Showing papers on "Feed horn published in 2015"

High-Efficient Wideband Slot Transmitarray Antenna

Abstract: A novel high-efficient, wideband, and single-linear-polarized slot-based transmitarray antenna is presented. The unit cell comprises three thin metallic layers with air gap in between, without use of any dielectric substrate. Each metallic layer has a square wide slot within which there are a number of parallel stubs. The wide slot has a high-pass response with notch at zero frequency. Addition of the stubs creates an extra controllable notch within the wide slot high-pass response. Due to the large spacing between the two notches, a passband with low-slope phase shift response is created which leads to a wideband transmitarray. The linear polarization behavior of the antenna along with a suitable feed horn and with no dielectric loss present has resulted in higher antenna efficiency. The design of a three metallic layer unit cell is also carried out through a simple circuit-based analysis approach. The transmitarray is fabricated and results are compared with those of simulation. The proposed transmitarray has a measured $- 1\;\text{dB}$ -gain bandwidth of 15.5%, peak efficiency of 55%, and a cross-polarization level of better than $-29\;\text{dB}$ . The structure is simulated via HFSS software and ADS package is used for equivalent circuit (EC) simulation.

28 GHz indoor channel measurements and modelling in laboratory environment using directional antennas

Abstract: The millimeter-wave band will be one of the key components for the fifth generation (5G) wireless communication systems. A radio channel measurement was conducted at 28 GHz in a laboratory environment. Two horn antennas were used with a vector network analyzer. The transmitter antenna was fixed in one direction while the receiver antenna was rotated 360° in azimuth in the measurement. The space-alternating generalized expectation-maximization algorithm was utilized for the rotated directional antenna scenario to estimate channel parameters of multipath components. Power delay profile, power angle profile and root mean square delay spread were obtained from the measured results. The Saleh-Valenzuela model was used to characterize the measured channel and the intra-cluster parameters were extracted.

Reflector Antenna Developments: A Perspective on the Past, Present and Future

Abstract: i»?Reflector antennas confine most of the electromagnetic energy captured over their apertures into a focal plane or redirect the radiated field of the feed into far field. This paper presents a concise history of reflector antenna developments over an extended time span. Representative examples are provided for different periods that impacted various developments of reflector antennas covering past, present, and future. Due to page limitations, not all worldwide aspects of reflector antenna developments are touched upon in this paper, and the authors have confined themselves to the areas that have influenced their research activities.

The 1.3mm Full-Stokes Polarization System at CARMA

Abstract: The CARMA 1.3mm polarization system consists of dual-polarization receivers that are sensitive to right- (R) and left-circular (L) polarization, and a spectral-line correlator that measures all four cross polarizations (RR, LL, LR, RL) on each of the 105 baselines connecting the 15 telescopes. Each receiver comprises a single feed horn, a waveguide circular polarizer, an orthomode transducer (OMT), two heterodyne mixers, and two low-noise amplifiers (LNAs), all mounted in a cryogenically cooled dewar. Here we review the basics of polarization observations, describe the construction and performance of key receiver components (circular polarizer, OMT, and mixers — but not the correlator), and discuss in detail the calibration of the system, particularly the calibration of the R–L phase offsets and the polarization leakage corrections. The absolute accuracy of polarization position angle measurements was checked by mapping the radial polarization pattern across the disk of Mars. Transferring the Mars calibra...

77-GHz High-Gain Bull’s-Eye Antenna With Sinusoidal Profile

Abstract: A high-gain Bull’s-Eye leaky-wave horn antenna working at 77 GHz with sinusoidal profile has been designed, fabricated, and experimentally measured. The influence of the number of periods on the gain and beamwidth is numerically investigated. Experimental measurements show a high gain of 28.9 dB, with low sidelobe level and a very narrow beamwidth in good agreement with results obtained from simulations.

