Frequency Scanning Antenna Research Articles

A series‐fed frequency scanning antenna for millimeter wave wireless communication

AbstractIn the realms of 5G and the upcoming 6G communications, the millimeter‐wave bands offer substantially greater bandwidth. However, due to their propagation characteristics, aligning antennas becomes a challenging issue, particularly at the node side in industrial and vehicular network applications. Angle‐scanning antennas can significantly enhance communication reliability or provide new possibilities for spatial multiplexing. Previous studies have predominantly concentrated on frequency‐scanning antennas characterized by either low‐gain individual units or expensive digital arrays. Consequently, there has been a scarcity of solutions that are both cost‐effective and high‐gain. In this study, a method is proposed for achieving frequency scanning by extending the feed lines between elements. Based on this approach, a millimeter‐wave high‐gain serial‐feed frequency‐scanning antenna is developed. This antenna operates within the 60–64 GHz millimeter‐wave ISM (Industrial, Scientific, and Medical) band and is capable of performing a 10 scan in the E‐plane. Moreover, the antenna maintains a width of less than half a wavelength, allowing for the assembly of multiple antennas into a MIMO array.

Robust textile-based spoof plasmonic frequency scanning antenna for on-body IoT applications

Robust textile-based spoof plasmonic frequency scanning antenna for on-body IoT applications

Millimeter‐wave end‐fire dual‐polarized frequency scanning antenna using LTCC technology

AbstractThis letter proposes a millimeter‐wave dual‐polarized (DP) end‐fire frequency scanning antenna utilizing low temperature co‐fired ceramic (LTCC) technology. The antenna features DP radiating elements, each comprising a quasi‐Yagi antenna for horizontal polarization (H‐pol) and a pyramidal horn antenna for vertical polarization (V‐pol). These elements are excited via a mode‐composited transmission line (MCTL), integrating substrate integrated coaxial line (TEM mode) with substrate integrated waveguide (TE10 mode). To mitigate phase imbalances between polarizations during beam scanning, a delay line is embedded in each quasi‐Yagi element, ensuring consistent scanning ranges for the two polarizations. Furthermore, the implementation of amplitude weighting in the feeding networks contributes to the enhancement of antenna efficiency. A 1 × 8‐element prototype was fabricated and its performance is assessed. The results show closely matched beam scanning ranges for the two polarizations (±28° for H‐pol and −30° to +34° for V‐pol) across the 26–29 GHz frequency band, with a measured maximum peak gain exceeding 9.2 dBi for both polarizations. The proposed design emerges as a promising candidate for compact mmW frequency scanning front‐end antenna systems.

A Dual-Mode FMCW-Doppler Radar With a Frequency Scanning Antenna for River Imaging Applications

A Dual-Mode FMCW-Doppler Radar With a Frequency Scanning Antenna for River Imaging Applications

A SISO FMCW radar based on inherently frequency scanning antennas for 2-D indoor tracking of multiple subjects

The contextual non-invasive monitoring and tracking of multiple human targets for health and surveillance purposes is an increasingly investigated application. Radars are good candidates, since they are able to remotely monitor people without raising privacy concerns. However, radar systems are typically based on complex architectures involving multiple channels and antennas, such as multiple-input and multiple-output (MIMO) or electronic beam scanning, resulting also in a high power consumption. In contrast with existing technologies, this paper proposes a single-input and single-output (SISO) frequency-modulated continuous wave (FMCW) radar in combination with frequency scanning antennas for tracking multiple subjects in indoor environments. A data processing method is also presented for angular separation and clutter removal. The system was successfully tested in five realistic indoor scenarios involving paired subjects, which were either static or moving along predefined paths varying their range and angular position. In all scenarios, the radar was able to track the targets, reporting a maximum mean absolute error (MAE) of 20 cm and 5.64^circ in range and angle, respectively. Practical applications arise for ambient assisted living, telemedicine, smart building applications and surveillance.

