Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/22—Longitudinal slot in boundary wall of waveguide or transmission line
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/061—Two dimensional planar arrays
  • H01Q21/064—Two dimensional planar arrays using horn or slot aerials

Definitions

• the present invention relates to a flat plate transmit/receive antenna, a system for receiving electromagnetic energy, a system for transmitting electromagnetic energy, a system for transmitting and receiving electromagnetic energy, a method for receiving electromagnetic energy, a method for transmitting electromagnetic energy, and a method for transmitting and receiving electromagnetic energy.
• the present i nventor has come to the realisation that there is a need for a two-layer parallel-plate waveguide antenna which transforms a cylindrical phase front in a first parallel plate waveguide to a plane phase front in an associated transmission/receiving waveguide since such an antenna has a number of desirable characteristics which make it
• electromagnetic energy a system for transmitting electromagnetic energy, a system for transmitting and receiving electromagnetic energy, a method for receiving electromagnetic energy, a method for transmitting electromagnetic energy, and a method for transmitting and receiving electromagnetic energy.
• a flat plate transmit/receive antenna comprising:
• a coupler for coupling energy into and out of the first waveguide; a waveguide bend for communicating energy between the first and second parallel plate waveguides and providing a transformation between a cylindrical phase front in the first waveguide and a planar phase front in the second waveguide;
• a transmit/receive plate comprising one plate of the second waveguide and having an array of apertures for coupling electromagnetic energy between the second waveguide and free space;
• the apertures are spaced from each other such that electromagnetic energy between the second waveguide and free space is coupled to provide a selected phase of electromagnetic energy transmitted by the
• the selected phase is either:
• a system for receiving electromagnetic energy comprising:
• a flat plate transmit/receive antenna of the first embodiment for receiving the electromagnetic energy from free space and outputting a received signal
• a receiver operatlvely associated with the coupler of the antenna.
• the receiver includes a filter and amplifier connected to the antenna to filter and amplify the received signal and a demodulator connected to the filter and amplifier for demodulating the received signal to provide an output information signal.
• a system for transmitting electromagnetic energy comprising:
• a flat plate transmit/receive antenna of the first embodiment for transmitting electromagnetic energy into free space
• a transmitter operatlvely associated with the coupler of the antenna.
• the transmitter of the third embodiment Includes a microwave frequency generator, a modulator for mixing the microwave frequency with an input information signal to produce a modulated signal and a power ampl ifi er for ampl ifyi ng the modul ated si gnal and outputti ng it to a transmit/receive antenna of the first embodiment for transmission of the modulation signal to free space.
• a system for transmi tti ng and recei vi ng el ectromagneti c energy , sai d system comprising:
• a flat plate transmit/receive antenna of the first embodiment for receiving and outputting a received signal from free space and for transmitting electromagnetic energy into free space;
• the antenna is coupled to a circulator, the circulator transferring energy received by the antenna to a filter, amplifier and receiver to provide an output
• the circulator also transfers energy from a frequency generator, modulator and power amplifier to the antenna for transmission of the modulated input Information signal to free space.
• a method for receiving electromagnetic energy comprising the step of receiving the energy with a system of the second embodiment.
• a method for transmitting electromagnetic energy comprising applying an information input signal to the transmitter of the system of the third embodiment.
• a seventh embodiment of the present invention there is disclosed a method for transmitting and receiving electromagnetic energy, the method comprising:
• first and second parallel plate waveguides are disposed adjacent to one another in a sandwich type arrangement. This is preferably achieved using a single common plate between each of the waveguides.
• the antenna be operated within the range of about 5 GHz to about 60 GHz
• Examples of preferred couplers are coaxially coupled top-loaded monopole and dielectrlcally loaded monopole.
• the waveguide bend is a metal or metals which form a common substantially U-shaped wall at one end of the first and second parallel plate waveguides with an aperture adjacent the common wall and
• the transmit/receive plate may can also be manufactured using printed circuit techniques to provide a dielectric sheet with a metallic bonded coating, with the required slots having been etched into the metal layer.
• transmit/receive plate are preferably copper, brass or aluminium.
• the apertures in the transmit/receive plate are typically rectangular slots arranged transverse the direction of wave propagation in the second parallel plate waveguide. Any other orientation, except parallel to the direction of propagation, is also useful.
• Other slot shapes can be used to provide circular or elliptical polarisations, such as a crossed slot for example.
• the dimensions of the slots determines the characteristics of the beam. Also the spacing between the slots determines the displacement of undesirable grating lobes and as such it is preferred that the slot centres be spaced by the wavelength ( ⁇ ) in the plane of the wave in the second waveguide and spaced by a value less than or equal to ⁇ , and most
• the waveguides it is preferred to fill the waveguides with a dielectric.
• a dielectric such as a doped foam (such dielectrics are available commercially eg from Emerson & Cumming).
• the shape may be varied from parabolic for purposes of obtaining a shaped, non-focussed beam.
• Fig. 1 is an isometric view of the external structure of an antenna of the preferred embodiment
• Fig. 2 is a top plan view of the antenna of Fig. 1 illustrating the arrangement of the slots in the upper waveguide;
• Fig. 3 1s a vertical cross-section of section III-III of Fig. 2;
• Fig. 4 illustrates a transmitting/receiving system coupled to the antenna of the preferred embodiment
