Note: Descriptions are shown in the official language in which they were submitted.
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METHOD AND DEVICE FOR DIRECTIONAL EMISSION
AND RECEPTION OF ELECTROMAGNETIC WAVE
Field of the Invention
The invention relates to a method for the directionally
selective transmission of electromagnetic waves, in particular
for application in radio communications, as. well as to a
device for carrying out said method.
Related Art
Due to the propagation-properties of electromagnetic waves
in the atmosphere, only a frequency band of between 30 Mfiz
and 300D MHz is available for terrestrial radio communications
covering large service areas. The growing importance of radio
communications leads to the necessity of exploiting-~tfiis.
limited available range as efficiently as possible. Special
so-called multiplex methods are employed in connection with
existing radio communication systems for enhanced exploitation
of the time and frequency ranges, as well as in the coding
sector. Sawever,:only limited expansion of the capacity is,
possible-in said ranges. Directionally selective transmission
of information may offer as alternative.
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antennas with a directional effect are known, which,
because of their special geometry, have an azimuthally
anisotropic radiation characteristic (cf, e.g., LUEGER:
Zexikon der Technik, Elektrotechnik and Kerntechnik-Grundlagen
[Lexicon of Technology; Fundamentals of Electrical and .Nuclear
Engineeringl, Reinbek near Hamburg; ;9721.: In the frequency
range specified above, predominantly so-called aperture antennas
or group arrangements of a plurality of individual antennas
Y
are used, which are controlled by means of an extensive supply
network. If the main direction of transmission of a group
of antennas~is to be variable, electronically controllable
setting elements have to be employed in the supply network for
the amplitude and/or phase. However, the use of such setting
elements is costly and connected with capacity losses. For
this reason, directionally selective transmission of electro-
magnetic waves has hardly been used heretofore for capacity
expansion purposes in the. sector of radio communications.
An approach for generating directional beams deviating
from the above is specified in US.4,947,178. The object of
this document is an antenna arrangement 'in which several
circular disk-shaped individual antennas are arranged coaxially
but equidistantly spaced from each other vertically, and excited
independently of each other by separate feed lines. The individual
antennas have different diameters, which are selected in such a
way that a predetermined electromagnetic oscillation mode can be
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f
1
resonantly coupled to each individual antenna. The fields
emitted by the excited individual antennas superimpose one
another, forming an overall field of radiation, the geometry
of which corresponds with the geometry of a linear superposition
of the coupled-in oscillation modes of the individual antennas.
However, the desired superposition of predetermined
oscillation modes is only incomplete with said object because
interference fields originate from an excited individual antenna
that noticeably impair the development of the mode in adjacent
individual antennas. Furthermore, as each of the individual
antennas has to be provided with its own feed line as well as
with amplitude and phase shifters, the structural expenditure..
of said arrangement is very high, and the total number of
individual antennas which can be assembled for the antenna
arrangement is at the same time hmited,'the consequence of
which is that only a low number of different modes of oscillation
can be combined with each other and the achievable directional
effect is therefore quite unsatisfactory overall.
Therefore, the problem of the present invention is to create
a possibility for the directionally selective transmitting
and/or receiving of electromagnetic waves, in connection with
which the directional characteristic can be selected and influenced
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in a simplified manner versus the state of the art.
Summary of the Invent~.on
As opposed to-the directional antennas according to the
state of the art, where the directional selectivity of the
transmission is achieved through a special. geometry of the
antenna or antexiz~.a arrangement, a directional selection is
created in connection w~.th the invention already in the
excitation ffield in the feed line serving far the excitation
of the antenna. This is accomplished by superposing electro-
magnetic oscillation modes, which are generated in a resonator
as its natural modes, said resonator being operatable in excess
mode. Each electromagnetic oscillation mode effects a
characteristic local dependence of the electric or magnetic
field vectors. By the linear superposition of suitable
oscillation modes it is possible to achieve almost any desired
dependence upon the az~;matt~.al angle of the resulting field.
If such a ffield is used for exciting an antenna, the emission
from the antenna also can take place with only one aaimuthal
directional characteristic conforming to the directional
dependence of the exciting field. Such a method permits in
connection With directional transmission the use of antennas .
without own directionally selective radiation characteristic.
