In the original form of simple Marconi aerial, the aerial itself when insulated forms one coating or surface of a condenser, the dielectric being the air and ether around it, and the other conductor being the earth.
"Hertzian Wave Wireless Telegraphy"
John Ambrose Fleming
As the dielectric for such a condenser, only two materials seem to be of any practical use, viz.
"Hertzian Wave Wireless Telegraphy"
John Ambrose Fleming
M. d'Arsonval has employed micanite, but although this material has a considerably higher dielectric strength than glass, it is much more expensive to obtain a given capacity by means of micanite than by glass, although the bulk of the condenser for a given capacity is less.
"Hertzian Wave Wireless Telegraphy"
John Ambrose Fleming