Rectangular Horn Antenna Research Articles

Study the potential of micro laser sintering additive manufacturing technology for metallic 3D printing horn antenna structure

AbstractApplications for an antenna structure produced with additive manufacturing technology are numerous and promising. This study focuses explicitly on utilizing micro‐laser sintering (MLS) three‐dimensional (3D) printing technology to fabricate two rectangular horn antennas identical to a standard Pasternack® horn antenna, making the fabrication straightforward. The objective is to investigate how surface roughness affects antenna performance in a frequency range of 18 to 26.5 GHz. One antenna is polished and the other is left untouched, resulting in surface roughness of 4 and 6 µm, respectively, measured using a profilometer. Then, a vector network analyzer was used to assess their reflection coefficient, transmission characteristics, and radiation pattern and determine gains of 8.83 and 9.14 dBi for the polished and unpolished antennas, respectively. The study finds that both polished and unpolished antennas perform similarly, and their characteristics closely resembling simulated and standard antennas. Finally, the performance of the MLS‐printed metallic antennas is compared with horn antennas created using other 3D printing techniques. It reveals that the MLS‐printed metallic structures exhibit better performance, indicating that the MLS technology has great potential to print 3D metallic electromagnetic designs.

Cost-effective horn antennas; from E-plane sectionalized to octagonal shapes

ABSTRACT In this paper, low-cost methods of improving horn antennas are studied based on the recently introduced E-plane sectionalized rectangular horn antennas. In the beginning, application of E-plane sectionalizing of the rectangular horn antennas on open-boundary E-plane sectoral horn antennas is reexamined and a simple method for obtaining high gain and low sidelobe levels (SLLs) is introduced. Subsequently, effects of removing the conductive sheets from the modified E-plane sectionalized horn antenna are studied and a simple horn antenna with octagonal aperture is obtained with slightly reduced efficiency. Finally, an ultra-low-cost method of improving simple rectangular horn antennas is introduced based on this study. The purpose is to compensate the destructive effects of high SLLs of reference antennas in the antenna measurements, since a common reference antenna type is the rectangular horn antenna, which has high SLLs on the E-plane. In particular, efficiency improvement and SLL reduction of rectangular horn antennas are achieved by adding only four triangular conductive sheets to construct octagonal horn antennas.

Modeling, Characterization, and Machine Learning Algorithm for Rectangular Choke Horn Antennas

Modeling, Characterization, and Machine Learning Algorithm for Rectangular Choke Horn Antennas

Simulation Design of Different Rectangular Horn Antenna Shapes Operating at 28 GHz Using CST and HFSS Techniques

Simulation Design of Different Rectangular Horn Antenna Shapes Operating at 28 GHz Using CST and HFSS Techniques

SLA-Printed K-Band Waveguide Components Using Tollens Reaction Silver Plating

Dielectric printed and plated waveguide components offer cost and weight benefits over metal printed equivalents, with silver plating using Tollens reagents holding significant advantages over electroplating. This work extends on previous demonstrations of this process in plating stereolithography (SLA) printed resin waveguide parts by investigating number of plating rounds, reaction temperature and plastic base. It is found that less than 1.5 dB/m attenuation is achievable in WR42 waveguide using white SLA plastic and silver plating, comparing favourably with the 10 dB/m achieved by printing the same part using Ti64 powder bed fusion. This process improvement is further demonstrated using waveguide power dividers, slow-wave delay sections and rectangular horn antennas.

UTD-PO Solution for E-Plane Radiation Pattern Calculation of Rectangular Horn Antennas With Rectangular-Shaped Corrugations

Proposing a novel hybrid uniform theory of diffraction-physical optics (UTD-PO) formulation, we develop a method to calculate the E-plane radiation pattern of corrugated E-plane rectangular horn antennas with rectangular corrugations. We derive the technique from the estimation of the total field that reaches the emitting source (a magnetic current line), thereby assuming the impingement of a plane wave above the horn (reciprocity is applied). To validate our method, we compare the performance of the UTD-PO analysis with that of the electric field integral equation (EFIE) solved using the method of moments (MoM). Our method shows improved computational efficiency over EFIE and other numerical techniques that fully discretize the geometry.

