Double-ridged Horn Antenna Research Articles

A 3D wideband electromagnetic horn antenna applicator for biomedical applications

Abstract This paper proposes a new, compact, wideband 3D horn antenna for biomedical wireless applications such as cancer and tumor detection. In order to achieve the best penetration level, the antenna has been built and tuned to work in the low frequency range of 0.48–1.24 GHz, which can exhibit a high-resolution detection result. The proposed applicator is a double ridge horn antenna (DRHA). The layout and operation of the key needed components to assemble a wideband hyperthermia system are provided in this study. We assume a cylindrical human tissue phantom with wideband dispersive tissue properties, and simulation results are given. The resulting field maps are displayed in several planes to illustrate the energy localization process. The findings indicate that, in contrast to traditional narrowband systems, wideband operation may improve energy localization in deep tumor locations while eliminating hot spots. The suggested antenna was built and measured to verify the result.

A performance enhanced P- and L-band double-ridged horn antenna

With the continuous development of electromagnetic detection systems, the working frequency of radar gradually expands towards the low-frequency band such as P- and L-band, and the low-frequency horn antenna has also attracted more and more attention. Given the problems of miniaturization, lightweight and ultra-wideband design of low-frequency horn antenna, this paper presents the optimal design for the feed balun, ridge curve, back-feed cavity and sidewall of the traditional horn antenna, and proposes a performance-enhanced double-ridged horn antenna covering 0.21-2.3 GHz. In the entire working band, the antenna has stable radiation patterns and good port-matching characteristics; its VSWR is less than 2 and the main lobes of patterns do not split or deteriorate. The proposed horn antenna can be used as a standard calibration or measurement antenna in antenna or material measurement systems.

Fused deposition modeling for 1 × 2 array of double ridge horn antenna

AbstractIn this letter, fused deposition modeling (FDM) was used to create a 1 × 2 array of the double ridge horn antenna (DRHA). The material used for FDM was acrylonitrile butadiene styrene. The DRHA was designed using an electromagnetic simulator and printed using FDM as well as the inner surface of the DRHA was painted with silver conducting paint. Two printed DRHA were connected together as a 1 × 2 array via a power divider. The main operating frequency of the array antenna was focussed on the range from 3 to 7 GHz. The 1 × 2 array DRHA is capable of better than −10 dB return loss, greater than 10 dBi gain, and a minimum half‐power bandwidth of 27.5°.

A Circularly Polarized Dielectric Discrete Lens Antenna With Wide Axial Ratio and Gain Bandwidths

This letter presents a novel circularly polarized (CP) discrete lens antenna, which exhibits wide axial ratio and gain bandwidths. It consists of a transmitting surface (TS) and a linearly polarized feeding source. For the former, it is based on a dielectric unit cell (UC) which is composed of two parallel slabs. This UC is anisotropic in its cross-section and variable in its height, which provide two degrees of freedom to manipulate the phase difference and the phase shifts of two orthogonal electric field components, and thus the TS can seamlessly attain linear to circular polarization conversion and collimated beam. In the design of the TS, 3-bit phase quantization is adopted. Owing to the non-dispersive characteristic of the UCs, the proposed TS shows superior bandwidth performance over the existing studies. For the latter, it is a commercial wideband double-ridged horn antenna which matches with the TS in terms of bandwidth. As a proof of concept, a 9×9 prototype is fabricated by using 3-D printing technology. Experimental results show that the proposed antenna has a 3-dB axial ratio bandwidth (ARBW) of 44.2 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (8.8-13.8 GHz). The 1-dB and 3-dB gain bandwidths are 16.5 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (11.7-13.8 GHz) and 40 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\%$</tex-math></inline-formula> (9.2-13.8 GHz), respectively.

