Showing papers on "Ka band published in 2020"
TL;DR: In this article, a dual-polarized magnetoelectric (ME) dipole antenna with the feeding structure consisting of two orthogonal L-shaped probes with different heights is presented based on the low-temperature co-fired ceramic (LTCC) technology.
Abstract: A Ka -band wideband dual-polarized magnetoelectric (ME) dipole antenna with the feeding structure consisting of two orthogonal L-shaped probes with different heights is presented based on the low-temperature cofired ceramic (LTCC) technology. A simulated overlapped impedance bandwidth of 42.5% is achieved together with an isolation of higher than 24 dB between the two input ports and stable radiation characteristics over the operating band. By combining the radiating elements with a single-layered feed network composed of microstrip lines, a $4\times 4$ dual-polarized ME dipole antenna array is designed, fabricated, and measured. An overlapped impedance bandwidth of 45% that can cover the entire Ka -band, a gain up to 16.1 dBi, and stable symmetrical radiation patterns in the two orthogonal planes with cross polarization of less than −15 dB are experimentally confirmed. With advantages of the compact geometry, wide operating band, and promising radiation performance, the proposed antenna array with dual polarization would be attractive for millimeter-wave wireless applications in Ka -band.
68 citations
TL;DR: In this paper, an electronically steerable transmit array (TA) with 2 bits of phase quantization per unit cell was proposed. But the phase quantisation was performed by four p-i-n diodes on each unit-cell.
Abstract: This communication presents the design, optimization, fabrication, and characterization of an electronically steerable transmitarray (TA) with 2 bits of phase quantization per unit cell. The proposed TA operates in linear polarization at Ka -band and is composed of $14\times14$ reconfigurable unit-cells. Four p-i-n diodes are integrated on each unit-cell to control the radiated field phase distribution across the TA aperture. The prototype demonstrates experimentally pencil beam scanning over a $120^{\circ } \times 120^{\circ }$ window, a maximum gain at broadside of 19.8 dBi, and a 3 dB fractional bandwidth of 16.2%.
65 citations
TL;DR: The design and measurement of the 1024-element transmit array have presented a feasible way for mass production of a low cost active phased array for Ka-band satellite communication (SATCOM) terminal applications.
Abstract: This paper presents a scalable 1024-element transmit dual-circularly-polarized phased array for Ka-band satellite communication (SATCOM) terminal applications. The transmit array based on the CMOS beamformer and a multilayer printed circuit board (PCB) can steer up to large scan angles (±60°) with a scan loss less than 4.5 dB. With the 8-channel transmit beamformer, the array can realize dual circular polarization and the axial ratio (AR) of the array is less than 3 dB in the scanning range of ±30° in both left-hand circular polarization (LHCP) and right-hand circular polarization (RHCP) mode. The effective isotropic radiated power (EIRP) of the array achieves 74 dBm from 29.5 GHz to 30 GHz. The design and measurement of the 1024-element transmit array have presented a feasible way for mass production of a low cost active phased array.
54 citations
TL;DR: In this article, a substrate-integrated gap waveguide (SIGW)-fed metasurface antenna (metantenna) array with nonuniform excitation is proposed for wideband operation and sidelobe-level (SLL) reduction at millimeter-wave Ka-band.
Abstract: substrate-integrated gap waveguide (SIGW)-fed metasurface antenna (metantenna) array with nonuniform excitation is proposed for wideband operation and sidelobe-level (SLL) reduction at millimeter-wave Ka -band. To achieve wideband and low profile, a $2 \times 2$ square patch-based metasurface is introduced based on characteristic mode analysis (CMA). The ridged microstrip-fed slot is employed to excite the metasurface, while the mushroom-like patches are positioned around feeding lines to operate as the SIGW for suppressing the undesired modes. Due to the compactness of the proposed SIGW, the amplitude of each element is controllable using unbalanced T-junctions. A nonuniformly excited $4 \times 4$ antenna array is designed and fabricated for validation. The measured results show an impedance bandwidth ( $\vert \text{S}_{11}\vert dB) of full Ka -band with a 3 dB gain bandwidth of 28–40 GHz (35.3%) and SLLs less than −12.1 and −15.6 dB in the E- and H-planes, respectively.
54 citations
TL;DR: In this article, an integrated millimeter-wave (mmW) broadband circularly polarized (CP) single-beam/multibeam antennas (MBAs) are reported.
