Sectoral Horn Research Articles

Plasmonic sectoral horn nanoantennas.

In this Letter, plasmonic sectoral horn nanoantennas working at near-infrared wavelength (1550nm) have been investigated. We demonstrate that, although there are certain differences between the plasmonic and classical radiofrequency (RF) sectoral horn antennas, the plasmonic horns still possess a number of attractive features, like their RF counterparts, such as tunable high directivities, simplicity in fabrication, and ease of coupling to waveguides. As a specific application, we further show how to exploit these findings to optimize an optical wireless nanolink using the proposed horn nanoantennas, and obtain a 60-fold increase in the received power compared with the situation of matched dipole nanoantennas.

60 GHz foam‐based antenna for near‐field focusing

An innovative way to manufacture a sectoral horn antenna with a biconvex dielectric lens is presented. The antenna focuses on the near-field signal in the H-plane to illuminate a linear array for example. It is made of only two symmetrical pieces of foam and a metallic support. A prototype is manufactured and measured at 60 GHz to verify its focusing properties and validate the technological process.

Printed sectoral horn power combiner

In this work, it is presented a new configuration of planar power combiner/divider based on an H-plane sectoral horn antenna. This component is proposed to realise the basic building blocks of printed power-combining amplifiers. It will be shown how the sectoral horn elements can be implemented on substrate integrated waveguide and multilayer printed circuit board technologies, thus obtaining a high integration level. In the following, the design procedure will be described reporting an example of an 11-stage power divider/combiner in C-band. A prototype has been fabricated, and the measured results compared with the numerical model. Experimental results are in good agreement with theoretical expectations showing a single-stage efficiency of about 90% and a bandwidth of 40%.

An optimized quad-ridged horn antenna with pyramidal sidewalls

The wideband gain and voltage standing wave ratio (VSWR) performance of quad-ridged horn antennas in general are restricted due to the excitation of higher order modes in the coaxial to quad-ridged waveguide transition. This results in large gain variations vs. frequency and break-up of the radiation patterns at higher frequencies. In this paper, a quad-ridged horn antenna is presented with optimized radiation characteristics and VSWR performance. The performance of the antenna was optimized by separating the antenna into two subsections, viz. a coaxial to quad-ridged waveguide transition section and a flared quad-ridged horn section. The performance of each section was optimized individually using a numerical solver – CST Microwave Studio. Three possible configuration of the coaxial to quad-ridged waveguide transition section were considered and optimized. Four configurations for the flared quad-ridged horn section were also investigated. The best performing configuration from each one of the two sections were combined to yield the final design of the optimized quad-ridged horn antenna. The numerical performance of the quad-ridged horn antenna was validated through measurements, performed in a compact antenna test range. The optimized antenna has a 12.5:1 frequency bandwidth from 0.8 to 10 GHz. Over this frequency range, the antenna has a VSWR performance typically better than 2.5:1, stable boresight gain and radiation patterns for both ports with more than 30 dB isolation between the two ports.

A Visual Critique of Racism: African American Art from Southern California

A Visual Critique of Racism: African American Art from Southern California

NEAR-FIELD FOCUSING IN ONE PLANE USING A LOADED SECTORAL HORN ANTENNA

A near-fleld focused antenna used as a feed for linear array is presented in this paper. This antenna is an H-plane sectoral horn with a biconvex dielectric lens placed in its aperture. This antenna focuses the beam in one plane (H-plane) to illuminate a linear array with a small width and provide a large aperture on the other plan to illuminate the length of the array. The simulated fleld distribution on the array is found to be in good agreement with the measurement of a prototype at 9.41GHz.

Gain Enhancement of H-Plane Sectoral Post-Wall Horn Antenna by Connecting Tapered Slots for Millimeter-Wave Communication

We propose a millimeter-wave antenna to serve as an element antenna for a multi-sector switched-beam antenna, which can be fed by a post-wall waveguide. Several tapered slot antennas are connected to an aperture of an H-plane sectoral post-wall horn antenna whose radiation pattern is narrowed in the H-plane to further narrow the pattern in the E-plane. Moreover, the aperture of each tapered slot antenna is loaded with a dielectric to increase the gain. We designed an antenna whose gain is over 16 dBi in the frequency band of 57-66 GHz. The wideband property is experimentally examined.

Wide-Band Wide-Coverage Linear Array of Four Semi-Circular Sector Horns

A linear array antenna consisting of four semi-circular sector horns is proposed to achieve wide-band and wide-coverage radiation characteristics. The array can operate over a wide frequency band from 850 MHz to 2570 MHz and cover a wide range of 120° in the azimuth plane. Each semi-circular sector horn is fed by a centred coaxial probe loaded with a conducting cylinder to obtain a wide-band and symmetric radiation pattern of vertical polarization. Measured and simulated results of a designed array show its potential applications for base stations serving wide-range mobile users and other wide-band spectrum-monitoring systems.

