Department of nano-micro-antennas and nano-electromagnetic waves (Nano-Micro-Antena)

The most important parameters of each Nano Antenna Nano Antenna  (from  electromagnetic current distribution  to checking  the important  characteristics   of Nano Antennas) 

Researcher  and author: Dr.   (   Afshin Rashid)

Note: One of the most important parameters of any nano antenna is the current distribution on it. This  characteristic determines the radiation pattern, radiation resistance and reactance, and many  important properties of the nano antenna.  Despite the possibilities of making nanotubes with a length of several centimeters, it is possible to  make electrical conductors with a length-to-width ratio of the order of 10^7  . 

At first glance, nanotube antennas  give us the impression that they are similar to Dipole antennas designed in  small dimensions. But in fact, it is not  the case in the main theory of Dipole antennas to determine the distribution of current on the antenna,  where the Dipole radius is larger than the skin depth and also  the resistance losses are so low that they can be ignored.  Due  to the fact that the nanodipole L/d has been reduced significantly, it becomes unusable  . In one-dimensional electrical conductors such as nanotubes, the  skin-depth mode is completely eliminated. Because here the electrons are only allowed to move along the length of the conductor, and therefore the current distribution is effectively one-dimensional. In addition to the fact that electrons move in only one dimension, two important Dicker problems also occur, large inductance and resistance. These features create a very different behavior for nanotube antennas compared to classical antennas.

The main difference in  the Nano Antenna  is that the current distribution is alternating with a wavelength that is 100 times smaller than the free space wavelength for a specific thermal frequency. The wavelength of the current distribution depends on the wave speed in that mode. If the speed of the wave is the same as the speed of light, the wavelength of the current distribution is the wavelength of electromagnetic waves in free space. On the other hand, the wave speed in nanotubes is about one hundred times lower than the speed of light. This is because in circuit theory, the wave speed is equal to the inverse of the square root of the capacitive capacitance per unit length multiplied by the inductive capacitance per unit length.

The kinetic inductance per unit length of the nanotube is ten thousand times greater than the magnetic inductance per unit length of conventional antennas. Therefore, the speed of the wave will be 100 times smaller than the speed of light. The efficiency of a classic nanotube antenna is around -90dB, which is due to resistive losses. Meanwhile, the dimensions of the antenna and nano system or nano sensor set, operating frequency, power losses, the scope and dimensions of the sensor network, the structure and facilities of the power supply system and the physical platform of communication between different parts of a nano system, major factors and parameters are that each of them is decisive in a way and determines the ability to build and the performance of the final system.


Conclusion:

One of the most important parameters of any nano antenna is the current distribution on it. This  characteristic determines the radiation pattern, radiation resistance and reactance, and many  important properties of the nano antenna.  Despite the possibilities of making nanotubes with a length of several centimeters, it is possible to  make electrical conductors with a length-to-width ratio of the order of 10^7  .

Researcher  and author: Dr.   (   Afshin Rashid)

Specialized doctorate in nano-microelectronics