Horn antenna for launching electromagnetic signal from microstrip to dielectric waveguide
A horn antenna is formed within a multilayer substrate and has a generally trapezoidal shaped top plate and bottom plate formed in different layers of the multilayer substrate. A set of densely spaced vias form two sidewalls of the horn antenna by coupling adjacent edges of the top plate and the bottom plate. The horn antenna has a narrow input end and a wider flare end. A microstrip line is coupled to the top plate and a ground plane element is coupled to the bottom plate at the input end of the horn antenna.
1. A system comprising:
a multilayer substrate having multiple conductive layers separated by layers of insulation, the substrate including a horn antenna with a narrow, waveguide portion, input end and a wider output end, the horn antenna being formed of the conductive layers and the layers of insulation and including a top plate conductive layer, a bottom plate conductive layer, and densely spaced vias forming vertical sidewalls of the horn antenna and waveguide portion by coupling adjacent edges of the top plate and bottom plate, the horn antenna being trapezoidal and the waveguide portion being rectangular;
a microstrip line formed in one of the conductive layers adjacent the waveguide portion input end, the microstrip line having a tapered portion that increases in width as it approaches the waveguide portion input end and the tapered portion not extending into the waveguide portion; and
a ground plane formed in another one of the conductive layers at the waveguide portion input end.
2. The system of claim 1 in which the microstrip line is formed in the top plate conductive layer and the ground plane is formed in the bottom plate conductive layer.
3. The system of claim 1 in which the tapered portion adjacent the waveguide portion input end has an impedance that matches an impedance of the waveguide portion input end.
4. The system of claim 1 including one or more filament lines formed in one or more of the layers of the multilayer substrate, and each of the filament lines is coupled to a portion of the plurality of vias on a side of the horn antenna.
5. The system of claim 4 in which one or more of the filament lines extends in a planar manner beyond the horn antenna.
6. The system of claim 1 including an integrated circuit (IC) mounted on the multilayer substrate, the integrated circuit including a sub-terahertz radio frequency circuit that is coupled to the microstrip line.
7. The system of claim 6 including a dielectric waveguide with an interface surface adjacent the wider output end of the horn antenna.
8. The system of claim 7 including a system substrate and the multilayer substrate and the dielectric waveguide are mounted on the system substrate.
9. The system of claim 1 in which the microstrip line and the top plate are formed in different conductive layers of the multilayer substrate.