Planar slot coupled microwave hybrid

A symmetrical 180.degree. microwave hybrid is constructed by opening a slot line in a ground plane below a conducting strip disposed on a dielectric substrate, creating a slot coupled conductor. Difference signals propagating on the slot coupled conductor are isolated on the slot line leaving sum signals to propagate on the microstrip. The difference signal is coupled from the slot line onto a second microstrip line for transmission to a desired location. The microstrip branches in a symmetrical fashion to provide the input/output ports of the 180.degree. hybrid. The symmetry of the device provides for balance and isolation between sum and difference signals, and provides an advantageous balance between the power handling capabilities and the bandwidth of the device.

What is claimed is:

1. An apparatus for propagating microwave energy comprising:

a dielectric substrate having first and second opposed faces;

a first conducting member disposed on said first face of said dielectric substrate including a first portion having a longitudinal center line and terminating at a first end in a first port and having a second end, and second and third portions connected to said second end of said first portion extending away from said center line to terminate at second and third ports respectively; and

a ground plane disposed on said second face of said dielectric substrate, said ground plane having a gap therein defining an elongated slot parallel to and opposite said first portion and aligned with said center line for creating a slot coupled section, and arranged for energy propagation between said slot coupled section and a fourth port,

wherein said ground plane has a first side disposed on said second face of said dielectric surface and a second side opposite said first side, and further comprising a second dielectric substrate having an inner face and outer face disposed with said inner face on said second side of said ground plane and a second conducting strip disposed on said outer face terminating at said fourth port and arranged for said energy propagation between a transition portion of said elongated slot and said fourth port.

2. The apparatus of claim 1 wherein said elongated slot and said second conducting strip are disposed in orthogonal relation.

3. An apparatus for propagating microwave energy comprising:

a first dielectric substrate having first and second opposed faces;

a first conducting member disposed on said first face of said dielectric substrate including a first portion having a longitudinal center line terminating at a first end in a first port and having a second end, and second and third portions connected to said second end of said first portion extending away from said center line to terminate at second and third ports respectively;

a ground plane having a first surface and a second surface, said first surface disposed on said second face of said dielectric substrate, said ground plane having a gap therein defining an elongated slot parallel to and opposite said first portion and aligned with said center line for creating a slot coupled section, and arranged for energy propagation between said slot coupled section and a fourth port;

a second dielectric substrate having a first face disposed on the second surface of said ground plane; and

a fourth conducting strip disposed on a second face of said second dielectric substrate opposite said first face, terminating at a first end at said fouth port and arranged for said energy propagation between a transition portion of said elongated slot and said fourth port.

4. The apparatus of claim 3 wherein said first conducting member is mirror symmetric about said center line.

5. The apparatus of claim 3 wherein said elongated slot extends beyond said first portion and terminates at a first end at a virtual open circuit.

6. The apparatus of claim 3 wherein said second conducting strip terminates at a first end beyond said transition portion in a virtual short.