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Therefore, as opposed to the object of US 4,947,178, no defined
antenna geometry is required for promoting the development of
individual electromagnetic field modes..The geometry of the
exiter;field and thus also the radiation characteristic of
the emitted electromagnetic field are variable in a very
comprehensive and rapid manner by a change effected in the
control of the resonator. This creates a highly efficient
possibility for directionally selective transmission.
In order to obtain a predetermined directional characteristic,
the individual oscillation modes are coupled into the resonator,
with a preset amplitude and/or phase ratio. The directional
characteristic is variable also in a predetermined manner by
changing the length of the resonator.
The direction of radiation can be advantageously changed
also by coupling the oscillation modes into the resonator
from a predetermined but variable azimuthal direction.
In addition to the transverse electromagnetic basic mode,
the so-called TEM--mode, one or several higher modes of the
TES,-type are usefully generated in the resonator and super-
posed on.the basic mode. In particular, by superposing the
TEM-mode with the T~11-mode, an exciting field is created
which effects the development of a unilateral radiation
characteristic on the antenna. When a higher oscillation mode
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is superposed on the TEM basic mode with a predetermined
amplitude and phase ratio, an anisotropic directional
characteristic with a predetermined main direction of radiation
of the emitted electromagnetic wave is effected according
to the method of the invention. By changing the phase ratio
between the higher mode of oseillat3on and the TEM basic mode
in a targeted way, a change takes place in the preferred
direction of emission that is adapted to the given requirements.
According to another~advantageous development of the
invention, a directional characteristic is generated on the
antenna which has at least two different main directions of
radiation. Thus a so-called "point-to-multipoint" application is
possible; i.e., communication of the antenna with a plurality
of other transmitting and/or receiving antennas.
The method of the invention differs from the method according to claim 1
in that the antenna is used as a-receiving antenna, whereby the
main direction of radiation of a aransmitting~ 'antenna' .. . . . i.~:
communicating with the receiving antenna is determined at
regular intervals ana the directional: characteristic of the
receiving antenna is adjusted according to the~direction of
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maximum receiving power. The variation of the main direction
of radiation in the detection of~the direction of maximum
receiving power and in the new adjustment of the main direction
of radiation takes place in an entirely simple manner by
accordingly changing the amplitude and/or the phase ratio
and/or the direction of azimuthal coupling of the oscillation
modes into the resonator actively connected to the receiving
antenna. Thus the main direction of radiation is adjustable
in each case by electronic weasures and consequently such
adjustments~can be carried out rapidly. The method
according to the invention is thus suitable especially
for application in mobile radio communication installations.
In said device, a resonator is provided with at least one
coupling connection far coupling-in an electromagnetic field.
The resoriatox has to be operatable in this connection in
excess mode, i.e., so that also higher electromagnetic:
oscillation modes can be generated in addition to the TEM-mode.
With suitable excitation, a electric field consisting.of a
mix of modes develops in the resonator, and said field is
used for exciting an antenna: The electromagnetic wave.: emitted
from the antenna has a directional characteristic cowforming to
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the mix of modes generated in the resonator.
According to an advantageous further development, a single-
conical or a biconical antenna serves as the aerial. Such
antennas are known, for example from US 4,851,859, and are
characterized by a transmitting and receiving capability that
is azimuthally uniform over 360 degrees. Such antennas have been
used heretofore for vmnidirectional transmissions. By exciting
such an antenna with a directionally selective field of
excitation, the transmission, too, takes place with a corresponding
directionally selective radiation characteristic.
The application of such an antenna is advantageous primarily
for the reason that it permits transmission in almost any desired
azimuthal direction with dependence only upon the geometry of
the exciting field - which is variable by simple electronic
measures ~ without having to change the antenna arrangement in
any way. The two halves of the single-conical or biconical
antenna also may have different radial diameters, or the inner
angles of the two conical haves may be different.
According to another advantageous further development, the
resonator in which the electromagnetic oscillation modes are
generated can be designed in such a way that it can be tuned by
changing its length. The ratio at which the individual oscillation
modes develop in the resonator relative to each other
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is variable in this way,.
