(electrical - telecommunication nano-antennas) nano-antennas in various applications of telecommunication and communication systems common with nano-scale systems
Researcher and author: Dr. ( Afshin Rashid)
Note: Nano telecommunication includes electronic devices and tools , one of whose dimensions is about one to several hundred nanometers. Based on this , if the antennas used in nano parts are to be in this range, it should be expected that the electromagnetic waves used in the communication of these systems and devices will be around several tens of terahertz, which will include the wavelengths of the infrared, visible and ultraviolet regions. .
Antenna is considered as the primary means of absorbing electromagnetic waves in space and has its related engineering knowledge which is very developed and wide. In general, in order to receive the electromagnetic wave in the space, the dimensions of the antenna must be in the same order as the wavelength of the input to its surface. Due to the very small dimensions of nano sensors, nano antennas need to have a very high working frequency to be usable. The use of graphene helps to solve this problem to a great extent. The speed of propagation of waves in CNTs and GNRs can be 100 times lower than its speed in vacuum, and this is related to the physical structure, temperature and energy. Based on this, the resonance frequency of graphene-based nano-antennas can be two times lower than nano-antennas based on nano-carbon materials.
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 characteristics of the 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 is significantly reduced, impossible is used. In one-dimensional electrical conductors such as nanotubes, the skin-depth mode is completely eliminated. Because here the electrons are only allowed to move They have the length of the conductor and therefore the current distribution is effectively one-dimensional. In addition to the fact that the electrons move in only one dimension, two important Dicker problems also occur, large inductance and resistance. These characteristics create a very different behavior for nanotube antennas compared to classical antennas. The main difference is that the current distribution is alternating with a wavelength that is 100 times smaller than the free space wavelength for a certain thermal frequency. The wavelength of 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. This is the case. 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 feeding system and the physical communication platform 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 :
Graphene structures can be used to make nano antennas and this valuable structure can play a very important role. The construction of nano-antennas in various applications of telecommunication systems and common communication with nano-scale systems is the basis for new fields and functions of nano-electronic telecommunication systems and equipment.
Researcher and author: Dr. ( Afshin Rashid)
Specialized doctorate in nano-microelectronics