• Fig. 5 illustrates the various arrangement of grating lobes
• Fig. 6 illustrates an alternative embodiment that enables a transmit/ receive lobe to be scanned
• Fig. 7 illustrates a further embodiment of a dual polarisation antenna
• Figs. 8 and 9 illustrate systems for receiving and transmitting information signals; and Figs. 10A-C show examples of apertures that can be used to obtain different polarisations.
• a flat plate antenna 1 comprising a lower parallel plate waveguide 2 connected to an upper parallel plate waveguide 3 by a parabolic waveguide bend 4.
• the upper waveguide 3 is formed by a transmit/receive plate 5 and a common plate 40.
• the transmit/receive plate 5 comprises an array of slots 6 adapted to couple energy between waveguide 3 and free space.
• the upper waveguide 3 ends in a microwave absorber 7 that prevents energy being reflected from the end of the waveguide 3.
• the lower waveguide 2 is formed between the common plate 40 and a base plate 41. As seen in plan in Fig. 2, the waveguide 2 is preferably substantially conical to achieve focussing on the bend 4. Energy is coupled into and out of the lower waveguide 2 via probe 8.
• the parabolic waveguide bend 4 is substantially U-shaped and connects the transmit/receive plate 5 with the base plate 41 to provide an aperture 42 that communicates between the adjacent ends of the waveguides 2 and 3.
• the bend 4 acts to redirect the waves in the waveguides 2 and 3 through a physical 180°, by a 360° change in phase.
• the bend 4 also transforms the plane of waveform propagation between the waveguides 2 and 3.
• the operation of the antenna 1 is best described 1n transmission, although it will be understood by those skilled in the art that a reverse operation occurs when operating in reception.
• the waveguide bend 4 has a parabolic profile in the plane of the waveguides 2 and 3, and thus provides a focusing action which causes a planar wave to propagate in the upper waveguide 3.
• the transmit/receive plate 5 and the array of slots 6 arranged therein allow the wave to radiate in a direction substantially perpendicular to the plane of the surface of the plate 5. This is achieved by the planar wave reaching each slot in-phase thus affording maximum directional gain. For perpendicular propagation to be successfully achieved, two conditions must be met.
• the upper waveguide 3 must be a slow wave structure, for example by appropriate dielectric loading, such that each of the slots 6 are fed in phase or by a phase difference equal to a multiple of 2 ⁇ radians.
• Dielectric 9 in each of the waveguides 2 and 3 is shown in Fig. 3 to achieve this operation.
• the spacing between each of the slots must be sufficiently small to avoid the production of grating lobes, that are known in the art.
• the size of Individual slots will, in general, vary over the surface of the plate 5 in order to maximise efficiency with a phase appropriate to the type of beam desired. For example, in-phase for a substantially perpendicular beam affording maximum directional gain.
• a dielectric matching layer 10 which improves the operation of the waveguide bend 4.
• the antenna 1 is useful for transmitting and receiving frequencies between about 5 GHz and about 60 GHz with the preferred embodiments adapted specifically to the AUSSAT satellite system which transmits between 14 and 14.5 Ghz and receives between 12 and 12.5 GHz.
• the frequency band of signals determines the overall size of the antenna.
• a transceiver 11 coupled to the antenna 1 by a circulator 12.
• the circulator 12 couples energy between the antenna 1 and the power amplifier 13 on the transmitting side and the bandpass filter
• the bandpass filter 14 and low noise amplifier 17 are located on the antenna immediately adjacent the probe 8 as indicated in Fig. 3.
• Fig. 5 illustrates the transmission and formation of grating lobes in the flat plate antenna 1.
• the antenna 1 creates a main beam 19
• grating lobes 20 perpendicular to the main beam 19 form in the plane of the antenna 1, reducing the efficiency of the antenna and caus i ng
• Fig. 6 illustrates a another flat plate antenna 22 which has a number of probes 8 arranged about the focus of the lower parallel plate waveguide 23.
• the waveguide 23 is coupled into an upper waveguide 24 via a parabolic waveguide bend 25 as previously described.
• the arrangement of the probes 8 in Fig. 6 allows multiple main beams to be produced by the antenna in a plane transverse to the propagation of the wave in the upper waveguide 24. Such an arrangement will provide for the antenna 22 to be able to transmit and/or receive from more than one satellite substantially simultaneously.
• Fig. 7 illustrates an embodiment of a dual polarisation antenna 26.
• the antenna 26 has two separate lower parallel plate waveguides 27 and 28 that respectively couple via waveguide bends 29 and 30 to a common upper parallel plate waveguide 31.
• the upper waveguide 31 has a transmit/receive plate with two arrays of slots 32 and 33 adapted for transmission/reception of waves into and out of the respective lower waveguides 27 and 28. It will be understood by those skilled in the art that the
• Fig. 7 can at least double the communication volume handled by the antenna 26.
• Figs 8 and 9 illustrate respectively systems for receiving and transmitting information signals.
• the components of each system is the same as that earlier described with respect to Fig. 4.
• Figs. 10A-C provide various polarisations and are each preferably arranged at an angle of 45° to the direction of propagation of the wave in the second waveguide.
• Fig. 10A shows a crossed slot or cruciform shape that provides circular polarisation.
• the elliptoid of Fig. 10b and notched circle of Fig. 10C are also useful.
• a flat plate antenna in accordance with the present invention is particularly useful in systems for transmitting and/or receiving satellite communication signals.
• the lower waveguide 2 of Fig. 2 can be rectangular in shape rather than substantially conical.

Landscapes

• Variable-Direction Aerials And Aerial Arrays (AREA)
• Waveguide Aerials (AREA)

Applications Claiming Priority (2)

Publications (2)

Family

ID=3774627

Family Applications (1)

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• 1991
  • 1991-04-29 CA CA 2080244 patent/CA2080244A1/en not_active Abandoned
  • 1991-04-29 JP JP91508095A patent/JPH05506759A/ja active Pending
  • 1991-04-29 WO PCT/AU1991/000165 patent/WO1991017586A1/en not_active Ceased
  • 1991-04-29 EP EP19910908681 patent/EP0527178A4/en not_active Withdrawn

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