Abstract: In this article, integrated millimeter-wave (mmW) broadband circularly polarized (CP) single-beam/multibeam antennas (MBAs) are reported. The antennas comprised a Berry-phase (BP) transmit-array (TA) containing three layers of slotted elliptical metallic resonator arrays and a cluster of substrate integrated waveguide (SIW) -fed CP source radiators with an anisotropic impedance surface (AIS) superstrate. By utilizing broadband mmW CP radiators, BP-based transmission phase compensation, and tailoring the dispersive transfer function of the TA cell, broadband CP high-gain beams can be generated with improved gain flatness and an antenna profile of only $2.6\lambda _{0}$ . Moreover, by employing multifocal strategies in the design of TAs, the scanning loss for the multifeed MBAs can be alleviated, expanding their range of coverage. Two Ka -band prototypes were fabricated and characterized. The single-feed single-beam antenna experimentally achieves a peak gain of 22.6 dBic and a 2 dB gain bandwidth of 20.7%, within which the $S_{11}$ is below −10 dB and axial ratio (AR) is smaller than 3 dB. The second prototype, which contains five source radiators and a bifocal TA, generates five pencil beams that cover a range between ±33°. It features a peak broadside gain of 22.2 dBic, a joint AR $S_{11}$ is below −10 dB and mutual coupling is smaller than −20 dB. Finally, the numerical simulation of a broadband CP 21-beam antenna with a quad-focal TA is shown, which provides a 2-D coverage of 32° cone. The demonstrated single-beam antenna/MBA can be promising candidates for various mmW applications, such as satellite and fifth-generation (5G) communications.
46 citations
TL;DR: In this article, a polarization rotator based on substrate integrated waveguide (SIW) is proposed, which transmits a wave rotated of 90° with respect to the incident one in one of the two bands maintaining unchanged the polarization in the other one.
Abstract: A polarization rotator based on substrate integrated waveguide (SIW) is proposed in this article. The rotator is designed as a dual-band, single-layer, frequency-selective surface (FSS) that transmits a wave rotated of 90° with respect to the incident one in one of the two bands maintaining unchanged the polarization in the other one. Other than the design and characterization of the rotator, its application to a linear-to-circular dual-band polarizer is also investigated. To this purpose, the rotator is coupled to a conventional meander line polarizer generating orthogonal circular polarizations (CP) in the two bands. This configuration is useful in SatCom applications where the required high isolation between TX and RX channels is obtained assigning orthogonal polarizations to the two bands. As a design example, a prototype is designed and experimentally validated in the SatCom K-/Ka -bands. Measured performance shows an isolation between the TX and RX channels of more than 35 dB and insertion losses which do not exceed 1.5 dB in the two operating bands.
45 citations
TL;DR: In this article, a millimeter-wave aperture-coupled magnetoelectric (ME) dipole antenna with a low profile metallic geometry is proposed based on the 3-D printing technology.
Abstract: A novel millimeter-wave aperture-coupled magnetoelectric (ME) dipole antenna with a low-profile metallic geometry is proposed based on the 3-D printing technology. An impedance bandwidth of 53.7%, a gain up to 10.8 dBi, and stable unidirectional radiation patterns with the cross polarization of less than −38 dB are achieved by the antenna. Its operating mechanism and design process are studied in detail as well. In order to widen the bandwidth of the millimeter-wave full-corporate H-plane air-filled waveguide feed network, a wideband H-plane stepped waveguide T-junction with a compact size is then investigated, which has a bandwidth of about 50% for the reflection coefficient of less than −20 dB. By combining the presented radiating element with the feed network, an $8 \times 8$ ME dipole array is designed, printed, and tested in the Ka -band. An enhanced bandwidth of 31%, symmetric radiation patterns with the cross polarization of less than −35 dB, and a gain varying from 25.5 to 28.5 dBi are experimentally obtained. The proposed design demonstrates the advantage of utilizing the 3-D printing method to improve the operating characteristics of the millimeter-wave antenna array and is attractive for the emerging wideband millimeter-wave wireless applications.
37 citations
TL;DR: In this article, a compact $Ka$ -band 4-bit switch-type phase shifter with low group delay deviation (GDD) using 28-nm CMOS technology is presented.
