Patent Publication Number: US-8525747-B2

Title: Scanning antenna

Description:
RELATED APPLICATION INFORMATION 
     The present application claims priority to and the benefit of German patent application no. 10 2009 055 345.2, which was filed in Germany on Dec. 29, 2009, the disclosure, of which is incorporated herein by reference. 
     FIELD OF THE INVENTION 
     The present invention relates to an antenna. 
     BACKGROUND INFORMATION 
     Radar systems use antennas to emit radar beams. There are known radar systems which scan a visible range using a bundled radar beam. This requires an antenna which emits only in a narrowly defined direction in space. In addition, this direction of emission must be variable in order to allow sequential scanning of the visible range. Antennas suitable for this purpose are also known as scanners. 
     In addition, there are known antennas whose emission direction depends on the frequency of the radar beam emitted. Such antennas are understood to be frequency scanners and are discussed in WO 95/20169 and DE 10 2007 056 910.8, for example. However, frequency-scanning antennas known so far are complex and expensive to manufacture and offer only a suboptimal directional characteristic, i.e., beam bundling. 
     SUMMARY OF THE INVENTION 
     An object of the exemplary embodiments and/or exemplary methods of the present invention is therefore to provide an improved antenna. This object is achieved by an antenna having the features described herein. Further refinements are described herein. 
     An antenna according to the present invention has an antenna body having a plurality of first antenna elements, which are situated along a first straight line. The antenna body includes a first conductive grounded surface and a second conductive grounded surface, the first and second grounded surfaces being situated essentially parallel to one another. A dielectric is situated between the first and second grounded surfaces. Furthermore, a signal conductor is situated between the first and second grounded surfaces. The first antenna elements are designed as apertures in the first grounded surface situated above the signal conductor. Furthermore, the antenna is designed to emit a signal in a direction which depends on a frequency of the signal. A distinction is made between at least two of the first antenna elements in relation to one another, such that they emit at different power levels. The antenna configuration of the antenna may advantageously be optimized by this design of the first antenna elements, so that a particularly favorable emission characteristic is achievable. 
     The power emitted by the first antenna elements in particular may cause interference in that side-lobe suppression of the emitted power amounts to more than 25 dB in the far field. 
     The first antenna elements expediently include an exterior antenna element and a central antenna element, the aperture forming the exterior antenna element having a first diameter, and the aperture forming the second antenna element having a second diameter. The first and second diameters are different. The antenna configuration may then advantageously be set via the size of the hole. 
     The first antenna elements in particular which may be include a central first antenna element, the power emitted by a first antenna element being approximately proportional to the square of the cosine of the distance of this first antenna element from the central first antenna element, normalized to n/2. Tests and calculations have advantageously shown that a particularly favorable emission characteristic of the antenna is achievable by using such an antenna configuration. 
     The signal conductor which may be has at least one compensation structure designed in such a way that interference in the signal conductor caused by reflection on the first antenna elements is compensated. It is advantageously possible to improve the antenna emission characteristic in this way. 
     In a further refinement, the antenna has a lens the shape of a cylindrical segment. A longitudinal axis of the lens is oriented parallel to the first straight line. Furthermore, the lens is made of a dielectric material. The beam emitted by the antenna is therefore advantageously focusable in a direction perpendicular to the antenna swiveling direction. This increases the antenna gain. 
     The lens is expediently made of polyetherimide. This material has advantageously proven to be particularly suitable. 
     In a further refinement, the antenna has a plurality of second antenna elements situated outside of the first straight line. The second antenna elements are designed as patch elements and at least two of the second antenna elements are interconnected by a microstrip conductor. The second antenna elements may then be used advantageously for detecting a reflected radar signal and thereby improve the antenna resolution in a direction perpendicular to the antenna swiveling direction. 
     The second antenna elements may also be used for emitting a radar signal. 
     The second antenna elements are which may be situated in a row oriented parallel to the first straight lines. The second antenna elements in the row are interconnected by a microstrip conductor. This design is advantageously suitable in particular for detecting the reflected signal, but may also be used for emitting a radar signal. 
