US3781894A - Balloon carried directional antenna - Google Patents

Balloon carried directional antenna Download PDF

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Publication number
US3781894A
US3781894A US00178910A US3781894DA US3781894A US 3781894 A US3781894 A US 3781894A US 00178910 A US00178910 A US 00178910A US 3781894D A US3781894D A US 3781894DA US 3781894 A US3781894 A US 3781894A
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United States
Prior art keywords
unipole
skirt
antenna
skirts
coaxial
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Expired - Lifetime
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US00178910A
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English (en)
Inventor
C Ancona
J Choquer
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Centre National dEtudes Spatiales CNES
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Centre National dEtudes Spatiales CNES
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/12—Supports; Mounting means
    • H01Q1/1292—Supports; Mounting means for mounting on balloons
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04—Resonant antennas
    • H01Q9/16—Resonant antennas with feed intermediate between the extremities of the antenna, e.g. centre-fed dipole
    • H01Q9/18—Vertical disposition of the antenna

Definitions

  • the unipole has a length of 0.25 A
  • the skirt has a length of 0.35 )t0.65 k and a diameter of 005-02 x, whereby the antenna has a radiation pattern which lies substantially entirely on the side of the plane of the skirt base opposed to the unipole.
  • the present invention relates in a general way to very high frequency antennas and more particularly to an antenna adapted to establish communications for example between a meterological balloon and a satellite within a frequency range of for example 100 MHz-l GHz.
  • the antenna according to the present invention although not limited to the aforementioned particular application, is particularly designed to ensure a ballonsatellite communication and for this purpose it can be suspended from a balloon and accompanied by a very high frequency transmitter-receiver.
  • antennas of this type In the construction of antennas of this type, several manufacturing problems are encountered owing to the fact that it must be possible to meet air security requirements at any moment.
  • the security conditions require in particular that the antenna must be destructible by a flying aircraft without however damaging the latter.
  • the antenna must therefore be as light as possible and its mass per unit length M/L must be less than 5 g/cm.
  • reflections are, in respect of incidences skimming the sea, substantially specular, so that only the slope of the radiation pattern of the antenna in the vicinity of the horizontal plane can be relied upon for improving the discrimination of the direct wave from the reflected wave.
  • FIG. 1 of the accompanying drawings clearly illustrates this important condition.
  • the radiation pattern of the antenna must have a shape such as that shown in FIG. 2, in which:
  • the pattern has two large lobes L L above the horizontal plane (H-H) and much smaller lobes 1,, 1 below this plane.
  • an antenna having these characteristics can be constructed which has a unipole disposed in the extension of the axis of a conductive cylindrical skirt of adequate diameter, this skirt extending vertically upward in use of the antenna.
  • One end of the unipole is located roughly in one of the base planes of the cylindrical skirt.
  • the antenna is excited by supplying power to the end ofa unipole and the cylindrical skirt in phase opposition.
  • U.S. Pat. No. 3,009,154 discloses a discone antenna comprising a unipole having a capacity disc which is associatedwith a conical conductive body on the axis of the disc. The assembly is mounted at the focus of a parabolic reflector by a tubular support on the axis of the reflector.
  • the antenna of this patent has two major drawbacks which render it unsuitable for the aforementioned particular applications. Indeed, owing to its conical shape and as concerns frequency ranges of interest, this antenna has a relatively large size. Moreover, owing to its robust construction (massive cone for example) and its large mass per unit length it does not meet the aforementioned air security requirements. Further, this patent does not describe means for avoiding the electric coupling phenomena which exist between the discone antenna and the tubular support disposed on the axis of this primary source. These couplings considerably affect the performance of the discone antenna whose radiation pattern has numerous corrugations incompatible with a good separation of the upper and lower radiations.