Stable phase‐centre horn antenna using 3D printed dielectric rod for aperture efficiency improvement of space‐fed antennas

The design strategy to stabilise the phase centre (PC) of the conventional horn antenna using a shaped dielectric rod is presented for aperture efficiency improvement of space-fed antennas. In most practical horn antennas, PC location has significant variations with frequency leading to phase error loss and aperture efficiency reduction over the bandwidth of interest. To overcome this drawback, based on physical reasoning, shaped dielectric rods with appropriate excitation mode are designed and placed on the aperture of conventional rectangular and conical horn antennas. The simulation results show that using a shaped dielectric rod inside the horn antenna leads to a decrease in phase-centre variations versus frequency without disturbing the radiation pattern and reflection coefficient. To investigate the performance, a conical corrugated horn antenna loaded by a conical tapered dielectric rod is used as a feed of the transmitarray antenna. Using a shaped dielectric rod fabricated by 3D printing technology, the PC variations of the proposed horn decrease from 1.06 λ to 0.08 λ over the X-band (λ at 8 GHz). The measurement of the fabricated transmitarray antenna shows an improvement of maximum aperture efficiency from 55% to 64.7% at 10 GHz. The aperture efficiency bandwidth above 50% level is also increased from 1 to 2.2 GHz.

Study of the radiation pattern of a rectangular horn antenna in the operation of multimode propagation of electromagnetic waves

The object of research in the work is the process of radiation of electromagnetic waves and the directional properties of a rectangular horn antenna in a multimode operation. The existing problem is that in practice when developing and researching horn antennas, only the single-mode mode of their operation is taken into account. The fundamental mode of the rectangular waveguide that feeds this horn antenna is chosen as the base mode of the emitted electromagnetic wave. Radiation of higher types of electromagnetic waves is not taken into account. To take into account the impact of higher types of electromagnetic waves on the directional properties of a rectangular horn antenna, it is proposed to investigate a multimode mode consisting of three types of magnetic waves H10, H20, and H30. Horn antennas have high-quality wide-range properties and make it possible to obtain a maximum frequency coverage ratio of 1.5–1.8. In this paper, the directional properties of a rectangular horn antenna are determined by the example of calculating and modeling normalized radiation patterns of a standard horn-type for a wide frequency range with an average frequency of 12 GHz and a frequency overlap factor of 1.67. It has been established that when emitting three higher types of waves, it is possible to simultaneously improve the characteristics and directional properties of a horn antenna by changing the amplitude of each component of the constituent waves of electromagnetic radiation. The work aimed to study the normalized radiation patterns of a rectangular horn antenna to improve its directional properties. It was found that with increasing frequency, starting from the middle frequency of the operating frequency range, the radiation pattern of a rectangular horn antenna expanded. That is, the opening angle increased in the direction of the main radiation, with a decrease in the radiation amplitude, the level of the side and rear lobes increased, which leads to a deterioration in the characteristics of the horn antenna. For the selected geometric dimensions of the horn antenna in the frequency range of 12–12.5 GHz in the multimode mode, it was possible to provide almost the same beam width in the horizontal and vertical planes at the level of 13.2–13.6°.

Bandwidth and efficiency improvements of E-plane sectionalized horn antenna

In this paper, bandwidth improvement of E-plane sectionalized rectangular horn antenna is studied, which has been introduced for sidelobe level (SLL) reduction and gain improvement of traditional rectangular horn antennas. The main drawback of initial sectionalized horn antenna is the limited bandwidth. In this paper, a reason of this drawback is explained, which is the presence of phase variance of electromagnetic fields on the aperture, and a method is proposed for solving this issue, which is the modification of the phase velocity based on the equations for rectangular waveguides. Consequently, as well as modifying the field amplitudes on the aperture, the proposed method can be used for modification of the phase variance on the aperture. Based on this method, an approximately constant phase on the E-plane of the aperture is obtained. The effectiveness of this method is validated by illustrating the field distributions inside the antenna and on the aperture in simulations. Consequently, bandwidth enhancement by resolve of the initial antenna drawback at the higher frequencies, efficiency improvement without changing the antenna length, and successful measurements for validating the calculations and simulations are the main achievements of this paper. The aperture efficiency of the proposed X-band antenna is higher than 54 % for the frequencies below 11.3 GHz.

