[RFI] RFI cured with 1/4 wave wire

[Jim Brown]

On Sun,2/21/2016 10:06 AM, JW via RFI wrote:
> Has anyone said it yet - laying a 1/4 wavelength of wire out 'on the ground' creates an (albeit somewhat lossy) open-endedquarter wave 'stub' of somewhat indeterminate Z.

WAY too lossy to be useful.

> Recall, a quarter length away from the *open* end of a QW stubthe Z exhibits a low Z value. This is tantamount to 'walking' halfway around the perimeter of the Smith Chart (Z transformationor inversion in this case) and is the simple application of "The Quarter Wave Rule" that any RF savvy engineer should 'take tohis or her grave.

Of course. But of what use is such a "stub" in this application? And, 
BTW, the Vp of the transmission line formed by the stub and the earth as 
a return is much less than 1. Resonance of radials is also shifted by 
their proximity to earth. Vp in the range of 0.7 is typical.

> This is, BTW, a common trick (open-ended QW stub or microstrip 'line') used on uWave MMICs to decouple Vgg and Vdd DC supply lines at millimeter wave lengths.

Useful on PC boards, but I can't think of why it would be useful here.

73, Jim K9YC