C-Band Multiple Beam Antennas for Communication Satellites

Abstract: Nowadays, broadband satellites operating at Ka-band and providing high capacity (above 100 Mbps) are mostly based on single-feed-per-beam (SFB) antenna configurations. This antenna farm, using typically three or four reflectors to produce the full dual-band (Tx/Rx) multiple beam coverage, provides high performance but leaves no or little room on the spacecraft for other missions. Accommodation constraints and the desire of operators to maximize and diversify their revenues per satellite have led to several studies on innovative antenna solutions enabling to reduce the number of reflector apertures. Multiple-feed-per-beam (MFB) antenna configurations, using only two apertures, are currently under development for broadband missions at Ka-band. C-band is a more mature business and operators are contemplating the possibility to apply the benefits of multiple beam antennas (MBA) to this frequency band. Due to the lower operating frequency, accommodation constraints are even more stringent and although still scarcely discussed, MFB antenna configurations at C-band are clearly of interest. This paper presents investigations on this topic. In particular, it is found that the MFB architecture applied in C-band is a more realistic approach when compared to the SFB option. Beam Forming Networks (BFNs) with periodic structure is the key to get compact feed clusters that can be allocated in large and medium-size platforms. A new four color scheme compatible with a very compact MFB feed array architecture is introduced.

Design Guidelines of Horn Antennas That Combine Horizontal and Vertical Corrugations for Satellite Communications

Abstract: Today, telecommunication satellite horn antennas are required to be wideband mainly because of the additional bandwidth necessary to accommodate more transponders to increase the capacity of the new satellite services. In this aspect, horn antennas play a key role in the development of wider bandwidth services on board satellites because now-a-days, with recent advances in orthomode junctions and transducers, they are usually the bandwidth limiting component of a satellite antenna as often low crosspolar level is the toughest specification parameter. In this paper, the design guidelines for horn antennas that combine horizontal and vertical corrugations are explained, the method to prepare a preliminary profile for optimization is shown, and an example of a satellite feedhorn with severe requirements is presented.

An ultra-wideband dielectrically loaded quad-ridged feed horn for radio astronomy

Abstract: We present a broadband dielectrically loaded quad-ridged feed horn for illuminating reflector antennas. The feed horn combines a central dielectric spear with a corrugated skirt to achieve a near constant beam width over a 6:1 bandwidth from 0.7–4.2GHz. The feed accepts two linear polarizations which are differentially fed. We present the directivity of the feed measured in an anechoic chamber. The feed exhibits a directivity of 12dB±1.5 and a measured return loss of greater than 14dB across the frequency band.

A simple approach to achieve polarization diversity in broadband reflectarrays using single-layered rectangular patch elements

Abstract: This article presents a simple method to realize polarization diversity in broadband reflectarrays. The wideband characteristic of the reflectarray is achieved using rectangular patch elements arranged in a subwavelength grid on a single layer of substrate; while the polarization diversity of the reflectarray is obtained by simply rotating the feed horn antenna. As the two orthogonal x- and y-component of the rectangular patch element demonstrate relatively negligible interaction, the circular polarized (CP) reflectarrays with linearly polarized feed that have been proposed previously are found to be capable of supporting quadruple polarizations by means of rotating the feed. Based on the rectangular patch elements, an offset-fed 405 × 405 mm2 reflectarray with 0.3λ grid and centered at 10 GHz is designed and developed for right-hand circular polarization (RHCP). In an effort to realize the polarization diversity, the feed horn antenna is subsequently rotated relative to the array with angles of 0°, 90°, and 135° for vertical polarization, horizontal polarization, and left-hand circular polarization (LHCP), respectively. The viability and effectiveness of the proposed simple method for polarization diversity is experimentally verified. The measured results show that the 1-dB gain bandwidth for all four polarizations can reach as large as 18%. Furthermore, the 3-dB axial ratio bandwidths for CP operations are remarkably wide, above 36% and 40% for RHCP and LHCP, respectively. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:305–310, 2015

Directional delay spread characteristics based on indoor channel measurements at 28GHz

Abstract: Millimeter-wave propagation characteristics and channel models are being recently studied for applicability of the fifth generation (5G) mobile communication systems. To overcome the larger path loss on the higher frequency band above 6 GHz, highly directive antennas or beamforming techniques using large array antennas can be used to establish a reliable communication link between a transmitter and a receiver. In this paper, a recently conducted channel measurement campaign is introduced which makes use of a direction-scanning-sounding technique to study channel characteristics of 28 GHz millimeter-wave propagation in indoor environments. The measurement campaign has been conducted in passenger terminals at Seoul Railway Station and Incheon International Airport, which are representative indoor hotspot regions in Korea. Based on our experimental data, we investigate the relationship between the beamwidth of antenna and r.m.s. delay spread characteristics.

