US2895134A - Directional antenna systems - Google Patents

Directional antenna systems Download PDF

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Publication number
US2895134A
US2895134A US332424A US33242453A US2895134A US 2895134 A US2895134 A US 2895134A US 332424 A US332424 A US 332424A US 33242453 A US33242453 A US 33242453A US 2895134 A US2895134 A US 2895134A
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US
United States
Prior art keywords
conductor
line
branch
radiators
planar conductor
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Expired - Lifetime
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US332424A
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English (en)
Inventor
Sichak William
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TDK Micronas GmbH
International Telephone and Telegraph Corp
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Deutsche ITT Industries GmbH
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Priority to BE542180D priority Critical patent/BE542180A/xx
Application filed by Deutsche ITT Industries GmbH filed Critical Deutsche ITT Industries GmbH
Priority to US332424A priority patent/US2895134A/en
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    • 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
    • H01Q21/08—Arrays of individually energised antenna units similarly polarised and spaced apart the units being spaced along or adjacent to a rectilinear path
    • 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
    • H01Q13/08—Radiating ends of two-conductor microwave transmission lines, e.g. of coaxial lines, of microstrip lines
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00—Antenna arrays or systems
    • H01Q21/0006—Particular feeding systems
    • H01Q21/0075—Stripline fed arrays

Definitions

  • This invention relates to directional antenna systems and more particularly to antenna arrays and feeders therefor.
  • Elforts have been made heretofore to provide high resolution antenna arrays, such that the beam width is less than about one degree.
  • Such arrays are generally used with a separate reflector to produce the desired vertical pattern, generally cosecant.
  • the advantages of the array-reflector combination over the single fed antennareflector combination are that separate control of azimuth and elevation patterns is possible, the reflector may comprise a simple cylindrically curved member and better control is obtained of polarization.
  • the main disadvantage is the greater complexity of the feeding system for the array.
  • One object of this invention is to provide a novel endfire radiator structure readily adaptable for use in linear arrays and which is relatively simple in construction, light weight and relatively inexpensive.
  • Another object of this invention is to provide a novel linear array, either vertically or horizontally polarized; and a further object is the provision of an improved feeder system or power divider for such a linear array.
  • One of the features of this invention is the use of a line-above-ground type of transmission line or waveguide, the end of which is modified to provide an endfire radiator similar in shape to that of a horn radiator. Such end-fire radiators are further employed in side by side relationship to form a linear array, line-above-ground power dividers being employed as feeders.
  • Still another feature of the invention is the manner of obtaining power division for antenna feeding purposes to obtain desirable impedance matching and a desired radiation pattern with a minimum of reflections in the feeder system.
  • power division is relatively easy while control of phase is difficult because two dimensions, length and width, must be controlled.
  • coaxial lines are employed, the length only need be controlled, but difficulties are encountered in supporting the inner conductor at frequencies above 3000 mcs. per see.
  • these difficulties are overcome by employing a line-above-ground type of energy divider for effecting division of radio frequency power in the microwave region.
  • the phase of the radio frequency energies along the different branches may be controlled by proper determination of the width of the line conductor and the relative length of the branches.
  • Fig. l is a plan view of an end-fire antenna according to the principles of this invention.
  • Fig. 2 is a longitudinal sectional view taken along line 22 of Fig. 1;
  • Fig. 3 is an H-plane pattern of the radiation of the antenna type illustrated in Figs. 1 and 2;
  • Fig. 4 is a view in plan of a linear array and power feeder arrangement in accordance with the principles of this invention.
  • Fig. 5 is a longitudinal sectional view taken along line 55 of Fig. 4;
  • Fig. 6 is a plan view of an array with the end-fire antenna structures disposed for horizontal polarization of radiation;
  • Fig. 7 is a view in side elevation with parts broken away, taken along line 7-7 of Fig. 6;
  • Fig. 8 is a view in plan of a modified form of linear array and power feeder arrangement
  • Fig. 9 is a view in side elevation of the array taken along line 99 of Fig. 8;
  • Fig. 10 is a view in plan of a power feeder for three radiators
  • Fig. 11 is a View in side elevation of one branch of the feeder taken along line 11-41 of Fig. 10;
  • Fig. 12 is a view in plan of a further embodiment of a linear array, arranged to minimize radiator reflections.
