Why perpendicular lines make a difference? (DRO, patent US4357582)

[Terminator3]

I already had asked this question around year ago, but still did not find out.
https://www.freepatentsonline.com/4357582.html

The angle between the source transmission line 50 and the drain transmission line 40 does not need to be a right angle although the angle between the gate transmission line 30 and the drain transmission line 40 should be a right angle.

...

As described above, the oscillator according to the present invention, which enables easy design and has a simple structure, is not influenced in its oscillating characteristics by deviations of the transmission lines in size which are inevitable in mass production. The oscillating frequency of the oscillator is determined by the resonant frequency of the dielectric resonator and is well stabilized.

Actually it is the only important difference between this DRO and "classical" DROs. I mean that "right angle" part. Drain stub is half wavelength. Gate is terminated with 50 ohm. Angle between drain and gate lines must be 90 degrees, and somehow it have some advantage of "is not influenced in its oscillating characteristics by deviations of the transmission lines in size".

So why using right angle?