  • An object of the invention is to provide an antenna which is derived from that of U.S. Pat. No. 3,267,951 but which is able to avoid all this drawbacks. Consequently, according to a first feature of the invention, the antenna is essentially asymmetric so that with A equal to the operating wave length of the antenna, the unipole has a length of s 0.25 k and the cylindrical skirt has a length between 0.35 k and 0.65 )t and a diameter between 0.05 and 0.2 )t.
  • Another object of the present invention is therefore to provide a directional antenna in which this matching is achieved.
  • the directional antenna of the type comprising a unipole defining an axis, a conductive disc located in a plane perpendicular to said axis at one of the ends of the unipole, a first skirt coaxial with said unipole and extending from said plane in the opposite direction to the unipole to which it is electrically connected, comprises at least one second cylindrical skirt which is coaxial with the first skirt and electrically connected at its end adjacent the unipole to the first skirt and has an extent from said end different from the extent of the first skirt, spacer means for positioning the free edges of said skirts and a coaxial supply line whose outer sheath is connected to said skirts and whose inner conductor is connected to said unipole.
  • the dimensions of the antenna are intimately related to the wavelength so that if a AA choke of given dimension is chosen, the matching at another operating frequency is less effective.
  • the antenna comprises a third cylindrical skirt which is coaxial with the two other skirts and electrically connected to the latter at one of its ends adjacent the unipole and has an extent from said end different from the extents of the first and second skirts, the free edge of said third skirt being in contact with said spacer means.
  • the length of the third skirt is preferably chosen as a function of a second operating frequency of the antenna.
  • the matching skirts arranged in this way already enable the radiation of the antenna to be improved, it is advantageous, in accordance with another feature of the invention, to provide at least one choke formed by the coaxial supply line of the antenna.
  • This choke is preferably constituted by a helical winding of several turns of the supply cable itself a full stop.
  • the helical chokes constructed in this way are devices having a high-pass band which attenuate, both by their high series impedance distributed over a plurality of centimeters and by their over voltage, the induced currents propagated in the outer sheath of the coaxial line of the antenna, source of disturbance of the radiation proper of the antenna.
  • a matching line for matching said unipole to the impedance of the coaxial line, this matching line being connected in parallel to the point of connection between the inner conductor of the coaxial line and the unipole.
  • This matching line is preferably constituted by a conductive band which is connected to, but insulated from, the conductive disc.
  • Another object of the invention is to provide an improved case for an antenna of the type defined hereinbefore.
  • FIG. 1 is a diagram showing the conditions of operation of an antenna according to the invention
  • FIG. 2 shows the radiation pattern of this antenna
  • FIG. 3 shows diagramatically an antenna according to a first embodiment of the invention
  • FIG. 4 is an axial sectional view of the embodiment according to the schematic shown in FIG. 3;
  • FIG. 5 is a diagram showing the gain in dB of the direct wave relative to the reflected wave as a function of the frequency for several diameters of the antenna shown in FIG. 4;
  • FIG. 6 is the schematic of the principle of operation of another embodiment of the antenna according to the present invention.
  • FIG. 7 is a longitudinal axial sectional view of the embodiment the principle of which is shown in FIG. 6;
  • FIG. 8 is a radial sectional view taken along line 8--8 of FIG. 7;
  • FIG. 9 is a partial outside view of the upper end of the antenna shown in FIG. 7 turned through
  • FIG. 10 is a partial sectional view of the lower end of the antenna shown in FIG. 7 turned through 90;
  • FIG. 11 is an exploded view of this antenna without its protective case
