HALF-WAVE DIPOLE WITH AN ACTIVE REFLECTOR BASED ON OPTO-CONTROLLED METAMATERIAL

Author(s):  
Е.А. Ищенко ◽  
Ю.Г. Пастернак ◽  
В.А. Пендюрин ◽  
С.М. Фёдоров

Для обеспечения радиосвязи применяются различные конструкции антенн, которые могут обладать всенаправленными или узконаправленными диаграммами направленности, при этом наибольшей защитой канала связи от помех и от перехвата обладают направленные антенны. Но их недостатком является то, что для обеспечения связи во всех направлениях требуется или установка группы антенн, или использование поворотных платформ, которые ухудшают показатели надежности системы, а также усложняют ее. Поэтому, как правило, для обеспечения связи применяют всенаправленные антенны, которые имеют диаграмму направленности в виде тороида. Недостаткaми таких антенн являются малый коэффициент направленного действия, а также прием большого числа шумов, что усложняет последующую обработку сигналов. Предлагается конструкция дипольной антенны, помещенной в активный метаматериал, с возможностью формирования луча путем коммутации слоев конструкции, что формирует динамически перестраиваемые рефлекторы. Получаемые в процессе функционирования системы диаграммы направленности обладают высокими значениями КНД, а также высокой помехозащищённостью и защитой от перехвата ввиду направленных свойств. Была получена конструкция антенны, помещенная в кубическую структуру активного метаматериала, с возможностью коммутации проводников с использованием pin-диодов или МЭМС-коммутаторов, что позволяет обеспечить быстрое переключение режимов работы устройства, формирование направленного луча и обеспечение помехозащищенной и защищенной от перехвата связи To ensure radio communication, various antenna designs are used, which can have omnidirectional or narrowly directional radiation patterns, while directional antennas have the greatest protection of the communication channel from interference and interception. However, their disadvantage is that to ensure communication in all directions, either the installation of a group of antennas or the use of turntables are required, which degrade the reliability of the system, as well as complicate it. Therefore, as a rule, to provide communication, omnidirectional antennas are used, which have a radiation pattern in the form of a toroid. The disadvantage of such antennas is, as a rule, a small directional coefficient, as well as the reception of a large number of noises, which complicates the subsequent signal processing. In this work, we propose a design of a dipole antenna placed in an active metamaterial with the possibility of forming a beam by switching the layers of the structure, which forms dynamically tunable reflectors. Directional patterns obtained in the course of system operation have high directivity values, as well as high noise immunity and protection against interception due to directional properties. As a result of the study, we obtained an antenna design, placed in a cubic structure of an active metamaterial with the possibility of switching conductors using pin diodes or MEMS switches, which allows for fast switching of device operating modes, formation of a directed beam and providing noise-immune and interception-proof communication

Author(s):  
O. Iohov ◽  
◽  
V. Maliuk ◽  
Ye. Kaplun ◽  
◽  
...  

A method for determining the limits of the maximum size of the stable radio reception area in the UHF / VHF range for mobile radio communication under the conditions of the radio interference system is proposed. The radio is intended to use a directional antenna or screen. Increasing the size of the stable radio reception area is provided by the optimal orientation at each point of the antenna device in azimuth and angle using the model of the radio channel, which allows to calculate the signal / interference ratio taking into account the spatial location of radio interference sources and digital 3D antenna pattern. receiver. The problem of determining the boundaries of the zone of stable radio exchange of mobile radio means using directional antennas in the conditions of real interference is formulated in the form of the problem of finding a single isoline in a scalar field. To determine the coordinates of the points of the map belonging to the isoline, a modification of the wave algorithm is proposed, which is low complexity and unambiguous results. Examples of practical use of the proposed numerical method allow us to conclude that the results are inconsistent with the data obtained in the known works by the analytical method for a particular case. At the same time, the numerical approach used significantly expands the possibilities of calculations by taking into account the location of multiple sources of radio interference at different altitudes, as well as the optimal orientation of the digital 3D - pattern of the antenna device of the signal receiver. The effectiveness of the proposed method is confirmed by increasing the area of the noise-tolerant radio exchange zone by 2.8 times in relation to the option of using a mobile radio with a dipole antenna. For the case of optimal orientation of the directional antenna of the receiver by the azimuth angle, additional optimization by the angle of the place gives a gain of 1.5 times.