     In an additional further refinement, the antenna includes a second antenna body having a plurality of third antenna elements situated along a second straight line. The second straight line is oriented parallel to the first straight line. Furthermore, a waveguide running between the third antenna elements is situated in the second antenna body. Furthermore, the third antenna elements are designed as apertures running between the waveguide and a surface of the second antenna body. Either the second antenna body may then advantageously be used for detecting a reflected radar signal, so that antenna resolution is improved in a direction perpendicular to the antenna swiveling direction, or the signals emitted by the first and second antenna bodies may interfere so as to yield improved focusing perpendicular to the antenna swiveling direction. 
     In yet another further refinement of the antenna, at least one antenna gap is provided with a plurality of fifth antenna elements, such that the antenna gap is oriented perpendicularly to the first straight line and the antenna gap is coupled to a first antenna element via a coupling structure. The antenna gap then advantageously causes the signal emitted by the antenna to focus in a direction perpendicular to the antenna swiveling direction. This improves the emission characteristic of the antenna. 
     According to one specific embodiment, the antenna gap is designed as a microstrip conductor antenna, the fifth antenna elements being designed as patch elements. Advantageously, the antenna gap may then be manufactured easily and inexpensively. 
     A substrate is expediently provided between the antenna body and the antenna gap. The substrate advantageously provides electric insulation of the antenna gap from the antenna body. 
     According to an alternative specific embodiment, the antenna gap is designed as a waveguide, the fifth antenna elements being designed as apertures in this waveguide. Such an antenna gap designed as a waveguide advantageously also causes the signal emitted by the antenna to focus in a direction perpendicular to the antenna swiveling direction. 
     The exemplary embodiments and/or exemplary methods of the present invention is explained in greater detail below on the basis of the appended figures. The same reference numerals are used for the same elements or those having the same effect. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a perspective view of an antenna body of an antenna. 
         FIG. 2  shows a perspective view of the opened antenna body having a waveguide situated internally. 
         FIG. 3  shows a schematic representation of the waveguide. 
         FIG. 4  shows another representation of the waveguide having antenna elements. 
         FIG. 5  shows a graphic plot of the emission characteristic of the antenna. 
         FIG. 6  shows a perspective representation of the antenna having a cylinder lens. 
         FIG. 7  shows a representation of the antenna having additional antenna gaps according to a first specific embodiment. 
         FIG. 8  shows a representation of the antenna having additional antenna gaps according to a second specific embodiment. 
         FIG. 9  shows a section through the antenna having an additional antenna gap. 
         FIG. 10  shows a representation of the antenna having additional antenna gaps according to a third specific embodiment. 
         FIG. 11  shows a section through the antenna having additional antenna gaps according to the third specific embodiment. 
         FIG. 12  shows a representation of the antenna having additional patch elements. 
         FIG. 13  shows a representation of the antenna having additional antenna bodies. 
         FIG. 14  shows a representation of a waveguide designed as a strip conductor. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 and 2  show perspective views of an antenna body  105  of an antenna  100 . Antenna body  105  has a top part  110  and a bottom part  120 . In the representation in  FIG. 1 , top part  110  and bottom part  120  of antenna body  105  are joined by screws.  FIG. 2  shows top part  110  and bottom part  120  of antenna body  105  in an unconnected state. Top part  110  and bottom part  120  are each designed essentially as flat parallelepipeds. Top part  110  and bottom part  120  of the antenna body may be joined in such a way that a surface of top part  110  comes into contact with a surface of bottom part  120 . 
     The surfaces of top part  110  and bottom part  120 , which may be joined to one another, each have a meandering groove-type indentation. If top part  110  and bottom part  120  are joined together, the groove-type indentations supplement one another to form a waveguide  200  running in the interior of antenna body  105 . Waveguide  200  runs between inlet  210  situated on an edge of antenna body  105  and an outlet  220  situated on the same edge of antenna body  105 . A high-frequency electromagnetic signal may be injected into and extracted out of waveguide  200  via inlet  210  and outlet  220 . The signal may have a frequency of 77 GHz, for example. The frequency may be varied by an amount of 2 GHz, for example, for swiveling of the radar beam emitted by antenna  100 . 
