Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q15/00—Devices for reflection, refraction, diffraction or polarisation of waves radiated from an antenna, e.g. quasi-optical devices
  • H01Q15/0006—Devices acting selectively as reflecting surface, as diffracting or as refracting device, e.g. frequency filtering or angular spatial filtering devices
  • H01Q15/006—Selective devices having photonic band gap materials or materials of which the material properties are frequency dependent, e.g. perforated substrates, high-impedance surfaces
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q19/00—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic
  • H01Q19/10—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces
  • H01Q19/12—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave
  • H01Q19/17—Combinations of primary active antenna elements and units with secondary devices, e.g. with quasi-optical devices, for giving the antenna a desired directional characteristic using reflecting surfaces wherein the surfaces are concave the primary radiating source comprising two or more radiating elements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q25/00—Antennas or antenna systems providing at least two radiating patterns
  • H01Q25/007—Antennas or antenna systems providing at least two radiating patterns using two or more primary active elements in the focal region of a focusing device
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/30—Arrangements for providing operation on different wavebands
  • H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
  • H01Q5/342—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes
  • H01Q5/35—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes using two or more simultaneously fed points
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/40—Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements

Definitions

• the invention relates to a multi-frequency band antenna comprising:
• BIP having at least one non-passing band and forming a radiant exterior surface in transmission and / or in reception
• An excitation device capable of emitting and / or receiving electromagnetic waves inside said at least one narrow passband created by said at least one fault.
• BIP material antennas have the advantage of having a smaller footprint compared to other types of antennas, such as reflector, lens or horn antennas.
• Such antennas with BIP material are described in particular in patent application FR 99 14521, published under the number 2 801 428 in the name of C.N.R.S. (Scientific Research National Center).
• This patent precisely describes an embodiment of a BIP material having a single defect forming a resonant cavity with leaks.
• this patent also envisages the possibility of creating multi-band antennas from BIP materials. Indeed, this patent teaches that a defect created in the BIP material makes it possible to generate a narrow pass band within a wider non-pass band of this BIP material.
• a multi-band antenna designates an antenna capable of working at several different and distinct working frequencies from one another.
• the multi-band antenna has, for each of the working frequencies, the same radiation pattern and the same radiation polarization.
• the invention aims to remedy this drawback by proposing a multi-frequency band antenna with BIP material which is simpler to construct.
• the invention therefore also relates to a multi-frequency band antenna as described above, characterized in that: - the excitation device is able to work simultaneously at least around a first and a second separate working frequencies,
• the first and second working frequencies are located respectively inside a first and a second narrow bandwidths, distinct from each other, and the first and second narrow bandwidths are created by the same defect in periodicity of the BIP material.
• a defect in periodicity of the BIP material creating the first and second narrow bandwidths forms a resonant cavity with leaks having a constant height in one direction orthogonal to said radiating outer surface, and this height is suitable for placing the first and second narrow pass bands within said at least one non-pass band of BIP material
• the height of the cavity is adapted to place the first and the second narrow pass bands within the same non-pass band of the BIP material
• the BIP material has first and second non-passing bands which are disjoint and spaced apart from each other, and the height of the cavity is adapted to place the first and second narrow bandwidths within the first and second respectively the second non-passing bands of the BIP material
• said first narrow passband is substantially centered on a fundamental frequency
• said second narrow passband is substantially centered on an integer multiple of this fundamental frequency
• the cavity has a family of resonant frequencies formed by a fundamental frequency and its harmonics, the cavity resonance mode and the antenna radiation pattern being the same for each resonance frequency of the family, and the first and second working frequencies each correspond, in their respective narrow bandwidth, to a frequency of the same family
• the cavity has at least two families of resonance frequencies each formed by a fundamental frequency and its harmonics, the resonance mode and the radiation pattern of the antenna being the same for each resonance frequency of the same family and different those of the other families of resonant frequencies, and the first and second working frequencies each correspond, in their respective narrow bandwidth, to frequencies belonging to different families,