  • the line-above-ground type of transmission line or waveguide employed as a feeder, end-fire antenna comprises a first or planar conductor l and a second or line conductor 2 spaced apart by a thin strip or layer of dielectric material 3.
  • the two conductors l and 2 are preferably of flat strip form, the planar conductor being wider than the line conductor so that propagation of microwave energy therealong is in a mode similar to the TEM mode.
  • the line conductor may be round or otherwise shaped, if desired.
  • the parameters of importance are the width of the line conductor 2 and the thickness of the spacing dielectric 3.
  • the dielectric material may be polystyrene, polyethylene, Teflon, Fiberglas or laminated Fiberglas impregnated with Teflon, quartz, or other suitable material of high dielectric quality.
  • the transmission line may be made up of strip material or made in accordance with printed circuit technique.
  • the forward end of the line conductor 2 is flared as indicated at 4 and angled outwardly with respect to the planar conductor 1 at a desired acute angle on. This presents a horn type of radiator with open sides, the usual vertical side walls being unnecessary. While the dielectric 3 is shown extended to the forward end of the planar conductor 1, it may, of course, be terminated at the bend 5, and if desired, in a tapered manner. Forming a part of the planar conductor is an angular member 6 which provides a radio frequency trap a quarter air wavelength in depth to prevent currents from occurring on the bottom side of the planar conductor.
  • Fig. 3 shows an H-plane pattern 7 obtained from an end-fire antenna in accordance with the structural arrangements illustrated in Figs. 1 and 2.
  • the front lobe shows the directivity of the antenna.
  • the frequency employed was 9400 mc./s.
  • the horn construction employed had the following dimensions: the line conductor 2 was Mt" wide, the end of the flared portion 4 was 1%,
  • the length of the flared portion was 2", this length being in the order of Fig. 2, and the dielectric 3 was /8" thick and of Fiberglas material.
  • the array shown in Figs. 4 and 5 is made up of a plurality of individual horn-like radiators of the type shown in Figs. 1 and 2. While four such radiators 8, 9, and 11 are shown, a smaller or larger number may be employed as desired.
  • Each radiator includes a flared portion 4 inclined at a suitable angle with reference to the plane of the line conductor 2.
  • the planar conductor 1 is extended as shown in Figs. 4 and 5 to comprise the lower plate 12 of a parallel plate system including an upper plate 13.
  • the parallel plates 12 and 13 are provided at the ends thereof with flared portions 14 and 15 which function as a horn radiator. While these parallel plates need not be closed at the side walls thereof, they are in the present embodiment so connected by side walls 16 and 17.
  • the flared portions 4 of the radiators are spaced from the upper wall 13 and in effect constitute transducer structures for launching or receiving of energy between the line-above-ground type of feeder network and the rectangular or parallel plate waveguide 12, 13. Since the radiators 8 to 11 are disposed between the plates 12 and 13 there is no need for the trap 6 shown in Fig. 2, the flared portions 14 and 15 functioning as the radiator surfaces.
  • the network feeding system for the array shown in Figs. 4 and 5 comprises a main line-above-ground type of waveguide 20 comprising a first or planar conductor 21 and a second or line conductor 22 spaced apart by a layer of dielectric material 23.
  • the planar conductor 21 is extended laterally as indicated at 24 and may comprise a width corresponding to the width of the plate 12.
  • the line conductor 22 branches out into individual feeders for the radiators 8 to 11.
  • the first division of power in the desiredratio is obtained by providing an impedance transformer section 25, where in the line conductor 22 is changed in width before branching into separate branch feeders 26 and 27.
  • the transformer section includes a tapered portion 25a of length a and a second portion 25b of length b of an impedance equal to the two load irnpedances of branches 26 and 27 in parallel.
  • the length a of the tapered portion is selected greater than a half guide wavelength so as to provide a gradual transition between the low impedance portion 25b and the higher impedance of the input line 22.
  • the branch 26 is provided with a transformer sec tion 28 for coupling to two additional branches 29 and 30 which feed radiators 8 and 9.
