Arc Antenna Research Articles

Research on Quasi-isotropic Radiation of Small Circular Arc Antenna

The radiation characteristics of circular arc antennas are studied by applying the method of moments (MoM) to solve the electric field integral equation (EFIE). Based on the triangular current distribution of small circular arc antennas, the analytical expression of radiation fields of circular arc antennas is derived. It is found that the circular arc antenna is equivalent to a superposition of an electric dipole and a magnetic dipole, resulting in near isotropic radiation pattern. Finally, both MoM and CST simulations show that the small arc antenna can realize the near isotropic radiation pattern.

Additive manufacturing of IoT housings with integrated electronics

Additive manufacturing (AM) is an established fabrication method for diverse applications. Due to the versatile manufacturing possibilities, AM provides totally new approaches in designing objects. An emphasis in the field of research was set to the development of unique materials for AM. Among them, conductive filaments were examined for applications in printed electronics. The combination of new materials and the innovative design approach offered by AM generates a comprehensive field of applications. Promising applications can be found on the “Internet of Things (IoT)” sector. The development of connected products includes physical and electronic components. Traditionally, the fabrication process of these products is linear, thus, the design and the fabrication of the physical components is separated from the electronic part. To overcome this separation, an AM approach can be applied in the fabrication of IoT devices. This additive multi-material fabrication approach enables the fabrication of mechanical and electric components in one fabrication process. To prove this fabrication approach, antennas for IoT devices consisting of a supportive element and a antenna element for signal transmission were designed. The antennas were fabricated by material extrusion combining non-conductive and conductive filaments. Two different antennas (patch and arc antenna) were designed focusing on one specific frequencies range: 868 MHz (LoRa). To compare the AM antenna, reference antennas have been fabricated by etching. Antennas were characterized by simulation and measuring the return loss of the fabricated specimen. Finally, the transmission of a payload was tested in a real-world scenario. The tested antennas were able to transmit a payload, however, the return loss differed between the different designs and fabrication approaches. Nevertheless, the additive multi-material fabrication process enables an integrated production approach which led to functional devices. In this sense, electronics and physical components are merged into a truly smart product. Based on the findings, further applications of the hybrid approach will be investigated e.g., signal traces, passive electrical components to further strengthen the extensive application possibilities of additive manufacturing.Graphical abstract

Design and Analysis of High-Capacity MIMO System in Line-of-Sight Communication.

The phase of the channel matrix elements has a significant impact on channel capacity in a mobile multiple-input multiple-output (MIMO) communication system, notably in line-of-sight (LoS) communication. In this paper, the general expression for the phase of the channel matrix at maximum channel capacity is determined. Moreover, the optimal antenna configuration of the 2 × 2 and 3 × 3 transceiver antenna array is realized for LoS communication, providing methods for optimal antenna placement, which can be used in short-range LoS communication and non-scattering environment communication, such as coupling train communication and inter-satellite communication. Simulation results show that the 2 × 2 rectangular antenna array is more suitable for the communication of coupling trains, while the 3 × 3 circular arc antenna array is more suitable for virtual coupling trains according to antenna configurations. Moreover, the 2 × 2 antenna rectangular configuration proposed in this paper has reached the optimal channel in inter-satellite communication, which lays a foundation for the deployment of communication systems.

Design and Development of a Near Isotropic Printed Arc Antenna for Direction of Arrival (DoA) Applications

This research presents an easy to fabricate isotropic printed arc antenna element to be used for direction of arrival (DoA) arrays. The proposed antenna exhibits a total gain variation of 0.5 dB over the entire sphere for 40 MHz impedance bandwidth at 1 GHz, which is the best design isotropy reported in literature so far. In addition, the isotropic bandwidth of the antenna for total gain variation of ≤3 dB is 225 MHz with 86% efficiency. The isotropic wire antenna is first designed and simulated in Numerical Electromagnetic code (NEC). An equivalent printed antenna is then simulated in CST, where single (short circuited) stub is integrated with the antenna for input matching and the results of NEC simulations are verified. The planar antenna is then manufactured using FR4 substrate for measurements. Good agreement between the measured and simulated results is observed, however the total gain variation is increased to 2 dB for the fabricated antenna. This is because of the unavoidable field scattering from the antenna substrate, the feed cables, and the antenna testing platform.

Iterative adaptive approach STAP algorithm based on arc antenna array

The radar with arc antenna array has the advantages of all-orientation space scanning, simultaneous estimation of pitch-azimuth angle and good antenna pattern. However, due to the special geometry of the antenna, the echoes from different range cells are not independently and identically distributed (IID) samples, resulting in performance degradation in space-time adaptive processing technology. In this paper, the model of airborne radar with arc antenna array is established, and the clutter distribution is analyzed. The conclusion is that the nonlinear variation of spatial angular frequency with array element number results in the non-uniform clutter distribution in different range cells. Therefore, the traditional space-time adaptive processing is not fit for the target detection of arc array radar. Hence, the arc array-based iterative adaptive approach (IAA) algorithm is studied. The IAA algorithm is utilized to estimate the space-time spectrum, which can distinguish clutter and targets. Simulation experiments verify the effectiveness of the IAA algorithm in arc array radar.

Selection of Parameters of the Primary Feed of the Luneberg Lens for the Sum–Difference Operating Mode

Excitation of the Luneberg lens by an arc antenna array of open-ended rectangular waveguides forming the H10 wave is studied. Technical limitations imposed on the array of primary feeds in order to form the sum and difference operating modes of the antenna system are discussed.