New Holocene Capra pyrenaica (Mammalia, Artiodactyla, Bovidae) skulls from the southern Pyrénées

Three Capra pyrenaica pyrenaica skulls from the Holocene found in different karstic sinkholes in the mid-western Pyrénées are described. Two of the locations were at the highest elevations known for Capra fossils in the Pyrénées, which provides insights into the timing of the Holocene deglaciation. The skulls of the males were particularly large relative to those of other Capra from the Upper Pleistocene found in southwestern Europe. An increase in the availability of food, rather than a direct influence of global warming, during the Holocene (Bergmann's Rule) was likely responsible for the large size of the skulls. Comparisons between the horn sections of the Pyrenean skulls and those of neighbouring taxa show a morphological similarity between the former and C. i. ibex.

Effect of alloxan-induced diabetes on implantation sites of pregnant rats with special emphasis on angiogenesis

Background Diabetes is relatively common worldwide. According to the reports of the WHO, more than 150 million people suffer from diabetes across the world. A primary negative effect of a diabetic environment on the developing embryo is impaired vascularization of the yolk sac. Angiogenesis at the sites of blastocyst implantation is associated with increased vascular permeability. Aim The present study aimed to investigate the effect of diabetes on the implantation site and intersite in albino rats during the early period of pregnancy, with special emphasis on angiogenesis, by studying vascular endothelial growth factor expression. Materials and method Forty adult female albino rats aged 4–6 months were used in this study. Rats were divided into two groups (20 rats each). Group I constituted the control group and group II constituted the alloxan-induced diabetic group. Diabetes was induced in rats by intravenous injection of alloxan monohydrate dissolved in normal saline into the dorsal tail vein at a dose of 40 mg/kg body weight. Vaginal smears were collected from each animal; the presence of sperm in the smear was designated as day 1 of pregnancy. Pregnant rats from the control and diabetic groups were sacrificed at days 4, 5, 6, and 7 of pregnancy (n=5). Examination of the uterine horn sections showed occurrence of implantation on day 6 in the control group, whereas implantation in the diabetic group occurred only on day 7. Granulated metrial glandular cells were clearly seen in the control group, whereas lymphocytic infiltration was obvious in the diabetic group. The expression of vascular endothelial growth factor was stronger in the diabetic group.

Wideband H-Plane Horn Antenna Based on Ridge Substrate Integrated Waveguide (RSIW)

A substrate integrated waveguide (SIW) H-plane sectoral horn antenna, with significantly improved bandwidth, is presented. A tapered ridge, consisting of a simple arrangement of vias on the side flared wall within the multilayer substrate, is introduced to enlarge the operational bandwidth. A simple feed configuration is suggested to provide the propagating wave for the antenna structure. The proposed antenna is simulated by two well-known full-wave packages, Ansoft HFSS and CST Microwave Studio, based on segregate numerical methods. Close agreement between simulation results is reached. The designed antenna shows good radiation characteristics and low VSWR, lower than 2.5, for the whole frequency range of 18-40 GHz.

SIW Slotted Waveguide Array With Pillbox Transition for Mechanical Beam Scanning

A dual-layer pillbox antenna is proposed for mechanical beam-scanning applications at millimeter-wave frequencies. It consists of three main subsystems (multislot quasi-optical transition, input part, and radiating part). The input and radiating parts are placed in two different layers, and the quasi-optical transition behaves as a 180 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ} ~E$</tex></formula> -plane coupler-type bent. The latter is made of an integrated parabolic reflector and several coupling slots etched in the metal layer located between the two substrates hosting the input and radiating parts. A physical optics analysis of the transition is proposed and compared to full-wave simulations. The radiating part is a planar slotted waveguide array. The input part is an <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex></formula> -plane integrated sectoral horn placed in the focal plane of the parabola and moved along a straight line to obtain the beam scanning. For the horn aligned with the parabola axis, the radiation patterns present half-power beamwidth equal to 6 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ} $</tex></formula> and 15 <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{\circ} $</tex></formula> in <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$E$</tex></formula> - and <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$H$</tex></formula> -plane, respectively. The scan range is <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$\pm 35^{\circ} $</tex></formula> . This mechanical scanning approach represents an attractive solution for those applications where a continuous steering of the main beam is required.

Parametric analysis of flare edge rolling throat bending and asymmetric flare effects for H-plane horn radiator

In this paper, radiation characteristics of H-plane sectoral horn antenna are treated systematically by investigation of main structural design parameters and, flare edge rolling, throat bending and asymmetric flare effects. The analytical regularization method (ARM) is used to solve the problem of E-polarized wave diffraction in a fast and accurate way. The numerical procedure is initially verified by the analytical solutions, and then the calculated directivity gain patterns are demonstrated for the modeled horn antenna configurations. Proper choices of the antenna parameters, such as horn depth, aperture length, feeder waveguide width, flare angle, wall thickness, flare edge rolling and throat bending are proposed for the designers to reach high directivity gain, narrow beam width, suppressed side lobe levels, increased front-to back ratio and improved aperture efficiency.