     Top part  110  of antenna body  105  has a plurality of first antenna elements  300  situated along a straight line. First antenna elements  300  are designed as apertures running between an exterior surface of antenna body  105  and waveguide  200  in the interior of antenna body  105 . This straight line, along which first antenna elements  300  are situated, runs parallel to the direction of extent of meandering waveguide  200 . Each bend of meandering waveguide  200  has an aperture forming an antenna element  300 . Antenna elements  300  are each situated centrally between two successive bends of waveguide  200 . However, it is also possible for antenna elements  300  to be situated in other positions of waveguide  200 , for example, in the vicinity of or directly on the bends in the meandering course of waveguide  200 . For example, 24 or 48 or some other number of antenna elements  300  may be provided. The direct distance between two neighboring antenna elements  300  is selected as a function of the frequency of the signal to be emitted into waveguide  200  and may correspond to approximately half the wavelength of the signal, for example. The length of waveguide  200  between two neighboring antenna elements  300  is larger due to the meandering shape of waveguide  200  and may correspond to 5.5 times the wavelength of the signal, for example. 
     Antenna body  105  includes an electrically insulating material coated with a conductive material. The electrically insulating material may be, for example, a plastic, which may be polyetherimide or polybutylene terephthalate. In this case, antenna body  105  may be manufactured by an injection molding method. Alternatively, antenna body  105  may also be made of a glass. In this case, antenna body  105  may be manufactured by an embossing method, for example. Antenna body  105  may also be made of some other insulating material. A coating of a conductive material is applied to the insulating material of antenna body  105 . This is necessary in order for waveguide  200  to be suitable for transmission of an electromagnetic wave. The conductive coating may include different layer combinations and materials. A coating with gold or aluminum only a few micrometers thick has proven to be very suitable. The coating may be applied by physical gas phase deposition or by a galvanic coating method, for example. 
     Waveguide  200  may be filled with a medium transparent for radar radiation to protect the conductive coating from corrosion. Largely inert gases, Teflon, various foams or a vacuum, for example, are suitable for this purpose. Either only waveguide  200  is filled with the medium, to which end antenna elements  300 , inlet  210  and outlet  220  must be coated with a medium transparent for radar radiation, or alternatively, the entire antenna body  105  may be situated in the desired medium. 
       FIG. 3  shows another schematic representation of waveguide  200  in the interior of antenna body  105  of antenna  100 . Waveguide  200  includes a plurality of sections oriented parallel to the x axis, interconnected in a meandering form by bends so that waveguide  200  extends on the whole in the y direction. First antenna elements  300  are situated along the first straight lines oriented parallel to the y axis. First antenna elements  300 , designed as apertures to waveguide  200 , represent interference for waveguide  200  and negatively affect its wave conduction properties. To compensate for the interference in waveguide  200  caused by first antenna elements  300 , waveguide  200  has a plurality of compensation structures  230 . Compensation structures  230  are embodied as taperings of waveguide  200  in the vicinity of apertures forming first antenna elements  300 . Compensation structures  230  are of such dimensions that they compensate for the effect of first antenna elements  300  on waveguide  200 . Compensation structures  230  may also be situated elsewhere, for example, at a greater distance from the first antenna elements. However, it has proven to be favorable in particular to provide compensation structures  230  as close to first antenna elements  300  as possible. Compensation structures  230  improve the emission properties of antenna  100 . 
       FIG. 4  shows another view of top part  110  of antenna body  105  and waveguide  200  situated therein.  FIG. 4  shows that the apertures forming first antenna elements  300  have different diameters. The apertures need not be designed to be circular but instead may also have a different shape, for example, a rectangular shape. The term diameter in this context refers to the size of the aperture, regardless of the exact shape of the aperture. An exterior antenna element  330  situated closest to inlet  210  of waveguide  200  has a first diameter  310 . A central antenna element  340  situated at the center of waveguide  200  has a second diameter  320 . Second diameter  320  is greater than first diameter  310 . First antenna elements  300  situated between central antenna element  340  and exterior antenna element  330  have diameters between first diameter  310  and second diameter  320 . The diameter of first antenna elements  300  increases toward the center of waveguide  200 . This also applies similarly to first antenna elements  300  situated between the center of waveguide  200  and outlet  220  of waveguide  200 . 