Indoor office channel measurements and analysis of propagation characteristics at 14 GHz

Abstract: In this paper, we present the small scale characteristics of indoor office scenario based on the channel measurement at 14 GHz with 250 MHz bandwidth. The measurements were operated at more than 100 receiver locations including LOS and NLOS cases over distances up to 55 meters by utilizing a sliding correlator sounder with 125 mega-chip per second (Mcps). Besides, highly directional horn antennas and dipole antennas were used, respectively, to get the channel characteristics including power delay profile (PDP), path number and root-mean-square (rms) delay spread. The results of path number and rms delay spread measured by dipole antennas and horn antennas are different in LOS case. Compared with the results measured by horn antennas, the path number and rms delay spread value obtained by dipole antennas is bigger in LOS case, where rms delay spread values are 30 ns and 52 ns, respectively. It is reasonable that some multipath information is lost when using horn antenna to measure. In NLOS case, path number and rms delay spread only measured by dipole antennas are given.

Design of a horn lens antenna for OAM generation

Abstract: A horn lens antenna designed for the generation of OAM-carrying radio waves is presented. The conventional horn antenna is integrated with a single-layer perforated planar dielectric lens by covering its aperture. Through varying the diameter of holes, an azimuthal variation of the permittivity is obtained and the corresponding azimuthal phase delay creates a vortex, thus an OAM wave is generated. The lens antenna works in the millimeter frequency band, and can be used to generate the OAM states of l =+1 or −1.

A Novel Matched Feed Structure for Achieving Wide Cross-polar Bandwidth for an Offset Parabolic Reflector Antenna System

Abstract: This letter presents the details of a novel matched feed structure which promises improved cross-polar performance for an offset parabolic reflector antenna. Feed aperture formed by an intersection of circular and rectangular waveguides provides wide cross-polar bandwidth due to the cutoff wave numbers being close for the two modes used in conjugate matching. The mode coefficients and relative phase difference are estimated using particle swarm optimization (PSO) technique for the specified antenna system. Physical optics (PO) is used to evaluate the reflector pattern; feed radiation pattern is obtained using mode field patterns and cutoff wave numbers, which are computed using 2-D finite element method (FEM). The higher order mode which is combined with the main operating mode of the waveguide for conjugate matching is generated using two posts placed behind the aperture. The antenna system performance is evaluated using HFSS and CST Microwave Studio.

WSPEC: A waveguide filter-bank focal plane array spectrometer for millimeter wave astronomy and cosmology

Abstract: Imaging and spectroscopy at (sub-)millimeter wavelengths are key frontiers in astronomy and cosmology. Large area spectral surveys with moderate spectral resolution (R=50-200) will be used to characterize large scale structure and star formation through intensity mapping surveys in emission lines such as the CO rotational transitions. Such surveys will also be used to study the SZ effect, and will detect the emission lines and continuum spectrum of individual objects. WSPEC is an instrument proposed to target these science goals. It is a channelizing spectrometer realized in rectangular waveguide, fabricated using conventional high-precision metal machining. Each spectrometer is coupled to free space with a machined feed horn, and the devices are tiled into a 2D array to fill the focal plane of the telescope. The detectors will be aluminum Lumped-Element Kinetic Inductance Detectors (LEKIDs). To target the CO lines and SZ effect, we will have bands at 135-175 GHz and 190-250 GHz, each Nyquist-sampled at R~200 resolution. Here we discuss the instrument concept and design, and successful initial testing of a WR10 (i.e. 90 GHz) prototype spectrometer. We recently tested a WR5 (180 GHz) prototype to verify that the concept works at higher frequencies, and also designed a resonant backshort structure that may further increase the optical efficiency. We are making progress towards integrating a spectrometer with a LEKID array and deploying a prototype device to a telescope for first light.

