ANNULAR SLOT ANTENNA WITH STRIPLINE FEED

• US 3,665,480 A
• Filed: 01/23/1969
• Issued: 05/23/1972
• Est. Priority Date: 01/23/1969
• Status: Expired due to Term

• Current Assignee: Matthew Fassett
• Original Assignee: Matthew Fassett
• Inventors: Fassett, Matthew
• Primary Examiner(s): Lieberman, Eli
• Application Number:
  US04/793,266
• Time in Patent Office: 1,216 Days
• Field of Search: 343/767,768,769,770,771,854,754 333/84M
• US Class Current: 343/754
• CPC Class Codes: H01Q 13/16 Folded slot antennas
• CPC Class Codes: H01Q 21/24 Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001
• CPC Class Codes: H01Q 9/0435 using two feed points

Abstract

A stripline antenna having a radiating aperture in the form of an annular slot provided in one of its conducting plates and a pair of orthogonal narrow strip conductor feeds disposed between its two conducting plates and terminating under the central disk formed by the annular slot. Adjustment of the relative phase and amplitude of the electromagnetic energy applied to the strip conductor feeds permits radiation from the annular slot of circular, elliptical or orthogonal linear polarizations into space or into a waveguide.

Claims

1. An antenna for radiating electromagnetic radiation comprising a plurality of electrically conducting plates, at least one of said plates being provided with an opening having a closed outline, an electrically conducting member of smaller dimensions than said opening supported within said opening such that the boundary of said member which has substantially the same form as said closed outline is aligned with the boundary of said opening to form a radiating aperture, a plurality of feed elements supported by means of at least one dielectric support structure in spaced relation to said conducting plates to couple electromagnetic energy into said radiating aperture, said feed elements being positioned about the circumference of said radiating aperture to provide a continuously variable polarization to radiation radiated from said aperture.

2. An antenna comprising two substantially parallel electrically conducting plates in spaced apart relationship, a generally annular radiating aperture of substantially uniform width provided in at least one of said conducting plates, a plurality of feed elements supported by means of a dielectric Support structure in spaced relation between said conducting plates to couple electromagnetic energy into said radiating aperture, said feed structures being positioned about the circumference of said radiating aperture to provide a continuously variable polarization to radiation radiated from said aperture.

3. An antenna comprising first and second feed elements supported in spaced relationship between two substantially parallel conducting plates by means of a dielectric support structure, at least one of said conducting plates having a radiating aperture in the form of a generally annular slot having substantially uniform width and a circumference which permits said slot to support at least one resonant mode of electromagnetic radiation radiated from said aperture, said first feed element being positioned relative to said slot to couple electromagnetic energy into said slot, said second feed element being positioned at a null of the resonant waveform excited in said slot by said first feed element so that said second feed element couples electromagnetic energy into said slot independently of the energy being coupled by said first feed element.

4. The antenna of claim 3 including a plurality of electrically conducting pins disposed with substantially equal spacing circumferentially around said slot to reduce the propagation of radiation between said conducting plates radially outwards from said slot.

5. The antennas of claim 3 including a variable phase shifter connected electrically between said first and second feed elements whereby radiation having a first polarization received by said first feed element is phase shifted by said variable phase shifter and transmitted by said second feed element at a second polarization.

6. An antenna comprising an electrically conducting plate having a generally annular radiating aperture of substantially uniform width enclosing a central disk which is supported by a metallic shorted quarter-wave transmission line segment, a plurality of microstrip feed elements in parallel spaced relationship to said conducting plate which are supported by a plurality of metallic shorted quarter-wave transmission line segments to couple electromagnetic energy into said radiating aperture, said feed elements being positioned about the circumference of said radiating aperture to provide a continuously variable polarization to radiation radiated from said aperture.

7. An antenna comprising first and second feed elements supported by means of a dielectric support structure in parallel spaced relationship to an electrically conducting plate, said conducting plate having a radiating aperture in the form of a generally annular slot having a substantially uniform width and adapted to support at least one resonant mode of electromagnetic radiation radiated from said aperture, said first feed element being positioned to couple electromagnetic energy into said slot, said second feed element being positioned at a null of the resonant waveform excited in said slot by said first feed structure so that said second feed element couples electromagnetic energy into said slot independently of the energy being coupled by said first feed element.