2018 ◽  
Vol 10 (4) ◽  
pp. 430-436 ◽  
Author(s):  
Sarin Valiyaveettil Pushpakaran ◽  
Jayakrishnan M. Purushothama ◽  
Manoj Mani ◽  
Aanandan Chandroth ◽  
Mohanan Pezholil ◽  
...  

AbstractA novel idea for generating directional electromagnetic beam using a metamaterial absorber for enhancing radiation from a microwave antenna in the S-band is presented herewith. The metamaterial structure constitutes the well-known stacked dogbone doublet working in the absorption mode. The reflection property of the dogbone metamaterial absorber, for the non-propagating reactive near-field, is utilized for achieving highly enhanced and directional radiation characteristics. The metamaterial absorber converts the high-spatial reactive spectrum in the near-field into propagating low-spatial spectrum resulting in enhanced radiation efficiency and gain. The gain of a printed standard half-wave dipole is enhanced to 10 dBi from 2.3 dBi with highly directional radiation characteristics at resonance.


2021 ◽  
Vol 21 (4) ◽  
pp. 291-298
Author(s):  
Chandana SaiRam ◽  
Damera Vakula ◽  
Mada Chakravarthy

In this paper, a novel compact broadband antenna at UHF frequencies is presented with canonical shapes. Hemispherical, conical and cylindrical shapes have all been considered for antenna configuration. The designed antenna provides an instantaneous frequency range from 370 to 5,000 MHz with omnidirectional characteristics. The antenna was simulated in CST Microwave Studio, fabricated and evaluated; the results are presented. The simulated and measurement results are in good agreement. The antenna has voltage standing wave ratio (VSWR) ≤ 1.9:1 in 400–570 MHz, 2,530–3,740 MHz and 4,180–4,620 MHz; it has VSWR ≤ 3:1 over the operating frequency range 370–5,000 MHz and the measured gain varies from -0.6 to 4.5 dBi over the frequency band. The concept of canonical-shaped antenna elements and the incorporation of triple sleeves resulted in a reduction of the length of the antenna by 62% compared to the length of a half-wave dipole antenna designed at the lowest frequency. The antenna can be used for trans-receiving applications in wireless communication.


Author(s):  
M. K. Nurgaliyev ◽  
A. K. Saymbetov ◽  
B. N. Zholamanov ◽  
A. Т. Yeralkhanova ◽  
G. B. Zhuman

Real-time monitoring systems and sensors are not complete without wireless data transmission modules. Improving energy efficiency requires examining various system parameters that affect the power consumption of transmitting and receiving devices. The most important parameter of any autonomous wireless network is its uptime. In this work, we used LoRa wireless modules on the SX1278 chip manufactured by Semtech to determine their power consumption in various operating modes. The obtained data were used to build a consumption model of the device when connected to a receiver. Three operating modes are considered: transmit mode, receive mode and sleep mode. In an ideal communication channel, all transmitted data reaches the receiver with 100% probability. In a real situation, data reaches the receiver with a certain probability, depending on the communication channel, transmission power, distance to the addressee, and network parameters. In this work, the occurrence of an error is random. In this case, the occurrence of an error during reception entails a lack of confirmation of receipt or a request for re-sending data. Sending data again increases the power consumption of the device and, consequently, decreases the operating time of the wireless device. This paper shows the dependences of the operating time on various initial monitored parameters of the device, such as: confirmation timeout, packet length, time of one transmission cycle and the maximum number of retransmissions in one cycle. The developed model for predicting the consumption of the device can be used in the design of autonomous wireless sensor monitoring networks.


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