We propose 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 approximate the desired electromagnetic field near its centre. We show numerically that a specific embodiment of the antenna with a radius of 61.2 cm and only 20 element pairs driven at a frequency of 2.45 GHz can yield linked and torus-knotted electric and magnetic field lines approximating those of an "electromagnetic tangle": a monochromatic electromagnetic knot closely related to the well-known Ra\~nada-Hopf type electromagnetic knots but simpler in its construction. The antenna could be used to locally excite plasmas.
@article{arxiv.2101.10108,
title = {Theoretical proposal for the experimental realisation of a monochromatic electromagnetic knot},
author = {R. P. Cameron and W. Löffler and K. D. Stephan},
journal= {arXiv preprint arXiv:2101.10108},
year = {2021}
}