Broadband large-angle beam scanning with dynamic spin energy distribution based on liquid crystal cascaded bilayer metasurface

Abstract Dynamic manipulation of terahertz (THz) beams plays an important role in THz application systems. The PB metasurface provides an effective scheme for space separation and deflection of the spin beam. However, mirror symmetry locking of the conjugated spin states severely limits the versatility of the device. In this work, we demonstrate a liquid crystal (LC) cascaded bilayer metasurface that includes an LC layer, anisotropic metasurface, and PB metasurface. By controlling anisotropy and polarization conversion effects, dynamic spin asymmetric transmission is realized. Meanwhile, two different dynamic energy distribution processes are realized between the L and R state with the corresponding deflection side. The results show that the device achieves a large angular spatial dispersion within the frequency-angle scanning range of ±35° to ±75° corresponding to the broadband range of 0.6–1.1 THz. Moreover, it achieves a spin beam spatial separation with a maximum proportion of energy distribution greater than 26 dB, and the active modulation rate in the energy distribution process reaches 98 %. This work provides a dynamic THz spin conversion and efficient large-angle beam scanning, with important potentials in wavelength/polarization division multiplexing and frequency-scanning antenna for large-capacity THz wireless communication, radar, and imaging systems.

Spoof Surface Plasmon Polariton Based Frequency Scanning Antennas

Frequency scanning antennas realized by loading the radiating elements on both sides of the microstrip, asymmetrically corrugated spoof surface plasmon polariton (SSPP), and symmetrically corrugated SSPP transmission lines are discussed in this paper. Both traveling and standing wave antennas are considered and performance in terms of S-parameters, radiation pattern, scan range, and gain is reported. Additionally, the crosstalk between two transmission lines is observed in all cases. Based on the analysis, it was proved that the crosstalk was minimum in the case of symmetrically corrugated SSPP transmission lines. The proven advantages of the SSPP lines find better signal integrity, high gain, and wide-angle scan frequency scanning antennas.

2-D Localization System for Mobile IoT Devices Using a Single Wi-Fi Access Point With a Passive Frequency-Scanned Antenna

A novel two-dimensional indoor location system for IoT devices employing a single Wi-Fi Access Point is presented. The x, y position is estimated with a combination of Directionof-Arrival (DoA) and Time-of-Flight (ToF) algorithms. The azimuthal DoA is estimated using a modified MUSIC technique, which requires the acquisition of the Received Signal Strength Indicator (RSSI) using different Wi-Fi frequency channels in the 2.4 GHz band, together with a dual-port frequency-scanning antenna (FSA). This allows a wide Field-of-View (FoV) of 180: for the DoA. To estimate the ranging distance, an algorithm based in the 802.11mc Fine Time Measurement (FTM) protocol is employed to consider the effects of the channel hopping. Therefore, the proposed system does not rely on Channel State Information (CSI) or complex IQ information, which is not available in commercial Wi-Fi APs. The proposed system has been fully implemented with a commercial Wi-Fi AP and tested in a practical scenario, proving a root-mean-square error (RMSE) when estimating the localization of mobile devices of only 1.43m, in a wide area of 12 m x 12 m.

Design of Leaky-Wave Antenna With Wide-Angle Backfire-to-Forward Beam Scanning Based on Generalized Pattern Synthesis

Frequency-scanning antenna has been extensively explored in radar and vehicle communication systems, but it is a challenge to provide methodological guidance to achieve a wide scanning angle. Here, a generalized pattern synthesis method is proposed and a leaky-wave antenna with wide scanning range is designed to verify the technique. First, a generalized antenna element (GAE) is presented, whose main beam can steer continuously with frequency. Meanwhile, the phase constant of the leaky wave determines the beam direction of the array factor. Then, a leaky-wave antenna can steer with a large beam scanning angle and stable gain as patterns of the array factor and the GAE are manipulated simultaneously. To verify, a prototype SIW LWA with double-layer transverse slots is fabricated and measured. Experimental results show this antenna achieves continuous dual-beam scanning from backfire (-90∘) to forward (±20∘) from 12.4 GHz to 19.9 GHz with a total coverage range of 220∘ and the realized gain varying from 8.3 dBi to 12.8 dBi.

