"Paul Burridge" wrote
A 1/4-wave shorted stub is used at frequencies as low as the MW broadcast
band. The need there is to add a deep notch at stations whose 2nd
harmonic
falls in the broadcast band. This stub is used to add to the attenuation
of
the already compliant 2nd harmonic level coming out of the tx, but which,
without the stub can be heard on broadcast receivers within a short
distance
from the broadcast antenna site. WJR (760 kHz) is one station using this
technique. (RF quote)

That just strikes me as plain stoopid. At MW, such filtering would be
far better achieved by lumped elements. A quarter wave stub at such
frequencies appears impractical, unwieldy and rather expensive!
____________

It also provides a low-impedance and fairly wideband path to ground for the
insulated, series-fed tower used by most broadcast stations -- which drains
off any static charges that may collect on the tower, and so reduces the
probability of lightning strikes.

Lumped elements are less effective at this.

RF