Horn Antenna Analysis and Simulation for the 18-40 GHz Frequency Band

An antenna is a type of transducer that converts radio signals into alternating electromagnetic waves before transmitting them into space. Polarization is a phase in the selection and installation of an antenna. It can send and receive signals. An antenna is a metal structure that transmits or receives electromagnetic radiation. The antenna, on the other hand, connects the directing device to free space. It sends a signal from the generator into space through transmission cables. High-frequency double-ridged horn (DRH) antennas for electromagnetic compatibility (EMC) are built using a special technique. When using this technique, at the beginning, consider a standard DRH antenna that operates between 1 and 18 GHz. A detailed sensitivity analysis of the 1-18 GHz DRH antenna's structural characteristics addresses some of the DRH antenna's weaknesses, notably in terms of its radiation pattern at higher frequencies. After that, the design is frequency scaled up to support a greater frequency range. This technology might be used to build a wideband DRH antenna that can operate between 18 and 40 GHz. Because the new antenna has a lower frequency ratio of 1:12.2 compared to the normal antenna's 1:18 ratio, we may choose the appropriate frequency window for scaling up. A voltage standing wave ratio (VSWR) of less than a single main lobe that is uninterruptedly oriented along the horn axis and a minimum of 10 dB of acceptable broadband gain are all necessary. The resulting design was used to produce a prototype antenna that was smaller than previous commercial antennas. The dimensions and design objectives were used to develop the prototype.

Design of a Metal 3D Printed Double-Ridged Horn Antenna With Stable Gain and Symmetric Radiation Pattern Over a Wide Frequency Range

Design of a Metal 3D Printed Double-Ridged Horn Antenna With Stable Gain and Symmetric Radiation Pattern Over a Wide Frequency Range

Design of robust and low‐loss 3‐D printed double‐ridged waveguide to microstrip transition

In this paper, we present a new microstrip to waveguide transition design for interfacing printed circuit board (PCB) microstrip transmission lines with 3-D printed metallised-plastic waveguide components. Compared with traditional metal waveguides, interfacing with plastic-based waveguides are challenging due to thermal and mechanical constraints. Despite the development of 3-D printing technology, the precision of 3-D printed waveguides is not as good as the machined metal counterparts. This is critical for microwave components and must be considered in the design process. To minimise the effect of non-ideal waveguide components, a design methodology minimising sensitivity to geometrical variations in the 3-D printed parts is proposed. By sandwiching the PCB between two waveguide sections and optimising the waveguide impedance transformation geometry, the design shows very low insertion loss. It is mechanically robust, cost effective and simple to manufacture. In full system integration, this transition design eliminates the need for expensive microwave cabling and connectors by directly mounting the waveguide to the microwave transceiver PCB. The proof-of-concept transition structure presented in this paper is suitable for microwave applications where low cost and low weight are critical, for example, drone-based radars for remote sensing and space-born satellites. The fabricated structure is characterised using two sets of waveguide components manufactured with different 3-D printing technology and metallisation process': conductive spray painted Fused Deposition Modelling—Polylactic Acid (PLA Painted) and copper electroplated Stereolithography (SLA Plated). Scattering parameters for both types are measured in a short and back-to-back configuration, obtaining the reflection coefficient and insertion loss. Measurements indicate good agreement with modelling and measured performance exceeding prior art. The measured operation band of the Copper-SLA version is 2.9–7.2 GHz with <−10 dB reflection coefficient (S11) and with an insertion loss (S21) of <0.7 dB. With the reduced metallisation and surface quality of the Spray-PLA model, the band is shifted to 3.0–8.0 GHz with an increased S21 of <1.8 dB. The results demonstrate the importance of adopting new transition structures for 3-D printed microwave components where the surface roughness, metallisation quality, and mechanical properties are less optimal. By combining the proposed design with 3-D printed metallised microwave components, very light weight and cost-effective antenna systems can be implemented. Radiation measurements of a 3-D printed double ridge horn antenna connected to the waveguide and used as a feed are also presented, where the operation band is measured to 3–10 GHz with a gain of 5–10 dBi.

An ultra‐wideband compact design for hyperthermia: Open ridged‐waveguide antenna

Antennas are the building block of radiative hyperthermia (HT) applicators. This study proposes a compact UWB antenna specifically tailored to meet the requirements for deep HT array applicators. The proposed Open Ridged-Waveguide (ORWG) antenna, which is an adaptation of a double-ridged horn antenna, operates over the frequency band of 400–800 MHz. It was experimentally assessed as a single element. The quality metrics considered were reflection coefficient, penetration depth, effective field size (EFS), and mutual coupling. The design shows a 75.5% fractional bandwidth with a reflection coefficient measured to be below −10 dB from 367 up to 820 MHz. The EFS is greater than the physical dimensions of the 3-by-4 cm aperture. The mutual coupling between two adjacent elements in the array, measured in a flat phantom arrangement, is lower than −30 dB throughout the entire band. The antenna's performance was further tested in two deep HT scenarios in order to assess the mutual coupling and focussing abilities while in the array configuration. To this end, phased array applicators consisting of 10 and 16 ORWG antennas were simulated in CST, and the results are presented for a homogeneous cylindrical muscle phantom and a realistic patient model, respectively. The good agreement between the simulated and measured results suggests that the antenna can be successfully used for HT.