     The size of the holes forming first antenna elements  300  determines the power emitted by first antenna elements  300 . The distribution of the power emitted by the various first antenna elements  300  is referred to as the antenna configuration. The form of the antenna configuration has a significant influence on the directional characteristic of antenna  100 . At a constant configuration at which all first antenna elements  300  emit approximately the same power, the resulting directional characteristic has only a low side-lobe suppression. However, the side-lobe suppression may also be improved through an improved antenna configuration. The directional characteristic of antenna  100  in the far field is obtained from a Fourier transform of the antenna configuration. Thus a suitable antenna configuration is calculable from the desired far field of antenna  100 . An antenna configuration at which the emitted power of each first antenna element  300  is approximately proportional to the square of the cosine of the distance of a particular first antenna element  300  from central antenna element  340  normalized to n/2 has proven favorable in particular. The normalized distance of exterior antenna element  330  from central antenna element  340  corresponds to a value of n/2. The power emitted by exterior antenna element  330  is proportional to the square of the cosine of n/2 and is thus equal to zero. 
     Antenna elements  300  situated between exterior antenna element  330  and central antenna element  340  have a normalized distance from central antenna element  340  of less than n/2 accordingly. Exterior antenna elements  330 , which emit a power of zero, may of course also be omitted. However, other antenna configurations are also possible. On the whole, side-lobe suppression of the emitted radiation in the far field of antenna  100  amounting to more than 25 dB is achievable. 
     The exact diameters of the apertures forming first antenna elements  300  are derived from the desired antenna configuration, and a correction which takes into account the fact that the high-frequency electromagnetic signal is supplied to waveguide  200  at one end through inlet  210 . Therefore antenna elements  300  a greater distance away from inlet  210  must have a larger diameter than antenna elements  300  situated close to inlet  210 . 
     The side-lobe suppression of the signal emitted by the antenna is optimizable, as already explained, by a suitable antenna configuration of first antenna elements  300 .  FIG. 5  shows in a schematic representation a comparison of the directional characteristics of an antenna  100  having compensation structures  230  described above and an optimized antenna configuration of first antenna elements  300  in comparison with the directional characteristic of an antenna without the optimizations described. The emission angle of the antenna is plotted on the horizontal axis and a normalized antenna gain is plotted on the vertical axis. First directional characteristic  400  of the unoptimized antenna has a first side-lobe suppression  410 . A second directional characteristic  420  of optimized antenna  100  has a second side-lobe suppression  430 . It is discernible that second side-lobe suppression  430  of optimized antenna  100  is better than first side-lobe suppression  410  of the unoptimized antenna. 
       FIG. 6  shows another perspective view of antenna  100  having antenna body  105 . First antenna elements  300  of antenna  100  are situated along the first straight line, which is oriented parallel to the y axis. The emission angle of antenna  100  changes in the y-z plane through a variation in the frequency of the high-frequency signal injected into waveguide  200 . However, antenna  100  emits in direction x in a wide angle range. Therefore, a lens  500  is situated in front of antenna body  105  in  FIG. 6 . Lens  500  is in the shape of a cylindrical segment whose longitudinal axis is oriented parallel to the y axis. Lens  500  focuses the beam emitted through antenna  100  in the x direction and thereby increases the gain of antenna  100 . The signal emitted by antenna  100  is not altered by lens  500  in the y direction. Lens  500  may be made of various materials. Polyetherimide has proven to be particularly suitable. Lens  500  may increase the antenna gain of antenna  100  by up to 7 dB. 
