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American Journal of Public Health Research
DOI: 10.12691/ajphr-1-1-3

The Implementation of a Tele-Homecare System with Service Oriented Architecture and HL7 Message Transmission Standard
Ching-Sung Wang

American Journal of Medical and Biological Research
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The Influence of Ethanol on Pyruvate Kinases Activity in Vivo, in Vitro, in Silico
Lelevich Sergey Vladimirovich, Khrustalev Vladislav Victorovich, Barkovsky Eugene Victorovich, Shedogubova Tatyana Aleksandrovna

American Journal of Medical Sciences and Medicine
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Clinical and Histological Features in Wegener Granulomatosis
Li Cavoli Gioacchino, Passantino Rita, Bono Luisa, Tortorici Calogera, Ferrantelli Angelo, Giammarresi Carlo, Rotolo Ugo

American Journal of Infectious Diseases and Microbiology
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The Curse of Lymphatic Filariasis: Would the Continual Use of Diethylcarbamazine Eliminate this Scourge in Papua New Guinea?
Anne Lanham, Lillian Mwanri

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Switched Beam through Parasatic Antenna Array for Radio Direction Finding Using I/Q Samples

Ahmed Siddig Ibrahim Mustafa, Mohammed Almoiz Abd-Almoniem Mohammed, Nassrin Ibrahim Mohamed Elamin*

Department of Electrical and Electronic Engineering (Telecommunication), Faculty of Engineering, International University of Africa, Khartoum, Sudan

Abstract: An electronically controlled parasitic antenna array consisting of one active element connected to a software defined radio (SDR) receiver and four passive parasitic elements used to design and construct affordable radio direction finding system. The directivity of the antenna array achieved by increasing/degreasing the electrical length of the parasitic elements. The design based on a central active monopole and an array of four parasitic monopoles equidistantly from the central element by 0.20 λ, placed on ground plane to provide the 360 degree azimuthal coverage without any moving parts, provides excellent directional resolution. The system is controlled by using Arduino to switch between regions (0-90),(90-180),(180-270) or (270-360) and analysed by using a newly developed method based on I/Q samples to extract the amplitude and phase of the desired signal to find the exact direction in that region. The antenna design, its application to determine the direction finding, the new algorithm are presented below.

Keywords: RDF, AoA, parasitic monopoles

Received September 12, 2018; Revised October 28, 2018; Accepted November 13, 2018

Citation: Ahmed Siddig Ibrahim Mustafa, Mohammed Almoiz Abd-Almoniem Mohammed, Nassrin Ibrahim Mohamed Elamin, Switched Beam through Parasatic Antenna Array for Radio Direction Finding Using I/Q Samples. American Journal of Electrical and Electronic Engineering, 6 (3). 90-92. January 2018. doi:10.12691/ajeee-6-3-3

1. Introduction

This paper presents a new method of determination of an angle of arrival (AoA) and hence radio signal direction finder (RDF) by using electronic beam steering of an antenna array system based on one active element and four switched parasitic elements.

The antenna system is a circular array of quarter wavelength dipoles, with four parasitic elements positioned equidistantly, surrounding one active central element. All parasitic elements are assumed to be electronically switched between short-circuit by inductor termination or open circuit by capacitor termination states to change their resonant length.

This technique allows the short-circuited parasitic elements to act as a reflector, whereas other parasitic elements act as directors when they are open-circuited.

For and for most, the direction of maximum gain is being controlled by open - and short-circuiting the relative parasitic elements with respect to the four quarters of the circular antenna, a set of radiation patterns is formed covering the horizontal plane at 0°, 90°, 180°, and/or 270°.

Furthermore a new algorithm is developed using amalgamation of a SDR#, Matlab and Visual Studio to extract the exact direction of the signal (AoA) by analyzing the stored I/Q data.

2. Methodology

A steel plate, one meter in diameter, reinforced by rectangular frame of wood, as shown in Figure 1 below, as ground plane where the five monopoles antenna elements that with magnetic base are placed and the Cartesian coordinates is being marked where the active element at the origin and ANT 1 and ANT 3 represent the Y-axis and ANT 2 and ANT 4 represent the X-axis and ANT 1 and ANT 2 represent the first quarter and ANT 3 and ANT 4 represent the fourth quarter. The gain of the antennas is equal to 2.15dBi.

Figure 1. The RDF setup

The electronic antenna switching system is done by eight relays that are controlled by Arduino and ULN 2803 IC as a relay driver.

HackRF One, software defined radio, and SDR# driver represent the receiving unit used for the DF setup to capture and store the I/Q, in phase/ quadrature, signal of concern where by using Matlab amalgamated with Visual Studio is being processed and analyzed to determine the (AoA).

3. Results and Discussions

The following results are obtained using SDR# software as the switching action was done manually:

Figure 2. Signal strength when the transmitter facing the opposite side of the parasitic element that is shorted by inductor

Figure 3. Figure Signal strength when the transmitter facing the parasitic element shorted by inductor

Figure 4. Signal strength when the transmitter facing the left parasitic element shorted by capacitor

Figure 5. Signal strength when the transmitter facing the right parasitic element shorted by capacitor

Figure 6. RDF interface and signals amplitude

Figure 7. Direction of the captured signal

4. Conclusion

The switching of the beam was achieved through the termination of parasitic elements by capacitors and an inductor combination and from the maximum signal strength the direction of the target was established using the captured I/Q samples.

5. Future Work

One of the most important we’ll do is using the raspberry pi 3 with the RDF setup and run the pi 3 as a server in order to get the data from anywhere we are in without any physical connection to the computer.

It is also very important to increase the number of parasitic elements in order to narrow down the region of target thus increasing the accuracy.

References

[1]   | Radiomonitoring and Radiolocating catalog 2007/2008 ROHDE & SCHWARZ.
[2]   | Makoto Taromaru and Takashi Ohira, “electronically steerable parasitic array radiator antenna”.
[3]   | Albert A. Lysko and Mofolo Mofolo, “Influence of a Realistic Loading on Characteristics and Design of ESPAR”, University of Johannesburg.
[4]   | How to capture raw IQ data from a RTL-SDR dongle and FM demodulate with MATLAB. [online] Available at: http://aaronscher.com/wireless_com_SDR/RTL_SDR_AM_spectrum_demod.html.
[5]   | Paul Denisowski, “An Introduction to Radio Direction Finding Methodologies”.
[6]   | Thiel, David, Preston, S., “Direction Finding Using a Switched Parasitic Antenna Array”, Griffith university, 1997.
[7]   | Mofolo Mofolo, Albert Lysko and Willem Clarke, “A Method of Electronic Beam Steering for Circular Switched Parasitic Dipole Arrays”, University of Johannesburg.