Abstract: This letter presents a compact $Ka$ -band 4-bit switch-type phase shifter with low group delay deviation (GDD) using 28-nm CMOS technology. A magnetically coupled all-pass network (APN) configuration is employed to achieve both equal and flat group delay characteristics versus frequency at each phase state. The measured rms phase error is 1.2°, and the gain error is 1.1 dB at 33 GHz. The average measured insertion loss is 12.8 dB at 33 GHz, and the input and output return losses are both lower than −10 dB from 29 to 37 GHz. The fabricated phase shifter has a compact size of 0.08 mm2 excluding pads, low GDD of ±4 ps, and rms group delay error of $Ka$ -band phase shifter has the lowest GDD per bandwidth (GDD/BW) compared with other reported passive phase shifters.
34 citations
09 Jun 2020
TL;DR: In this paper, the Spanish Ministry of Economy and Competitiveness (Ministerio de Economia y Competitividad) under Project TEC2016-79700-C2-1-R was supported by the Spanish government.
Abstract: This work was supported by the Spanish Ministry of Economy and Competitiveness (Ministerio de Economia y Competitividad) under Project TEC2016-79700-C2-1-R.
34 citations
TL;DR: In this article, the design and optimization of a deployable 1 m mesh reflector compatible with a 12U-class CubeSat is presented, which is designed for telecommunication and is compatible with NASA's deep-space network (DSN) at the ${X}$ -band (i.e., uplink: 7.145-7.19 GHz; downlink: 8.4-8.45 GHz).
Abstract: This article presents the design and optimization of a deployable 1 m mesh reflector compatible with a 12U-class CubeSat. This antenna is designed for telecommunication and is compatible with NASA’s deep-space network (DSN) at ${X}$ -band (i.e., uplink: 7.145–7.19 GHz; downlink: 8.4–8.45 GHz) and Ka -band frequencies (i.e., uplink: 34.2–34.7 GHz; downlink: 31.8–32.3 GHz). Three right-handed circularly polarized (RHCP) antennas, both transmit and receive, are introduced here: ${X}$ -band only, Ka -band only, and ${X}$ -/ Ka -band. For the ${X}$ -band-only antenna, a gain of 36.1 and 36.8 dBic is achieved at uplink and downlink frequency bands, respectively. This translates into an aperture efficiency of 72% and 62%. For the Ka -band-only antenna, a gain of 48.4 and 48.7 dBic is obtained at downlink and uplink frequency bands, which translate into an aperture efficiency of 62% and 72%, respectively.
33 citations
TL;DR: In this paper, a vertically folded slotted circular patch operating at the Ka-band is proposed in this communication, and the proposed circular patch resonates at its quasi-TM21 mode and exhibits a wide operational band of 23.5%, which is more superior than many reported millimeter-wave circular patch antennas.
Abstract: A vertically folded slotted circular patch operating at the Ka -band is proposed in this communication. Fed by a low-profile microstrip feeding structure, the proposed circular patch resonates at its quasi-TM21 mode and exhibits a wide operational band of 23.5%, which is more superior than many reported millimeter-wave circular patch antennas. A full-corporate fed $2 \times 2$ linearly polarized (LP) subarray based on the proposed circular patch is designed without any additional substrate layer, which is further extended into a $4 \times 4$ LP array and a $4 \times 4$ circularly polarized (CP) sequential rotation array. Both the LP and CP arrays are fabricated and measured. A good agreement between the simulated and measured results has been observed, thus validating the proposed design techniques. With the enhanced performance, for example, wideband, low-profile, low cost, and compact size, the demonstrated array antennas can present promising candidates for some popular Ka -band applications, such as 5G millimeter-wave communications and satellite communications.
TL;DR: A high-performance fully metallic dual-polarized wideband Vivaldi array for the 26–40 GHz-band, which is going to be used, for example, in 5G millimeter-wave (mmWave) communication networks.
Abstract: This article presents a high-performance fully metallic dual-polarized wideband Vivaldi array for the $Ka$ -band (26–40 GHz), which is going to be used, for example, in 5G millimeter-wave (mmWave) communication networks. Antenna-array elements are fed straight from a single printed circuit board (PCB) that allows integrating active components in the immediate proximity of antenna elements. A whole array can be placed on a PCB as a through-hole or surface-mount technology component. The antenna is simulated in a unit cell with periodic boundary conditions and in an $8\times8$ array configuration. The simulations show that the active reflection coefficient is below −10 dB across the entire $Ka$ -band and throughout most of the beam-steering angles up to ±60°. Lower than 3 dB scan loss is achieved in approximately ±60° range in the elementary planes and ±50° in the diagonal planes. The reflection coefficient and gain of each of the four elements in different parts of the manufactured dual-polarized $8\,\,\times8$ array were measured and simulated with the remaining elements terminated with a $50~\Omega $ load. The measured results follow closely the full-wave finite array simulation results; the reflection coefficient is low and the element pattern is wide over the entire frequency range.