  • FIG. 12 is a detail axial sectional view on an enlarged scale of the connection between the coaxial line and the unipole.
  • the antenna comprises a radiating element or unipole l constituted by a metal rod and having a length equal to or less than 541%, A being the operating wavelength of the antenna.
  • a cylindrical skirt 2 of uniform diameter which is closed at the end adjacent the unipole 1 by a conductive disc 3 through which passes the inner conductor 6 of a coaxial line 5, which conductor is connected to the unipole 1 at the point of connection 4 which is substantially in the plane of the conductive disc 3.
  • the outer conductor 7 of the coaxial line 5 is connected to the disc 3.
  • An antenna whose schematic is that described hereinbefore has the radiation pattern shown in FIG. I when the dimensions are carefully chosen as a function of the wavelength.
  • the length of the unipole is equal to or less than 025k, the length of the cylindrical skirt being chosen between 0.35% and 0.65) ⁇ whereas the diameter of the skirt is preferably chosen within the range of 0.05k to 0.2L
  • the material of the cylindrical skirt can be very thin copper foil or rustless stell having a thickness of for example 0.05 mm.
  • the illustrated antenna is freely suspended in such manner that the unipole is pointing downwardly; in these conditions the radiation pattern is oriented in the way shown in FIG. 1.
  • FIG. 4 shows the embodiment of the invention in which the antenna shown in FIG. 3 is disposed in a protective case.
  • the cylindrical skirt 2 extends within a case body 8 having a slightly part-conical or tapered shape and downwardly convergent. This shape has no effect on v the electrical operation of the antenna.
  • the base 9 of the body 8 has a blind aperture 10 receiving the free end of the unipole 1.
  • connection point 4 is constituted by a connector 12 to which the unipole 1 and the coaxial line 5 are fixed in such manner that the inner conductor 6 of this line is directly connected to the unipole 1 whereas the outer conductor is connected to the conductive disc 3.
  • the body 8 is closed by a cover 13 provided with an aperture 14 in its center for the passage of the coaxial line 5.
  • the diameter of this aperture is so chosen as to slightly grip the line and thus hold the latter taut inside the case.
  • FIG. 4 shows that the cover l3 has in its center a circular projecting portion 16 whose diameter exactly corresponds to the inside diameter of the cylindrical skirt 2.
  • the body 8 is provided with an extension portion 17 which, in co-operation with the projecting portion 16 of the cover 13, maintains the free edge portion of the cylindrical skirt 2 in position.
  • the cover 13 has a flange 18 which engages around the extension portion 17 and closes the case body 8.
  • a suspension strap 19 is secured to the cover for suspending the antenna from a balloon (not shown).
  • the material of the case is preferably expanded polystyrene or polystyrene foam, such as the material known under the trade name STYROPOR so that the assembly has the required lightness.
  • FIG. 5 shows the effect of the diameter of the cylindrical skirt on the sensitivity of the antenna receiving the direct wave OD (FIG. 1) relative to that of a reflected wave (OP), the ratio being expressed in dB and 6 being equal to 80.
  • FIGS. 6-12 constitutes the preferred embodiment of the invention.
  • this antenna comprises a unipole 2d constructed from a metal sheet cut into the shape of a U.
  • This unipole is connected to the inner conductor 21 of the coaxial line 23.
  • the outer conductor 22 of the latter is connected to a first cylindrical skirt 24 coaxial with the unipole 20.
  • the skirt 24 is connected to a conductive disc 25 which is perpendicular to its axis.
  • the skirt 24 and the unipole 20 extend from the disc 25 in opposite directions.
  • the antenna further comprises two auxiliary skirts 26 and 27 which are coaxial with the first-mentioned skirt and extend in a part of and project axially from the latter, their lengths being adapted to two respective operating frequencies of the antenna and preferably chosen to be 049A.
  • the free end of the longest and innermost skirt 27 is closed by a star-shaped shorting disc 29 through which the coaxial line 23 extends.
  • the case is preferably composed of polystyrene foam such as that known under the trade mark STYRO- POR.
  • Each case half 30a or 3012 has a slightly part-conical or tapered shape and a roughly spherical end wall.
  • Shoulders 32 are provided inside the halves for locating the various component parts of the antenna.