8. In combination:

a source of electromagnetic energy emitting radiation having a first polarization;

a plurality of antennas each of which comprises at least one electrically conducting plate provided with an opening having a closed outline, an electrically conducting member supported within said opening such that the boundary of said member which has substantially the same form as said closed outline is aligned with the boundary of said opening to form an aperture for receiving radiation having said first polarization and transmitting radiation having a second polarization, said aperture being positioned to receive a portion of the electromagnetic energy emitted by said source of electromagnetic energy, first and second feed elements having at least portions thereof substantially uniformly spaced from said coNducting plate to support respectively first and second electromagnetic traveling waves which travel respectively from and towards said aperture, said second feed element being positioned to excite a resonant mode of electromagnetic radiation within said aperture, said first feed element being positioned at a null of said resonant mode to couple from said aperture radiation of said first polarization;

a plurality of variable phase shifters, one of said variable phase shifters being connected between an output of said first feed element and an input of said second feed element to impart a phase shift between said first and second travelling waves;

each of said antennas being positioned to transmit radiation having said second polarization in a common direction to provide a resultant radiation pattern formed in accordance with the phase shifts imparted by said phase shifters.

9. In combination:

a source of electromagnetic energy emitting radiation having a first polarization;

a plurality of antennas each of which comprises at least one electrically conducting plate provided with a generally annular radiating aperture having a circumferential length which permits first and second orthogonal electric fields to be supported within said aperture, a first feed element positioned relative to said aperture for coupling electromagnetic energy from said first orthogonal field, a second feed element positioned relative to said aperture for coupling electromagnetic energy into said aperture to excite said second orthogonal field, said first orthogonal field being excited by radiation having said first polarization received from said source of electromagnetic energy;

a plurality of phase shifters one of which is connected between said first and second feed elements of each antenna whereby radiation provided by said first feed element is phase shifted and coupled to said second feed element;

each of said antennas being positioned to transmit radiation of a second polarization emanating from each of said second orthogonal fields in a common direction to provide a resultant radiation pattern formed in accordance with the phase shifts imparted by said phase shifters.

10. In combination:

antenna means comprising a plurality of electrically conducting plates provided with radiating apertures and positioned to receive radiation of a first polarization arriving from a common source, a first feed element respectively positioned relative to each of said apertures and extending substantially normally therefrom to couple energy from received radiation of said first polarization, a second feed element coupled to each of said apertures to excite radiation of a second polarization in said apertures for transmission therefrom, each of said second feed elements respectively spaced along the periphery of each of said apertures from each of said first feed elements whereby each of said first and second feed elements are substantially electromagnetically decoupled;

a plurality of phase shifters respectively connected to each of said first feed elements to impart phase shifts to radiation provided by each of said first feed elements, the outputs of said phase shifters being connected respectively to each of said second feed elements whereby radiation of said second polarization is phase shifted relative to the phase of radiation of said first polarization for forming a combined radiation pattern of the transmitted radiation of said second polarization.

11. In combination:

at least one antenna which comprises first and second feed elements supported in spaced relationship between two substantially parallel conducting plates by means of a dielectric support structure, at least one of said conducting plates having a radiating aperture in the form of a generally annular slot of substantially uniform width and circumferential length to permit said slot to support at least one resonant mode of electromagnetic radiation radiated from said aperture, said first feed elemeNt being positioned relative to said slot to couple electromagnetic energy into said slot, said second feed element being positioned at a null of the resonant waveform excited in said slot by said first feed element so that said second feed element couples electromagnetic energy into said slot independently of the energy being coupled by said first feed element; and

waveguide means equipped with mounting means at one end thereof whereby each of said antennas is mounted in a position to couple electromagnetic energy into said waveguide means.

12. In combination:

a source of electromagnetic radiation;

a plurality of receiving antennas positioned to receive radiation from said source of electromagnetic radiation, each of said receiving antennas comprising at least one electrically conducting plate provided with an opening having a closed outline, an electrically conducting member of smaller dimensions than said opening supported within said opening such that the boundary of said member which has substantially the same form as said closed outline is aligned with the boundary of said opening to form a receiving aperture for receiving electromagnetic radiation, at least one feed element positioned relative to said receiving aperture whereby a component of the received field of the radiation provided by said source of electromagnetic radiation induces a received signal in said feed element, said receiving feed element being spaced relative to said conducting plate whereby said received signal propagates along said feed element from said receiving aperture;

a plurality of phase shifters each of which is coupled respectively to feed elements of said receiving antennas for imparting phase shifts respectively to each of said received signals;