TL;DR: In this paper, a coplanar Magic-T waveguide based on a combination of ridge and Eplane groove gap waveguides is proposed for Ka-band applications. But, the MagicT isolation is better than 40 dB in the whole bandwidth while its insertion loss is about 0.25 dB.
Abstract: A coplanar Magic-T is proposed based on a combination of ridge and E -plane groove gap waveguides for Ka-band applications. All four ports of the proposed Magic-T are coplanar. The impedance bandwidth of the proposed Magic-T is about 43% covering the whole Ka-band from 26 to 40 GHz. The Magic-T isolation is better than 40 dB in the whole bandwidth while its insertion loss is about 0.25 dB.
TL;DR: The experimental results of a 2-bit electronically reconfigurable unit-cell for transmitarrays at Ka-band based on a six-metal layers design and three dielectric substrates and shows minimum transmission loss in the range 1.5 – 2.3 dB.
Abstract: This paper presents the experimental results of a 2-bit electronically reconfigurable unit-cell for transmitarrays at Ka-band. The proposed unit-cell architecture is based on a six-metal layers design and three dielectric substrates. Two patch antennas are printed respectively on the top and bottom layers of the stack-up to achieve an antenna-filter-antenna structure. To implement the desired 2-bit phase resolution, two p-i-n diodes are bonded on each patch. The unit-cell has been fabricated and characterized in a specific waveguide simulator. The measurement results are compared to the simulated ones and show minimum transmission loss in the range 1.5 - 2.3 dB. The 3-dB fractional bandwidth is in the range 10.1 - 12.1%.
TL;DR: In this paper, a dual-band dual-circularly polarized (CP) reflector is proposed to radiate independently shaped beams in the desired directions for each polarization in each band.
Abstract: Reflectarrays (RAs) offer low-cost and low-profile solutions for reflector antennas that are polarization and frequency selective. These features augment their capabilities for point-to-point communications compared to conventional reflectors. Here, a dual-band dual-circularly polarized (CP) RA that can radiate independently shaped beams in the desired directions for each polarization in each band is proposed. The RA is composed of a dual-band dual-linearly polarized (LP) RA and a dual-band LP-to-CP polarizer. The proposed RA can be employed to reduce the number of the required apertures for a four-color multiple spot beam coverage implemented using a single-feed-per-beam configuration from four to two. The underlying unit cell of the proposed RA is designed for 18.3–18.8 GHz and 27.0–27.5 GHz. It provides a 323° phase shift in the lower band and 381° phase shift in the higher band while maintaining a cross-polarization level better than 15 dB in both bands and excellent decoupling between the two bands. An offset-fed RA is designed, fabricated, and measured.
TL;DR: In this article, a dual-band coaperture reflector antenna which sustains the 3.5 GHz band and the 28 GHz band simultaneously is proposed, which allows a switch working mode or dualband working modes to accommodate different application scenarios.
Abstract: A novel dual-band coaperture reflector antenna which sustains the 3.5 GHz band and the 28 GHz band simultaneously is proposed in this article. It allows a switch working mode or dual-band working modes to accommodate different application scenarios. To achieve high efficiencies simultaneously at dual bands, a shared aperture strategy is proposed for the reflector antenna with a large frequency ratio and small aperture. A very compact composite feed consisting of a pair of dipoles and a conical horn is designed to illuminate a shaped axially displaced ellipse (ADE) reflector antenna. At the higher frequency band, the antenna is a classical ADE design. But at the lower frequency band, it is actually a single reflector. The main reflector acts as a back cavity for the lower band dipole pair which is fed by a coaxial cavity with a length of only 5/8 wavelength and the subreflector works like a director of the low-band feed. The measured antenna with aperture diameters of $2.4\lambda $ at 3.6 GHz and $18.7\lambda $ at 28 GHz achieves total efficiencies of 42% and 47%, respectively.