  • the branch 27 likewise includes a transformer section 31 which is coupled to branches 32 and 33 to feed radiators 10 and 11. Reflections from the junctions of the branches are minimized by making the line lengths to the junctions different by a quarter Wavelength at the mid band of the operating frequency.
  • the length of the branch 26 to the transformer 28 is shown as length 0 while the corresponding length of branch 27 is Likewise, the length of the branches 29 and 30 from transformer 28 to the radiators 8 and 9 are shown to be a length whilethe corresponding lengths of branches 32 and 33 are of length d.
  • radiators of'the array shown in'Figs. 4 and 5 are illustrated as "horn-like structures, it'will be readily apparent to those skilled in the art that other end-fire radiators or transducers may be substituted therefor. Examples of dipole and slot radiator arrangements that may be so employed are disclosed in my copending application, Serial No. 329,775 filed January 6, 1953, Patent No. 2,794,185, issued May 28, 1957 to which reference may be had.
  • the array illustrated in Figs. 4 and 5 provide for a radiation beam vertically polarized.
  • Figs. 6 and 7 another array is shown in which the same type of radiators are illustrated revolved between the parallel plates 12a and 13a so that radiation is obtained from the parallel plates horizontally polarized.
  • Each of the radiators 34 and 35 are provided with line-above-ground waveguides comprising a planar conductor 36, a line conductor 37 spaced by a layer of dielectric material 38.
  • the planar conductors 36 of the two feeders are of the same width as the spacing between plates 12a and 130. Since the parallel plates 12a and 13a may be sufficiently supported by the feeder structure, they need not be provided with side walls, as indicated in Figs. 4 and 5.
  • radiators 3.4 and 35 may, of course, be provided.
  • the feeding system for the radiators of 6 may, of course, include a power divider arrangement similarly as illustrated in Figs. 4 and 8.
  • FIGs. 8 and 9 another array is shown .wherein the flared radiator portions 39, 40,41 and 42 are extended so as to flare into the adjacent radiators and thus form integrally the forward upper plate 43 of the slot radiator.
  • the lower plate 44 comprises an extension of the ground conductor 45 which underlies the feeder network connected to the radiator portions 39 to 42.
  • the power dividing network of the feeders constitute curved junc .tions which contain transformer sections as indicated at 46.
  • the width of the main line conductor 47 is gradually curved throughout the section 46 to the wider low impedance width required for the two branches 48 and 49 into which it is divided.
  • the transformer section 46 is of a length e which preferably is greater than a half wavelength.
  • the junction 50 coupling branch .48 with branches 51 and 52 feeding radiators 39 and 40 is similar to that shown at 46.
  • the branches 53 and 54 coupled to the branch 49 is likewise provided with a transformer junction 55 similar to that shown at 46.
  • the curvature is so chosen for the turns of the branches 48, 49, 51, 52, S3 and 54 and the junctions thereof as to avoid loss due to radiation at such bends at frequencies in the order of 6,000 to 12,000 mcs./ sec. and higher. In other words, where is in the order of about A where h is the thickness of the dielectric spacing between conductors, the curved form of Fig. 8 is preferred. For lower frequencies of the order of 3000 to 6000 mes/sec. the network feeder may be of the configuration shown in Fig.
  • Fig. 4 without appreciable loss due to radiation.
  • the form of Fig. 4 is satisfactory where is in the order of about &
  • the branch lines are chosen of different lengths, the branch 48 being one quarter wavelength longer than the branch 49, and'the branches S3 and 54 being one quarter wavelength longer than the branches 51 and 52.
  • Figs. 10 and 11 have been shown-by way of example to indicate how the junction may be arranged for three or more branches. While the same type of transformer junction as that shown in Fig. 4 is employed in this illustration as indicated at 56, it will be understood that a curve junction such as shown in Fig. 8 may be employed.
  • the low impedance section of the junction is divided into three branches 57, 58 and 59. Where it is desirable to have these branches feeding an array of radiators in linear arrangement some provision must be made with regard to relative lengths of the branches.
  • the center branch 58 is accordingly bowed up sufliciently so that the three branches are of equal length thereby insuring equal phase at the radiators coupled to the three branches.