Investigation of Wavenumber Domain Imaging Algorithm for Ground-Based Arc Array SAR

Ground-based synthetic aperture radar (GB-SAR) has become an important technique for remote sensing deformation monitoring. However, most of the existing GB-SAR systems realize synthetic aperture by exploiting two closely spaced horn antennas to move along a linear rail. In order to obtain higher data acquisition efficiency and a wider view angle, we introduce arc antenna array technology into the GB-SAR system, which realizes a novel kind of system: ground-based arc array SAR (GB-AA-SAR). In this paper, we analyze arc observation geometry and derive analytic expressions of sampling criteria. Then, we propose a novel wavenumber domain imaging algorithm for GB-AA-SAR, which can achieve high image reconstruction precision through numerical solutions in the wavenumber domain. The proposed algorithm can be applied in wide azimuth view angle scenarios, and the problem of azimuth mismatch caused by distance approximation in arc geometric efficient omega-k imaging can be solved successfully. Finally, we analyze the two-dimensional (2D) spatial resolution of GB-AA-SAR, and verify the effectiveness of the proposed algorithm through numerical simulation experiments.

Ultra-Wideband Monostatic Antenna for behind the Wall Detection

<span>This article introduces an ultra-wideband (UWB) shifted arc antenna, designed using Rogers RT-5880 Duroid substrate for the human detection behind the wall. The frequency for this proposed antenna ranges from 2.8 - 15.6 GHz with the gain of around 6.05 dB. A high gain for antenna has been achieved by the implementation of defected ground structure (DGS) method to make it a suitable configuration for through wall detection applications. For the verification of through wall detection configuration, a simulation-based experiment using ground penetrating radar (GPR) technology has been conducted. The results showed that proposed single antenna can act as a monostatic transceiver in order to detect human skin behind the concrete wall. Later, the reflections received from the target have been analyzed to detect and identify the antenna, wall and target for distance calculation.</span>

Synthesis of Phased Cylindrical Arc Antenna Arrays

This paper describes a new approach to synthesize cylindrical antenna arrays controlled by the phase excitation, to synthesize directive lobe and multilobe patterns with steered zero. The proposed method is based on iterative minimization of a function that incorporates constraints imposed in each direction. An 8-element cylindrical antenna has been simulated and tested for various types of beam configurations.

Placing Quasi-Nulls in Planar and Conformal Arrays

ABSTRACT We describe the use of the simulated annealing optimization method to introduce minimal modifications in the excitations and/or geometries of planar and circular arc antenna arrays so as to depress the radiation pattern in arbitrary directions while maintaining side lobe levels and beamwidth.

A Study of Centre-fed Antiphase Circular Antennas in a Warm Plasma

The radiation characteristics of a centre-fed antiphase circular arc antenna immersed in a warm electron plasma are studied using linearized hydrodynamic theory. The effects of antenna and plasma parameters on the radiation properties have been studied by computing the results and presenting them graphically. It is found that, whereas the power radiated in the TEM mode depends on the length as well as on the angle of the arc antenna, the power in the LP mode is independent of the angle and depends only on the length of the arc. It is also found that the power in the LP mode is relatively much larger in the case of small angled centre-fed antiphase arc antennas. Hence small angled arcs should be suitable for the launching of plasma waves, whereas large angled arcs will be more useful for communication through a plasma medium.

Travelling wave arc antenna in a warm plasma

Analytical expressions are developed for the far-zone field and the radiation resistance of an arbitrary travelling wave arc antenna embedded in a compressible plasma. These give the effects of different antenna parameters, as well as of plasma frequency, on the radiation properties. From the graphical presentation of the results, it is concluded that small angled arc antennas give better results in the plasma regions of frequencies comparable to that of the operation frequency of the antenna, while large angled arc and loop antennas are found to be more useful in the low-frequency plasma regions. The power radiated in the plasma mode by an arc antenna is found to depend on its length, but for a given length it is practically independent of its shape.

Radiation Properties of Arc Antennas in a Warm Plasma

General expressions for the radiation properties of centre-fed standing wave circular arc antennas in a compressible electron plasma are derived in terms of the plasma and antenna parameters. The effects of these parameters on the antenna radiation characteristics are evaluated numerically and shown graphically for quarter-, semi- and three-quarter-circular arc and loop antennas. It is observed that the radiation properties depend ignificantly on the plasma frequency. For a given antenna size and plasma frequency, the power radiated in the electromagnetic mode decreases with increasing antenna curvature, while that radiated in the plasma mode remains almost independent of the antenna's shape. The radiation efficiency of an arc antenna thus decreases with increasing curvature.

Radiation from a Continuous Semi-circular Arc Antenna Array

The nature of radiation from a continuous semi-circular arc antenna array has been theoretically studied. The pattern expressions are made to appear in closed mathematical forms by making use of an analysis analogous to one presented elsewhere by the authors in connection with spiral antenna arrays. The vertical radiation patterns have been numerically computed and graphically discussed.

Radiation From Circular Arc Antenna Arrays

The properties of radiation from circular arc antennas are discussed by using an asymptotic expansion method. Approximate pattern calculations of these antennas have usually been made by employing related techniques, such as the method of stationary phase. However, the stationary phase method has certain limitations, and it is not as accurate as the method presented here. The asymptotic expansion gives relatively accurate results when the radius of the arc source is large with respect to the wavelength. This requirement is usually satisfied if the antenna is to have a high directivity. The asymptotic expansion converges rapidly for observation angles away from the broadside direction, so that it is easy to determine the sidelobe energy distribution. The results given here can easily be applied to circular arc arrays with either uniform or nonuniform spacings of the elements along the arc by applying the Poisson sum formula. This is true because the resulting integrals governing the radiation fields from a circular arc array are similar to the ones discussed here.