Design of Offset Dual-Reflector Antennas for Improving Isolation Level between Transmitter and Receiver Antennas

Abstract: This paper presents the improved isolation property of the signals among transmitter and receiver antennas. The separation wall is laid at the center of the antennas to improve the isolation level between them. The introduced separation wall has serrated edges mounted on three sides, i.e., top, left and right sides. These mounted serrated edges are implemented to reduce the diffraction which may occur due to the linear edge of the wall. The Fresnel diffraction problem has been solved using analytical method in order to get the optimized structure of the serration. The Fresnel diffraction patterns due to different sizes of the serration are obtained, and their relative powers are compared to each other. The implemented antenna system with the serration wall is composed of corrugated feed horn, orthogonal mode transducer, and offset dual-reflector parabolic antennas. The effect of serration is well demonstrated by the measurement of isolation level of the antenna system. The measured results show that the serrated edges enhanced the isolation property among transmitter and receiver antennas.

15 GHz propagation channel measurement at a university campus for the 5G spectrum

Abstract: This paper presents the empirical measurements of 15 GHz outdoor channel propagation at a university campus for 5G communication system. Measurements are performed at the university campus using one receiver location and 100 transmitter locations placed in concentric circles within a 200-m radius. A 400 megachip-per-second channel measurement system, directional horn antenna, and omnidirectional antenna are used to measure propagation characteristic for the 15 GHz spectrum. This paper presents measurement results for the path loss of the transmitter-receiver separation distance, the different azimuthal angles corresponding to the received power, and the power delay spread for concentric circles of different radii and overall transmitter locations in the campus. The statistical data demonstrate that the 15 GHz spectrum is available for use as the next generation of radio communication.

On the size reduction of planar Yagi-Uda antenna using parabolic reflector

Abstract: A planar Yagi-Uda antenna using the parabolic reflector is designed and compared to that of using the conventional straight reflector. Both antennas are designed to have the same performance. Simulation results show that the parabolic reflector design can reduce the occupied antenna area by about 29.4% as compared to that of the straight reflector design, while the antenna directivity and efficiency are retained at 7.16 dBi and −0.70 dB, respectively. Thus the parabolic reflector design is suitable for designing compact directive antennas in the low-profile devices.

Fabrication and experimental validation of high gain lens antenna for 71–86GHz band

Abstract: This article presents the fabrication and experimental validation results of compact size high gain conical horn lens antenna for E-band (71–86GHz) applications. Very promising measured results are obtained in terms of return loss |S 11 |, gain, aperture efficiency, bandwidth and SLL as will be shown in this article. A peak measured gain of 25.8dB, gain improvement 6.5∼8.8dB over the gain of the horn without lens, maximum aperture efficiency of 48.8%, SLL 11 |<−10dB for 70–110GHz band.

An SIS mixer based focal-plane array at 230 GHz

Abstract: Efficiently mapping large areas of the sky with high spectral resolution at mm and sub-mm wavelengths will require a new generation of heterodyne focal-plane array receivers. The number of pixels in such arrays has not increased particularly rapidly in the last two decades, with maximum achieved pixel numbers between 16 and 64 (e.g. [1] and [2]). Thus new approaches are needed to address such problems as local oscillator (LO) injection, feed horn fabrication and SIS mixer design, fabrication and repeatability. Here we describe a prototype focal-plane array unit based on unilateral finline SIS mixers, fed with smooth-walled feed horns. LO injection power diplexing is achieved by a combination of directly machined waveguide Y-power splitters and bow-tie cross waveguide couplers. The 1×4 prototype array, currently under construction, will demonstrate several technologies relevant to the construction of large format arrays.