       FIG. 7  shows a top view of an antenna  3100  according to another specific embodiment. Antenna  3100  also has first antenna elements  300 , which are situated along the first straight lines. In addition, antenna  3100  has additional antenna gaps oriented perpendicularly to the first straight lines.  FIG. 7  shows a first antenna gap  3150 , a second antenna gap  3151 , a third antenna gap  3152  and a fourth antenna gap  3153 . Antenna  3100  may have as many antenna gaps  3150 ,  3151 ,  3152 ,  3153  as it has first antenna elements  300 . Each antenna gap  3150 ,  3151 ,  3152 ,  3153  has a plurality of fifth antenna elements  3300 , which are designed as patch elements. In the example in  FIG. 7 , each antenna gap  3150 ,  3151 ,  3152 ,  3153  has six fifth antenna elements  3300 . Fifth antenna elements  3300  of an antenna gap  3150 ,  3151 ,  3152 ,  3153  are interconnected via a microstrip conductor. The microstrip conductor and fifth antenna elements  3300  are made of an electrically conductive material, for example, a metal. In addition, each antenna gap  3150  to  3153  has a coupling web  3200 , which is also designed as a microstrip conductor and to which the microstrip conductors connecting fifth antenna elements  3300  are connected. Coupling web  3200  of each antenna gap  3150 ,  3151 ,  3152 ,  3153  is situated above a first antenna element  300  of antenna  3300  and forms with this antenna element  300  a first coupling structure  3700 . The power emitted by the respective first antenna element  300  is injected via first coupling structure  3700  into antenna gap  3150 ,  3151 ,  3152 ,  3153 , which is coupled to the respective first antenna element  300 . Since antenna gaps  3150 ,  3151 ,  3152 ,  3153  are oriented perpendicularly to the first straight lines, antenna gaps  3150 ,  3151 ,  3152 ,  3153  cause the signal emitted by the antenna  3100  to focus perpendicularly to the swiveling plane of antenna  3100 . Coupling structures  3700  may be situated in the middle of the respective antenna gaps  3150 ,  3151 ,  3152 ,  3153 , as shown in  FIG. 7 . Alternatively, coupling structures  3700  may also be provided at the edges or in any other positions of antenna gaps  3150 ,  3151 ,  3152 ,  3153 . 
       FIG. 8  shows a top view of an antenna  4100  according to another specific embodiment. Antenna  4100  also has a plurality of antenna gaps, each being situated above first antenna elements  300  and oriented perpendicularly to the first straight lines. In contrast with antenna  3100  shown in  FIG. 7 , however, the antenna gaps of antenna  4100  do not have a coupling web  3200 . Instead, one of the fifth antenna elements  3100  of each antenna gap is situated above a particular first antenna element  300  and together with it forms the first coupling structure  3700 . The power emitted by the particular first antenna element  300  is also injected into the antenna gap situated above the particular first antenna element  300  in this way, resulting in the signal emitted by antenna  4100  to focus perpendicularly to the swiveling direction. Any positions of coupling structures  3700  at the antenna gaps may be selected. 
       FIG. 9  shows a section through one of the first coupling structures  3700  of antennas  3100  of  FIG. 7 . It is discernible that a substrate  3710  is situated between first antenna element  300  and coupling web  3200  of antenna gap  3150 . Substrate  3710  is made of an electrically insulating material and insulates antenna gaps  3150  electrically from antenna body  105 . 
       FIG. 10  shows a view of an antenna  5100  according to another specific embodiment. Antenna  5100  in turn has a plurality of first antenna elements  300 , which are situated along a first straight line. In addition, antenna  5100  has a plurality of antenna gaps  3160 ,  3161 ,  3162 ,  3163 , each being oriented perpendicularly to the first straight line and each being situated over one of the first antenna elements  300 . Each antenna gap  3160 ,  3161 ,  3162 ,  3163  is designed as a waveguide antenna having a plurality of sixth antenna elements  3310 . In a central section of each antenna gap  3160 ,  3161 ,  3162 ,  3163 , the particular antenna gap  3160 ,  3161 ,  3162 ,  3163  is coupled to first antenna element  300  below it via a second coupling structure  3800 . The power emitted by first antenna elements  300  is therefore injected into antenna gaps  3160 ,  3161 ,  3162 ,  3163 , resulting in a focused signal emitted by antenna  5100  perpendicularly to the swiveling direction of antenna  5100 . 
