  We describe an antenna designed to generate monochromatic electromagnetic
knots and other "unusual electromagnetic disturbances" in the microwave domain.
Our antenna is a spherical array of radiating dipolar elements configured to
generate the desired electromagnetic field pattern near its centre. We show
numerically that an "electromagnetic tangle" of frequency 2.45 GHz can be
generated using an antenna of radius of 61.2 cm with only 20 pairs of dipolar
elements; a monochromatic electromagnetic knot with linked and torus-knotted
electric and magnetic field lines, closely related to the well-known
Ra\~nada-Hopf electromagnetic knots but easier to produce due to its
monochromaticity. The antenna could be used to locally excite plasmas.