  • the view shown in Fig. 11 indicates the bowing up of branch :58 with reference to the plane 643 of the planar conduc- :tOlS of the branches 57 and 59.
  • the reflections of the radiators are likewise in phase and while minimized by making the branch lines of the feeder network of dilferent lengths, the reflections may be further minimized by making the length of the feeders adjacent the series of radiators of different lengths.
  • Fig. 12 shows such a feeder arrangement, a transducer array being indicated diagrammatically at 61, 62, 63, 64 and 65, the radiators being disposed between parallel plates as indicated at 66, in the plan view of Fig. 12.
  • the feeders for the transducers 61 to 65 are fed with a phase front as indicated by the line 67
  • the length of the feeders from the phase front 67 to the different transducers are of difierent lengths.
  • the line of the transducers is disposed at an angle with respect to the phase front 67.
  • the radiating edge 63 of the parallel plates is selected at an :angle with respect to the wave front 67.
  • An antenna array comprising a planar conductor, a main line conductor, a plurality of branch line conductors, dielectric means spacing said main line and branch lines in a plane disposed in parallel relation with respect to said planar conductor, said main and branch lines each being of a width smaller than the width of said planar conductor and lying within the confines of said planar conductor thereby providing in conjunction with said planar conductor waveguides for propagation of radio frequency wave energy in a mode simulating substantially the TEM mode, radiators coupled to said branch lines at the ends thereof, and a junction coupling said main line to said branch lines including an impedance transformer section, said radiators each comprising an extension of said branch line conductor, said extension being flared outwardly and disposed at an acute angle to the plane of said planar conductor.
  • said impedance transformer comprises a conductive portion of a width greater than the width of said main line conductor to present an impedance equal to the load impedance of said branch lines in parallel and another ;portion interconnecting said main line conductor to said 6 low impedance portion of greater width, said interconnecting portion being tapered and of a length equal to at least one-half guide wavelength.
  • the impedance transformer includes a section of line tapered from the width of said main line conductor to twice the width thereof and said branch line conductors comprise two conductors each of a width corresponding to the width of said main line conductor.
  • An antenna array according to claim 1 wherein the radiators number more than two and said branch line conductors are further divided by transformer junctions into additional branch line conductors for coupling to said radiators, the corresponding lengths of certain of said branch line conductors being different by one quarter wavelength to minimize reflections from the junctions thereof.
  • An antenna array according to claim 1 further including parallel plate conductors with said radiators disposed therebetween and flared outwardly at an acute angle as transducers, the parallel plate conductors comprising a radiating horn.
  • a planar conductor a plate conductor disposed in spaced parallel relation to one portion of said planar conductor forming therewith a parallel plate Waveguide for radio frequency wave energy
  • a line conductor narrower than said planar conductor disposed in spaced parallel relation to said planar conductor also providing in conjunction therewith a waveguide for radio frequency wave energy, the end portion of said line conductor being flared outwardly and disposed at an acute angle to the plane of said planar conductor as a transducer for coupling radio frequency wave energy from one to the other of said waveguides.
  • a planar conductor a plate con ductor disposed in spaced parallel relation to one portion of said planar conductor forming therewith a parallel plate waveguide for radio frequency wave energy, a plurality of line conductors spaced apart in a plane parallel to and between said planar conductor and said plate conductor, said line conductors each being narrower than said planar conductor and lying within the confines of said planar conductor to form therewith waveguides for radio frequency energy, and the end portions of each of said line conductors being flared outwardly and disposed towards said plate conductor and at an acute angle to the planes of said planar and plate conductors.
  • a planar conductor a plate conductor disposed in spaced parallel relation to one portion of said planar conductor forming therewith a parallel plate waveguide for microwave energy
  • a feed line comprising a second planar conductor, a line conductor and dielectric means spacing said line conductor in parallel relation to said second planar conductor to provide for propagation of radio frequency wave energy, said line conductor being narrower than said second planar conductor, said second planar conductor being coupled electrically to said first mentioned planar conductor and said line conductor being disposed between said first mentioned planar conductor and said plate conductor and provided at its end with a flared portion disposed at an acute angle to the plane of said second planar conductor.