Dual-Polarized Shared-Aperture Frequency-Scanning CTS Antenna with Wide Angle

A dual-polarized (DP) shared-aperture frequency-scanning continuous transverse stub (CTS) antenna with wide scanning range is presented in this paper. In order to mitigate the open stopband and realize continuous beam-scanning including broadside, a novel “L”-type CTS radiation element is proposed. An equivalent circuit model is established to analyze the input impedance and reflection coefficient of the proposed CTS element by using the transmission line theory. The antenna array consists of an orthogonally arranged shared-aperture DP-CTS radiation array and the corresponding linear source generators (LSGs). The amplitude tapering of Taylor distribution is applied to suppress the sidelobe level (SLL). A metallic LSG is designed to reduce the transmission loss with a tapered feeding probe being adopted to broaden the bandwidth. A 12-element prototype is simulated and fabricated. A reasonable agreement between simulation and measurement is achieved. Experimental results show that the DP antenna has an impedance bandwidth of 8 ∼ 14 GHz and a port isolation higher than 21 dB. The scanning ranges for both polarizations are from −73° to 20° with a maximum gain of 23.9 dBi and a SLL lower than −16.6 dB. The proposed DP-CTS frequency-scanning antenna could be applied in radar detection systems.

ANTENNA AND ANTENNA ARRAY: A REVIEW PAPER

This paper is a review article on antenna and antenna array. The types of antennas discussed in this paper are linear, planar, frequency scanning, and microstrip patch antenna arrays. Along with these types of antennas, we also discuss various beamforming techniques, such as analog, digital, and hybrid beamforming techniques. We review several previously published studies on antenna and array designs related to beamforming, in which we discuss the methods adapted, findings obtained, types of materials used, and application areas intended for the designs. Beamforming techniques such as phase shifter selection, simultaneous wireless information and power transfer, hybrid beamforming, hybrid beamforming with orthogonal frequency division multiplexing and distributed antenna systems, and multiple input/multiple output systems are reviewed. Finally, a comparison table of the different types of antennas reviewed is presented.

A Planar SIW-Based Mm-Wave Frequency-Scanning Slot Antenna Array With No Scan Blindness at Normal

Planar antenna reflectors are the modern design trend of both multibeam and frequency-scanning antenna arrays. The planar implementation of reflectors is typically performed using substrate-integrated waveguide (SIW) technology. A reflector’s profile can be different from the canonical one (parabolic, elliptic, hyperbolic, etc.) because of the effect of spatial dispersion of the reflection coefficient of the SIW-based surface. It should be synthesized considering the magnitude and argument of the field reflected from such a surface to maximize the efficiency of the reflection. In this article, we present a planar millimeter-wave (mm-wave) slot antenna array with SIW-based horn–reflector feeding. We analytically formulate the optimization of the SIW surface dimensions while accounting for the spatial dispersion of the reflection coefficient. We minimize the dimensions of the planar horn–reflector feeding. Finally, we demonstrate that using a dual-slot radiating element, and we can avoid the effects of scan blindness along the normal direction. A prototype has been built and a good agreement has been achieved between the measured results and the predicted results based on calculations. The prototype achieved ±17° beam scanning within 16% of the operational frequency range, with no scan blindness along the normal direction.

General Approaches to Solving Problems of Analysis and Synthesis of Directional Properties of Antenna Arrays

The work carried out the calculation and synthesis of antenna arrays used in radio-electronic complexes on unmanned aerial vehicles. The analytical model is designed to find asymptotic estimates of the polarization components of the electric field of the grating in the far zone of the carrier surface; the results obtained with its use are the initial data for constructing a technique for the numerical solution of a boundary value problem for a grating on a carrier surface in the CST MWS electrodynamic simulation environment. The synthesis of gratings with the maximum achievable coefficient of directional action is carried out with the control of radiation patterns at a given set of angles. A two-mirror antenna system has been calculated. It is shown that with an increase in the number of re-reflections taken into account, the convergence of the result for the calculated characteristics of the antenna is observed. To test the proposed method, the same antenna was calculated using the integral equation method. The comparison showed a high degree of agreement between the results obtained by two different methods. The results of the simulation based on a software algorithm designed to quantify the input matching at the input of a multichannel frequency-scanning antenna array power divider are presented. It was found that when performing wide-angle scanning in a relative frequency band of more than a few percent, the disadvantage of the known method for eliminating the normal effect is a sharp deterioration in matching in the lower and upper frequencies of the operating range. A new method is proposed based on an automated iterative process of optimizing the divider geometry, which makes it possible to obtain an acceptable match over the entire operating frequency band. The feasibility of switching from a serial power divider construction scheme to a series-parallel scheme is analyzed for wide-angle scanning in a relative frequency band of about 5%.

