Microstrip antenna device with slot-line-fed antenna arrays
The present disclosure provides a microstrip antenna device, which may comprise a center-fed antenna array. Further, the present disclosure provides a radar device, which comprises the antenna device, and a method for fabricating the antenna device. The antenna device comprises a substrate with top and bottom surface, two-dimensional first and second conductive structures, which are arranged adjacent to each other on the top surface, and a two-dimensional third conductive structure, arranged on the bottom surface and providing an electric ground plane. The first conductive structure comprises a first array of antennas and a first feed network, and the second conductive structure comprises a second array of antennas and a second feed network. Further, a slot line is formed in the third conductive structure, for feeding a signal to the first feed network and to the second feed network.
1. A microstrip antenna device, comprising:
a substrate having a top surface and a bottom surface,
a two-dimensional first conductive structure and a two-dimensional second conductive structure arranged adjacent to each other on the top surface of the substrate, and
a two-dimensional third conductive structure arranged on the bottom surface of the substrate and providing an electric ground plane,
wherein the first conductive structure comprises a first array of antennas and a first feed network, each respective antenna in the first array of antennas being connected to the first feed network,
wherein the second conductive structure comprises a second array of antennas and a second feed network, each respective antenna in the second array of antennas being connected to the second feed network,
wherein a slot line is formed in the third conductive structure for feeding a signal to both the first feed network and the second feed network,
wherein the first feed network and the second feed network are electromagnetically coupled to the slot line in a coupling region,
wherein the slot line is coupled to the first feed network and to the second feed network, in the coupling region, via a coupling structure, and
wherein the coupling structure comprises a coupling portion of the slot line, a coupling portion of the first feed network, and a coupling portion of the second feed network.
2. The microstrip antenna device according to claim 1 , wherein the coupling region is located between the first array of antennas and the second array of antennas.
3. The microstrip antenna device according to claim 1 , wherein the coupling region is located centrally between the first array of antennas and the second array of antennas.
4. The microstrip antenna device according to claim 1 , wherein the coupling structure comprises a cross-over coupler.
5. The microstrip antenna device according to claim 1 , wherein the coupling portion of the slot line comprises an end portion of the slot line, the end portion of the slot line having a circular shape,
wherein the coupling structure of the first feed network comprises an end portion of the first feed network, the end portion of the first feed network terminating in a first curved stub, and
wherein the coupling structure of the second feed network comprises an end portion of the second feed network, the end portion of the second feed network terminating in a second curved stub,
wherein the first and second curved stubs and the end portion of the slot line have the same curvature.
6. The microstrip antenna device according to claim 1 , wherein the first curved stub and the second curved stub are located above an inner region of the circular shape of the end portion of the slot line.
7. The microstrip antenna device according to claim 1 , wherein the first array of antennas and the second array of antennas are symmetric to each other with respect to a symmetry axis.
8. The microstrip antenna device according to claim 1 , wherein the antennas of the first array of antennas are arranged in a first lattice and the antennas of the second array are arranged in a second lattice.
9. The microstrip antenna device according to claim 8 , wherein the first array of antennas is a first microstrip combline antenna array and the second array of antennas is a second microstrip combline antenna array.
10. A microstrip antenna device, comprising:
a substrate having a top surface and a bottom surface,
a two-dimensional first conductive structure and a two-dimensional second conductive structure arranged adjacent to each other on the top surface of the substrate, and
a two-dimensional third conductive structure arranged on the bottom surface of the substrate and providing an electric ground plane,
wherein the first conductive structure comprises a first array of antennas and a first feed network, each respective antenna in the first array of antennas being connected to the first feed network,
wherein the second conductive structure comprises a second array of antennas and a second feed network, each respective antenna in the second array of antennas being connected to the second feed network,
wherein a slot line is formed in the third conductive structure for feeding a signal to both the first feed network and the second feed network,
wherein the first feed network comprises a primary feed line and a plurality of secondary feed lines, the primary feed line passing through a central region of the first array of antennas, and the secondary feed lines branching off from the primary feed line at different branch-off points, and
wherein the second feed network comprises a primary feed line and a plurality of secondary feed lines, the primary feed line passing through a central region of the second array of antennas, and the secondary feed lines branching off from the primary feed line at different branch-off points.
11. The microstrip antenna device according to claim 10 , wherein the first array of antennas and the second array of antennas are symmetric to each other with respect to a symmetry axis.
12. The microstrip antenna device according to claim 11 , wherein a coupling structure comprises a coupling portion of the slot line, a coupling portion of the first feed network, and a coupling portion of the second feed network, and
wherein the coupling structure is configured to introduce a 180° phase shift between the signal in the first feed network and the signal in the second feed network.
13. The microstrip antenna device according to claim 11 , wherein: the slot line extends along the symmetry axis.
14. The microstrip antenna device according to claim 10 , wherein the first conductive structure and the second conductive structure are separated from each other by a distance in a range of 0.7-0.85 times a wavelength of operation of the microstrip antenna device.
15. The microstrip antenna device according to claim 10 , wherein the first array of antennas and the second array of antennas are both spatially periodic in a direction orthogonal to the slot line, with a spatial period in a range of 0.5-0.65 times a wavelength of operation of the microstrip antenna device.
16. The microstrip antenna device according to claim 10 , wherein the antennas of the first array of antennas are arranged in a first lattice and the antennas of the second array are arranged in a second lattice.
17. The microstrip antenna device according to claim 16 , wherein the first array of antennas is a first microstrip combline antenna array and the second array of antennas is a second microstrip combline antenna array.
18. A radar device comprising a microstrip antenna device according to claim 10 .
19. A method for producing a microstrip antenna device, the method comprising:
forming a two-dimensional first conductive structure and a two-dimensional second conductive structure adjacent to each other on a top surface of a substrate, the first conductive structure comprising a first array of antennas and a first feed network, the second conductive structure comprising a second array of antennas and a second feed network, each respective antenna in the first array of antennas being connected to the first feed network, each respective antenna in the second array of antennas being connected to the second feed network, and
forming a two-dimensional third conductive structure on a bottom surface of the substrate in order to provide an electric ground plane, wherein forming the two-dimensional third conductive structure comprises:
forming a conductive layer on the bottom surface of the substrate, and
forming a slot line in the conductive layer, the slot line being suitable for feeding a signal to the first feed network and to the second feed network,
wherein the first feed network comprises a primary feed line and a plurality of secondary feed lines, the primary feed line passing through a central region of the first array of antennas, and the secondary feed lines branching off from the primary feed line at different branch-off points, and
wherein the second feed network comprises a primary feed line and a plurality of secondary feed lines, the primary feed line passing through a central region of the second array of antennas, and the secondary feed lines branching off from the primary feed line at different branch-off points.
20. The method of claim 19 , wherein forming the slot line comprises removing conductive material from the conductive layer along a line.