  • each half 30a or 30b is provided with an aperture 33 receiving a plug which is of for example a material known under the trade name PLEXIGLASS and has an axial aperture.
  • a plug which is of for example a material known under the trade name PLEXIGLASS and has an axial aperture.
  • One of the plugs 34 is provided for the passage of a coaxial line 33 and the other 35 for discharging water which might accumulate in the case 13 owing to, for example; condensations.
  • the plug 341 is closed by an insulating sleeve 34a (FIG. 7) and a seal is achieved by inserting the product known under the trade name SILASTENE RTV 730 between the sleeve and the line 23 and between the sleeve and the plug 34.
  • the plugs 34 and 35 comprise a cylindrical portion 36 engaged in the corresponding aperture 33 and two strip portions 37 apertured attheir ends and extendingin a direction parallel to each other and perpendicular to the axis of the antenna.
  • Metal pins 38 are engaged in the apertures 33 and they may be connected to suspension straps 39 constituted, for example, by bands of plastics material.
  • the two halves 30a and 30b of the base 30 are held fitted together by a cord 40 which is folded back onto itself and extends through the case twice from one end to the other by starting at the plug 34 and passing through the plug 35 and returning to the plug 34, the cord being held taut and clamped at both ends in the plug 34 so as to suitably close the case 30.
  • each half 30a or 30b has several inner radial ribs 41 the ends of which form shoulders 32.
  • a maintaining washer 42 acts as a spacer member for the end edges of the auxiliary skirts 26 and 27 and bears against the shoulders 32 of the half 303a.
  • the washer 42 has a flange 43 which engages between the ends of the skirts 26 and 27 so as to maintain them in position in the radial direction.
  • skirts 26 and 27 are mechanically maintained in position relative to the main skirt 24 by means of two shorting elements 28.
  • the latter are constituted by metal bands 44 and 45 which are folded in a zig-zag fashion and fixed by their apices to the respective skirts 24, 26 and 27 and enable this arrangement to deform radially, which is necessary for the aforementioned air security.
  • the fixing of the bands 44 and 45 is preferably achieved by spot welding (FIG. 8).
  • the free end edge portion 46 of the skirt 24 is maintained against the inner tapered wall of the half 30a of the case 30.
  • skirt 24 is maintained in position by a shoulder 47 provided on the end edges of two identical half-shells 48.
  • the latter extend between the conductive disc and the shoulders 32 of the half b of the case 30.
  • Each of the half-shells 48 comprises a cylindrical portion 49 which is provided on the respective edge portions with a positioning rib 50a and a corresponding notch 50b, the rib and the notch of the same half-shell being spaced apart the width of the unipole 20 (FIG. 7). It will be clear that, upon assembly of the halfshells, the ribs 50a of one is engaged in the notch 50b of the other.
  • Each half-shell 48 further comprises a tapered portion 51 which is divergent in the direction of the wall of the case on which it bears through feet 52. The latter maintain the half-shell in position in the radial direction.
  • the unipole 20 is free to move in the axial direction between the two half-shells 48 so that the axial tolerances of the assembly can be compensated easily.
  • the coaxial line 23 is of any appropriate type. It comprises in the known manner an inner conductor or core 21 which is connected to the unipole 20, as clearly seen in FIG. 12.
  • the conductor 21 extends through a small insulating sleeve 55.
  • the latter has a screwthreaded cylindrical portion 56 engaged in a center aperture in the conductive disc 25 and a part-conical portion 57 having a cylindrical axial cavity 58. The latter receives the end member of the insulator 53 of the coaxial line 23.
  • the outer conductor 22 of the coaxial line has its end portion spread out and placed around the partconical portion 57 and clamped thereagainst by a ring 59 whose bore is complementary to the portion 57.
  • This outer conductor is bent in the direction parallel to the disc 25 and soldered to the ring 59 at its periphery.
  • a band 60 for example of silver Placed flat against the disc 25 is a band 60 for example of silver which may have the shape of a spiral in the plane perpendicular to the axis of the antenna.