Rectangular Waveguide-Fed Surface-Wave Frequency-Scanning Antenna Utilizing Wavevector Mismatch

In this letter, we propose a design of rectangular waveguide-fed surface-wave frequency-scanning antenna utilizing the principle of wavevector mismatch. First, the transition from a side-fed rectangular waveguide mode to spoof surface plasmon polariton (SSPP) is achieved. Then the SSPP propagating on the metal-dielectric interface is modulated through wavevector mismatching that induces the SSPP to spatial radiating wave conversion. Theoretical deduction proves the frequency scanning nature of the generated radiating beam. Phase gradient metasurface (PGM) is used to realize the wavevector engineering that causes artificial wavevector mismatch. Simulated and experimental results, agreeing well with each other, showed that the antenna can realize beam scanning from −8° to 11.6° across 6.8 to 7 GHz, with realized gain varying from 5 to 5.98 dBi.

Fully Metallic Glide-Symmetric Leaky-Wave Antenna at Kₐ-Band With Lens-Augmented Scanning

A fully metallic leaky-wave antenna (LWA) with enhanced scanning rate is presented. The leaky waveguide is implemented in groove gap waveguide technology and is periodically loaded to produce backward radiation. Furthermore, glide-symmetric pins are placed inside the leaky waveguide to increase the dispersion. A parallel-plate waveguide metasurface prism lens is used to disperse the backward radiation and increase the scanning rate of the LWA. The designed antenna can steer the radiation from −26° to 26° from 27 to 35 GHz, and an average total efficiency of 74% is achieved. A prototype of the designed antenna is manufactured, and measurements corroborate the simulated results. The proposed concept is applicable to other frequency-scanning antennas and can be used to increase the scanning rate in radar and imaging systems.

A dual-band frequency scanning antenna based on spoof SPPs transmission line

In this paper, a dual-band frequency scanning antenna based on spoof SPPs transmission line was proposed. The effect of each parameter in the rectangular holes of spoof SPPs on the dispersion characteristics and the frequency band of the spoof SPPs transmission line application was analyzed. The results show that the depths of rectangular hole have a large effect on the cut-off frequency, and etching two rectangular holes of different depths in a metal strip can generate standing waves in the transmission line. Based on this structure, a dual-band frequency scanning antenna was designed by combining magnetic coupling with the principle of leakage radiation. Loading two sets of circular patches of different sizes on both sides of the spoof SPPs transmission line achieved a dual-band frequency sweep of 90° – 196 ° in the 4–9 GHz and 126°–192° in the 16–32 GHz, with sweep angles of 106° and 66°. The antenna achieved a gain of 10–12 dBi in the operating band with an average radiation efficiency about 90%. The antenna was subjected to processing and testing, and the experimental results verified the good frequency scanning characteristics. The antenna proposed has a great potential for use in planar integrated communication systems and fifth-generation wireless communication system.

Triple‐mode resonant null frequency scanning antenna with positive scanned slope

A novel design approach to triple-mode resonant null frequency scanning antenna (NFSA) with positive scanned slope is proposed. Firstly, a circular sector patch radiator with short-circuited circumference is introduced to generate multiple TM0m (m = 1, 2, …) mode resonances. Then, as theoretically predicted and numerically proved, the first three TM0m (m = 1, 2, 3) modes can be effectively combined to yield null frequency scanning functionality with positive scanned slopes. Next, a prototype antenna is designed, fabricated, and measured. As numerically demonstrated and experimentally validated, the proposed NFSA can exhibit a null frequency scanning functionality in xz-plane with positive scanned slope ranging from θ = −90° to +45° (for null depth smaller than −10 dB) within a fractional impedance bandwidth of about 34.3% (i.e., 2.97‑4.20 GHz).