DESIGN AND SIMULATION OF NON-INVASIVE MICROWAVE ANTENNA FOR HYPERTHERMIA LIPOLYSIS SCHEME

A Non-invasive hyperthermia ablation technique of adipose tissue using a microwave is proposed. It uses dielectric heating to heat the adipose tissue using a rectangular Horn antenna. A selection of operating frequency 5.8 GHz, as an industrial, scientific, and medical radio bands (ISM band), for concentrating electromagnetic (EM) power radiated from the external antenna to the adipose tissue. To protect skin from heat, a silicon layer is used on the surface of the skin instead of water bolus to reduce the percentage of burns on the skin surface. The performance of this antenna is applied in three biological tissues (skin, fat, and muscles), using the simulation of computer simulation technology (CST) microwave studio. The main feature in this antenna is the centralization of the Specific absorption rate (SAR) at the fat tissue more than other tissues. Finally, results achieved good matching of the return loss (S11), and linear SAR value became high at fat tissue more than other tissues, and also the temperature distribution inside fat tissues became 42.7 °C while keeping the temperature inside the skin and muscles below 40 °C after 30 minutes.

E-plane sectionalized rectangular horn antenna

The possibility of reducing sidelobe levels (SLLs) of the E-plane radiation patterns of high-gain rectangular horn antennas by modifying the field distribution on the aperture is studied in this paper. A simple and efficient method for controlling the field distribution on the aperture is proposed by sectionalizing the aperture and using conductive plates inside the antenna to obtain the required tapering for SLL reduction. The resulting radiation patterns indicate significant SLL reductions and remarkable gain improvements over a wide bandwidth. Looking from another aspect, the proposed method can be used for SLL reduction and length reduction of high-gain rectangular horn antennas in a wide frequency band. Finally, a prototype of the proposed E-plane sectionalized rectangular horn antenna with 9 sections is fabricated and tested, successfully. The SLL of the proposed antenna compared with traditional horn antennas is reduced from above −15 dB to below −20 dB and the gain is improved by up to 1.8 dB. The measured gain is above 24.5 dB at 10 GHz with 1 GHz bandwidth.

Selective Laser Melting Process of Al–Based Pyramidal Horns for the W-Band: Fabrication and Testing

In the context of exploring the possibility of using Al-powder Selective Laser Melting to fabricate horn antennas for astronomical applications at millimeter wavelengths, we describe the design, the fabrication, the mechanical characterization, and the electromagnetic performance of additive manufactured horn antennas for the W-band. Our aim, in particular, is to evaluate the performance impact of two basic kinds of surface post-processing (manual grinding and sand-blasting) to deal with the well-known issue of high surface roughness in 3D printed devices. We performed comparative tests of co-polar and cross-polar angular response across the whole W-band, assuming a commercially available rectangular horn antenna as a reference. Based on gain and directivity measurements of the manufactured samples, we find decibel-level detectable deviations from the behavior of the reference horn antenna, and marginal evidence of performance degradation at the top edge of the W-band. We conclude that both kinds of post-processing allow achieving good performance for the W-band, but the higher reliability and uniformity of the sand-blasting post-process encourage exploring similar techniques for further development of aluminum devices at these frequencies.