       FIG. 11  shows one of the second coupling structures  3800  in a section through antenna  5100  from  FIG. 10 . The waveguide of antenna gap  3160  is situated perpendicularly above waveguide  200  of antenna  5100 . The waveguide of antenna  5100  is connected to the waveguide of antenna gap  3160  via one of the first antenna elements  300 . A sixth antenna element  3310  of antenna gaps  3160  is situated perpendicularly above the waveguides and first antenna element  300 . Sixth antenna element  3310  may be designed as an aperture or may be sealed by a dielectric material, for example. 
     Antennas  3100 ,  4100 ,  5100  from  FIGS. 7 through 11  have the advantage that the antenna gaps cause the signal emitted by antennas  3100 ,  4100 ,  5100  perpendicularly to the particular swiveling direction to be focused without requiring a lens. This reduces the installation space required for antennas  3100 ,  4100 ,  5100 . 
       FIG. 12  shows a top view of an antenna  1100  according to another specific embodiment. Antenna  1100  also has a plurality of first antenna elements  300 , which are situated along a first straight line oriented parallel to the y axis. In addition, antenna  1100  has a plurality of second antenna elements  600  situated in the x direction next to first antenna elements  300 . Second antenna elements  600  are situated in rows oriented parallel to the first straight line.  FIG. 12  shows as an example a first row  610  and a second row  620 . However, other rows having additional second antenna elements  600  may also be present. Second antenna elements  600  are designed as patch elements. Second antenna elements  600  of each row  610 ,  620  are interconnected via a microstrip conductor. The microstrip conductor is not shown in  FIG. 12 . Each row  610 ,  620  thus forms its own patch antenna. Each row  610 ,  620  may be connected to a separate electronic analyzer. Rows  610 ,  620  may be used for detecting a reflected radar signal. Since rows  610 ,  620  are situated next to one another in the x direction, rows  610 ,  620  of antenna  1100  allow resolution of the reflected radar signal in the x direction, i.e., at a right angle to the swiveling direction of antenna  1100 , regardless of the angle. Antenna  1100  may scan the space in front of antenna  1100 , i.e., in the y-z plane, by swiveling the radar beam emitted and resolve the reflected radar signal in the x-z plane as a function of angle. Antenna  1100  therefore achieves good angular resolution both vertically and horizontally. Alternatively, second antenna elements  600  may also be used for transmitting. 
       FIG. 13  shows a view of an antenna  2100  according to another specific embodiment. This antenna has antenna body  105 , already explained with reference to  FIG. 1 , having first antenna elements  300 . In addition, antenna  2100  has a second antenna body  2105  and a third antenna body  2106 . Antenna  2100  may also have additional antenna bodies. Second antenna body  2105  and third antenna body  2106  correspond in their design to first antenna body  105 . Second antenna body  2105  thus has third antenna elements  2300 , and third antenna body  2106  has fourth antenna elements  2305 . First antenna elements  300 , third antenna elements  2300  and fourth antenna elements  2305  are each oriented parallel to the y axis. The antenna elements of various antenna bodies  105 ,  2105 ,  2106  may be situated either directly one above the other or side-by-side next to one another in the x direction. 
     Antenna  2100  may be used in various ways. Individual antenna bodies  105 ,  2105 ,  2106  may be supplied by a common high-frequency source, so that individual antenna elements  105 ,  2105 ,  2106  emit synchronously with one another. In this case, the partial beams emitted by individual antenna bodies  105 ,  2105 ,  2106  may interfere with one another, resulting in a focused radar beam emitted by antenna  2100  in the y-z plane. The function of antenna  2100  corresponds to that of antennas  3100 ,  4100 ,  5100  of  FIGS. 7 ,  8  and  10 . 
