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Quarter Wave Antennae Solar Absorber

IP.com Disclosure Number: IPCOM000087526D
Original Publication Date: 1977-Feb-01
Included in the Prior Art Database: 2005-Mar-03
Document File: 2 page(s) / 13K

Publishing Venue

IBM

Related People

Kemlage, BM: AUTHOR [+2]

Abstract

Most substances absorb radiation at varying degrees of efficiency over the entire radiation spectrum and then re-emit radiation dependent upon the structural composition of the substance and its temperature. This emitted radiation acts as a cooling mechanism for the substance, reducing its energy. Thermal converters are based on this principle of absorbing high energy radiation but, due to its band gap, cannot emit energy in the lower energy spectrum for cooling.

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Quarter Wave Antennae Solar Absorber

Most substances absorb radiation at varying degrees of efficiency over the entire radiation spectrum and then re-emit radiation dependent upon the structural composition of the substance and its temperature. This emitted radiation acts as a cooling mechanism for the substance, reducing its energy. Thermal converters are based on this principle of absorbing high energy radiation but, due to its band gap, cannot emit energy in the lower energy spectrum for cooling.

The efficiency of an antenna to transmit a specific wavelength decreases as the length of the antenna becomes less than 1/4 Lambda. This is due to the fact that the antenna of less than 1/4 Lambda cannot support that wavelength. As an example, a radio whip antenna transmits at high efficiency perpendicular to its length, but the efficiency drops to zero in the direction of the antenna tip. Since these waves are electromagnetic in nature, radio waves transmitted by antennae and solar radiation are identical except in wavelength.

A material composed of a large number of antennae on a base will absorb all wavelengths which are characteristic of the material's absorption coefficients, with absorption occurring along the antenna length. Re-emission by the antennae will be normal to the antenna length, and thereby re-absorbed by other antennae. This re-emission or cooling radiation has a longer wavelength than the original absorbed radiation and is dependent on the temperature of the material. With this cooling radiation trapped within the material by the antennae, the temperature of the system increases.

As the temperature of the system increases from absorbed radiation, the cooling radiation increases in energy, going to shorter wavelengths. This effect continues until the cooling radiation can transmit...