A particularly simple resonator, which is advantageous
especially when cooperating with a single conical or biconial
antenna, is make available by a coaxial wave conductor_cahich
can be operated in excess mode far generating high electro-
magnetic oscillation modes. Furthermore, the inner and outer
conductors. of a coaxial wave conductor can be connected without
any problem to the two cones of a biconical antenna.
For developing well-defined electromagnetic oscillation
modes it is necessary that the coaxial wave conductor has a
termination at its end opposing~.ithe connection to the antenna.
Said termination may either consist df a short circuit, for
example in the form of a metallic plate electrically connecting
both conductors, or such termination is produced by a
completely reflection-free arrangement.
ladvantageously, the electromagnetic field is coupled in
via at least one coupling connection, which is arranged radially
on the ..coaxial wave conduc.tor-on the outside. Reliable coupling
of the electromagnetic modes into the resonator is achieved in
this way. It is par-ricularly advantageous if the arrangement
comprises a plurality of coupling connections, which are arranged
in the circumferential di_reation of the coaxial wave conductor
_g~
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with the same angular spacings. In such an arrangement, the
radiation.characteristics each having a different main direction
of radiation can be obtained in a simple manner without changing
the arrangement of the resonator by addressing different
coupling connections depending on the desired direction of
emission.
Alternatively to the lateral coupling of the electromagnetic
'field into the resonator coupling takes place by means of a
' coupling connection arranged at the end of the resonator opposing
the connection to the antenna. Axial coupling-in is effected in
this way.
Coaxial sleeves are suitable as reliable and low-radiation
coupling connections.
\~.The electromagnetic field is coupled
in via capacitive~and/or inductive coupling elemenfs. Coupling
pins or dead-end feeders can be considered in this connection
as capaeitive coupling elements, and. coupling loops or coils
as inductive coupling .elements. It is particularly advantageous.
if such coupling elements are etched as conducting paths on
a conductor board or applied in some other~~aay, whereby the
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r
pc board is arranged in the resonator in a suitable way.
As.an alternative or to complete the coupling of the
electromagnetic wave into the resonator by means of capacitive
and/or inductive coupling elements, coupling of the electro-
magnetic field takes place by means of
one or a plurality of~hollow conductors, which are connected
to the resonator on coupling slits and/or coupling holes.
The, coupling connections provided for coupling the electro-
magnetic wave into the resonator are usefully connected to a
supply network, byWeans of which the amplitudes and/or phases
of~the coupled-in oscillation modes can be controlled as well.
This is particularly advantageous because the field distribution
of the mixed mode resulting from the superposition of the
oscillation modes, and thus also the directional characteristic
of the electromagnetic wave emitted by the antenna due to
excitation by a field of said mixed mode are dependent with
particular sensitivity upon the amplitude and phase ratio of~
the basic oscillation. modes. A great variation width of adjustable
directional characteristics is thus available owing to the
separate controllability of the amplitudes and~phases.of the
tuning modes coupled in.
According to one embodiment of the invention, a single-
conical and/or biconical antenna
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is connected to a coaxial wave conductor, which has coupling
connections for coupling in electromagnetic oscillation modes
both radially on the outside and at its end disposed opposite
the connection to the antenna. The coupling connections are
connected to a supply network, by means of which the oscillation
modes coupled in each can be varied in their amplitudes and/or
phases independently of each other. In this connection,
a coupling connection arranged opposite the antenna connection
preferably serves for coupling in a TEM basic mode, and the
other coupling connections serve fox coupling in higher,
azimuthally anisotropic oscillation modes. The superposition
of the azimuthally anisotropic oscillation modes leads to
a directional characteristic of the emitted electromagnetic
field that.!.has.one or a plurality of well-defined main
directions of radiation_ The main direction of radiation is
variably adjustable particularly by changing the phase relation
between the azimuthally anisotropic oscillation modes and the
TEM basic mode.
The arrangement consisting of the antEnna and the resonator
is suitable not only for transmitting but also for receiving
electromagnetic waves.
In an advantageous further development, the resonator and
the antenna are actively connected to a control electronics,
by means of which it is possible to determine a direction of
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maximum azimuthal receiving capacity and to ahen adjust the
main direction of radiation of the directional characteristic
of the maximum receiving capacity accordingly by suitably
varying the amplitude and/or the phase ratios and/or the
direction of the azimuthal coupling of the oscillation modes.
