7. Other antennas

7.1 Superconducting antennas

Since 1986, we've known about high-temperature superconducting materials that can use liquid nitrogen as a cooling agent, which is much cheaper and more efficient than the liquid helium used with conventional superconducting materials.

These materials are composed of ceramic metal oxides. One example is thallium-barium-calcium cupric oxide, with a critical temperature of –148°C.

Are there any possible antenna applications?

In a related field, high-temperature superconducting filters have been in use since 1997 in certain radiotelephone terminals, enabling the number of available channels to be doubled thanks to the improved stiffness of the filter flanks.

As...