  • a band 61 of insulating material such as that known under the trade name TEFLON is adehered to the silver band 60 and another metal layer 62 covers the band 60.
  • This layer is in contact with a blind conductive nut 63 which is screwed on the cylindrical portion 56 of the insulating sleeve and has a dome-shaped end portion 64.
  • the latter is split so as to receive the end of the unipole 20 which is carefully soldered thereto at the same time as the conductive inner end member 21 of the coaxial line.
  • the nut 63 clamps the disc 25, the bands and 61, the layer 62 and the spread portion of the outer conductor 22 against the ring 59.
  • the nut 63 is prevented from rotating by soldering or welding between the nut and the layer 62 of the matching line.
  • a parallel line is furnished by the stack or assembly of bands 60, 61 and layer 62, which line is adapted for the matching of the unipole 20 by the suitable choice of its shape and length.
  • FIG. 11 shows that the base of the matching line is provided with two apertures 65 which coincide with corresponding apertures in the disc 25 for the passage of the cord 40 in both directions.
  • the disc 29 has apertures 66 at its center provided for the same purpose.
  • the coaxial line 23 extends through the antenna up to its upper end by passing through a passage nut 67 which is fixed to the disc 29 in the center of the latter. This nut permits putting the cable 23 under suitable tension in the space between the discs 25 and 29.
  • a coaxial plug 68 is engaged in the passage nut 67 to connect an exterior coaxial line 70.
  • the line comprises at least three chokes 69 each of which is constituted by, for example, ten turns of the coaxial line 70 wound on itself. These turns can be suitably maintained in position by a small case of plastics material shown diagrammatically in FIGS. 7 and 9.
  • the coils are spaced a suitable distance apart, this distance being determined by experience.
  • All the metal parts of the antenna are preferably assembled by spot welding. They are of 0.05 mm thick rustless steel, copper foil or of some other suitable material, the thinness of these materials contributing to increase the air security.
  • a directional antenna comprising a hollow conducting cylindrical skirt of constant diameter having an axis and at one end a base extending in a plane perpendicular to said axis, a hole provided in said base, a unipole extending from said base along the axis of said skirt and outside of the latter, electrically isolated fixing means extending through said hole for mechanically fixing said unipole to said base, a coaxial feeder cable extending through said skirt and having an inner conductor and an outer conductor, said inner conductor extending through said isolated fixing means so as to be connected to said unipole through said hole, said outer conductor being connected to said skirt and A being the operating wavelength of the antenna, the unipole having a length of s 0.25 x, the cylindrical skirt having a length between 0.35 )t and 0.65 A and a diameter between 0.05 and 0.2 A, whereby the antenna is substantially asymmetric and has a radiation pattern which lies substantially entirely at the side of the plane of said base opposite to said unipole, an elongated casing of
  • a directional antenna comprising a unipole defining an axis, a conductive disc located in a plane perpendicular to said axis at one of the ends of the unipole, a first skirt coaxial with the unipole and extending from said plane in the opposite direction to the unipole to which it is electrically connected, said antenna further comprising a second cylindrical skirt which is coaxial with the first skirt and electrically connected at its end adjacent the unipole to the first skirt and has an extent from said end different from the extent of the first skirt, spacer means for positioning the free edges of said skirts, and a coaxial supply line whose outer sheath is connected to said skirts and whose inner conductor is connected to said unipole, the electrical connection between the first and second skirts being by means of a shorting element constituted by a conductive band folded in a zig-zag pattern and connected by its apices to the skirts, so that the band maintains the skirts together.
  • a directional antenna comprising a unipole defining an axis, a conductive disc located in a plane perpendicular to said axis at one of the ends of the unipole, a