Wideband Dual-Polarized 3D Printed Quad-Ridged Horn Antenna

This paper presents the development of a wideband dual-polarized 3D printed quad-ridged horn antenna (QRHA) that can be used for detecting and imaging applications. The QRHA consists of three main parts: the waveguide transducer, the horn, and the ridges. The waveguide transducer is modified into a square shape to obtain dual-polarization. Four variations of ridges were carried out to determine the ridge that best satisfies the required specifications, especially the bandwidth and sidelobe levels. Among the four ridge profiles, the quadratic model was used for the proposed QRHA as it generated the widest bandwidth and enhanced a lower operating frequency, which is beneficial for improving resolution and penetration depth. The double-ridged horn antenna (DRHA) was also investigated in order to make a comparison with QRHA’s performance. The characterization results show that when compared to DRHA, QRHA performs better in terms of bandwidth, beamwidth, gain, and side lobe suppression. Due to the benefits it provides, 3D printing based on polylactic acid (PLA) material was selected as the manufacturing process for the proposed QRHA. The fabricated QRHA had a weight that was three times lighter compared to conventional antennas. The measurement results indicate that the 3D printed QRHA has the wideband characteristics of a −10 dB working bandwidth of 7.9 GHz in frequency ranges of 3.5 GHz to 11.4 GHz. Isolation between the ridges below −20 dB was achieved for most frequency ranges. Co– and cross-polarizations were also performed to evaluate the dual-polarization of the proposed QRHA. The radiation patterns showed that the measurement results agree well with the simulations for low, middle, and high operating frequencies.

Error and uncertainty estimation in gain measurement of double ridge horn antenna working for 1–18 GHz

Error and uncertainty estimation in gain measurement of double ridge horn antenna working for 1–18 GHz

Slant polarized wideband double ridged horn antenna with a slant polarizer

ABSTRACT In this study, a novel wideband slant-polarized antenna consisting of a double-ridged horn antenna and a slant polarizer is proposed. The designed slant polarizer is placed in front of the designed double-ridged horn antenna. In this way, linear polarization of the traditional double-ridged horn antenna is changed to slant polarization over a wide frequency range. This design provides a double-ridged horn antenna to be capable of transmitting and receiving whole linearly and circularly polarized signals over a wide frequency range without affecting the antenna characteristics. It also provides the ability to simultaneously radiate vertical and horizontal polarization components. The frequency range of the proposed double-ridged horn antenna with the slant polarizer is 6–18 GHz with 12 dBi typical gain. The performance of the proposed design is examined with simulations and verified with the measurements. The measurement results are in very good agreement with the simulation results.

A Compact Double-Ridged Horn Antenna for Ultra-Wide Band Microwave Imaging

In this paper, we introduce a novel and compact double-ridged horn (DRH) antenna for ultra-wide band microwave imaging. We first develop theoretical considerations useful to derive effective design guidelines and, thus, realizing the antenna model. Afterwards, an electromagnetic numerical solver is employed to study the conceived antenna both in free space and in the presence of a biological load; in both the simulation set-ups, excellent radiating performance are obtained, demonstrating the antenna robustness. Finally, a prototype is fabricated and experimentally measured to validate the final design. The proposed model presents overall dimensions that are 30% smaller with respect to traditional and commercially available DRH antennas (151 mm ×108 mm ×146.6 mm), retaining, at the same time, a significantly large operative band (VSWR <; 3 over the 1-9 GHz band). Among the broad class of possible applications, this frequency range is particularly suitable for biomedical devices, such as in microwave imaging, where reduced dimensions are fundamental in order to allow an easy integration within these systems. In addition, a safety assessment has been performed on the designed antenna, demonstrating that SAR is well below the regulating limits and it can be safely used in proximity of human operators.