Horn antenna for generating Orbital Angular Momentum (OAM) waves

Abstract: We present a novel horn antenna to generate radio waves bearing Orbital Angular Momentum (OAM) by using a circular waveguide. The OAM mode l = 1 is generated by using a spiral phase plate (SPP) inside a circular waveguide. We present here two methods to transform the classical guided modes to OAM wave. The resulting electrical field distribution and the radiation patterns evidence the properties of waves carrying OAM.

A prototype of feed subsystem for a mutilple-beam array-fed reflector antenna

Abstract: This paper introduces the design of a feed subsystem for a multiple-beam array-fed reflector antenna. The prototype is composed of 37 circularly polarized horns and a complicated RF switch matrix. The feed horns are divided into four interleaved groups. Each time four adjacent feed horns, i.e., each from one group, are selected by the RF switch matrix to connect to a signal processor where the delivered signals are weighted and combined to form a radiation beam. The beam can be controlled to hop in a certain zone with the response time at the level of μs. The use of RF switch matrix reduces the cost of signal processing. By expanding the scale of feed array as well as the RF switch matrix, a much more comprehensive feed subsystem can be developed to produce multiple independent hopping beams in association with a reflector. The scheme and experimental results of the prototype are presented in the context.

A Reflector Antenna Concept Robust Against Feed Failures for Satellite Communications

Abstract: Since the first communications satellites have been launched to space with the beginning of the 1960s, these systems have undergone a rapid development. Amongst others, this development is driven by an increasing number of subscribers exchanging larger and larger data volumes. This need of data capacity cannot be satisfied alone by raising the sheer number of communications satellites, but requires powerful individual systems, which operate reliably and are cost effective at the same time. In this context two requirements on the communications antenna are the provision of high directional gain and robustness in terms of beam stability. Classically, large unfurlable mesh reflector antennas in conjunction with feed arrays are adopted to illuminate a certain region on ground with high gain. An inherent problem of such reflector-feed configurations is that these systems are prone to feed element failures. In the worst case, this could result in a ‘blind’ spot, where no communication is possible. This paper introduces a robust antenna concept, which combines the virtue of reflector antennas, namely the large aperture, with the advantage of direct radiating planar array antennas, which is the beam stability in the presence of element failures. In order to unfold its full potential this concept makes use of digital beamforming techniques, which allow to control the illumination in a flexible way.

A High-Power Microwave Zoom Antenna With Metal-Plate Lenses

Abstract: Metal-plate lens antennas were designed and constructed for a high-power microwave zoom antenna concept comprising a pyramidal horn feed antenna and two metal-plate lenses. Good agreement was found between experiment and simulation. This antenna provides true zoom capability with continuously variable collimated beam output, approximately 10% bandwidth, and very high power-handling capability. It can be designed to operate at any frequency in the range of about 100 MHz to 10 GHz. It was found that nano-modified carbon fiber composites could be used instead of metal plates in these lenses; these composites would reduce the weight of the lens significantly and would help to mitigate possible spurious TM modes induced in the lens when it is in the near-field of the feed horn antenna.

High speed transmission at 60 GHz for 5G communications

Abstract: The results of a wideband channel measurement campaign carried out at the 60 GHz band are summarized in this paper. The propagation effects in this 5G radio link have been characterized using a sweep time delay cross-correlation sounder. We analyze the pointing of the on-road horn antenna using an angular scanning with a pan&tilt instrument. From these data, we obtain the root mean square delay spread of the radio channel. The low value found for the root mean square delay spread in this university campus environment suggests that channel equalization would not be needed for high data rate services. In terms of angular scanning, the receiver power is more sensitive to azimuth variations. We conclude that this channel would be a possibility for high speed transmission at long distance in open areas.

Cavity matching of high dielectric constant SIW H-Plane horn antenna

Abstract: A simple SIW H-plane horn antenna with a loaded open cavity is introduced. The new combination of the SIW H-plane horn and the open cavity results in a wide and constant impedance bandwidth, which has been hard to achieve by a single SIW horn antenna. Besides matching improvement, the new configuration results in higher gain with radiation pattern focused in antenna aperture. The longitudinal size of the structure is kept as the simple SIW horn; however, it is three times thicker than the simple horn.