• the excitation device is capable of emitting electromagnetic waves at the first working frequency having a different polarization from the electromagnetic waves emitted at the second working frequency.
• the excitation device comprises at least one and the same excitation element capable of emitting and / or receiving electromagnetic waves simultaneously with the first and the second working frequencies
• the excitation device comprises first and second excitation elements each capable of emitting and / or receiving electromagnetic waves, and in that the first excitation element is capable of work at the first working frequency, while the second excitation element is able to work at the second working frequency,
• each of the excitation elements is capable of generating, on said external surface, respectively a first and a second radiating spots disjoint from one another, each of these radiating spots representing the origin of a beam of waves electromagnetic radiated in transmission and / or reception by the antenna,
• FIG. 1 is an illustration of a multi-frequency band antenna according to the invention
• FIG. 1 is a graph showing the transmission coefficient of the antenna of Figure 1;
• FIGS. 3A and 3B are illustrations of the radiation patterns of the antenna of Figure 1;
• - Figure 4 is an illustration of a second embodiment of a multi-frequency band antenna according to the invention.
• - Figure 5 is a graph representing the transmission coefficient of the antenna of Figure 4.
• FIG. 1 represents a multi-frequency band antenna 140 comprising a material 142 with photonic prohibition band or BIP material and a metallic plane 144 reflecting electromagnetic waves.
• a BIP material is a material which has the property of absorbing certain frequency ranges, so that it has one or more non-pass bands, in which any transmission of electromagnetic waves is prohibited.
• the BIP material generally consists of a periodic arrangement of dielectric with variable permittivity and / or permeability.
• the BIP material is, under these conditions, designated by default BIP material.
• the BIP 142 material is here chosen to have the widest possible non-passband B.
• This non-passband B is illustrated on the graph in FIG. 2 representing the evolution of the transmission coefficient in decibels of the BIP material at fault 142 as a function of the frequency of the electromagnetic waves. This transmission coefficient represents the ratio between the quantity of electromagnetic energy emitted and the quantity of electromagnetic energy received.
• the non-passband B of the BIP material here ranges from 5 GHz to 17 GHz.
• the BIP 142 material comprises a stack of flat dielectric strips, along a direction perpendicular to the reflective plane 144.
• This stack consists here, for example, of two strips 150, 152 made of a first dielectric material such as, for example , alumina, and two blades 154 and 156 made of a different dielectric material such as, for example, air.
• the blade 154 is interposed between the blades 150 and 152, while the blade 156 is interposed between the blade 152 and the reflective plane 144.
• the blade 150 is placed at the end of the stack opposite the reflective plane 144 and has an inner surface in contact with the blade 154 and an outer surface 158 opposite the inner surface.
• the external surface 158 forms a radiating surface of the antenna in transmission and / or in reception.
• the strips 150 to 156 are parallel to the reflective plane 144.
• the height of the blade 156 is greater than the height of the blade 154 and therefore forms a single break in the geometric periodicity of the stack of dielectric materials of the BIP material.
• BIP 142 material has therefore, in this exemplary embodiment, a single fault.
• the plate 156 here forms a parallelepipedic resonant cavity with leaks of constant height H in a direction perpendicular to the reflective plane 144.
• the cavity 156 creates a narrow bandwidth BP-i (FIG. 2) centered around a fundamental frequency f 0 .
• the height H determines the frequency fo and therefore the position of the narrow passband BP-i within the non-passband B.
• fo is substantially equal to 7 GHz.
• this same defect or cavity 156 also generates other narrow passbands substantially centered on integer multiples of the frequency fo. Until now, these other narrow bandwidths had not been observed, because they were outside of the non-bandwidth B. In fact, in known antennas of this type, the bandwidth is not sufficiently wide and the frequency fo is placed substantially in the middle of the non-pass band. In this embodiment, the height H is therefore chosen so that the bandwidth BPi is sufficiently off-center so that a bandwidth BP 2 (FIG. 2), centered on a frequency fi substantially equal to twice fo, either also placed inside the same non-pass band B. Here, fi is substantially equal to 14 GHz. In known manner, such a parallelepiped resonant cavity has several families of resonant frequencies.
• Each family of resonant frequencies is formed by a fundamental frequency and its harmonics or integer multiples of the fundamental frequency.
• Each resonance frequency of the same family excites the same resonance mode of the cavity.