Design of Broadband Double-Ridge Horn Antenna for Millimeter-Wave Applications

In this paper, a broadband double-ridge horn antenna (DRHA) covering 5G millimeter-wave (mm-wave) band is proposed, which maintains stable radiation pattern and gain in the entire band. By redesigning the transition between coaxial and waveguide, there is no splitting or deterioration in the axis pattern throughout the entire 18–54 GHz frequency band, and the VSWRs are all below 2. Meanwhile, by replacing the H-Side wall of the antenna with metal grid, the variation on 3 dB beamwidth of the radiation pattern also become more stable against frequencies. In order to fabricate the prototype successfully, the method of block processing and assembly is adopted, which can ensure high precision machining and make the assembly simple and easy to operate. Prototype measurement results show that the VSWR of the antenna is in well agreement with the simulation ones, while the gain is stable as well as no pattern splitting in the entire frequency band can be observed. It will find potential applications in 5G mm-wave frequency band, especially in the field of antenna measurement system as a standard calibration antenna or a probe antenna.

E- and H-Plane Constant Beamwidth Horn Antenna Over 4:1 Frequency Band

A wideband corrugation slot, called stepped-shape slot, is proposed in the design of E-plane corrugated double-ridged horn antenna (DRHA) with H-plane pin sidewalls to extend the constant beamwidth bandwidth (BW) of horn antennas. Closed-form expressions for the input admittance of the new slot are derived, and the BW is compared with the BWs of other conventional corrugations. The proposed slot presents wideband characteristics with a BW ratio of more than 4:1. The use of stepped-shape slot in a corrugated wall keeps the surface reactance capacitive over a relatively large frequency band. The H-plane sidewalls of the designed antenna are formed by curved pinwalls. The flare includes ridges to extend the frequency range, and the E-plane walls are corrugated with a wideband slot to improve the beamwidth constancy in elevation. Thus, constant beamwidth horn antenna (CBWHA) is obtained at both azimuth and elevation planes over the desired frequency band from 4.5 to 18 GHz. The measured performance of the proposed CBWHA reveals wideband characteristics with 31.0° ± 2.5° H-plane and 37.4° ± 5.2° E-plane half power beamwidths over 4:1 frequency range.

A new path loss model based on the volumetric occupancy rate for the pine forests at 5G frequency band

AbstractIn this paper, a new empirical path loss model based on frequency, distance, and volumetric occupancy rate is generated at the 3.5 and 4.2 GHz in the scope of 5G frequency bands. This study aims to determine the effect of the volumetric occupancy rate on path loss depending on the foliage density of the trees in the pine forest area. Using 4.2 GHz and the effect of the volumetric occupancy rate contributes to the literature in terms of novelty. Both the reference measurements to generate a model and verification measurements to verify the proposed models are conducted in three different regions of the forest area with double ridged horn antennas. These regions of the artificial forest area consist of regularly sorted and identical pine trees. Root mean square error (RMSE) and R-squared values are calculated to evaluate the performance of the proposed model. For 3.5 and 4.2 GHz, while the RMSEs are 3.983 and 3.883, the values of R-squared are 0.967 and 0.963, respectively. Additionally, the results are compared with four path loss models which are commonly used in the forest area. The proposed one has the best performance among the other models with values 3.98 and 3.88 dB for 3.5 and 4.2 GHz.

An Ultrawideband and High-Gain Antenna Based on 3-D Impedance-Matching Metamaterial Lens

In this article, we present an ultrawideband and high-gain antenna based on a 3-D impedance-matching metamaterial (IMM) lens. First, we design a 3-D IMM lens which can convert spherical-like waves to plane ones and is nearly perfect impedance-matching with the free space. To realize the 3-D lens, we propose and design two kinds of ultrawideband sandwich-structured metamaterial unit cells that can cover the refraction index ranges from 1.25 to 1.4 and from 1.4 to 3.8, respectively. We also design a double-ridged pyramid horn antenna as an ultrawideband feed source. Measured results verify that the presented lens antenna can work in an ultrawide bandwidth from 5.2 to 15.13 GHz, and the relative bandwidth is 97.7%. Moreover, it achieves a high aperture efficiency of more than 66% from 5.2 to 14.3 GHz, with a relative bandwidth of 93.3%. A maximum aperture efficiency of 85.6% is obtained at 11.5 GHz. The proposed lens antenna has an average of 2 dB gain enhancement versus optimal horn with the same aperture area. And the length of the lens antenna reduces to 22% compared to a bare horn antenna with the same gain and aperture efficiency.

