US3255455A - Cassegrain antenna - Google Patents

Cassegrain antenna Download PDF

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Publication number
US3255455A
US3255455A US212052A US21205262A US3255455A US 3255455 A US3255455 A US 3255455A US 212052 A US212052 A US 212052A US 21205262 A US21205262 A US 21205262A US 3255455 A US3255455 A US 3255455A
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US
United States
Prior art keywords
parabola
mirror
antenna
aperture
auxiliary reflector
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US212052A
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English (en)
Inventor
Trentini Giswalt Von
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Siemens and Halske AG
Siemens Corp
Original Assignee
Siemens Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Siemens Corp filed Critical Siemens Corp
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Publication of US3255455A publication Critical patent/US3255455A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
    • H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
    • H01Q19/18—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces
    • H01Q19/19—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface
    • H01Q19/191—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces having two or more spaced reflecting surfaces comprising one main concave reflecting surface associated with an auxiliary reflecting surface wherein the primary active element uses one or more deflecting surfaces, e.g. beam waveguide feeds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
    • H01Q3/02—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole
    • H01Q3/08—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system using mechanical movement of antenna or antenna system as a whole for varying two co-ordinates of the orientation

Definitions

  • the invention disclosed herein is concerned with an antenna for very short electromagnetic waves, comprising a parabola mirror ahead of which is arranged a hyperboloidlike auxiliary reflector having a considerably smaller aperture than the mirror, such reflector cooperating with a primary radiator disposed at the apex of the parabola mirror and serving for flooding of the mirror.
  • An antenna of this type is also known as Cassegrain Antenna.
  • the primary radiator is in such case often constructed as a funnel-like radiator with relatively very small aperture, with the radiation thereof directed to the noticeably larger hyperboloid-like auxiliary reflector from which the radiation passes to the parabola mirror proper.
  • the radiation path is upon receiving oppositely directed.
  • the operation of such antenna is considerably more favorable than that of a parabola mirror antenna which is fed directly by a horn radiator.
  • the focal point of the large parabola mirror coincides with the focal point lying in back of the auxiliary reflector and the second focal point of the hyperboloid-like auxiliary reflector falls in the phase center of the primary radiator.
  • Such antennas have, with strong focusing and great focal distance, the disadvantage that the primary radiator focuses likewise relatively strongly, therefore requiring a large aperture.
  • the primary radiator constructed as .funnel radiator, has for this reason great length. It is moreover in most cases diflicult to obtain good matching, good efliciency and a good radiation diagram in an extended frequency range.
  • the object of the invention is to improve a Cassegrain antenna particularly with respect to the above noted drawbacks.
  • an antenna for very short electromagnetic waves comprising a parabolic mirror having with respect to the waves a very large aperture, ahead of which is arranged a hyperboloid-like auxiliary reflector with con siderably smaller aperture, said auxiliary reflector cooperating with a primary radiator disposed at the apex of the parabola mirror to reflect waves from said primary radiator to said mirror, the object of the invention being realized by constructing the primary radiator as a horn I parabola antenna having, as compared with the aperture of the parabola mirror, a small aperture, such primary radiator radiating from the rear of the parabola mirror through the apex thereof and being directed to the hyperboloid-like auxiliary reflector the spacing of which, from the parabola mirror apex, corresponds approximately to one-half up to the entire Rayleigh spacing, and the aperture of which is equal to or somewhat larger than that of the horn parabola antenna.
  • a movable parabola mirror antenna for the reception of radiation from space or for effecting radiation into space, that the parabola mirror be arranged for rotation upon tracks, horizontally to the surface of the earth and for swinging or pivotal motion about an axis of rotation extending in back of the parabola mirror perpendicularly to the axis thereof.
