Hybrid tee waveguide assembly

DETAILED DESCRIPTION It is an object of the invention to provide a technique for determining the optimum post diameter for maximum power transfer in a magic tee.
It is a further object to produce magic tee hybrid junctions with matching posts determined according to the technique of the present invention.
A still further object is to produce a matching post for a magic tee, said matching post being produced with optimum post diameter determined by the teachings of the invention, and constructed such that regardless of the need to vary the post length, the distance between the top of the post and a reference point on the E-plane arm is fixed.
The objects of the invention are accomplished by selecting the diameter of the matching post of a magic tee such that it is in a predetermined mathematical relation with the height of the E-plane arm.
Using conventional waveguide nomenclature, the waveguide height refers to the shorter of the two dimensions defining the cross section of a rectangular waveguide.
For example, one form of an S band rectangular waveguide has a cross section defined by a height of 0.
670 inches and a width of 2.
840 inches.
We have determined that the power handling capacity of a magic tee can be maximized if the matching post and E-plane arm are designed according to criteria for maximum breakdown voltage in a coaxial transmission line.
More specifically, power into the H-plane arm can be maximized relative to the breakdown voltage between the matching post and the E-plane arm by selecting the post diameter such that the ratio of the E-plane waveguide height to the post diameter provides a characteristic impedance equal to the characteristic impedance of a coaxial transmission line constructed to withstand the maximum breakdown voltage between the shield and center conductor.
With post diameter determined according to the teachings of the invention, post length is then selected experimently.
It was found that as the post diameter was increased, the length of the post had to be made longer to achieve proper matching of the H-plane arm to the input waveguide