_ Section Nano antennas (Rectenna)
check the most important parameters of each nano antenna (Rectenna)
Researcher and author: Dr. Afshin Rashid
Note: One of the most important parameters of any nano antenna is the current distribution on it. This characteristics of the radiation pattern, radiation resistance and reactance, and many important characteristics of the antenna determine. despite the facilities The construction of nanotubes with a length of several centimeters allows the construction of electrical conductors with a ratio of length to width of the order of 7^10.
Nano tube antennas at a glance First, it gives us the impression that it is similar to the Dipole antenna designed in small dimensions . But in fact it is not the case. In the main theory of Dipole antennas to determine the current distribution on the antenna, that the Dipole radius is larger than the skin depth and also is completely excluded. Because here the electrons are only allowed to move along the conductor string and therefore the current distribution is effectively one-dimensional. In addition to the fact that the electrons only move in one dimension, there are two important issues. Also happens, large inductance and resistance. These characteristics create a very different behavior for nanotube antennas compared to classical antennas. In one-dimensional electrical conductors such as nanotubes, the skin depth mode . that the nanodipole L/d is significantly reduced, it cannot be used Considering The resistance loss is so low that it can be ignored.
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 given 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 communication platform between different parts of a nano system, major factors and parameters are that each of them is decisive and determines the manufacturing capability and performance of the final system. Graphene structures can be used to make nano antennas. And this valuable structure can play a very fundamental role. Construction of nano antennas in various applications of telecommunication and communication systems
Conclusion :
One of the most important parameters of any nano antenna is the current distribution on it. This characteristics of the radiation pattern, radiation resistance and reactance, and many important characteristics of the antenna determine. despite the facilities The construction of nanotubes with a length of several centimeters allows the construction of electrical conductors with a ratio of length to width of the order of 7^10.
Researcher and author: Dr. Afshin Rashid
Specialized doctorate in nano-microelectronics