TL;DR: In this article, a GaN-on-Si MMIC Low-Noise Amplifier (LNA) working in the Ka-band is shown. The chosen technology for the design is a 100 nm gate length HEMT provided by OMMIC foundry, and the amplifier presents an average noise figure of 2.4 dB, a 30 dB average gain value, and input/output matching higher than 10 dB in the whole 34.5 Ghz design band.
Abstract: In this paper a GaN-on-Si MMIC Low-Noise Amplifier (LNA) working in the Ka-band is shown. The chosen technology for the design is a 100 nm gate length HEMT provided by OMMIC foundry. Both small-signal and noise models had been previously extracted by the means of an extensive measurement campaign, and were then employed in the design of the presented LNA. The amplifier presents an average noise figure of 2.4 dB, a 30 dB average gain value, and input/output matching higher than 10 dB in the whole 34–37.5 Ghz design band, while non-linear measurements testify a minimum output 1 dB compression point of 23 dBm in the specific 35–36.5 GHz target band. This shows the suitability of the chosen technology for low-noise applications.
TL;DR: In this article, a dual-linearly polarized (dual-LP) TA panel based on the interleaving technique combined with an add-on broadband polarizer is proposed to generate independent right-handed circular polarization (CP) (RHCP) and left-handed CP (LHCP) beams.
Abstract: This communication describes the performance of the dual-circularly polarized transmitarray antennas at the Ka -band with independent radiation characteristics. The proposed antenna architecture consists of a dual-linearly polarized (dual-LP) TA panel based on the interleaving technique combined with an add-on broadband polarizer to generate independent right-handed circular polarization (CP) (RHCP) and left-handed CP (LHCP) beams. This offers both dual-LP and dual-CP operation depending on the topology of the polarizer. The LP unit-cell is designed to achieve a 3 bit phase resolution, and the dual-LP TA panel is made of two interleaved single-LP subarrays with $52\times52$ and $53\times53$ elements operating in 45° and 135° single LP, respectively. The polarizer transforms the dual-LP into dual-CP while keeping the radiation independence of each polarization across the Ka -band. The experimental results obtained with three different prototypes pointing up to 50° validate the proposed concepts.
TL;DR: In this article, a reflectarray is designed to produce two adjacent beams per feed in orthogonal circular polarization (CP) simultaneously at transmit (Tx) and receive (Rx) frequencies in the Ka band.
Abstract: This contribution describes the design of a reflectarray to produce two adjacent beams per feed in orthogonal circular polarization (CP) simultaneously at transmit (Tx) and receive (Rx) frequencies in the Ka band. The discrimination in CP is achieved by the variable rotation technique (VRT), whose dual band operation is validated for the first time by the manufacture and measurement of a 25 cm $\times \,\, 25$ cm reflectarray demonstrator. Moreover, an optimization procedure has been implemented to improve the narrowband performance of the VRT (which leads to high cross-polar levels when the VRT is applied). The reflectarray prototype has been designed to deviate by ±5° the beams radiated by a dual-CP feed-horn at Tx and Rx frequencies in the $Ka$ band (20/30 GHz). The results are satisfactory and validate the concept of generating two spaced beams in orthogonal CP and dual band by the VRT with a single feed. This concept can be suitable for multiple spot satellites in the $Ka$ band, enabling a reduction in the number of antennas and feeds needed to provide the multispot coverage.
TL;DR: In this paper, two kinds of high compression electron gun with the solid or hollow beams, the derivative electron optics systems using the compact permanent magnet uniform focusing and the shared efficient interaction circuit based on the multigap ladder cavity, have been studied in detail and well designed through a mass of calculations.
Abstract: The Ka -band extended interaction klystrons (EIK) have been developed at the Institute of Electronics, Chinese Academy of Sciences (IECAS), to satisfy the requirement for the high-power millimeter-wave sources in scientific researches. In this work, two kinds of high compression electron gun with the solid or hollow beams, the derivative electron optics systems using the compact permanent magnet uniform focusing and the shared efficient interaction circuit based on the multigap ladder cavity, have been studied in detail and well designed through a mass of calculations. After the mechanical design, finely manufacturing, and a series of technical processes, the Ka -band EIK prototype tubes have been successfully built and tested. For the solid beam scheme, the maximum output power achieves 20 kW in the bandwidth of 60 MHz, and, correspondingly, the gain of 53 dB and the efficiency of 24% are observed. The measured −1 and −3 dB bandwidths are about 220 and 350 MHz, respectively. Meanwhile, the beam transmission is excellent, that is over 97% in dc state and over 90% in RF operation. For the hollow beam case, an over 91% dc transmission test has finished.
