Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/02—Waveguide horns
  • H01Q13/0233—Horns fed by a slotted waveguide array
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/20—Non-resonant leaky-waveguide or transmission-line antennas; Equivalent structures causing radiation along the transmission path of a guided wave
  • H01Q13/22—Longitudinal slot in boundary wall of waveguide or transmission line
• • 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
  • H01Q19/06—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 refracting or diffracting devices, e.g. lens
  • H01Q19/08—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 refracting or diffracting devices, e.g. lens for modifying the radiation pattern of a radiating horn in which it is located
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/0006—Particular feeding systems
  • H01Q21/0037—Particular feeding systems linear waveguide fed arrays
  • H01Q21/0043—Slotted waveguides
  • H01Q21/005—Slotted waveguides arrays
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
  • H01Q21/061—Two dimensional planar arrays
  • H01Q21/064—Two dimensional planar arrays using horn or slot aerials
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q21/00—Antenna arrays or systems
  • H01Q21/28—Combinations of substantially independent non-interacting antenna units or systems

Definitions

• This invention is related to slotted waveguide antennas that can receive and transmit electromagnetic waves with circular polarization.
• Circularly polarized slotted waveguide antenna arrays which transmit receive in a directional manner, are realized using slots which are not enabling the control of the aperture amplitude distribution or other slot types which are very hard to manufacture especially at high frequencies.
• all the elements are excited with equal amplitudes and this causes the side lobe level at the far zone of the antenna to be high.
• patent document KRl 00686606 slots are used which are opened on the corners of waveguides exciting the cavity at the upper side. On the top side of the cavities, a PCB (printed circuit board) based polarizer is placed. Since the slot parameters are fixed, the excitation of the slots is not possible. Therefore, the invention in patent document KRl 00686606 does not enable the control of the amplitude distribution of the array.
• patent document US2007273599 open ended waveguide which are fed by waveguides are used and this invention does not enable the control of aperture amplitude distribution.
• the antenna slots are carved on waveguide broad wall with 45° angle and with a fixed offset from waveguide centerline.
• the elliptical structures in which the slots are radiating are used to suppress grating lobes.
• Grating lobes are different than side lobes and they appear due to large inter element spacing in antenna arrays. Suppressing grating lobes does not affect the side lobe level of the antenna and there is no mention of side lobe level reduction in the document.
• the aim of this invention is enabling the reduction of far zone side lobe level of a circularly polarized slotted waveguide antenna array without sacrificing radiation efficiency.
• Figure 1 Perspective view of the antena.
• Sekil Cut view of the antenna.
• Sekil 3 The perspective view of the antenna structure having the polarizing waveguide and a single slot.
• the circularly polarized slotted waveguide antenna which is the subject of this invention (1) basically comprises of:
• At least one secondary waveguide (4) which is placed on top of the surface of the rectangular cross section waveguide (2) on which the slots (3) are carved,
• the circularly polarized slotted waveguide antenna which is the subject of this invention comprises of a rectangular cross section waveguide (2) on which slots (3) are carved and which is exciting the slots (3), slots (3) which are carved on the rectangular waveguide (2), secondary waveguide (4) which is placed on top of the rectangular waveguide (2) positioned with a definite angle ( ⁇ ) with respect to the slots (3).
• TE10 mode excites the slots (3).
• the field distribution created on the slots (3) excites the secondary waveguide (4).
• the fact that secondary waveguide (4) is placed with and angle ( ⁇ ) causes both TE10 and TE01 modes to be excited. To obtain circular polarization, these two modes should be excited with equal amplitudes and they should have a phase difference of 90° between them.
• the parameter controlling the excitation amplitude ratio of the two modes is the placement angle ( ⁇ ) of the secondary waveguide (4). Since there is not an analytical expression relating the excitation amplitude ratio to the secondary waveguide (4) placement angle ( ⁇ ), the angle ( ⁇ ) causing the excitation of the modes TE10 and TE01 with equal amplitudes is determined using numerical electromagnetic simulations. The determined value is generally between 40° and 50°.
• phase difference between TE10 and TE01 modes should be 90° ( ⁇ /2 radian). If it is assumed that the phase difference of the modes on the slot (3) surface ⁇ 0 , the modal electric field expressions at a distance "d" away from the slot (3) surface by neglecting the reflections from the aperture at the upper section of the secondary waveguide (4) are given by:
• ⁇ ⁇ Phase of TE10 mode
• Phase of TE01 mode.
• a and b are the edge lengths of the secondary waveguide (4) cross section (shown in figures), c: speed of the light in vacuum,/- frequency. This expression neglects the reflections at the waveguide (4) aperture and therefore, it is approximate. A more accurate value can be obtained via electromagnetic simulations.
• the cross section of the secondary waveguide (4) should be narrow enough to prevent modes other than TEIO and TEOl from propagating.
• the mode with the lowest cut-off frequency after TEIO and TEOl is the TE/TMl 1 mode.
• the cut-off frequency of the TE/TMl 1 mode,f c u is:
• f max the highest usable frequency of the antenna
• TE10 and TE01 modes are made 90° out of phase at the aperture of the secondary waveguide (4).
• Circularly polarized electric field distribution at the aperture of the secondary waveguide (4) radiates circularly polarized waves into free space. If it is desired to have elliptical polarizations of arbitrary axial ratios instead of circular polarization, the phase difference between modes should be made different than 90°. In this case, the dimensions of the secondary waveguide (4) should be chosen differently from the values given 90° phase difference.
• Excitation amplitude and phase of the slot (3) is controlled by changing the length of the slot (3) and by changing the distance between the slot (3) and the centerline of the waveguide (2) as it is known from the literature. Additionally, depending on the excitation amplitude and phase, the slots (3) can be modeled as shunt admittances for rectangular cross section waveguide (2). By taking advantage of this fact, the amplitude distribution at the apertures of the designed arrays can be easily controlled. This leads to low side lobe level and low cross polarization level slotted waveguide antenna arrays.
• the cross section of the secondary waveguide is elliptical.
• the circularly polarized slotted waveguide antenna (1) which is the subject of this invention is radiating circularly polarized waves without requiring an additional polarizer layer. This enables a fully metal construction which minimizes ohmic losses and increasing antenna efficiency.

Landscapes

• Waveguide Aerials (AREA)

Priority Applications (3)

Applications Claiming Priority (2)

Publications (1)

Family

ID=47827398

Family Applications (1)

Country Status (4)

Cited By (2)

Citations (6)

• 2013
  • 2013-01-23 LU LU92506A patent/LU92506B1/fr active
  • 2013-01-23 EP EP13707719.4A patent/EP2923415B1/en active Active
  • 2013-01-23 WO PCT/IB2013/050567 patent/WO2014080298A1/en active Application Filing
  • 2013-01-23 ES ES13707719T patent/ES2773269T3/es active Active

Patent Citations (6)

Also Published As

Similar Documents

Legal Events