  • An antenna of this type is of particular advantage in case of an arrangement in which a sender and/ or a preferably extremely noiseless receiver are to be connected with the terminal means of the horn parabola antenna, as it meets requirements posed with respect to short leads, small line losses and good matching in a broad frequency band.
  • the illustrated antenna comprises a parabola mirror 1 with relatively very large diameter, measuring, for example, from twenty to thirty meters, which is positioned upon the surface of the earth by means of a mounting provided with rotary tracks 2, 3.
  • the parabola mirror 1 is thus rotatable about the axis 4 and may also be swung or pivoted about the .axis 6 by means of a pivot journal 5.
  • the horn parabola antenna serving as primary radiator for the parabola mirror, comprises a parabola radiator 7 which merges into a hollow cone 8 of known construction.
  • the aperture 9 of the horn parabola antenna is trained upon the hyperboloid-like auxiliary reflector 10 having an aperture which is preferably somewhat larger than the aperture 9 of the horn parabola antenna.
  • the connection of the root of the cone 8 with the high frequency devices 11, including a sender S and a receiver E, which are fixedly disposed, preferably rigidly fastened upon the rotation track and thus moving along with the parabola mirror 1 only upon rotation thereof about the axis 4, is effected by means of the rotary coupling 12 which is arranged in the vicinity of the pivot journal 5.
  • the spacing between the aperture 9 of the horn parabola antenna and the auxiliary reflector 10 corresponds approximately to one-half up to the full Rayleigh spacing.
  • the curvature of the hyperboloid-like auxiliary reflector 10 is dimensioned so that there results for the hyperboloid, as a second focal point, in back of the parabola mirror antenna 1, a finite focal point which is so selected that the phase front of the parabola mirror antenna 1 is at least nearly plane.
  • auxiliary reflector with an aperture diameter amounting to 1.2 meters, with the auxiliary reflector 10 spaced by about 5.5 meters from the mirror apex, ata focal distance of the auxiliary reflector 10 on the order of about 20 to 30 meters.
  • the horn parabola is, insofar as the feed cone is concerned, advantageously made as follows:
  • the rotary coupling 12 is disposed in the vicinity of the pivot journal 5, the cone 8 extending continuously and as linearly the hyperboloid-like auxiliary reflector.
  • the field strength of the waves reflected at the hyperbol-oid shall strongly decrease toward the mirror margin in order to keep the side maxima of the antenna as small as possible.
  • the side maxima lying farther away from the main maximum of the parabola mirror proper are in the described embodiment already small owing to the relatively low-ratio of the mirror focal length of the parabola mirror 1 to the diameter thereof, such ratio being in the assumed case about 0.25.
  • a further decrease, if desired, may be obtained by providing a cylindrical extension disposed ahead of the parabola mirror or by providing an asymmetrically formed diaphragm therefor. It is also feasible to affect in this sense the current loading, by the use of blocking circuits or grids.
  • a type of a known apex plate may be arranged ahead of the hyperboloid-like auxiliary reflector 1a in order to improve the matching.
  • An antenna for very short electromagnetic waves comprising a parabola mirror with an aperture which is very large as compared with the waves, a hyperboloid-like auxiliary reflector having an aperture which is considerably smaller than that of the mirror, a primary radiator disposed at the back of said mirror adjacent the apex of the latter, said auxiliary reflector being cooperable with said primary radiator for reflecting said waves from the latter to said mirror, said primary radiator comprising a horn parabola having an aperture which is small as compared with the aperture of the parabola mirror, the funnel portion of said'horn parabola extending radially with respect to the mirror axis, and the radiation of said horn parabola extending from the back of the parabola mirror through the apex thereof and being trained upon said by perboloid-like auxiliary reflector, the spacing of the auxiliary reflector from the apex of the parabola mirror corresponding to about one-half up to the full Rayleigh spacing, and the aperture of said auxiliary reflector being approximately equal to or somewhat larger than the aperture
  • An antenna according to' claim 4 wherein said horn parabola is provided with a funnel extending radially in the direction of said pivot axis, and coupling means disposed in the vicinity of said journal means for rotatably coupling the end of said funnel with high frequency de vices provided for cooperation with said antenna.

