Asymmetrical dipole antenna based on a phase-correcting dielectric lens

Problem. Modern mobile robotic systems are increasingly used in various fields of human activity. More and more stringent requirements are imposed on them to ensure high throughput, broadband and reliability of data transmission and control channels at the maximum distance from the control center. And what I would like to note separately is the requirement to reduce the cost of such complexes as much as possible. Therefore, the development of technologically advanced, economically feasible antenna systems that provide an increase in the energy potential of the radio channel in the interval of the robotic complex - control point is one of the ways to solve this problem. Formulation of the problem. It is required to develop a mechanically strong, technological antenna, built on the basis of lens structures of various configurations, made of modern dielectric materials, characterized by reduced weight and size characteristics and cost price, which will increase the level of radiated electromagnetic energy in a wide frequency band. Purpose of the article. Present the developed model of an asymmetric dipole antenna and the results of a numerical experiment. Result. The antenna design is made on a metallized round substrate and is a polystyrene cylinder with a funnel-shaped hole, inside which there is an asymmetrical conical vibrator arm. The results of calculations showed that in the frequency band, which is used to organize direct broadband radio communication channels with robotic complexes, the gain varies within 5.5-9 dB, which is superior in this parameter to the commonly used whip antennas. The calculated standing wave ratio confirms the performance of the developed antenna model in a wide frequency band. The impedance response and the Smith-Smith diagram showed a preliminary calculated spread of the input impedance of the antenna from 30 to 95 ohms. Practical significance. The proposed antenna model ensures manufacturability, mechanical strength, and low cost. The full-azimuth radiation mode and increased gain make it possible to predict the possibility of using this antenna as part of the equipment for the data transmission channel and control of robotic complexes such as unmanned aerial vehicles.

The broadband reflectionless filtering and matching circuit operating with high transformation ratio

For matching transformed impedances, various methods are known in the literature that are used reactive, dissipative, and combined circuits. The operation of such circuits is possible either in a wide frequency band, but in the same standard paths, or in a narrow frequency band when matching impedances that differ from each other by a high transformation ratio. Unfortunately, with the help of known methods, it is impossible to matching impedances with a high transformation ratio and simultaneously to operating of the circuit in a wide frequency band. For a reflectionless high-pass filter, the task is to investigate the possibilities of expanding its operating frequencies band when matching impedances have high transformation ratio. For a typical reflectionless high-pass filter, the reflection coefficients of its two equivalent circuits operating in even and odd excitation modes are determined. They are used to find the frequency transmission coefficients for this device, as well as the transfer functions of the complex frequency. It is established that such device has a narrow band of operating frequencies when matching impedances have a high transformation ratio. Possible ways to expand the frequency band by introducing additional electromagnetic coupling to this device are considered. An absorbing filter-transformer with an additional electromagnetic coupling is investigated. The relations for calculating its main elements of the scheme are obtained. It is established that electromagnetic coupling in this device extends the operating frequencies band. Thus, when the magnetic coupling coefficient k tends to 1, this band can be expanded 1 1k2  times. The obtained theo- retical conclusions are fully confirmed by experimental results. The performed studies of reflectionless high-pass filter-transformer confirm the possibility of expanding the operating frequency band when matching impedances have high transformation. The proposed filter-transformer is recommended for use in the design of input matching circuits in power amplifiers using modern GaN transistors, for which broadband reflectionless matching is a necessary condition for eliminating parasitic excitations at low frequencies.

Wideband Metamaterial Absorber Based on Combination of Unit Cells

Metamaterial absorber is an electromagnetic wave absorber made from metamaterial. It basically works in narrow band frequency as it is designed in a particular shape that related to its resonance frequency. However, some applications, e.g., anechoic chamber, require metamaterial absorber that can work in a wide frequency band. This paper discussed the design of wide band metamaterial absorber using the combination of multiple unit cells. The unit cells type was split ring resonator (SRR). SRR had advantages in terms of its simple shape, it could have more than one resonant frequencies depending on the number of its ring, and its shape could be modified easily to obtain the desired resonant frequencies. We designed metamaterial absorber having good absorbtion rate in 2-10 GHz frequency band. To cover this wide frequency band, we used five unit cells which were arranged on a flat plane. Each unit cell had several resonant frequencies. The design was carried out using simulation software of CST (Computer Simulation System). The fabricated design was measured and the results shown that it had an absorbtion rate of 99% in the measured frequency band.

A hairpin DGS resonator for application to microstrip lowpass filters

A hairpin shaped DGS, consisting of two tilted slots with a separation angle, is studied as a unit cell in this contribution. It is further served as a microwave resonator for microstrip lowpass filter applications. Two prototype filters that respectively cascade the same unit cells and the scaled cells with a different scale ratio are analyzed. For demonstration purposes, the two prototype filters are optimally developed, fabricated and examined both from numerical simulations and from experimental validations. Results show the cascaded scaled type demonstrator features a high stopband suppression level within a wide frequency band.