• These resonance modes are known under the terms of modes TM 0) TM-i, ..., TMj. These resonance modes are described in more detail in the document by F. Cardiol, "Electromagnetism, Treatise on Electricity, Electronics and Electrical Engineering", Ed. Dunod, 1987.
• Each resonance mode TMj is likely to be excited or activated by an electromagnetic wave close to a fundamental frequency f m j.
• These frequencies f m i or their harmonics are present in each of the narrow passbands BPi and BP 2 .
• Each resonance mode corresponds to a radiating diagram or form of radiation from the particular antenna 140.
• FIGS. 3A and 3B each represent a radiation diagram or form of radiation corresponding respectively to the resonance modes TMo and TM-i.
• the characteristics of the blades in the direction perpendicular to the reflective plane is determined in accordance with the teaching of patent application FR 99 14521. More precisely, these characteristics are determined so that the TMo resonance mode corresponds to a directional radiation in a preferred direction of emission and / or reception perpendicular to the external surface 158.
• this directional radiation is represented in FIG. 3A by an elongated main lobe along the direction perpendicular to the surface 158. It has been found that the shape of the radiation represented in FIG. 3A does not depend on the lateral dimensions of the cavity 156, that is to say on the dimensions of this cavity in a plane parallel to the reflecting plane if these lateral dimensions are greater than ⁇ , ⁇ given by the following formula:
• the radius R is substantially equal to 2.15 ⁇ .
• the shape of the radiation corresponding to resonance modes greater than the resonance mode TM 0 varies according to the lateral dimensions of the cavity 156.
• these lateral dimensions are determined so that the resonance mode TMi corresponds to a substantially omnidirectional radiation pattern in a three-dimensional half-space delimited by the plane passing through the reflective plane 144.
• the dimensions of the antenna 140 making it possible to obtain the desired forms of radiation are determined, for example, by experimentation.
• these experiments consist, using software of simulation of the antenna 140, in determining the forms of radiation corresponding to given dimensions, then in varying these dimensions until the desired radiation patterns are obtained.
• the antenna 140 here comprises two excitation elements 160 and 162 arranged one next to the other on the surface of the plane 144 inside the cavity 156.
• These excitation elements 160 and 162 are suitable for emitting and / or receiving an electromagnetic wave respectively at frequencies ⁇ and f T2 .
• the frequency f T ⁇ is close to the frequency f m o or one of its harmonics. It is located inside the narrow passband BPi so as to excite the resonance mode TMo of the cavity 156.
• the frequency f ⁇ 2 is close to the frequency f m ⁇ or one of its harmonics. It is placed inside the bandwidth BP 2 so as to excite the TM-i resonance mode.
• excitation elements are known as such. These are, for example, plate or patch antennas, dipoles or slot antennas capable of transforming electrical signals into electromagnetic waves. To this end, the excitation elements 160 and 162 are connected to a generator / receiver 164 of conventional electrical signals.
• the generator / receiver 164 transmits electrical signals to one or simultaneously to the two excitation elements 160 and 162. These electrical signals are converted by the element 160 into an electromagnetic wave of frequency fn and by the element 162 in an electromagnetic wave of frequency f ⁇ 2 - These electromagnetic waves at frequencies n and f ⁇ 2 do not interfere with each other, since the frequencies f ⁇ and f ⁇ 2 are very different. Indeed, here, the frequencies f ⁇ 1 and f ⁇ 2 are each located in a narrow passband, spaced from one another by a range of absorbed frequencies of width of the order of 7 GHz. In addition, these working frequencies fn and fj2 being each located within a narrow pass band inside the non-pass band B, they are not absorbed by the BIP 142 material.
• the electromagnetic wave of frequency f ⁇ excites the TMo resonance mode of the cavity 156, which results in radiation from the antenna 140 directive for this frequency and by the appearance of a radiating spot in emission and / or in reception formed on the surface 158.
• the radiating spot is here the area of the external surface containing all the points where the radiated power in transmission and / or in reception is greater than or equal to half of the maximum radiated power from this outer surface by the antenna 4.
• Each radiating spot has a geometric center corresponding to the point where the radiated power is substantially equal to the maximum radiated power.
• this radiating spot is inscribed in a circle whose diameter ⁇ is given by formula (1).
• the electromagnetic wave of frequency fo excites, for its part, the resonance mode TM-i, which results in omnidirectional radiation in a half-space at this frequency fo and by the appearance of a second radiating spot in transmission and / or reception formed on the surface 158.
• Each radiating spot corresponds to the base or cross section at the origin of a beam of radiated electromagnetic waves.
• the radiating spots are separated.