a plurality of transmitting antennas each of which comprises at least one electrically conducting plate provided with an opening having a closed outline, an electrically conducting member of smaller dimensions than said opening supported within said opening such that the boundary of said member which has substantially the same form as said closed outline is aligned with the boundary of said opening to form a transmitting aperture for transmitting electromagnetic radiation, at least one transmitting feed element positioned relative to said transmitting aperture to excite therein a component of the tramsmitted field of electromagnetic radiation, said transmitting feed element being spaced relative to said conducting plate whereby electromagnetic energy for said transmitted component field propagates along said transmitting feed element to said transmitting aperture;

the outputs of each of said phase shifters being connected respectively to each feed element of each of said transmitting antennas for coupling thereto electromagnetic energy of each of said components of said received radiation, said transmitting antennas being positioned to radiate in a common direction whereby the radiations from each of said transmitting antennas sum together to provide at least one resultant radiation pattern which is formed in accordance with the phase shifts imparted by said phase shifters to said received signals.

13. In combination:

a source of electromagnetic radiation;

a plurality of receiving antennas which are positioned to receive said radiation, a plurality of phase shifters, a plurality of transmitting antennas, each of said receiving and transmitting antennas having an annular slot radiating aperture disposed within a conducting plate, said aperture being coupled to a pair of orthogonal feed elements which are uniformly spaced with respect to said plate for exciting within said aperture orthogonal electric fields having sinusoidal amplitude distributions around the circumference of said radiating aperture;

the two feed elements in each of said receiving antennas being connected, respectively, to a pair of phase shifters to couple respective components of the received electromagnetic field from the radiatIng aperture into the respective phase shifters to provide a corresponding pair of phase shifted electromagnetic signals;

the two feed elements in each of said transmitting antennas being positioned to couple corresponding pairs of said phase shifted electromagnetic signals from pairs of said phase shifters into the radiating aperture in each of said transmitting antennas to excite within the aperture of each of said transmitting antennas corresponding components of an electromagnetic field for subsequent transmission;

each of said transmitting antennas being positioned to radiate in a common direction whereby the radiations from each of the orthogonal electric fields within the radiating apertures of said transmitting antennas sum together to provide at least one resultant radiation pattern which is formed in accordance with the phase shifts imparted by said phase shifters to said received signals.

14. An antenna for radiating electromagnetic radiation comprising at least one electrically conducting plate provided with an opening having a closed outline, an electrically conducting member of smaller dimensions than said opening supported within said opening such that the boundary of said member which has substantially the same form as said closed outline is aligned with the boundary of said opening to form an aperture which can support a resonant mode of electromagnetic radiation having a wavelength approximately equal to the length of said aperture, at least one feed element having at least a portion thereof substantially uniformly spaced from said conducting plate to support an electromagnetic wave which propagates toward said aperture, said feed element terminating adjacent one point of said aperture to couple electromagnetic energy from said feed element to said aperture such that the electromagnetic radiation resulting from the interaction of said feed element and said aperture is polarized in a single direction.

15. In combination:

a plurality of receiving antennas positioned to receive electromagnetic radiation from a common source of electromagnetic radiation and a plurality of transmitting antennas positioned to radiate at least a portion of their individual radiations in a common direction, each of said receiving antennas and each of said transmitting antennas comprising at least one electrically conducting plate provided with an opening having a closed outline larger than a wavelength of said radiation, an electrically conducting member of smaller dimensions than said opening supported within said opening such that the boundary of said member which has substantially the same form as said closed outline is aligned with the boundary of said opening to form a radiating aperture which can support a resonant mode of said radiation;

a plurality of feed elements positioned relative to said aperture for coupling electromagnetic radiation to said aperture, said feed elements being spaced relative to said conducting plate to permit electromagnetic radiation to propagate along said feed elements to couple with said aperture; and

a plurality of groups of phase shifters, each of said group of phase shifters interconnecting one of said receiving antennas to one of said transmitting antennas such that each of said phase shifters in said group of phase shifters interconnects a feed element of said receiving antenna with a corresponding feed element of said transmitting antenna for coupling electromagnetic energy from said receiving antenna to said transmitting antenna, each of said phase shifters imparting individual phase shifts to electromagnetic energy coupled by said phase shifter for varying the polarization of said radiation transmitted by said transmitting antennas relative to the polarization of radiation received by said receiving antennas.