  • first skirt coaxial with the unipole and extending from with said first and second skirts and electrically connected thereto at one of its ends adjacent the unipole and extending from said last-mentioned end a distance different from the first and second skirts, spacer means for positioning the free edges of said skirts, a coaxial supply line whose outer sheath is connected to said skirts and whose inner conductor is connected to said unipole, said first, second and third skirts being electrically connected to each other through shorting elements, each being constituted by a band folded in a zigzag pattern and connected by its apices to adjacent skirts so as to maintain the skirts assembled.
  • a directional antenna comprising a unipole defining an axis, a conductive disc located in a plane perpendicular to said axis at one of the ends of the unipole, a first skirt coaxial with the unipole and extending from said plane in the opposite direction to the unipole to which it is electrically connected, a second cylindrical skirt which is coaxial with the first skirt and electrically connected at its end adjacent the unipole to the first skirt and has an extent from said end different from the extent of said first skirt, a third cylindrical skirt coaxial with said first and second skirts and electrically connected thereto at one of its ends adjacent the unipole and extending from said last-mentioned end a distance different from the first and second skirts, spacer means for positioning the free edges of said skirts, a coaxial supply line whose outer sheath is connected to said skirts and whose inner conductor is connected to said unipole, the third skirt being closed at its free end by a shorting disc having a center aperture for the passage of the coaxial line
  • said spacer means comprises a washer having a circular flange which maintains said free edges of said first and wsessile k pa d, a a
  • a directional antenna comprising a unipole defining an axis, a conductive disc located in a plane perpendicular to said axis at one of the ends of the unipole, a first skirt coaxial with the unipole and extending from said plane in the opposite direction to the unipole to which it is electrically connected, said antenna further comprising a second cylindrical skirt which is coaxial with the first skirt and electrically connected at its end adjacent the unipole to the first skirt and has an extent from said end different from the extent of the first skirt, spacer means for positioning the free edges of said skirts, and a coaxial supply line whose outer sheath is connected to said skirts and whose inner conductor is connected to said unipole, said unipole having an U- shape and being cut from a sheet of foil, said antenna further comprising two half-shells which have a generally semicylindrical shape and are adjoining in an axial plane, the unipole being clamped between respective adjoining edges of said half-shells.
  • An antenna as claimed in claim 3 comprising a case having two identical halves which are in adjoining relation in a radial plane, and means for fixing in position component parts of the antenna inside the case.
  • a directional antenna comprising a unipole defining an axis, a conductive disc located in a plane perpendicular to said axis at one of the ends of the unipole, a
  • said antenna further comprising a second cylindrical skirt which is coaxial with the first skirt and electrically connected at its end adjacent the unipole to the first skirt and has an extent from said end different from the extent of the first skirt, spacer means for positioning the free edges of said skirts and a coaxial supply line whose outer sheath is connected to said skirts and whose inner conductor is connected to said unipole, a third cylindrical skirt coaxial with the other two skirts and electrically connected to the other two skirts at one of its ends adjacent the unipole and extending from the last-mentioned end a distance different from the first and second skirts, the free edge portion of the third skirt being in contact with said spacer means, said unipole being made of metal foil having U-shape, and a casing comprising two identical halves which are in adjoining relation in a radial plane, the case being provided with means for fixing in position the component
  • a directional antenna as claimed in claim 11, comprising a matching line for matching said unipole to the impedance of the coaxial line, said matching line being connected in parallel to a point of connection between the inner conductor of the coaxial line and the unipole,
  • said spacer means comprises a washer having a circular flange which maintains said free edges of said first and second skirts spaced apart.