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  • Aerials With Secondary Devices (AREA)
US212052A 1961-07-31 1962-07-24 Cassegrain antenna Expired - Lifetime US3255455A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DES75104A DE1257226B (de) 1961-07-31 1961-07-31 Antenne fuer sehr kurze elektromagnetische Wellen, bestehend aus einem Parabolspiegel und einem hyperboloidfoermigen Hilfsreflektor

Publications (1)

Publication Number Publication Date
US3255455A true US3255455A (en) 1966-06-07

Family

ID=7505140

Family Applications (1)

Application Number Title Priority Date Filing Date
US212052A Expired - Lifetime US3255455A (en) 1961-07-31 1962-07-24 Cassegrain antenna

Country Status (4)

Country Link
US (1) US3255455A (enrdf_load_html_response)
JP (1) JPS552763B1 (enrdf_load_html_response)
DE (1) DE1257226B (enrdf_load_html_response)
NL (2) NL143376B (enrdf_load_html_response)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3332083A (en) * 1963-06-14 1967-07-18 Csf Cassegrain antenna with offset feed
US3414904A (en) * 1966-05-16 1968-12-03 Hughes Aircraft Co Multiple reflector antenna
US4692771A (en) * 1985-03-28 1987-09-08 Satellite Technology Services, Inc. Antenna dish reflector with integral azimuth track
US4716416A (en) * 1985-03-28 1987-12-29 Satellite Technology Services, Inc. Antenna dish reflector with integral declination adjustment
US20220352642A1 (en) * 2019-06-20 2022-11-03 Nec Corporation Antenna device and method for designing same

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2032588A (en) * 1931-09-12 1936-03-03 Jr Herman Potts Miller Communication and detection system
DE861718C (de) * 1939-05-18 1953-01-05 Telefunken Gmbh Richtstrahlanordnung
US2817837A (en) * 1953-06-16 1957-12-24 Bell Telephone Labor Inc Microwave horn and paraboloidal reflector antenna system
US2996716A (en) * 1959-05-27 1961-08-15 Thomas H Witherby Rotating feed for microwave conical scan
US3072905A (en) * 1953-07-20 1963-01-08 Wilkes Gilbert Unsymmetrical antenna feed for conical scanning antenna

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL272152A (enrdf_load_html_response) 1960-12-27

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2032588A (en) * 1931-09-12 1936-03-03 Jr Herman Potts Miller Communication and detection system
DE861718C (de) * 1939-05-18 1953-01-05 Telefunken Gmbh Richtstrahlanordnung
US2817837A (en) * 1953-06-16 1957-12-24 Bell Telephone Labor Inc Microwave horn and paraboloidal reflector antenna system
US3072905A (en) * 1953-07-20 1963-01-08 Wilkes Gilbert Unsymmetrical antenna feed for conical scanning antenna
US2996716A (en) * 1959-05-27 1961-08-15 Thomas H Witherby Rotating feed for microwave conical scan

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3332083A (en) * 1963-06-14 1967-07-18 Csf Cassegrain antenna with offset feed
US3414904A (en) * 1966-05-16 1968-12-03 Hughes Aircraft Co Multiple reflector antenna
US4692771A (en) * 1985-03-28 1987-09-08 Satellite Technology Services, Inc. Antenna dish reflector with integral azimuth track
US4716416A (en) * 1985-03-28 1987-12-29 Satellite Technology Services, Inc. Antenna dish reflector with integral declination adjustment
US20220352642A1 (en) * 2019-06-20 2022-11-03 Nec Corporation Antenna device and method for designing same
US11769953B2 (en) * 2019-06-20 2023-09-26 Nec Corporation Antenna device and method for designing same

Also Published As

Publication number Publication date
NL278997A (enrdf_load_html_response)
NL143376B (nl) 1974-09-16
JPS552763B1 (enrdf_load_html_response) 1980-01-22
DE1257226B (de) 1967-12-28

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