Low-cost diplexed multiple beam integrated antenna system for LEO satellite constellation

Abstract: A multiple beam integrated antenna system for a satellite including a support structure having an alignment plate. The antenna system further includes a plurality of feed horns mounted to the alignment plate, where each feed horn includes a plurality of tapered sections that support propagation modes for both up-link signals and down-link signals. A septum polarizer is mounted to an input end of each feed horn that converts linearly polarized signals to circularly polarized signals for the up-link signals and converts circularly polarized signals to linearly polarized signals for the down-link signals. A Y-shaped waveguide is coupled to each of the polarizers and includes separate receive reject and transmit reject filters so as to keep the up-link signals and the down-link signals from interfering with each other. Flex waveguides couple the transmit leg and the receive leg of each Y-shaped waveguide to RF modules.

A Compact Dipole Antenna With Curved Reflector for 1.0–4.2 GHz EMC Measurement

Abstract: A figure of merit for electromagnetic compatibility (EMC) testing antennas is first introduced and some design considerations are presented. A compact dipole antenna with curved reflector is proposed for 1.0–4.2 GHz EMC measurement. Structure of the curved reflector, defined by a power function, is studied by full-wave simulations and verified by experiments. A comparison between the curved reflector, corner reflector, and pyramidal reflector is presented and discussed. The presented antenna has nearly constant radiation patterns and realized gain. The minimum measurement distance is only 1.0 m for the proposed antenna, which reaches the lower limit recommended by CISPR. For small equipments under test, the measurement distance can be alternated and higher field strength can be provided by the proposed antenna without increasing the input power. In contrast, double-rigided horn antennas do not have the flexibility as they have much larger dimensions.

On-glass automotive diversity antenna and LNA design for S-band satellite digital radio

Abstract: Selection combining diversity system with antennas mounted on windshield and backlite of a vehicle is proposed for satellite digital audio radio applications. Standalone exterior mount antennas on metallic vehicles perform well for satellite digital audio radio applications, but for composite body vehicles or interior mount antennas, antenna performance becomes a real issue. Proposed on-glass two-antenna diversity is one solution for such applications. The antenna correlation is calculated using the S-parameters of the antennas and found to be very low due to many wavelengths separation between the antennas. Design of low noise amplifier, which has sub 1 dB noise figure and good P1dB due to strong cellular signals, is also detailed. A diversity receiver is described and ride tests are performed to assess the performance of the diversity system in real-time, under weak satellite signal environment which is regarded as the most challenging reception condition.

Dual-polarized monopulse antenna for millimeter-wave band seeker

Abstract: According to the present invention, disclosed is a dual-polarized monopulse antenna for a millimeter wave detector. The dual-polarized monopulse antenna according to the present invention includes: a reflection plate antenna which comprises a main reflection plate and a sub-reflection plate, and transmits and receives a dual-polarized signal; a power feed horn which is located on a focus of a main reflection plate of the reflection plate antenna; a polarized wave separation device which receives the dual-polarized signal from the power feed horn and separates the received dual-polarized signal into a vertical polarized signal and a horizontal polarized signal; and a monopulse power feed unit which generates an addition pattern from the vertical polarized signal and the horizontal polarized signal which are separated by the polarized wave separation device and also generates a deduction pattern with respect to an azimuth and an altitude. The power feed horn includes an input and output unit comprising a waveguide of 2X2. The waveguide has a 90-degree symmetric structure and is formed in a square shape.

A K/Ka/EHF feed chain for dual-use telecom

Abstract: A novel triple-band, self-diplexing feed system operating in K/Ka/EHF bands is presented. The feed system is particularly suitable in space telecom reflector antennas for dual-use applications. Two different RF chain architectures have been traded-off, designed and optimized through full wave modelling, in order to support the optimal choice solution. An EQM of the selected configuration has been realized and subjected to a full qualification test campaign. Very good correlation of the RF performance to the theoretical design has been achieved.