The direction of maximum receiving capacity can be determined
in this connection, for example in such a way that the main
direction of radiation of the directional characteristic of
the antenna is varied at predetermined time intervals and
the outputs received from different azimuthal directions are
compared. Owing to the fact that the main direction of radiation
can be adjusted by only electronic measures it is possible to
newly adjust the main direction of radiation again in a
very rapid way, which is advantageous especially in applications
in mobile or partly mobile radio communication installations.
According to another advantageous further~::de~~lopment, the
control electronics - by means of which the direction of maximum
azimuthal receiving capacity is determined - is actively
connected to an indicator device, by means of which the
azimuthal directional dependence of the receiving capacity
is representable by sound or visually. Such a device is
particularly suitable for radiolocation.
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The device as defined by the invention is suitable in
a particularly advantageous manner as a relay station in
a radio communications network. By suitably adjustir_g different
main directions of radiation of the directional characteristic
it is possible to simultaneously receive signals of a ,
transmitter as well as to transmit signals to a receiver other
than the transmitter. The transmitter and the receiver do not
have to be stationary at all in this connection; the rapid
Y
electronic adjustability of the principal direction of radiation
of the relay station rather permits also the application of
the device as defined by the invention in a radio communications
network consisting of mobile units_
According to yet another further development, the device
as defined by the invention is used in a diversity system for
receiving particularly weak signals or signals strongly
interfered with. Zn this connection., the diversity consists
of a separation between two antennas in terms of space, on
the one hand, and of an individually variable directional
characteristic of such two antennas, on the other. The correlation
of the two receive signals is dependent upon the local
separation, on the one hand, and additionally also on the
different directional characteristic. The receiving capacity
of the arrangement is increased overall by suitably combining
the receive signals of both antennas electronically.
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The solution of the problem as defined by the invention
may be also implemented as a radio communication system.
The radio communication system consists of at least two
transmitting and receiving units, which each have a resonator
provided with at least one coupling connection for coupling in
an electromagnetic field, such resonator being actively
connected to an antenna. When used as intended, the antenna
emits electromagnetic waves with a directional characteristic
corresponding with the field dependence of the electromagnetic
oscillation modes linearly superposed in the resonator, and
at the same time has a predetermined directional characteristic.
A control electronics aligns the main directions of radiation
- of a transmitting and receiving unit with the main direction
of radiation of transmitting and receiving units each being
in radio contact with transmitting and receiving unit.
According to an advantageous further development,, the radio
communication system has at least three transmitting-and
receiving units, of~which at least one unit is applicable
at the same time as a relay point..Due to the rapid electronic.
adjustability.of the main directions,of radiation, the radio
communication system is suitable to a particularly high degree
for application in radio-communications between mobile
subscribers between each other, or between stationary subscribers
on the one side and mobile subsc=fibers on the other. The relay
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a
station, for example, may be arranged in a vehicle or on
board of a helicopter.
In a particularly advantageous application, the-radi.o
communication system is used in a mobile radio communication
network, for example in a mobile telephone system. The special
advantage of the radio communication system as defined by
the invention lies zn.that due to the efficient spatial
bunching by means of the electronic adjustment of the main
directions of radiation of the participating transmitting and
receiving units, the required transmitting power is reduced
and the safety against listening-in is enhanced.
Brief Description of the Drawings
The invention is explained in greater detail in the
following with the help of -the attached .drawing, in which
the following is shown schematically:
FIG. 1 shows a biconical antenna connected to a coaxial
wave conductor.
FTG. .2 is a longitudinal center section.through the
arrangement according to FIG. 1.
FIG. 3 is a sketch illustrating the principle of the
method as defined by the invention with the help of field
lines and directional characteristics.
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FIG. 4 shows a biconical antenna. with a connected coaxial
wave conductor in another embodiment.
FIG. S is a sketch illustrating the principle of
determination o~ a direction of maximum receiving power
in radio communications between two transmitting and receiving
units.
FZG. 6 is a sketch illustrating the principle of radio
communication between two transmitting and receiving units
with interconnection of a relay station.
FIG. 7 is a sketch~illust'rating the principle of radio
communication between a~transmitting unit and a plurality o~
r.epe~ving units; and
FIG. 8 is a sketch of,the principhe for explaining how
the devices as defined by the invention are applied in a local/
anghe diversity system.