Polymer-Based 3-D Printed 140-220 GHz Low-Cost Quasi-Optical Components and Integrated Subsystem Assembly

Few examples of individual polymer-based 3-D printed quasi-optical component types have been previously demonstrated above ca. 100 GHz. This paper presents the characterization of polymer-based 3-D printed components and complete subsystems for quasi-optical applications operating at G-band (140 to 220 GHz). Two low-cost consumer-level 3-D printing technologies (vat polymerization and fused deposition modeling) are employed, normally associated with microwave frequencies and longer wavelength applications. Here, five different quasi-optical component types are investigated; rectangular horn antennas, 90° off-axis parabolic mirrors, radiation absorbent material (RAM), grid polarizers and dielectric lenses. As an alternative to conventional electroplating, gold-leaf gilding is used for the polarizer. A detailed investigation is undertaken to compare the performance of our 3-D printed antennas, mirrors and RAM with their commercial equivalents. In addition, a fully 3-D printed, RAM-lined housing with central two-axis rotational platform is constructed for performing two-port measurements of a quasi-optical horn-mirror-polarizer-mirror-horn subsystem. Measured results generally show excellent performances, although the grid polarizer is limited by the minimum strip width, separation distance and metallization thickness. The ultra-low cost, ‘plug and play’ housing is designed to give a fast measurement setup, while minimizing misaligning losses. Its RAM lining is designed to suppress reflections due to diffraction from components under test that may cause adverse multi-path interference. Our work investigates each component type at G-band and integrates them within subsystem assemblies; operating at frequencies well above those normally associated with low-cost consumer-level 3-D printing technologies. This opens-up new opportunities for rapid prototyping of complete low-cost front-end quasi-optical upper-millimeter-wave subsystems.

Dual-Polarization and Low-Sidelobe Corrugated Rectangular Horn Antennas for Outdoor RCS Measurement

AbstractOutdoor radar cross section (RCS) measurement suffers background clutter. Such clutter needs to be minimized, especially when measuring low RCS level objects. To do this, a pair of corrugated horn antennas with a rectangular aperture has been designed, fabricated, and measured to improve the performance of outdoor RCS measurement. This antenna consists of a coaxial-waveguide adaptor, a square-rectangular waveguide transition, a corrugated rectangular horn, and chokes. A comparison of the performances of several corrugation profiles is provided. The tangential profile surpasses others because it provides the necessary low sidelobe level and narrow elevation beamwidth. The proposed antenna achieves −30 dB sidelobe level, fan-shaped beam pattern, and dual-polarization with −26 dB cross-polarization level over the band from 8.5 GHz to 12.5 GHz. The effectiveness of the antenna has been verified experimentally on a roof with two corner reflectors that were deployed intentionally to enlarge the effects of background clutter.

Designing a Water-Immersed Rectangular Horn Antenna for Generating Underwater OAM Waves

In order to extend the applications of vortex waves, we propose a water-immersed rectangular horn antenna array for generating underwater vortex waves carrying the orbital angular momentum (OAM). Firstly, a single dielectric-loaded rectangular horn antenna with the central frequency of 2.6 GHz was designed for generating underwater electromagnetic (EM) waves. Due to the supplementing dielectric-loaded waveguide in this single antenna, the problems with difficult sealing and fixation of the feed probe could be solved effectively. The simulation results show that it has a good impedance characteristics (S11 < −10 dB) and reasonable losses (less than 3.5 dB total for two antennas and a coaxial line) from 2.5 GHz to 2.7 GHz. Experiments on the single antenna were also carried out, which agree well with the simulations. Based on the designed single antenna, the water-immersed rectangular horn antenna array was proposed, and the phase gradient from 0~2π was fed to the horn antennas for generating underwater OAM waves. The simulation results demonstrate high fidelity of the generated OAM waves from the intensity and phase distributions. The purity of the generated OAM modes was also investigated and further verifies the high fidelity of the generated OAM waves. The generated high-quality OAM waves meet the requirements for underwater applications of OAM, such as underwater communication and underwater imaging.

Creating a Gain Improvement Technique for a Horn Antenna using a Metamaterial Structure Inserted with a Thin Dielectric Sheet

Objective: This paper proposed a new technique for the metamaterial on the structure of the curved-woodpile Electromagnetic Band Gap (EBG) inserted with a dielectric slab for gain improvement in a conventional rectangular horn antenna. Methods: We described a method to enhance gain by transferring the electromagnetic fields from the aperture of a horn through the EBG structure. Furthermore, we present the design procedures for inserting a dielectric slab into two layers of the EBG structure for the reduction of distance between the horn and proposed EBG structure. Results and Conclusions: Such a proposed technique not only has the advantage of decreasing the total length of the antenna system but also providing higher gain with a low profile structure. This idea has been verified by both simulation and experimental results. The fabricated antenna can achieve 23.9 dBi of gain or higher than the gain, which is obtained using a conventional rectangular horn antenna at around 7 dBi at an operating frequency of 10 GHz. It is apparent that a good qualitative agreement between the measurements and simulations was achieved.