In Memoriam: Robert M. Chanock, MD, 1924-2010

In Memoriam: Robert M. Chanock, MD, 1924-2010

Central Projections of Primary Sensory Afferents to the Spinal Dorsal Horn in the Long-Tailed Stingray, Himantura fai

The central projections of primary sensory afferents innervating the caudal region of the pectoral fin of the long-tailed stingray (Himantura fai) were labeled by applying the lipophilic carbocyanine dye DiI to the dorsal roots in fixed tissue. These observations were complemented by examination of hemotoxylin and eosin-stained paraffin sections of the dorsal root entry zone, and transmission electron microscopy of the dorsal horn. Transverse sections of the sensory nerve and dorsal root revealed two distinct myelinated axon sizes in the sensory nerve. Although the thick and thin axons do not appear to group together in the sensory nerves and dorsal root, they segregate into a dorsally directed bundle of thin fibers and a more horizontally directed bundle of thick fibers soon after entering the spinal cord. In DiI-labeled horizontal sections, fibers were observed to enter the spinal cord and diverge into rostrally and caudally directed trajectories. Branching varicose axons could be traced in the dorsal horn gray matter in the segment of entry and about half of the adjacent rostral and caudal segments. In transverse and sagittal sections, DiI-labeled afferents were seen to innervate the superficial and, to a lesser extent, deeper laminae of the dorsal horn, but not the ventral horn. Electron microscopy of unlabeled dorsal horn sections revealed a variety of synaptic morphologies including large presynaptic elements (some containing dense-core vesicles) making synaptic contacts with multiple processes in a glomerular arrangement; in this respect, the synaptic ultrastructure is broadly similar to that seen in the dorsal horn of rodents and other mammals.

Dual Property of Mu-near zero to Epsilon-near Zero Material

In this paper, a mu-near-zero (MNZ) material is theoretically demonstrated to have a dual property of an epsilon-near-zero (ENZ) material, such as narrow channel tunneling and a zero transmitted angle. In order for an electromagnetic wave to transmit through arbitrarily-shaped subwavelength narrow channel filled with an ENZ or MNZ material, both a proper boundary and a proper geometry of the narrow channel are required. These conditions turn out to have a duality relation between the ENZ and the MNZ materials. As an application of zero transmitted angle through a MNZ material, a X-band E-plane sectoral horn, which has improved directivity and which uses a MNZ material slab with a plasma frequency of 9.34 GHz, is designed. The results show that the directivity of the E-plane sectoral horn is increased by 2.59 dB when a MNZ material slab is inserted at the horn aperture.

Analysis and Design of $E$-Plane Scanning Grid Arrays

A quasi-optical beam steering multilayer lens with scanning in E -plane is analyzed. A full-wave mathematical model is developed to predict the scanning characteristics of the lens. The model is used to optimize the performance of a three-bit beam steering lens. It is demonstrated that the calculated conversion coefficients for the optimized lens are better than -2.1 dB in the frequency band from 27.5 to 32.5 GHz for transmission elevation angles up to 28°. A two-bit lens that corrects the phase front at the aperture of a short .E-plane sectoral horn has been designed, fabricated and tested to verify the model. Measured radiation pattern of the E -plane sectoral horn with correcting lens agrees well with the predictions based on the model.

Dielectric Loaded Substrate Integrated Waveguide (SIW) ${H}$-Plane Horn Antennas

A dielectric loaded substrate integrated waveguide (SIW) H-plane sectoral horn antenna has been proposed in this paper. The horn and the loaded dielectric are integrated by using the same single substrate resulting in easy fabrication and low cost. Two antennas with rectangular and elliptical shaped loaded dielectrics were designed and fabricated. These antennas have high gain and narrow beamwidths both in the E-plane and in the H-plane. The results from the simulation and those from the measurement are in good agreement. To demonstrate applications of the array, the small aperture elliptical dielectric loaded antenna has been used to form an array to obtain higher gain and to form a one-dimensional monopulse antenna array.

E -plane sectoral horn power divider

E-plane sectoral horn power divider design method for high-power antenna array applications is presented. In this method, power division is proportional to the cross section areas of the waveguide channels at the aperture of an E-plane sectoral horn antenna. Two different power dividers are designed and produced to be used with an X-band antenna array having 30 dB Taylor distribution. The first one employs a simple E-plane sectoral horn antenna. This straightforward application of the method might be limited with production tolerances. The second one incorporates a corrugated E-plane sectoral horn antenna, whose design is relatively complex but less sensitive to production tolerances. The produced dividers are compared based on simulations and measurements and good agreement with the theoretical expectations is observed for both types.

Polynomial-Based Evaluation of the Impact of Aperture Phase Taper on the Gain of Rectangular Horns

The aperture phase taper due to quadratic phase errors in the principal planes of a rectangular horn imposes signifi-cant constraints on the on-axis far-field gain of the horn. The precise calculation of gain reduction involves Fresnel integrals; therefore, exact results are obtained only from numerical methods. However, in horns’ analysis and design, simple closed-form expressions are often required for the description of horn-gain. This paper provides a set of simple polynomial approximations that adequately describe the gain reduction factors of pyramidal and sectoral horns. The proposed formulas are derived using least-squares polynomial regression analysis and they are valid for a broad range of quadratic phase error values. Numerical results verify the accuracy of the derived expressions. Application examples and comparisons with methods in the literature demonstrate the efficacy of the approach.