Carbon Nanotube Antenna To Transmit and Receive Radio Waves Revealed by Nanocomp Technologies

Nanocomp Technologies, Inc. (Concord, NH) earned U.S. Patent 7,714,793 for nanostructures, and more particularly, to extended length carbon nanotubes or carbon nanotube aggregates for use as an antenna or sensor for the transmission and reception of electromagnetic radiation.

According to inventors David S. Lashmore and Antoinette Peter,  the antenna includes a body portion, which can be flexible to permit incorporation of the antenna into a material. The antenna also includes an aggregate of extended length nanotubes along the body portion, and a plurality of contact points between adjacent nanotubes to permit transmission of electromagnetic radiation, while reducing resistivity along the antenna at a high frequency, for example, above 100 MHz and well into the 100 gigahertz range. 

Nanocomp’s carbon nanotube antenna can provide a much stronger, lighter, and flexing antenna system for the reception and transmission of electromagnetic radiation. The very high strength of carbon nanotubes (.about.30 GPa) made from the process of the present invention can be many times stronger than steel. Furthermore, carbon nanotubes can have a low density (1.8 g/cc) compared with copper (8.9 g/cc) resulting in a substantially lighter antenna. In fact, carbon nanotubes are lighter than aluminum, i.e., about 30% lighter by weight than aluminum. Finally, the carbon nanotubes can have a high strain to failure (10%) or strong ability to flex.

The extended length nanotubes can withstand extremely corrosive environments. Because of their ability to resist to ultraviolet radiation damage, the nanotubes of the present invention can be relatively more durable than other polymeric materials. Furthermore, the nanotubes of the present invention may be anti-corrosive in nature, thereby allowing them to be employed underwater, in a high salt environment, as well as in high radiation or hazardous environments without jeopardizing their structural integrity.

The antenna includes a body portion that can be flexible to permit weaving or embedding of the antenna into fabric, cloth or any other material. The antenna also includes an aggregate of extended length nanotubes along the body portion. In an embodiment, the aggregate may have a length ranging from a few nanometers to over a meter or more. The aggregate may be designed to transmit and receive high frequency electromagnetic radiation, for instance, over 100 MHz, enhance ballistic conduction, minimize surface currents in order to minimize signal distortion, and/or minimize thermal signature along the body portion.

In an embodiment, the aggregate may include a polymeric resin dispersed there throughout to maintain the integrity of aggregate. The antenna further includes a plurality of contact points between adjacent nanotubes to permit transmission of electromagnetic radiation while reducing resistivity in the antenna at high frequencies. The antenna can be designed to be elongated in shape, as a loop, as an array, or any other geometric shape.

Nanocomp has patented a method for manufacturing an antenna for the transmission and reception of electromagnetic radiation. The method includes initially providing a plurality of extended length nanotubes. These nanotubes, of course, can be generated by a variety of methods known in the art, including chemical vapor deposition, or can be obtained from any commercially available source. Next, the nanotubes can be aggregated so as to provide a plurality of contact points between adjacent nanotubes to permit transmission of electromagnetic radiation, while reducing resistivity at a high frequency. In aggregating the nanotubes, the nanotubes can be permitted interact with one another through intermolecular forces, such as van der Waal's force to maintain the integrity of the aggregate. Alternatively, a polymeric resin may be dispersed throughout the aggregate to maintain its integrity. Thereafter, the aggregate may be manipulated into a desirable shape for use as an antenna. 

Antennas for transmission and reception need to provide high fidelity information on the nature of the signals received or transmitted. These signals can be distorted in a number of ways, including by the design of the antenna, through its frequency band of operation, and by the manner in which the antenna may be mounted. In addition, signal distortion may be caused by the materials from which the antenna is made. For instance, the materials from which the antenna is made may cause phase distortion. Phase distortion is typically frequency dependent and can be set up by surface currents induced in conductors by high frequency AC fields. However, the resistance provided by such materials is usually isotropic in nature. As a result, the signal is attenuated along the length of the antenna, as well as across the narrow diameter of the antenna.

The materials from which the antenna is made may also give rise to the occurrence of surface currents. Typically, surface currents can be inducted in high frequency transmission of information. The presence of surface currents can lead to frequency related phase shifts with the potential to distort or degrade transmitted information.

The materials from which the antenna is made can further enhance the thermal signature of the antenna. In particular, the material used can affect the resistivity and limit the current carrying capacity in the antenna. As a result, when a relatively high amount of currents is being carried along the antenna, the antenna may heat up, thereby increasing the thermal signature of the antenna. Such enhancement in the thermal signature, under most circumstances can be undesirable and the thermal energy expended is a waste of power