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Abstract

Сontents

Introduction

It is difficult to imagine the life of modern man without electronic technology. Any device designed for communication, contains one of the most important components — an antenna or antenna system. It is by means of the antenna that an electrical signal is converted into radio waves at the transmitting end and from radio waves into an electrical signal at the receiving end. Under certain conditions, one of the main requirements is to minimize the size of the antenna while maintaining given specifications, such as gain of the antenna, beamwidth etc, weight and size characteristics of the antennas is particularly acute for artificial satellites, because launching a satellite into orbit has limits on the weight.

1. Theme urgency

Currently, the ability to reduce the weight and size characteristics of antennas are limited by the physical properties of the materials used. The use of metals is due to the need for high electrical conductivity for receiving and emitting radio waves. The efficiency of thin metal antennas is limited by a parameter called skin layer depth, which is the thickness of the material where the high frequency electric current flows with the greatest efficiency [1]. To provide the necessary space for the flow of electric current, the thickness of the material conducting the current must have a certain value that satisfies the depth of the skin layer. Thus, to reduce the weight and size characteristics of antennas, it is necessary to introduce alternative materials with a small depth of the skin layer, such as nanomaterials.

2. Goal and tasks of the research

The purpose of the study is to identify the possibilities of using titanium carbide nanofilms (Ti3C2) in antenna technology as a conductive coating instead of metals.

Main tasks of the research:

3. Review of literature

In 2013 research was shown that the use of graphene in a microstrip antenna significantly degrades its characteristics compared to copper [2]. It was concluded that for most antennas operating in the microwave range, graphene does not provide miniaturization, as for mechanical flexibility or optical transparency, they become irrelevant if some part is made of metal or if the removal of graphene allows for better performance.

Among all the considered two-dimensional materials that are now known, MXene films of titanium carbide have the highest electrical conductivity (up to 5000...10,000 Cm⁄cm) [1], which is higher than other two-dimensional materials known at the moment. This makes the film of titanium carbide is the best candidate for application in antenna technology. Titanium carbide nanofilms are thin layers of material whose thickness ranges from fractions of a nanometer (monatomic layer) to several microns [1]. The existence of this material (MXene) was first stated by specialists of Drexel University.

In research conducted in 2016, a thin film Ti3C2 thickness of 45 microns showed the efficiency of shielding from electromagnetic interference in 92 dB, which is the highest among synthetic materials of comparable thickness produced to date and comparable to the performance of shielding metals [3].

In a 2018 study, researchers at Drexel University created the first flexible MXene dipole antennas with a thickness of 62 nm to 1.4 microns, sprayed on polyethylene terephthalate (PET) sheets, operating in the Wi-Fi and Bluetooth frequency bands [1].

Specialists of Drexel University studied the return loss and radiating properties of the antenna. According to research, titanium carbide nanofilm antennas show good impedance matching of 50 Ohms: for Ti3C2 antennas with thickness from 114 nm to 8 microns, the maximum return loss are from minus 12 to minus 65 dB, respectively [1]. Even when using an MXene antenna with a thickness of 1.4 microns, the return loss was minus 36 dB, which is superior to graphene with a thickness of 12 microns and printed silver ink. The calculated gain of the MXene antenna with a thickness of 1.4 microns was 1.7 dB.

Scientists carried out simulation in the program CST Microwave Studio (MWS). The values of the reflection coefficient S11 obtained from the simulation results with a permissible error coincided with the measured values for all antenna thicknesses. Also, electrodynamic simulation showed the coincidence of the antenna gain at different thicknesses with the calculated values with a small discrepancy.

The mechanical properties of MXene films are not fully understood at the moment, but there are some studies in which the experimentally obtained value of the effective Young modulus is given. It is the Young's modulus that is a kind of quantitative characteristic that allows us to judge the strength of a material. According to the study, the Young modulus of one Ti3C2 layer is 0,33 ± 0,03 TPa [4] (for comparison, the Young modulus of steel is 0.21 TPa).

