suitable for receiving several types of satellites applied to

  different fields such as telecommunications and televi-

  These two types of information can even be received

  simultaneously, provided that the electronic circuits

  particularly low noise converter, are doubled and

  that ad-hoc separation means are available.

  Finally, another significant advantage is the aesthetics of the system, which makes it possible, with a single reflector, possibly of square section and near plane, to minimize the disadvantages of

  these structures arranged on buildings, these structures are

  tégrant more easily in the architecture of cities.

  The invention is not limited to the embodiments described and shown. Indeed, it has been indicated above that the sectors of the reflector could either consist of a

  the only dish sector receiving the radiation from

  direction D to focus it in F or more

  portions of paraboloids always receiving the same

  D and focusing the radiation at the same point F The number of sectors with different directions 2 or 3 in the examples

  represented can obviously be adapted provided that each

  that sector has a sufficient surface to ensure the reception of the satellite for which it is intended, with its given effective radiated power The limit is thus fixed by the received power

  different satellites on different parts of the reflections

  Finally, any combination of satellites capable of being received in the same place is possible, the radiation coming from each being defined by its direction, frequency and polarization, provided that the radiation coming from these satellites placed on different orbital positions do not transmit at the same time on the same frequency and with the

same polarization.

Claims (5)

  A single-point receiving antenna for a plurality of satellites of different orbital positions, having a multi-sector reflector having a central sector (2) and at least one outer sector (1) in a ring around the central sector, characterized in that the sectors of the reflector are formed from paraboloid portions of different axes defining the reception directions (D 1, D 2) corresponding to the different orbital positions, the sectors focusing the radiation they receive in the same focusing zone (E ), and that a multipolarization broadband source (S) is placed in the area (F), the source being coupled to a channel of   electronic processing for the selection of useful signals.   2 Antenna according to claim 1, characterized in that for a quasi-planar antenna, at least one of the sectors is formed from several paraboloid portions of the same axis whose virtual vertices are shifted by an integer of half wavelengths and which focus all the radiation they receive in the focusing zone F.   Antenna according to one of claims 1 and 2, characterized   in that the projection of the reflector on an orthogonal plane   to the receiving direction of the external sector is a rectangular section.   Antenna according to one of claims 1 to 3, characterized   in that for receiving two satellites, it comprises a central sector (2) formed of a paraboloid portion for receiving the satellite having the lowest effective radiated power, and an outer sector (1) formed of several portions. paraboloids for the reception of the satellite with the highest effective radiated power, the ratio of the   of the two sectors being a function of the ratio between the powers.   Antenna according to one of claims 1 to 3, characterized   in that, for sequential reception of the satellites, the electronic processing channel comprises a polarization selector (11) and a reception microwave head (10) having frequency conversion and amplification means   Low noise adapted to the frequencies to receive.   Antenna according to one of claims 1 to 3, characterized   in that, for simultaneous reception of at least two satellites, the electronic processing channel comprises at least two polarization selectors (21, 31), each connected to a receiving microwave head (20, 30) each having means adapted frequency conversion and low noise amplification frequencies to be received.