A 3-D-Printed High-Dielectric Materials-Filled Pyramidal Double-Ridged Horn Antenna for Abdominal Fat Measurement System

This article presents a novel 3-D-printed, pyramidal double-ridged horn antenna, filled with a high-dielectric material comprising a mixture of linseed oil and titanium oxide, for biomedical applications. In particular, this investigation explores the use of the antenna design to measure the abdominal fat layers of the human body. The antenna is designed to operate at the low-frequency microwave bands and complemented with an absorber layer at the aperture to improve directivity. The proposed method aims to assess the fat layer thicknesses based on an analysis of the variations of the reflection coefficients. The system has been calibrated and validated based on a number of numerical time-domain simulations, as well as experimental analysis. Assessment of the first transition point in the reflection coefficient spectrum has successfully predicted the rate of magnitude change caused by different layer thicknesses (e.g., oil and fat). Comparing coefficient spectra from various simulation experiments has allowed for eliminating the interferences arising from mismatches with the skin and muscle layers, resulting in the measurements of the fat layer thicknesses through the remaining power change rate.

Inductive Frequency Selective Surface: An Application for Dichroic Sub-Reflectors

An Inductive Frequency Selective Surface (IFSS) self-standing dichroic sub-reflector is presented, which allows the transmission of two frequency bands and reflection of a third band. The operating frequency of the sub-reflector is designed to work at Ku, K and Ka frequency bands, intended for earth to space and space to earth satellite communications. The proposed unit cell is a Jerusalem cross intertwined with an Brigid’s cross. The IFSS is investigated using transmission line theory, along with equivalent-circuit model technique. It has been designed, and simulated using CST Microwave Studio and Advance Design Simulator (ADS). The cascade configuration of the IFSS is also investigated to improve frequency roll-off and bandwidth of the reflection and transmission coefficients. The IFSS has been manufactured using two-sided Photo Chemical Machining (PCM) technique, and has been experimentally characterized using an optical configuration, comprising two double ridged horn antennas connected to a VNA and a rotation system. Measured results are in good agreement with theoretical and simulation data, which validates the reliability of the design and manufacturing process.

Modeling and Practical Implementation of a Broadband Double-Ridged Horn Antenna with an Operating Range More Than an Octave and a High Level of Cross-Polarization Discrimination

Introduction. The resolution of the problem of radio polarimetry in multiposition microwave screening systems (MMSS) with aperture synthesis requires the use of antennas with a high level of cross-polarization discrimination (XPD) in a wide spatial angle. The radio images are reconstructed in MMSS at distances commensurate with the aperture of the antenna structures. Therefore, the value of the spatial angle, at which high XPD is required, can reach 30°. This leads to a new problem of creating an antenna configuration of the X and Ku band, the application of which in MMSS will resolve the problem of constructing a radio image of depolarized microwave radiation scattered on the human body in the form of hidden dangerous objects.Aim. To develop a double-ridged receiving antenna for long-term operation in MMSS with an XPD level of 28 dB at a spatial angle of 30° and operating frequencies of 8…20 GHz.Materials and methods. The requirements for the receiving antenna in MMSS were determined. Theoretical justifications were proposed for the choice of antenna design. Aperture synthesis was used to construct microwave images in MMSS. The stages and results of modelling broadband double-ridge antennas were presented using the CST Studio software broadly applied for three-dimensional electro-magnetic field modelling. The results of modelling pyramidal and conical double-ridged antennas, as well as those in circular and elliptical waveguides, were analyzed. The designed antenna was tested in an anechoic chamber. The measurement results were compared with those obtained during simulation.Results. An elliptical double-ridged horn antenna with a VSWR of no more than 2 and cross-polarization discrimination in a spatial angle of 30° of no less than 28 dB for the frequency range that covers an octave was designed and constructed.Conclusion. The developed antenna can be used in MMSS for the purpose of detecting the effect of micro-wave radiation depolarization as hidden dangerous objects on a human body. Such characteristics of the antenna as its high XPD value in a wide spatial angle will allow the future introduction of microwave polarimetry in MMSS.

3-D Printed Monolithic GRIN Dielectric-Loaded Double-Ridged Horn Antennas

Monolithic integration of 3-D printed gradient index (GRIN) dielectric loading with a double-ridged rectangular horn standard gain horn (SGH) and its impact on antenna performance are demonstrated. Results show that the GRIN loaded horns improve sidelobe levels (SLLs) and beam symmetry, while maintaining good impedance match and relatively high radiation efficiency over more than an octave bandwidth from 7.5 to 18 GHz. Moreover, they have low weight and show good robustness to fabrication imperfections. This work paves the way for seamless integration of complex wideband antennas in 3-D printed systems such as unmanned aerial vehicles (UAVs).