     A second possibility for using antenna  2100  is to use only first antenna body  105  for emitting radar beams and to detect the reflected radar signal with the aid of second antenna body  2105  and third antenna body  2106 . Antenna  2100  then achieves an angular resolution at a right angle to the swiveling direction of antenna  2100 . This corresponds to the function of antenna  1100  of  FIG. 12 . 
     The antennas of the specific embodiments described so far each use a waveguide  200  having apertures which form first antenna elements  300 . However, a strip conductor may also be used instead of antenna body  105  and waveguide  200 .  FIG. 14  shows a suitable strip conductor  700  in a schematic sectional representation. Strip conductor  700  has a first grounded surface  720  and a second grounded surface  730 . First grounded surface  720  and second grounded surface  730  are each made of an electrically conductive material, for example, a metal. First grounded surface  720  and second grounded surface  730  may be electrically short-circuited. Both grounded surfaces  720 ,  730  extend in one plane and are situated essentially parallel to one another. A dielectric  740  is situated between first grounded surface  720  and second grounded surface  730 . The dielectric may have a low relative dielectric constant. The dielectric may be Teflon or a foam-type material, for example. 
     A signal conductor  710  is embedded in dielectric  740 . Signal conductor  710  is made of an electrically conductive material, for example, a metal. The signal conductor extends essentially along one direction. Signal conductor  710  need not necessarily be centered in the middle between first grounded surface  720  and second grounded surface  730 . Another dielectric may also be provided between signal conductor  710  and first grounded surface  720  rather than between signal conductor  710  and second grounded surface  730 . Signal conductor  710  and grounded surfaces  720 ,  730  may jointly transmit a high-frequency electromagnetic signal. 
     Strip conductor  700  may replace antenna body  105  having waveguide  200  or may function as an alternative antenna body. In this case, first ground surface  720  and/or second ground surface  730  have one or more apertures functioning as antenna elements. The antenna elements formed in this way correspond to first antenna elements  300  of antenna  100  in  FIG. 1 . Signal conductor  710  may run in a meandering pattern like waveguide  200  or in a straight line between the apertures forming the antenna elements in first ground surface  720  and/or second ground surface  730 . 
     The further refinements described on the basis of  FIGS. 3 to 13  may be combined with an antenna based on strip conductor  700 . Thus the apertures forming the antenna elements may have different diameters in first ground surface  720  and/or second ground surface  730  to optimize the antenna configuration, as described on the basis of  FIGS. 4 and 5 . Signal conductor  710  may have compensation structures, as in  FIG. 3 , which compensate for a disturbance caused by reflection on the antenna elements. Cylindrical lens  500  may also be combined with strip conductor  700 . Additional antenna gaps may also be provided on the surface of the strip conductor. 
     THE LIST OF REFERENCE NUMERALS IS AS FOLLOWS: 
     
         
           100  antenna 
           105  antenna body 
           110  top part of the antenna body 
           120  bottom part of the antenna body 
           200  waveguide 
           210  inlet 
           220  outlet 
           230  compensation structure 
           300  first antenna elements 
           310  first diameter 
           320  second diameter 
           330  exterior antenna element 
           340  central antenna element 
           400  first directional characteristic 
           410  first side-lobe suppression 
           420  second directional characteristic 
           430  second side-lobe suppression 
           500  lens 
           600  second antenna elements 
           610  first row 
           620  second row 
           700  strip conductor 
           710  signal conductor 
           720  first grounded surface 
           730  second grounded surface 
           740  dielectric 
           1100  antenna 
           2100  antenna 
           2105  second antenna body 
           2106  third antenna body 
           2300  third antenna elements 
           2305  fourth antenna elements 
           3100  antenna 
           3150  first antenna gap 
           3151  second antenna gap 
           3152  third antenna gap 
           3153  fourth antenna gap 
           3160  antenna gap 
           3161  antenna gap 
           3162  antenna gap 
           3163  antenna gap 
           3200  coupling web 
           3300  fifth antenna elements 
           3310  sixth antenna elements 
           3700  first coupling structure 
           3710  substrate 
           3800  second coupling structure 
           4100  antenna 
           5100  antenna