4. Simulation of dish antenna in CST MWS program

Scientists carried out simulation in the program CST Microwave Studio (MWS). The values of the reflection coefficient S11 obtained from the simulation results with a permissible error coincided with the measured values for all antenna thicknesses. Also, electrodynamic simulation showed the coincidence of the antenna gain at different thicknesses with the calculated values with a small discrepancy.

Due to the large number of electrodynamic modeling software products, it is possible to study antennas created on the basis of Ti3C2 nanofilms without creating prototypes, as well as significant time and financial costs.

At the Department of Radio Engineering and Information Protection, a model of a mirror antenna based on Ti3C2 nanofilm was created in the CST Microwave Studio program. CST MWS is a specialized software tool for fast and accurate three-dimensional modeling of high-frequency problems [5]. Titanium carbide nanofilms are modeled as a material with a surface impedance equal to the sheet resistance [1] and a corresponding thickness. The parabolic reflector of the dish antenna was specified as a Ti3C2 nanomaterial, and the horn irradiator was specified as an ideal electrical conductor (PEC) to simplify and accelerate calculations. The simulation was carried out at a frequency of 3.6 GHz. The thickness of the Ti3C2 sheet was 1.4 microns. A sheet of polyethylene terephthalate was used as a substrate. The model of the mirror antenna is shown in Fig. 1.

Figure 1 — Model of dish antenna based on Ti3C2 nanomaterial in CST Microwave Studio
(animation: 7 frames, 8 cycles of repeating, 108 kilobytes)

The radiation pattern of the dish antenna in 3D and rectangular coordinate system are shown in Fig. 2–3, respectively.

Figure 2 — Radiation pattern of dish antenna based on Ti3C2 nanomaterial in 3D

Figure 3 — Radiation pattern of dish antenna based on Ti3C2 nanomaterial in rectangular coordinate system

Conclusion

Thus, with the help of modeling it was found that the dish antenna designed on the basis of Ti3C2 nanofilm showed an efficiency comparable to traditional metal antennas, the width of the radiation pattern of the simulated antenna coincided with the calculated one. It can be concluded that the use of titanium carbide nanofilms to reduce the weight and size characteristics of antennas is possible and technically feasible. Moreover, such antennas can be flexible and optically transparent, depending on the thickness and material of the substrate.

Work on the study of the properties of titanium carbide nanofilms and the construction of antenna models based on them continues. Full conclusions according this work can be found at the end of writing a master's thesis from the author or supervisor.

References

  1. Asia Sarycheva, Alessia Polemi, Yuqiao Liu, Kapil Dandekar, Babak Anasori, Yury Gogotsi. 2D titanium carbide (MXene) for wireless communication // Science Advances. — 2018. — Vol. 4, No. 9.
  2. J. Perruisseau-Carrier, M. Tamagnone, J. S. Gomez-Diaz, E. Carrasco / Graphene Antennas: Can Integration and Reconfigurability Compensate for the Loss? [Электронный ресурс]. — Режим доступа: https://www.researchgate.net...
  3. Faisal Shahzad, Mohamed Alhabeb, Christine B. Hatter, Babak Anasori, Soon Man Hong, Chong Min Koo, Yury Gogotsi. Electromagnetic interference shielding with 2D transition metal carbides (MXenes) // Science. — 2016. — Vol. 353, No. 6304, P. 1137–1140.
  4. Alexey Lipatov, Haidong Lu, Mohamed Alhabeb, Babak Anasori, Alexei Gruverman, Yuri Gogotsi, Alexander Sinitskii. Elastic properties of 2D Ti3C2Tx MXene monolayers and bilayers // Science Advances. — 2018. — Vol. 4, No. 6.
  5. Курушин, А. А. Школа проектирования СВЧ устройств в CST STUDIO SUITE / А. А. Курушин. — М.: One-Book, 2014. — 433 с.