APPLICATION OF PLASMA ANTENNA TECHNOLOGY TO IMPROVE RADIO COMMUNICATION STEALTH IN VHF BAND

Рассматривается плазменная вибраторная антенна, которая предназначена для работы в VHF диапазоне на частоте 140 МГц. Вибраторные плазменные антенны отличаются от обычных вибраторных антенн тем, что металлический проводник заменяется плазмой в газоразрядной трубке. Плазменный вибратор, создаваемый разрядом в трубке, способен включаться и выключаться за время порядка микросекунд. Применение плазменной антенны позволяет обеспечить два режима работы: активный, когда плазма индуцирует проводящую поверхность, и скрытый, когда антенна становится практически невидимой для электромагнитных волн, а плазменное облако отсутствует. Для определения характеристик антенны использовалось электродинамическое моделирование. Полученные результаты показывают, что характеристики плазменной вибраторной антенны близки к характеристикам эквивалентного ей металлического диполя, при этом длина плазменной антенны меньше. Для определения эффективности скрытного режима антенны производилось сравнение характеристик эффективной площади рассеяния плазменной антенны с выключенным плазменным облаком и эквивалентного металлического диполя. Полученные результаты показывают, что плазменная антенна обладает высокой эффективностью излучения, диаграммами направленности, схожими с эквивалентной дипольной антенной, и значительно меньшими значениями эффективной площади рассеяния (ЭПР) в выключенном режиме The article discusses a plasma dipole antenna, which is designed to operate in the VHF band at a frequency of 140 MHz. Plasma dipole antennas differ from conventional dipole antennas in that the metal conductor is replaced by plasma in the discharge tube. The plasma dipole created by the discharge in the tube is capable of turning on and off in times of the order of microseconds. The use of a plasma antenna makes it possible to provide two modes of operation: active, when the plasma induces a conductive surface, and hidden, when the antenna becomes practically invisible to electromagnetic waves, and the plasma cloud is absent. We used electrodynamic modeling to determine the characteristics of the antenna. The results show that the characteristics of the plasma dipole antenna are close to those of the equivalent metal dipole, while the length of the plasma antenna is shorter. To determine the efficiency of the hidden mode of the antenna, we compared the characteristics of radar cross-section of the plasma antenna with the plasma cloud turned off and the equivalent metal dipole. The results obtained show that the plasma antenna has a high radiation efficiency, directional patterns similar to an equivalent dipole antenna, and significantly lower RCS values in the off mode

Radio Network Forensic with mmWave Using the Dominant Path Algorithm

For the last two decades, cybercrimes are growing on a daily basis. To track down cybercrimes and radio network crimes, digital forensic for radio networks provides foundations. The data transfer rate for the next-generation wireless networks would be much greater than today’s network in the coming years. The fifth-generation wireless systems are considering bands beyond 6 GHz. The network design of the next-generation wireless systems depends on propagation characteristics, frequency reuse, and bandwidth variation. This article declares the channel’s propagation characteristics of both line of sight (LoS) and non-LOS (NLoS) to construct and detect the path of rays coming from anomalies. The simulations were carried out to investigate the diffraction loss (DL) and frequency drop (FD). Indoor and outdoor measurements were taken with the omnidirectional circular dipole antenna with a transmitting frequency of 28 GHz and 60 GHz to compare the two bands of the 5th generation. Millimeter-wave communication comes with a higher constraint for implementing and deploying higher losses, low diffractions, and low signal penetrations for the mentioned two bands. For outdoor, a MATLAB built-in 3D ray tracing algorithm is used while for an indoor office environment, an in-house algorithmic simulator built using MATLAB is used to analyze the channel characteristics.

Battery-Free Shape Memory Alloy Antennas for Detection and Recording of Peak Temperature Activity

Economical sensing and recording of temperatures are important for monitoring the supply chain. Existing approaches measure the entire temperature profile over time using electronic devices running on a battery. This paper presents a simple, intelligent, battery-free solution for capturing key temperature events using the natural thermo-mechanical state of a Shape Memory Alloy (SMA). This approach utilizes the temperature-induced irreversible mechanical deformation of the SMA as a natural way to capture the temperature history without the need for electronic data logging. In this article, two-way SMA is used to record both high-temperature and low-temperature peak events. Precise thermo-mechanically trained SMA are employed as arms of the dipole antenna for Radio Frequency (RF) readout. The fabricated antenna sensor works at 1 GHz and achieves a sensitivity of 0.24 dB/°C and −0.16 dB/°C for recording temperature maxima and minima, respectively.