TL;DR: In this article, a folded waveguide traveling wave tube (FWG-TWT) composed of a folding waveguide slow wave structure (SWS) and a compact lumped resistance metamaterial absorber (LR-MMA) as a sever load is proposed.
Abstract: A Ka -band, folded waveguide traveling wave tube (FWG-TWT) composed of a folded waveguide (FWG) slow wave structure (SWS) and a compact lumped resistance metamaterial absorber (LR-MMA) as a sever load is proposed in this article. The LR-MMA consists of five resonant rings with a metallic ground plane and a separating silica layer. Lumped resistances are used and concentrated resistances are added at the opening of the resonant ring to match the surface impedance of the LR-MMA with that of the metallic waveguide. Simulation results show that the proposed LR-MMA has an absorption bandwidth of 3 GHz at 34-GHz center frequency with absorption exceeding 90%. A FWG-TWT using this LR-MMA is simulated; the output power of this traveling wave tube (TWT) is 112.5 W at 34 GHz, corresponding to a gain of 51.5 dB. The performance of the FWG-SWS using the LR-MMA is similar to that of the FWG-SWS using a wedge sever (WS). For this FWG-SWS, the sever load length of the proposed metamaterial attenuator (MMA) is 0.5 mm, which is much shorter than 9.4 mm of the traditional WS. The LR-MMA is suitable for microfabrication technology and it can be easily assembled with a FWG-SWS, which is helpful for achieving an integrated SWS for the TWT.
TL;DR: A Ka-band receiver front-end for future CubeSats Low-Earth Orbit (LEO) to Geostationary (GEO) inter-satellite links and a noise injection circuit capable of measuring and calibrating the receiver gain, also during in-orbit operation are proposed.
Abstract: This paper proposes a Ka-band receiver front-end for future CubeSats Low-Earth Orbit (LEO) to Geostationary (GEO) inter-satellite links. The receiver is able to support very high data rates (up to 100 Mbit/s) in Quadrature Phase-Shift Keying (QPSK) when in the line of sight of a GEO satellite that is equipped with a steerable 70-cm antenna and transmitting a 25-W signal. The originality of the proposed approach is twofold. First we will demonstrate the receiver feasibility based on a class of miniaturized and low-cost microwave integrated circuits, currently available on the market. In particular, our receiver is based on a novel combination of integrated Low-Noise Amplifiers (LNA) with an image rejection filter, the latter exploiting the Substrate Integrated Waveguide (SIW) technology. An optimization of the via placement proved to be able to reduce the need for shielding apparatuses, thus simplifying the mechanics and reducing mass, volume and hardware costs. Secondly, we will propose a noise injection circuit capable of measuring and calibrating the receiver gain, also during in-orbit operation. Self testing capabilities are particularly relevant for CubeSats because the usage of commercial components poses serious reliability issues.
TL;DR: In this article, an axial corrugated horn covering the full Ka-band (26.5-40 GHz) was designed and developed based on modal analysis, which showed good beam symmetry and crosspolarization level better than 29 dB in the principal planes over the frequency band.
Abstract: This letter presents design and development of an axial corrugated horn covering the full Ka-band (26.5–40 GHz) based on modal analysis. Physical parameters of corrugation steps are studied in terms of modal power coupled into the dominant and higher order modes. This gives physical insight into the influence of design parameters on the radiation pattern. Design steps based on the modal power coupling are discussed. The designed horn is fabricated using three-dimensional metal printing. Measured radiation pattern show good beam symmetry and cross-polarization level better than 29 dB is achieved in the principal planes over the frequency band.
TL;DR: In this paper, a dual-band linear polarization (LP) to circular polarization (CP) converter is presented using a novel design procedure based on geometric parameters optimization of a meta-array.
Abstract: Polarization converters play an important role in modern communication systems, but their wide and multiple band operation to facilitate volume and size reduction is quite challenging. In this letter, a dual-band linear polarization (LP) to circular polarization (CP) converter is presented using a novel design procedure based on geometric parameters optimization of a meta-array. For dual-band operation, the concept of mutual interaction of two distinct resonators is used. Step-by-step design procedure is proposed and an example is presented to convert incident x ( y ) polarization into transmitted left-hand circular polarized (LH-CP) [right-hand circular polarized (RH-CP)] in Ku band (15.15–19.5 GHz) and RHCP (LHCP) in Ka -band (33.1–39.05 GHz). After performing model-based theoretical paradigm analysis, and full-wave simulation and optimization, the converter is fabricated and the measurements are performed with a vector network analyzer. The measured results, close to simulation results, depict the validity and reliability of the design. The proposed meta-array is ultrathin, wideband, and polarization diverse, which is very suitable for wide range of applications including millimeter-wave-communication.
