Classifications

• • 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
  • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
  • H01Q9/40—Element having extended radiating surface
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/44—Details of, or arrangements associated with, antennas using equipment having another main function to serve additionally as an antenna, e.g. means for giving an antenna an aesthetic aspect

Definitions

• the present invention relates to a high frequency broadband antenna. More particularly, it is fixed to the body of a vehicle as a receiving antenna in frequency-modulated sound broadcasting.
• Such a known antenna is of the "whip" or "end of wire” type consisting of a substantially vertical conductive strand.
• the horizontal directivity diagram is theoretically circular, and the antenna is almost omnidirectional if it is placed correctly on the vehicle, without being too disturbed by the body of the latter.
• the "whip" antenna In a vertical plane, the "whip" antenna with its image in the mirror formed by the vehicle body behaves like a doublet. Very roughly, the vertical directivity diagram consists of two substantially semicircular lobes like ears, symmetrical with respect to the vertical axis of the antenna, tangent to this axis at the foot of the antenna and located above the horizontal formed by the vehicle body. The power captured by the "whip” antenna thus extends in an elevated sector from 40 ° to 50 ° from the horizontal.
• the sources emitting the sound broadcasting signals are very directive to radiate a few meters from the ground.
• the "whip" antenna then picks up only a small useful power, due to the low vertical directivity of the antenna, and is largely subject to parasites, all the more since it has a lobe consequent vertical secondary along the axis of the antenna.
• the present invention aims to remedy the drawbacks of the vertical directivity diagram of the "whip" antenna by providing a high frequency antenna which in a vertical plane is very directive almost along the horizontal, that is to say almost according to directions perpendicular to the axis of the antenna, while retaining the almost omnidirectional character in a horizontal plane.
• a high frequency antenna is characterized by a structure with four wings substantially in a rectangular triangle having in common a side of a right angle.
• This structure gives the antenna a very marked directivity almost perpendicular to its axis, that is to say to the side of common right angle, and therefore in directions substantially parallel to the horizontal when the antenna is vertical.
• the antenna is almost omnidirectional in a plane almost perpendicular to the axis of the antenna.
• the right angle vertices of the wings are connected to one foot of the antenna collecting the radiated power received towards an appropriate receiver on board a vehicle.
• the wings of the antenna are preferably substantially identical, although they can be somewhat different, in particular as regards their contours without significantly modifying the performance of the antenna.
• the length of the common right angle side of the antenna is between 4 to 6 lengths of the other right angle side of each wing, for reception frequencies of the order of a gigahertz.
• the wings of the antenna can form between them two by two an angle substantially between 80 and 90 °, without significantly modifying the quasi-omnidirectional character of the antenna.
• the antenna can be manufactured from first and second plates substantially in an isosceles triangle, each forming two pairs of opposite wings.
• the two plates can be split to assemble.
• the first plate of the antenna has a slot which extends substantially along the half-height coming from the base of the first plate, from the top of the first plate, and into which a portion is inserted.
• the second plate extending substantially along the half-height of the base of the second plate, from the top of the second plate, and the second plate has a slot which extends substantially along the half-height from the base of the second plate, from the middle of the base of the second plate, and into which is inserted a portion of the first plate extending substantially along the half-height of the base of the first plate, from the middle of the base of the first plate.
• FIG. 1 is a perspective view of a winged antenna in a right triangle according to a first embodiment of one invention
• Figures 2 and 3 are views of the first embodiment of the antenna, taken respectively along the arrows F2 and F3 in Figure 1;
• - Figure 4 is a top view of the antenna of Figure 1;
• - Figures 5 and 6 are respectively front views of two plates each forming two opposite wings in the antenna of Figure 1;
• FIG. 7 is a perspective view of a wing antenna substantially in a rectangle rectangle according to a second embodiment of the invention.
• FIGS 8 and 9 are respectively front views of two plates each forming two opposite wings in one antenna of Figure 7;
• FIGS 10, 11 and 12 are vertical directivity diagrams of the second embodiment of the antenna, for azimuths of 45 °, 180 ° and 270 ° identified in Figure 7, respectively.
• a high frequency broadband antenna 1 has a structure having four vertical flat wings
• the wings have in common a large vertical right angle side 25 so that the short horizontal right angle sides of the wings are coplanar.
• a threaded foot 3 to be screwed into a threaded sleeve secured to an antenna support, for example the body of a vehicle, in particular the roof of the latter.
• the foot 3 is screwed into a removable magnetic base to be applied to the vehicle body.
• the four wings are monolithic in pairs 21, 23 and 22, 24 formed in two brass metal plates 4 and 5 substantially identical and with an isosceles triangle outline.
• the two plates are linked to each other to form between them a substantially right angle, between 80 ° and 90 °.
• the first plate 4 has an upper slot 41 which extends substantially along the half-height from the base 42 of the first plate, from the top 43 of the first plate.