Detailed Description of the Preferred Embodiments
~In arrangement 1 shown in'FZGS. 1 and 2, a biconical
antenna 2 is mounted on a coaxial wave conductor 3. The two
halves 4, 5 of biconical antenna. 2 are. arranged rad.$ally
symmetrically relative to each other and with respwet to coaxial
wave conductor 3, opposing one another,with their conical
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widenings, and are connected to conical wave conductor 3
in the manner described in the following.
The lower half 5 of biconical antenna 2, said half
being disposed directly adjacent to conical wave conductor 3,
has the approximate shape of a circular truncated cone,
the height of which is selected in such a way that its
smallest radius approximately corresponds with the radius
of outer conductor 7 of coaxial wave conductor 3. The area
of lower half 5 of bioonical antenna 2 is bent .inwardly at
the end with the smallest radial expanse and changes into
a cylinder-shaped inner section 8, the radius of which
corresponds with the one of the outer conductor 7, said
inner section being electrically connected to the latter.
Upper half 4 of coaxial wave conductor 3 ,of .Iiiconical~
antenna 2,..~said lia3:f being farther :reriloved;:from coaxial wave
conductor 3, changes into the tubular inner conductor 6
of coaxial wave conductor 3 in the manner of a ~unnel_
At the end of coaxial wave conductor 3 opposing biconical
antenna 2, outer conductor 7 feeds into a electrically
conductive, circular termination plate 9, which is electrically
connected also to inner conductor 6.
The short circuyt existing in this way between inner
conductor 6 and outer conductor 7 permits the development of
preset oscillation modes in coaxial wave conductor 3. In this
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arrangement, the electrical field vectors oscillating
zn the coaxial wave conductor between inner conductor 6
and outer conductor 7 in the radial direction are
transformed by the conical widenings of the two antenna
halves 4, 5 into an.oscillation mode axis-parallel with
conical wave conductor 3 without losing any azimuthal
field dependence that may be present. The electromagnetic
wave emitted by biconical antenna 2 thus°exhibits an
azimuthal dependence which corresponds with the azimuthal
directional dependence of the electric field in coaxial
wave conductor 3.
For coupling electromagnetic fields into coaxial wave
conductor 3, a total of eight connection sleeves 10 are
arranged radialiy on outer conductor 7 on the outer side
in the present exemplified embodimenty said connection
sleeves being of the same type among each other and each
having the same angular spacing. Between connection
sleeves 10, a conductor board 11 - which itself is not
conductive - extends radially through the entire coaxial
wave conductor 3, with capacitive and/or.inductove coupling
elements - not shown in the drawing - in the form of etched-in
conductor paths being arranged on said conductor board.
An electromagnetic wave is induced in coaxial wave
conductor 3 by means of the coupling elements arranged on
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conductor board 11. Coaxial wave conductor 3 is operated
in this connection in excess mode. Further, higher oscillation
conditions are generated in addition to the TEr2 basic mode.
The different oscillation modes of coaxial wave conductor 3
lead to corresponding oscillation modes in biconical
antenna 2, which is electrically connected to said modes,
and lead to corresponding electromagnetic waves in said
antenna for emission.
It is explained in the following with the help of
FIG. 3 on the example of superposition of two electromagnetic
oscillation modes, the TEM basic mode and the TE11-mode,
how a directionally selective transmission is effected by
the antenna in an arrangement according to FTG. 1 or FIG. 2_
The electric field distribution in coaxial wave conductor
3 is radially symmetric in the case of the TEM basic mode.
Azimuthal radiation characteristic 20, which corresponds
with said form o~ oscillation, shows an isotropic curve
accordingly_ On the other hand, excitation of a TE1.1-mode
leads to an anisotropic azimuthal dependence 21 in coaxial
wave conductor 3 as well as to an anisotropic azimuthal
radiation characteristic 22, which is characterized by an
axis of maximum radial electric field distribution in
coaxial wave conductor 3 and by a main direction of radiation
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in radiation characteristic 22, in the present example along
lines 90° - 270°. The electric field vectors oscillate in
the coaxial wave conductor along said axis on both sides
of inner conductor 6 in phase opposition.
