Printed Closely Spaced Antennas Loaded by Linear Stubs in a MIMO Style for Portable Wireless Electronic Devices

An easy-to-manufacture and efficient four-port-printed Multiple Input Multiple Output (MIMO) antenna operating across an ultra-wideband (UWB) region (2.9–13.6 GHz) is proposed and investigated here. The phenomenon of the polarization diversity is used to improve the isolation between MIMO antenna elements by deploying four orthogonal antenna elements. The proposed printed antenna (40 × 40 × 1.524 mm3) is made compact by optimizing the circular-shaped radiating components via vertical stubs on top of the initial design to maximally reduce unwanted interaction while placing them together in proximity. The measurements of the prototype MIMO antennas corroborate the simulation performance. The findings are compared to the recent relevant works presented in the literature to show that the proposed antenna is suitable for UWB MIMO applications. The proposed printed UWB MIMO antenna could be a good fit for compact portable wireless electronic devices.

Frequency method for measuring the angular coordinates of an underwater vehicle by a hydroacoustic system of local positioning.

The article is devoted to the application of the frequency method of measuring the angular coordinates of underwater vehicles by a positioning system which uses chirp signals. The method is designed to determine the spatial position of an underwater vehicle based on the signals of an installed acoustic beacon and uses measurements of the frequency difference of chirp signals received by two or more spaced antennas with a given spatial position. The experiment demonstrates possibility of the practical application the method for measuring the bearings of a towed or autonomous vehicle. The article presents the results of modeling and field tests of the considered calculating angular coordinate method.

Isolation Improvement between Closely-Spaced Antennas Using EBG

Isolation improvement between two closely spaced antennas using a single column EBG is proposed for compact wireless devices. The proposed design developed for the 2.4 GHz WLAN band achieves more than 17 dB isolation improvement between two planar inverted-F antennas (PIFAs) compared to the no-EBG case. As a result, improved MIMO capacity is also achieved. The proposed design can be scaled up or down in frequency and may be implemented for small devices such as, smart watches, Wi-Fi routers, internet of things (IoT) devices etc.

Experimental researches of the characteristics of antennas in the presence of electromagnetic screens

When placing various antenna systems in a confined space, one has to deal with a complex electromagnetic environment and insufficient isolation between the antennas. And, although the methods of ensuring electromagnetic compatibility of such groups of radio electronic means are well known, taking into account the peculiarities of the objects under consideration, they have very limited application. The use of innovative technologies developing in recent years, including the use of screens made of metamaterials, makes it possible to significantly expand the "limits of applicability" of these methods. As the studies have shown, the screen made of metamaterial has special characteristics in comparison with traditional screens, namely: at the operating frequency of the antenna, the screen is practically permeable to electromagnetic radiation, and at the interference frequency it becomes low-transparent and works as a reflector. The results can be used to improve isolation between closely spaced antennas, such as at the tops of towers or masts.

The All-Sky SignAl Short-Spacing INterferometer (ASSASSIN) – I. Global-sky measurements with the Engineering Development Array-2

ABSTRACT Aiming to fill a crucial gap in our observational knowledge of the early Universe, experiments around the world continue to attempt to verify the claimed detection of the redshifted 21-cm signal from Cosmic Dawn by the EDGES experiment. This sky-averaged or ‘global’ signal from neutral hydrogen should be detectable at low radio frequencies (50–200 MHz), but is difficult to measure due to bright foreground emission and difficulties in reaching the required levels of instrumental-calibration precision. In this paper, we outline our progress toward using a novel new method to measure the global redshifted 21-cm signal. Motivated by the need to use alternative methods with very different systematic errors to EDGES for an independent result, we employ an array of closely spaced antennas to measure the global-sky signal interferometrically, rather than using the conventional approach with a single antenna. We use simulations to demonstrate our newly developed methods and show that, for an idealized instrument, a 21-cm signal could theoretically be extracted from the visibilities of an array of closely spaced dipoles. We verify that our signal-extraction methods work on real data using observations made with a Square-Kilometre-Array-like prototype, the Engineering Development Array-2. Finally, we use the lessons learned in both our simulations and observations to lay out a clear plan for future work, which will ultimately lead to a new global redshifted 21-cm instrument: the All-Sky SignAl Short-Spacing INterferometer (ASSASSIN).

Spatial-phase focusing of matrix simulator radiators at two receiving points

This paper discusses the issues of constructing the configuration of a coherent matrix simulator for modeling echo signals of a two-position system. The condition is formulated in the form of a system of equations that the emitted signals are in-phase at both points of reception. A matrix satisfying this condition provides a simulation of a target in the same position for two spaced antennas. To ensure in-phase operation, it is proposed to use the possibilities of placing the radiators and controlling the initial phases of the signals. Relations are obtained for calculating the coordinates of the 2-point configuration and for calculating the phase addition value. Based on these relations, an algorithm for the synthesis of an extended one-dimensional matrix with the required angular size is developed. It is shown that the points of such a matrix can be located on one straight line. The obtained algorithm was used to synthesize a configuration of seven emitters for the given parameters of the two-position system. Using numerical experiments, the adequacy of the model was verified. Different positions of the point target were set, and a monopulse direction finder model was used to find its direction. The results of numerical experiments confirm the reliability of the theoretical results. They can be used in mathematical and simulation modeling of reflections from real radar targets for two-position systems.

Synthesis of the Radio-navigation Signals Parameters Measured by an Exploded Antenna Elements

Modern GNSS navigation equipment has a significant drawback — low noise immunity. To solve this problem, they are based on phased array antennas using adaptive signal processing algorithms. The final effect of such processing is determined by the level and completeness of using the existing differences, as well as the quality of accounting for each of them, depending on the degree of fame of the statistical characteristics of signals and interference. The article discusses the theory of synthesis of an algorithm for measuring the parameters of radio navigation signals received on spaced antennas under the influence of interference