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US00178910A 1968-01-22 1971-09-09 Balloon carried directional antenna Expired - Lifetime US3781894A (en)

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FR136819 1968-01-22
FR7128369A FR2147846B2 (enExample) 1968-01-22 1971-08-03

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Cited By (17)

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US5339089A (en) * 1990-11-23 1994-08-16 Andrew Corporation Antenna structure
US5363115A (en) * 1992-01-23 1994-11-08 Andrew Corporation Parallel-conductor transmission line antenna
WO1996037006A1 (en) * 1995-05-19 1996-11-21 Allen Telecom Group, Inc. Cellular and pcs antenna mounting assembly
US6167263A (en) * 1997-05-16 2000-12-26 Spherecore, Inc. Aerial communications network including a plurality of aerial platforms
US20030109281A1 (en) * 2001-04-18 2003-06-12 Knoblach Gerald M. Unmanned lighter-than-air safe termination and recovery methods
US6628941B2 (en) 1999-06-29 2003-09-30 Space Data Corporation Airborne constellation of communications platforms and method
US20050014499A1 (en) * 1999-06-29 2005-01-20 Space Data Corporation Systems and applications of lighter-than-air (LTA) platforms
RU2318274C1 (ru) * 2006-07-31 2008-02-27 Федеральное государственное унитарное предприятие "Научно-исследовательский институт "Рубин" Аэростатная антенна
RU2321109C1 (ru) * 2006-07-31 2008-03-27 Федеральное государственное унитарное предприятие "Научно-исследовательский институт "Рубин" Аэростатная контейнерная антенна
US9632503B2 (en) 2001-04-18 2017-04-25 Space Data Corporation Systems and applications of lighter-than-air (LTA) platforms
US9643706B2 (en) 2001-04-18 2017-05-09 Space Data Corporation Systems and applications of lighter-than-air (LTA) platforms
WO2017105657A1 (en) * 2015-12-16 2017-06-22 Skycom Corporation Lighter-than-air platform
US9908608B2 (en) 2001-04-18 2018-03-06 Space Data Corporation Systems and applications of lighter-than-air (LTA) platforms
US10059421B2 (en) 2014-12-30 2018-08-28 Space Data Corporation Multifunctional balloon membrane
US10207802B2 (en) 2014-12-24 2019-02-19 Space Data Corporation Breaking apart a platform upon pending collision
US10403160B2 (en) 2014-12-24 2019-09-03 Space Data Corporation Techniques for intelligent balloon/airship launch and recovery window location
EP3793026A1 (en) * 2019-09-12 2021-03-17 PC-Tel, Inc. Rf antenna assembly and system

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US3438042A (en) * 1966-03-03 1969-04-08 Gen Dynamics Corp Center fed vertical dipole antenna
US3588903A (en) * 1968-04-03 1971-06-28 Goodyear Aerospace Corp Vertical radiator antenna structure which eliminates the necessity of a ground plane

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US2704811A (en) * 1950-06-19 1955-03-22 Andrew W Walters Cylindrical antenna
US3315264A (en) * 1965-07-08 1967-04-18 Brueckmann Helmut Monopole antenna including electrical switching means for varying the length of the outer coaxial conductor with respect to the center conductor
US3438042A (en) * 1966-03-03 1969-04-08 Gen Dynamics Corp Center fed vertical dipole antenna
US3588903A (en) * 1968-04-03 1971-06-28 Goodyear Aerospace Corp Vertical radiator antenna structure which eliminates the necessity of a ground plane

Cited By (38)

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Publication number Priority date Publication date Assignee Title
US5339089A (en) * 1990-11-23 1994-08-16 Andrew Corporation Antenna structure
US5363115A (en) * 1992-01-23 1994-11-08 Andrew Corporation Parallel-conductor transmission line antenna
WO1996037006A1 (en) * 1995-05-19 1996-11-21 Allen Telecom Group, Inc. Cellular and pcs antenna mounting assembly
US5619217A (en) * 1995-05-19 1997-04-08 Allen Telecom Group, Inc. Cellular and PCS antenna mounting assembly
US6167263A (en) * 1997-05-16 2000-12-26 Spherecore, Inc. Aerial communications network including a plurality of aerial platforms
US20080299990A1 (en) * 1999-06-29 2008-12-04 Space Data Corporation Systems and applications of lighter-than-air (lta) platforms
US6628941B2 (en) 1999-06-29 2003-09-30 Space Data Corporation Airborne constellation of communications platforms and method
US20050014499A1 (en) * 1999-06-29 2005-01-20 Space Data Corporation Systems and applications of lighter-than-air (LTA) platforms
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FR2147846B2 (enExample) 1976-04-30
FR2147846A2 (enExample) 1973-03-11

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