Cavity slotted-waveguide antenna array, a method of manufacturing a cavity slotted-waveguide antenna array, and a radar antenna module comprising cavity slotted-waveguide antenna arrays
A cavity slotted-waveguide antenna array has several waveguide columns disposed in parallel in a housing. Several of the waveguide columns being provided with cavity slots on the front side of the housing. The housing includes a front part secured to a rear part, with a rear portion of the waveguide columns being formed in the rear part, and with a front portion of the waveguide columns being formed in said front part. The waveguide columns can have a rectangular cross-section, with the columns defined by two opposing wide inner surfaces, a narrow inner back surface, and a narrow inner front surface, with the plurality of cavity slots extending from the front side of the housing to said narrow inner front surface. A signal probe is disposed in the columns. Conductive parallel plate blinds are conductively secured to the front side of the housing.
1. A cavity slotted-waveguide antenna array comprising:
an array of waveguide columns, the waveguide columns of the array being disposed in parallel in a predetermined adjacent position with respect to one another in a housing, said housing having a front side and a rear side with several of the waveguide columns being provided with a plurality of cavity slots on the front side of said housing;
wherein said housing comprises a front part secured to a rear part, said rear part being formed by a first one-piece metal element and said front part being formed by a second one-piece metal element,
wherein a rear column portion of each of the waveguide columns is formed in the first one-piece metal element,
wherein a front column portion of each of the waveguide columns is formed in the second one-piece metal element, and
wherein the waveguide columns are waveguides with a rectangular cross-section, with each or at least part of the waveguide columns being defined by two opposing wide inner surfaces, a narrow inner back surface, and a narrow inner front surface, with the plurality of cavity s lots extending from the front side of the housing to said narrow inner front surface.
2. The antenna array according to claim 1 , wherein said first one-piece metal element and/or wherein said second one-piece metal element is machined from a single flat piece of metal or is cast in a die.
3. The antenna array according to claim 1 , wherein said front part has contact surfaces laying in a single plane on a rear side of the front part, which contact surfaces abut matching contact surfaces laying in a single plane on a front side of the rear part.
4. The antenna array according to claim 1 , further comprising
a signal probe operably disposed at the bottom of the rear column portion in each or at least some of the waveguide columns for emitting and/or receiving an electromagnetic signal having a free-space wavelength of λ0, which signal propagates within the column holding the signal probe as electromagnetic waves with a corresponding guided signal wavelength λg; and
wherein each or at least part of the signal probes are loop probes with a loop or an open ended loop for emitting and/or receiving said signal.
5. The antenna array according to claim 4 , wherein the distance between the longitudinal axes of two adjacent waveguide columns is at least one half the free space signal wavelength, such as at least 20, 25 or 30% larger than half the free space signal wavelength, and
wherein for each or at least part of the waveguide columns, the centres of two neighbouring slots are separated by a distance substantially equal to half the guided signal wavelength λg.
6. The antenna array according to claim 1 , further comprising several conductive parallel plate blinds conductively secured to the front side of the housing, which front side holds the cavity slots, said plate blinds being arranged substantially perpendicular to the longitudinal direction of the waveguide columns.