With linear superposition of a TEM-mode with a TElI-mode,
the component o~ the electric field of the TEll-mode
oscillating in-phase with the TEM-mode is therefore amplified
in coaxial wave conductor 3, whereas the inphase-opposed
component is weakened, as shown by ~ield distribution 23 of
the TEM-TEll-mixed mode. Radiation characteristic 24
corresponding with said mixed mode shows a single preferred
direction of maximum emission, in the example in the 270°
direction.
When arrangement 1 is applied as intended, emission is
achieved in this way in a predetermined direction. By addressing
one of connections 10 in a controlled manner it is possible
in this connection to vary the direction in azimuthal angles
corresponding with the angular spacings of the individual
connections Z0, whereby each addressing of one of connections
leads to a same type of supezposition of the oscillation
modes as described above, however, in each case with anatherw
preferred direction_ In the case of the eight connections
of arrangement l, eight different preferred directions can b~
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achieved in this way in the transmission of the electro-
magnetic wave on antenna 2.
Arrangement 30 shown in FIG. 4 has a structure modified
as compared to arrangement 1. Biconical antenna 2 and the
coaxial wave conductor 3 are structured in the same way
as in arrangement 1. l3owever, instead of the eight lateral
connections 10, arrangement 30 has only two radial connections
31, 32 arranged at an angle of 90° relative to each other,
said conr~ections being arranged radially on outer
conductor 7 on the outer side, as well as an axial connection
33 at the end of coaxial wave conductor 3 opposing the
antenna. Connections 31, 32, 33 are connected to a supply
network 35, which supplies the electria.energy reguired for
coupling in predetermined electromagnetic oscillation modes.
Setting elements 36, 37 for controlling the amplitudes of
the electromagnetic field modes coupled in on the lateral
connections 31, 32, as well as a setting element 38 for
varying the phase of the field modes coupled in via the
axial connection 33 are integrated in supply network 35.
When arrangement 30 is applied as intended, an electro-
magnetic wave of mode TE11 is coupled in via each of the
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lateral connections 31, 32. The azimuthal directional
characteristic of the associated mixed mode of type
TEllx/TElly has approximately the shape of an "eight" (8)
and has a preferred axis along a line corresponding with
the angle bisector between connections 31 and 32, with
maximum emission existing along said preferred axis. The TENt
basic mode is addit~.onally fed in on axial connection 33,
said basic mode being superposed with the field modes
coupled in by the lateral connections 31,_32 to form a
TEM-TE11/TEllx/TElly--mixed mode. with the same phase ratio
between the TEll-field modes, which are coupled in on
connections 31, 32, and the TENT-basic mode, which is coupled
in on connection 33, said mixed mode has the same preferred
axis of maximum field distribution or maximum emission as
the aforementioned TE1~/TEZly-mode. The phase ratio is
mutually adjustable on connections 31, 32 as well as on
axial connection 33 by means of the phase setting element 38
in supply network 35. fihe change of said phase ratio also
Leads to a change of the preferred axis of maximum field
distribution or maximum emission. In arrangement 30, an
electronically controlled swinging of the main direction of
radiation of the electromagnetic wave emitted by antenna 2
is effected in this way in any desired azimuthal direction.
The transmitting and receiving unit 40 shown in FIG. 5
consists in the manner described above of a biconical
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a
antenna 2 as well as a resonator 3 actively connected to
the latter, with a plurality of coupling connections being
arranged on said resonator in the circumferential direction
for feeding in electromagnetic oscillation modes. Transmitting
and receiving unit 40 is additionally equipped with an~
electronic control unit 41. Transmitting and receiving unit 40,
which is stationary.in the present case, is in radio communication
with a mobile transmitting and receiving unit 43.
The directional characteristic of antenna 2 of transmitting
and receiving unit 40 is adapted to the direction of maximum
receiving power with the help of electronic control,unit 41,
in the present exemplified embodiment to the main radiation
direction 44 of the mobile transmitting and receiving unit 43.