Polarization-Flexible and Frequency-Scanning Leaky-Wave HMSIW Antenna for Vehicular Applications

To achieve multifunctional communication and safe driving of a vehicle, a half-mode substrate-integrated waveguide (HMSIW) leaky-wave frequency-scanning antenna with flexible polarization is proposed in this article. It includes two linearly polarized interdigital slot antennas, a compact directional coupler, and microstrip transition lines. It can generate either linear polarization (LP) for base station communication or circular polarization (CP) for satellite navigation by configuring the means of excitation. Its radiation beam can be continuously steered with varying frequency in either the LP or the CP state, which is of benefit to safe vehicular driving. In addition, the use of the HMSIW structure reduces the size of the antenna by almost one-half in comparison with the full SIW structure. Measurements were performed on antenna scattering parameters, radiation patterns, gain, and axial ratio (for CP states); the results show good agreement with the simulated results. With its low profile, low weight, low cost, and capability for continuous frequency scanning and variable polarization states, the multifunctional antenna could be extensively used for adapting to changes in environmental conditions or system requirements.

High gain frequency scanning antenna using dumbbell‐shaped inclined slots and parallel plate waveguide polariser

A high gain vertically polarised travelling-wave frequency scanning array antenna fed by a meander rectangular waveguide is presented for Ku-band operation. The proposed antenna is used in a radar demonstrator setup to detect and monitor birds in direct proximity to the wind farms. The goal is to prevent collisions of birds with wind farms. The proposed antenna consists of 34 inclined dumbbell-shaped radiating slots integrated with a parallel-plate waveguide. The proposed meandered feeding structure is used to enlarge the beam scanning angle range over frequency. The dumbbell-shaped radiating slots are employed in the narrow wall of the meandered waveguide due to the space restriction of the meandering. The parallel-plate waveguide is used as a polarisation filter to reduce the cross-polarisation level of the proposed antenna owing to the inclination of the radiating slots. An E-plane horn is used to reduce the beamwidth in the elevation plane. The overall size of the antenna is 20.6λ in length and 15λ in width, where λ is the free space wavelength at 15.55 GHz. The antenna operates in the frequency range from 15.40 to 15.70 GHz. The half power beamwidth is about 4° in the azimuth plane and about 20° in the elevation plane at 15.55 GHz. The main beam of the antenna steers over frequency to cover 39° of angular range in the azimuth plane. A Taylor distribution is applied to achieve sidelobe level below −25 dB in the same plane and 26 dBi gain over the operating frequency range. The antenna array is fabricated and measured successfully to verify the proposed approach. The fabricated antenna shows an impedance matching significantly better than 10 dB in the operating frequency. The measured gain is higher than 25 dB throughout its frequency range.

Ultra-Broadband Full-Space Function-Integrated Stealth Antenna System Based on Metasurface

In this paper, an ultra-broadband full-space function-integrated stealth antenna is proposed based on metasurface (MS). After x-polarized and y-polarized spherical wave passing through the MS, the MS converts the y-polarized spherical wave into the x-polarized vortex wave in transmission space, deflects and focus the x-polarized spherical wave into x-polarized plane wave in reflection space simultaneously. Moreover, when y-polarized wave illuminates the MS in transmission space, the MS achieves scattering control on the y-polarized reflected wave to realize the diffuse scattering function. Exciting the MS with a horn antenna, the broadband antenna system with full-space function-integration and low backward RCS is realized. The antenna system achieves high-gain vortex wave radiation in transmission space, and high-gain beam frequency scanning in reflection space. Besides, when y-polarized wave illuminates the antenna array in transmission space, diffuse scattering stealth is achieved. Experimental results show that the 3 dB gain relative bandwidth of the vortex wave antenna in the transmission space is 67% (10∼20 GHz), the 3 dB gain relative bandwidth of the frequency scanning antenna in the reflection space is 54% (11.5∼20GHz), and the scanning angle covers 31°. The antenna backward RCS reduces more than 10dB between 11.7 GHz to 20 GHz.