• the antenna 140 Given the directivity of the radiation pattern of the antenna 140 for the frequency f ⁇ , only the electromagnetic waves at the frequency f ⁇ and substantially perpendicular to the outer surface 158, are transmitted to the excitation element 160. On the contrary , since, for the frequency f T2 , the antenna 140 is practically omnidirectional in half a space, the direction of reception of the electromagnetic waves at the frequency fe on the external surface is practically any.
• the excitation element 160 transforms the electromagnetic waves at the frequency f ⁇ into electrical signals transmitted to the generator / receiver 164.
• the excitation element 162 acts identically for the electromagnetic waves at the frequency f T2 .
• the antenna 140 has the characteristics of a multifunctional antenna, that is to say to be able to work at two different frequencies and to have, for each working frequency, a particular radiation pattern.
• the antenna 140 is directive for the working frequency ⁇ and omnidirectional in a half-space for the frequency f ⁇ 2 .
• FIG. 4 represents a second embodiment of a multi-frequency band antenna 170 comprising a BIP material 172 associated with a metallic plane 174 reflecting electromagnetic waves.
• the BIP material is arranged so as to present several non-passing bands separated from each other by wide bands where the electromagnetic waves are not absorbed.
• FIG. 5 represents the evolution of the transmission coefficient of this antenna 140 and, in particular, two non-passing bands Bi and B2 of the same BIP material 172.
• the non-passing band B 1 is centered on a frequency f 0 and the band not B 2 is centered on an integer multiple of f 0 , here 2 f 0 .
• the BIP 172 material comprises, similarly to the BIP 142 material, a break in the periodicity of its geometric characteristics forming a resonant parallelepiped cavity 180 having a constant height G.
• the height G is here determined so as to create a narrow pass band E t substantially in the middle of the non-pass band Bi and a pass band E 2 substantially placed in the middle of the non-pass band B 2 .
• the bandwidth E 1 is centered on the fundamental frequency fo substantially equal to 13 GHz.
• the narrow passband E 2 is centered on a frequency i equal to an integer multiple of the fundamental frequency f 0 . This frequency is here substantially equal to 26 GHz.
• a single excitation element 190 is placed on the reflecting plane 174 inside the cavity 180.
• This excitation element 190 is suitable for emitting and / or receiving electromagnetic waves at frequencies of work fo and fo-
• These frequencies f ⁇ and f ⁇ 2 are both suitable for exciting the same resonance mode of the cavity 180, for example here, the resonance mode TM 0 , so as to present, for each of these frequencies, practically the same radiation pattern.
• these frequencies f T ⁇ and f ⁇ 2 are included in the passbands Ei and E 2 respectively .
• the excitation element 190 is a rectangular plate or patch antenna, equipped with two ports 192, 194 connected to a generator / receiver 196 of electrical signals.
• the ports 192 and 194 are adapted to excite two polarizations, preferably two orthogonal polarizations between them, of the excitation element 190.
• the ports 192 and 194 are intended to receive and / or transmit the signals respectively at the frequencies fo and fo.
• This antenna 170 similarly to the antenna 140, exploits the fact that the same defect creates several narrow bandwidths centered on whole multiple frequencies of a fundamental frequency.
• a single excitation element is used to work simultaneously at the two working frequencies fo and fo.
• the electromagnetic waves emitted at frequencies fo and fo are polarized orthogonally to one another to limit the interference between these two working frequencies.
• this antenna 170 follows from that described for the antenna 140.
• the antenna 170 described here is a multi-band antenna, that is to say capable of working at several different frequencies, but having, for each frequency working, the same radiation pattern.
• the excitation elements 160 and 162 of the antenna 140 are replaced by a single excitation element capable of working simultaneously at the frequencies fo and fo. This single excitation element is, for example, identical to the excitation element 190.
• the excitation element 190 of the antenna 170 is replaced, as a variant, by two distinct and independent excitation elements one of the other capable respectively of working at the frequency fo and fo- These two excitation elements are, for example, identical to the excitation elements 160 and 162.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Optics & Photonics (AREA)
• Waveguide Aerials (AREA)
• Aerials With Secondary Devices (AREA)
• Variable-Direction Aerials And Aerial Arrays (AREA)

Applications Claiming Priority (5)

Publications (1)

Family

ID=32232266

Family Applications (1)

Country Status (5)

Families Citing this family (15)

Family Cites Families (7)

• 2003
  • 2003-10-23 US US10/532,303 patent/US7411564B2/en not_active Expired - Fee Related
  • 2003-10-23 AU AU2003285445A patent/AU2003285445A1/en not_active Abandoned
  • 2003-10-23 WO PCT/FR2003/003146 patent/WO2004040695A1/fr active Application Filing
  • 2003-10-23 JP JP2005501824A patent/JP4174507B2/ja not_active Expired - Fee Related
  • 2003-10-23 EP EP03778446A patent/EP1554776A1/de not_active Ceased

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events