• the second plate 5 has a lower slot 51 which extends substantially along the half-height coming from the base 52 of the second plate, from the middle of the base 52.
• the width of the slots 41 and 51 is of the order of the thickness of the plates 4 and 5.
• the second plate 5 is presented substantially at right angles above the top 43 of the first plate 42 and then lowered the along the base height of the first plate. Simultaneously and gradually, the portion of the second plate 5 extending substantially along the base half-height from the top 53 of the second plate, above the slot 51 is slid and contained in the slot 41 of the first plate, and the portion of the first plate 4 extending substantially along the base half-height from the middle of the first plate, below the slot 41, is slid and contained in the slot 51 of the second plate.
• the plates are then glued or welded to each other along the side of right angle common to the wings, that is to say along the base heights of the isosceles plates.
• the exactly right triangle shape of the wings as well as the identity between the dimensions of the wings are not essential to the functioning of the antenna, insofar as the wings have substantially similar triangular rectangle contours.
• an antenna 1a comprises two plates 4a and 5a which have an identical contour except for the respective assembly slots 41a and 51a along the right angle side common 25a and which each bring together two opposite wings 21a, 23a and 22a, 24a whose contours are different.
• the wings 21a and 24a differ from the wings 22a and 23a by the profile of their hypotenuses, and differ from the wings in right triangle 21 to 24 by a longer short side of horizontal right angle.
• the wings 21a and 24a Over about a third of the length of the hypotenuse from the plate bases 42a and 52a, the wings 21a and 24a each have a hypotenuse profile having two successive semi-circular projections 25a, 26a.
• the profile of the hypotenuse of the other two wings 22a and 23a has a projection 27a, 28a which extends substantially parallel to the hypotenuse of corresponding wings 22 and 23 and which is connected to the remaining two thirds of the hypotenuse and to the base of the plate by two convex fillets.
• Profiles of wings 21a, 24a and 23a, 22a in each of the plates 4a and 5a have an aesthetic appearance so as to read there the acronym DAB, the letter D being represented by the projection 28a, 27a, the letter A by the isosceles triangular apex 43a, 53a of the plate 4a, 4b, and the letter B by the double projection 25a, 26a.
• the antenna la for the high quality digital sound broadcasting service within the framework of the European program DAB has the dimensions indicated below to use it as a receiving antenna at about 1 , 5 GHz with a bandwidth typically between 1452 and 1492 MHz, or 40 MHz, in which 160 sub-carriers of high quality digital sound broadcasting signals are spaced in 250 kHz steps
• - wing height 85 mm
• - width of the wings 17.3 and 17.5 mm
• each plate 4a, 5a taken at the upper ends of the projections: 25 mm;
• the dimensions of the antenna 1 are deduced from those of the antenna 1a by linearly extending the rectilinear sections of the hypotenuses and of the bases of the wings of the antenna 1a to their base.
• FIGS. 10, 11 and 12 Three vertical directivity diagrams are shown in FIGS. 10, 11 and 12 respectively for azimuths A of 45 °, 180 ° and 270 ° marked around the axis 25a of the antenna from wing 21a, as shown in Figure 7, for several frequencies between 1482 and 1492 MHz.
• the antenna 1a was located 1.42 meters from the ground on the roof of a vehicle and was used as a transmitting antenna at the center of a vertical semi-circular gantry for measuring electromagnetic power comprising a mobile receiving antenna capable of be moved in elevation from O to ⁇ 90 ° around the antenna la on either side of the vertical axis 25a thereof.
• These vertical directivity diagrams are naturally valid for the antenna 1a used as a reception antenna, by virtue of the principle of reciprocity of electromagnetic waves.
• the major part of the ends of two main lobes comprised between attenuations of 0 and - 1 db extends substantially on either side of a site angle of 75 ° to 80 ° from the vertical over a width of plus or minus 5 to 10 °. Almost no secondary lobes appear in the center of the diagrams.
• the antenna according to the invention is very directive in a direction almost perpendicular to the axis 25a of the antenna, that is to say an almost horizontal direction in practice, and is thus particularly intended for picking up signals propagating near the ground.
• the antenna according to the invention has an almost circular horizontal directivity diagram, and is therefore almost omnidirectional.
• This horizontal directivity diagram is derived from the combination of two directivity diagrams of the pairs of wings 21a, 23a and 22a, 24a each comprising substantially two circles symmetrical with respect to the horizontal trace of the respective plate 4a, 5a and centered on the mediator of this trace, which mediator is merged with the trace of the other plate 5a, 4a when the plates 4a and 5a are perpendicular.

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• Details Of Aerials (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)

Applications Claiming Priority (3)

Publications (2)

Family

ID=9496397

Family Applications (1)

Country Status (5)

Families Citing this family (5)

Family Cites Families (3)

• 1996
  • 1996-10-02 FR FR9612165A patent/FR2754109B1/fr not_active Expired - Lifetime
• 1997
  • 1997-09-18 WO PCT/FR1997/001654 patent/WO1998015032A1/fr active IP Right Grant
  • 1997-09-18 ES ES97919128T patent/ES2173440T3/es not_active Expired - Lifetime
  • 1997-09-18 DE DE69712769T patent/DE69712769T2/de not_active Expired - Lifetime
  • 1997-09-18 EP EP97919128A patent/EP0929914B1/de not_active Expired - Lifetime

Non-Patent Citations (1)

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