  • An antenna comprising a first conductor, a second conductor, dielectric means spacing said conductors in substantially parallel relation to provide a waveguide for transmisison of radio frequency wave energy therealong, said first conductor being wider than said second conductor to present a planar surface with respect to said second conductor, and said second conductor having the end portion thereof flared outwardly and disposed at an acute angle to the plane of said planar surface.
  • a planar conductor a plate conductor disposed in spaced parallel relation to one pertionof said planar conductor forming-therewith a parallel plate Waveguide for microwave energy, the forward end of said parallel plate waveguide being open for slot radiation of energy, a main line conductor, a plurality of branch line conductors, dielectric means disposing said main line conductor and said branch line conductors in a plane parallel-to said planar conductor, said main line conductor and said branch line conductors each being of a width smaller than the width of said planar conductor and lying within the confines of said planar conductor thereby providing in conjunction with said planar conductor a waveguide for propagation of radio frequency wave energy in a mode simulating substantially a TEM mode, a linear array of transducers disposed between said parallel plates, said branch line conductors being coupled to said transducers as feed lines for said transducers and having a common linear phase front, and said linear array being disposed at an acute angle to said phase front.
  • a planar conductor a main line conductor, a plurality of branch line conductors, dielectric means disposing said main line conductor and said branch lineconductors in a plane parallel to said planar conductor, said mainline conductor and said branch line conductors each being of a width smaller than the width of said planar conductor and lying within the con- F line conductors, the corresponding lengths of certain of said branch lineconductors being different by one-quarter Wavelength to minimize reflections from the junctions thereof.

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Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3127579A (en) * 1962-08-07 1964-03-31 Bell Telephone Labor Inc Rotary joint using circumferentially uniform field to couple rotor to stator
US3173142A (en) * 1959-04-29 1965-03-09 Ite Circuit Breaker Ltd Rotating beacon antenna with strip line modulators
US4500887A (en) * 1982-09-30 1985-02-19 General Electric Company Microstrip notch antenna
US4743915A (en) * 1985-06-04 1988-05-10 U.S. Philips Corporation Four-horn radiating modules with integral power divider/supply network
US5963176A (en) * 1997-04-14 1999-10-05 The United States As Represented By The Secretary Of Commerce Antenna system with edge treatment means for diminishing antenna transmitting and receiving diffraction, sidelobes, and clutter
US20160020525A1 (en) * 2011-12-06 2016-01-21 Viasat, Inc. Dual-circular polarized antenna system
US10096877B2 (en) 2015-05-27 2018-10-09 Viasat, Inc. Partial dielectric loaded septum polarizer
US10249922B2 (en) 2015-05-27 2019-04-02 Viasat, Inc. Partial dielectric loaded septum polarizer

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3587110A (en) * 1969-07-01 1971-06-22 Rca Corp Corporate-network printed antenna system

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US2159648A (en) * 1937-09-08 1939-05-23 Mackay Radio & Telegraph Co Transmission modifying network
GB541380A (en) * 1940-03-08 1941-11-25 Standard Telephones Cables Ltd Improvements in or relating to electric transmission networks
US2297202A (en) * 1936-03-07 1942-09-29 Dallenbach Walter Transmission and/or the reception of electromagnetic waves
GB580115A (en) * 1943-05-21 1946-08-27 Edward Cecil Cork Improvements in or relating to transmitting or receiving aerials
US2425488A (en) * 1943-07-03 1947-08-12 Rca Corp Horn antenna
US2454766A (en) * 1943-04-24 1948-11-30 Standard Telephones Cables Ltd Broad band antenna
