Theoretical proposal for the experimental realisation of a monochromatic electromagnetic knot

Abstract

Abstract 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 Rañada–Hopf type electromagnetic knots but simpler in its construction. The antenna could be used to locally excite plasmas.