An electromagnetic field sensor may include a housing including an opening extending therethrough; a dielectric element including a first section having a first interior space and a second section having a second interior space, the dielectric element being received within the opening of the housing; and a conductor disposed within and approximating the first interior space and the second interior space of the dielectric element, the conductor including a first portion defining a first frustrum shape and a second portion defining a second frustrum shape, the first interior space receiving the first portion of the conductor and the second interior space receiving the second portion of the conductor. The electromagnetic field sensor for use in a matching network of a plasma generation system or other application.