Island, New York, the donut was replaced by a dome or mushroom design.
There has been speculation as to why the change…
- Is the dome just a better design?
- Perhaps there is a benefit to having a large interior cavity at the top of the tower?
As usual the real reason isn’t all that exciting. The original donut design was very expensive. The architects’ presented Tesla with an estimate of $450,0001 for the donut antenna. Tesla had to change the antenna to a more economical design.
1 Tesla, N. United States Patent: 1,119,732. APPARATUS FOR TRANSMITTING ELECTRICAL ENGERY. APPLICATION FILED JAN. 18, 1902. RENEWED MAY 4, 1907. Patented Dec. 1, 1914.
2 Anderson, Leland, I. NIKOLA TESLA ON HIS WORK WITH ALTERNATING CURRENTS AND THEIR APPLICATION TO WIRELESS TELEGRAPHY, TELEPHONY, AND TRANSMISSION OF POWER. Sun Publishing, Denver, Colorado. 1992, pp. 143-144.