GB629893A (en) * 1945-07-04 1949-09-30 Marconi Wireless Telegraph Co Improvements in or relating to radio aerials
US2496643A (en) * 1944-10-14 1950-02-07 Bell Telephone Labor Inc Impedance matching system
US2540839A (en) * 1940-07-18 1951-02-06 Bell Telephone Labor Inc Wave guide system
GB655803A (en) * 1948-08-30 1951-08-01 Cossor Ltd A C Improvements in and relating to transmission lines for radio-frequency electric oscillations
US2624003A (en) * 1948-01-07 1952-12-30 Rca Corp Dielectric rod antenna
US2654842A (en) * 1951-07-21 1953-10-06 Fed Telecomm Lab Inc Radio frequency antenna
US2689303A (en) * 1946-05-24 1954-09-14 Us Sec War Antenna array
US2749545A (en) * 1951-08-01 1956-06-05 Itt Electromagnetic horn

Patent Citations (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2297202A (en) * 1936-03-07 1942-09-29 Dallenbach Walter Transmission and/or the reception of electromagnetic waves
US2159648A (en) * 1937-09-08 1939-05-23 Mackay Radio & Telegraph Co Transmission modifying network
GB541380A (en) * 1940-03-08 1941-11-25 Standard Telephones Cables Ltd Improvements in or relating to electric transmission networks
US2540839A (en) * 1940-07-18 1951-02-06 Bell Telephone Labor Inc Wave guide system
US2454766A (en) * 1943-04-24 1948-11-30 Standard Telephones Cables Ltd Broad band antenna
GB580115A (en) * 1943-05-21 1946-08-27 Edward Cecil Cork Improvements in or relating to transmitting or receiving aerials
US2425488A (en) * 1943-07-03 1947-08-12 Rca Corp Horn antenna
US2496643A (en) * 1944-10-14 1950-02-07 Bell Telephone Labor Inc Impedance matching system
GB629893A (en) * 1945-07-04 1949-09-30 Marconi Wireless Telegraph Co Improvements in or relating to radio aerials
US2689303A (en) * 1946-05-24 1954-09-14 Us Sec War Antenna array
US2624003A (en) * 1948-01-07 1952-12-30 Rca Corp Dielectric rod antenna
GB655803A (en) * 1948-08-30 1951-08-01 Cossor Ltd A C Improvements in and relating to transmission lines for radio-frequency electric oscillations
US2654842A (en) * 1951-07-21 1953-10-06 Fed Telecomm Lab Inc Radio frequency antenna
US2749545A (en) * 1951-08-01 1956-06-05 Itt Electromagnetic horn

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3173142A (en) * 1959-04-29 1965-03-09 Ite Circuit Breaker Ltd Rotating beacon antenna with strip line modulators
US3127579A (en) * 1962-08-07 1964-03-31 Bell Telephone Labor Inc Rotary joint using circumferentially uniform field to couple rotor to stator
US4500887A (en) * 1982-09-30 1985-02-19 General Electric Company Microstrip notch antenna
US4743915A (en) * 1985-06-04 1988-05-10 U.S. Philips Corporation Four-horn radiating modules with integral power divider/supply network
US5963176A (en) * 1997-04-14 1999-10-05 The United States As Represented By The Secretary Of Commerce Antenna system with edge treatment means for diminishing antenna transmitting and receiving diffraction, sidelobes, and clutter
US10230150B2 (en) 2011-12-06 2019-03-12 Viasat, Inc. Dual-circular polarized antenna system
US10079422B2 (en) * 2011-12-06 2018-09-18 Viasat, Inc. Dual-circular polarized antenna system
US20160020525A1 (en) * 2011-12-06 2016-01-21 Viasat, Inc. Dual-circular polarized antenna system
US10530034B2 (en) 2011-12-06 2020-01-07 Viasat, Inc. Dual-circular polarized antenna system
US11101537B2 (en) 2011-12-06 2021-08-24 Viasat, Inc. Dual-circular polarized antenna system
US11171401B2 (en) 2011-12-06 2021-11-09 Viasat, Inc. Dual-circular polarized antenna system
US10096877B2 (en) 2015-05-27 2018-10-09 Viasat, Inc. Partial dielectric loaded septum polarizer
US10243245B2 (en) 2015-05-27 2019-03-26 Viasat, Inc. Partial dielectric loaded septum polarizer
US10249922B2 (en) 2015-05-27 2019-04-02 Viasat, Inc. Partial dielectric loaded septum polarizer
US10686235B2 (en) 2015-05-27 2020-06-16 Viasat, Inc. Partial dielectric loaded septum polarizer
US11095009B2 (en) 2015-05-27 2021-08-17 Viasat, Inc. Partial dielectric loaded septum polarizer

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