Optimum design of double ridge horn antennas with general cross‐section

In this study, an analytical method is proposed for design of double-ridged horn (DRH) antenna, which is based on impedance matching of the structure by the method of least squares (MLSs). New basis functions are used for the MLS to obtain optimum impedance functions for the realisation of maximum matching. The resultant reflection coefficients are compared with available methods. The proposed optimum synthesis method is applicable to the arbitrarily tapered DRH antenna with a general cross-section. As two applications, the proposed method is used for the design of linear and non-linear flares of DRH antennas with rectangular and elliptical cross-sections for operation in the frequency band 2–18 GHz. For the proof of concept, a prototype model of the proposed rectangular horn antenna is fabricated and measured in the frequency domain.

Dual-Polarized Antenna Fed by a Quasi-Planar Orthomode Transducer With Different Radiation Patterns

In this paper, a millimeter-wave (mmW) dual-polarized antenna with different radiation patterns is proposed. The antenna consists of a planar lens, a rectangular horn antenna, and a quasi-planar orthomode transducer (OMT) which provides two polarizations. The quasi-planar OMT with good isolation is based on the substrate-integrated waveguide technology, and it can be co-planar integrated with other mmW planar circuits seamlessly. A planar lens is designed on a quad-layered substrate and it has the priority of polarization selective that only takes effect on the horizontal polarization (H-pol). Consequently, high gain with the narrow beam in H-pol and low gain with wide beam in vertical polarization (V-pol) are achieved. To verify the idea, the proposed antenna is designed, fabricated, and measured, achieving a high gain of 26.4 dBi in H-pol, and a wide beamwidth in V-pol. This kind of antennas can be applied to make a balance between the range and coverage in communication and radar applications. In addition, the proposed quasi-planar OMT has potential applications in fifth-generation mmW wireless communications.

A terahertz spatial power combiner based on 2D periodic hole-shaped grating using nongradient optimization method

ABSTRACTThis paper describes a terahertz spatial power combiner based on a periodic hole-shaped hologram for a two-dimensional (2D) horn antenna array. The combiner consists of a 2D array of rectangular horns, a dielectric hole-shaped hologram, a focusing reflector, and a receiving horn antenna. The hologram is realized as 2D periodic holes, which transforms the beams of the antenna array into a pseudoplane wave. The transformed wave is coupled into a rectangular output horn antenna by a parabolic reflector with a shaped surface relief. The field distribution on the receiving plane can be obtained by using a nongradient optimization method to optimize the reflector surface. An example operating at 300 GHz is described. The theoretical power combining efficiency is about 63.1%. The computed field distribution agrees well with the result obtained using the commercial software FEKO Suite.

Ultra-thin metasurface microwave flat lens for broadband applications.

We demonstrate a metasurface-based ultrathin flat lens operating at microwave frequencies. A series of subwavelength metallic split-ring resonators, which are sandwiched between two cross-polarized metallic gratings, are defined to obtain a radially symmetric parabolic phase distribution, covering relative phase differences ranging from 0 to 2.5π radians to create a lens. The tri-layer lens exhibits focusing/collimating of broadband microwaves from 7.0 to 10.0 GHz, with a gain enhancement of 17 dBi at a central wavelength 9.0 GHz while fed by a rectangular horn antenna. The measured focal length agrees reasonably well with design, achieving a 3 dB directionality <4.5° and confirming high-quality beam collimation along the propagation direction. The demonstrated metasurface flat lens enables light-weight, low-cost, and easily deployable flat transceivers for microwave communication, detection, and imaging applications.