For said purpose, main radiation direction 46 of the
directional characteristic of antenna 2 of transmitting and
receiving unit 40 is swiveled at predetermined time intervals
acxoss the entire azimuth range of 360°, as indicated by
arrows 47. This is accomplished by either engaging the
coupling connections 10 one after the.:other in a predetermined
circumferential direction for feeding in the oscillation modes,
or by suitably addressing the coupling connections 10, which
leads to a change in the amplitude and/or phase ratio of
the electromagnetic oscillation modes coupled into
resonator 3_ The receiving power is measua:ed in -this connection
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CA 02246724 2004-02-16
at predetermined azimuthal angle spacings and the azimuthal
dependence of the receiving power is determined based on
said measurement, and the direction of maximum receiving
power is in turn computed based on said dependence. By
suitably adjusting the amplitude and/or phase ratios of
the oscillation modes coupled into resonator 3 of transmitting
and receiving unit 90, or by changing the direction,in
which the oscillation modes are coupled into the resonator,
the main radiation direction 46 is subsequently adjusted
in the direction of maximum receiving power.
With said method, it is possible without problems to
cause main radiation direction 45 to follow the main
radiation direction 44 of a moving transmitting and receiving
unit 43 and to thus assure a constantly good reception.
In the exemplified embodiment, control electronics 41
is connected to an indicating electronics 49 for representing
the azi.muthal dependence of the receiving power by sound
or visually. Transmitting and receiving unit 40 is therefore
particularly suitab7.e,for radiolocation.
FIG. 6 illustrated the principle of radio communication
c
between two transmitter receivers 40, 40", having an obstacle 52
positioned in between. A relay station 40' is used to avoid
obstacle 52. Transmitter receivers 40, 40' 40", may be either
fixed or mobile units.
FIG. 7 shows the application. of transmitting and receiving
unit 40 in a so-called "point-to-multipoint" connection,
-2 S--
AUG-14-1998 13=29 COLLARD & ROE _ 516 365 985 r.e'~i~4
_ CA 02246724 1998-08-17
where transmitting and receiving unit AO is simultaneously
in radio contact with a plurality of transmitting and receiving
units 43. For this purpose it is necessary only to select
those oscillation modes for coupling into the resonator
whose linear superposition leads to a directional characteristic
with three main directions of radiation.
In the mobile radio sector, sector base station antennas
are often used according to the state of the art so as to
be able to define the area of radio supply in a more targeted
manner. The sectors S3. 53', 53 " , 53 "' selected according
to the state of the art are predetermined by the base station
antenna configuration and cannot be changed rapidly and
in any desired way. According to the invention, however,
a radio sector is defined in each. case by a predetermined
main radiation direction 54, 54', 54 " . such main radiation
directions 54, 54', 54 " can be changed in any desired way
over the entire azimuth range and can be optimally adapted in
this way to the actual volume of radio traffic and its
distribution in terms of space.
Finally, the application of two biconical antennas for
realizing a combined local/angle diversity system is shown
in FIG_ 8.
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RUG-14-1998 13=29 COLLARD & ROE 516 365 9805 P.e8i24
CA 02246724 1998-08-17
The two transmitting and receiving~units 40, 40' axe
arranged spaced from each other and are actively connected
to an electronic control 54. The two transmitting and receiving
units are controllable independently of one another by means
of electronic control 54.
Transmitting and receiving units 40, 40' are controlled
by the electronic controller in such a way that different
directional characteristics 56, 5&' develop on the two
transmitting and receiving units 40, 40'_ In the exemplified
embodiment, the two directional characteristics 56, 56' have
two identical main radiation directions 57, 57'. However,
directional characteristic 56 is developed stronger in main
radiation direction S7' than in main radiation direction 57,
whereas directional characteristic 56' is developed stronger
in main radiation direction 57 than in main radiation
direction 57'. The receive signals of both transmitting and
receiving units 40, 40' are detected by electronic control 54
and correlated with each other. Both the spatial separation
of transmitting and receiving unit 40 and the different
directional characteristic lead to different receive signals,
and the correlation of said signals leads to a substantially
enhanced reception especially with weak signals.
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AUG-14-1998 13:29 COLLARD & ROE - 516 365 9885 P.09i24
CA 02246724 1998-08-17
Instead of the two transmitting and receiving units 40
shown in FIG. 8 it is possible to use one single biconical
antenna 2 in order to achieve an angular diversity across
all azimuth directions by realizing two receiving channels
each having a different antenna directional characteristic.
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