TL;DR: In this paper, a 20kW average power Ka-band gyro-traveling wave tube (gyro-TWT) with a cut-off waveguide section is presented and verified by hot test experiment for the first time.
Abstract: In this letter, a 20-kW-average-power Ka-band TE01 mode gyro-traveling wave tube (gyro-TWT) with a cut-off waveguide section is presented and verified by hot test experiment for the first time. To improve the average output power, the new type gyro-TWT adds a cut-off waveguide in high frequency beam-wave interaction circuits. The large signal nonlinear theory calculations and particle in cell (PIC) simulations show that the new type gyro-TWT has broadband and high-power output performances. The hot test experiment shows that the measured maximum average power is 20.3 kW at 34 GHz, corresponding to a saturated peak power of 169.2 kW, a saturated gain of 52 dB, an efficiency of ~26.9%, and 3 dB bandwidth of 3.2 GHz.
TL;DR: In this paper, a relativistic backward-wave oscillator (RBWO) operating in the TM02 mode was investigated theoretically and experimentally, and the experiment was done on the SINUS-881 accelerator, and with the diode voltage and current at 580 kV and 3.6 kA, respectively, at a guiding magnetic field of 1 T, the RBWO produced a microwave pulse with a power as high as 360 MW at a central frequency of 29.3 GHz.
Abstract: A Ka -band relativistic backward-wave oscillator (RBWO) operating in the TM02 mode is researched theoretically and experimentally in this article. The RBWO can overcome the disadvantages of a traditional RBWO, such as small size and low-power capability, when the operating frequency goes to the millimeter-wave band and is more suitable for adopting a lower-guiding magnetic field. The mode-selection mechanisms in the RBWO ensure that the electron beam interacts with the negative first-harmonic wave of the TM02 mode efficiently. The particle-in-cell (PIC) simulation preformed the 490-MW output power at a frequency of 29.3 GHz. The experiment was done on the SINUS-881 accelerator, and with the diode voltage and current at 580 kV and 3.6 kA, respectively, at a guiding magnetic field of 1 T, the RBWO produced a microwave pulse with a power as high as 360 MW at a central frequency of 29.3 GHz. The dependence of microwave power on diode voltage coincides with PIC simulation. Pulse shortening as well as severe bombarding damage of the electron beam on the postcascaded resonators were observed. By increasing the guiding magnetic field to 1.26 T, the pulsewidth was evidently improved.
TL;DR: In this paper, a low-profile broadband polarizing reflector is proposed to convert dual linear polarization (LP) into dual circular polarization (CP) in the Ka-band.
Abstract: This article presents a novel low-profile broadband polarizing reflector to convert dual linear polarization (LP) into dual circular polarization (CP). The polarizing cell is based on printed dipole technology and presents a wideband performance in Ka -band. The dimensions of the printed dipoles are adjusted cell by cell to improve the reflection phase performance against variations in the incidence angles or in the cell dimensions. A 25 cm flat polarizing reflector demonstrator has been designed, fabricated, and tested. The design has been optimized for transmit (19.2–20.2 GHz) and receive (29–30 GHz) frequencies in Ka -band, but the broadband behavior of the cell provides satisfactory results also at the intermediate frequencies. The measured patterns show a good agreement with the simulations, with an axial ratio lower than 1.8 dB within the 19.2–30 GHz band. The proposed polarizing reflector can be used for novel multibeam antenna configurations to produce multispot coverage in Ka -band with a smaller number of apertures.
21 Dec 2020-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: In this article, an electromagnetic design of a compact linearizer standing wave (SW) accelerating structure is presented, which operates on the π mode at 35.982 GHz, which is the third harmonic with respect to the Linac frequency (11.994 GHz).
Abstract: There is a strong demand for accelerating structures able to achieve higher gradients and more compact dimensions for the next generation of linear accelerators for research, industrial and medical applications. In the framework of the Compact Light XLS project, an ultra-high gradient higher harmonic RF accelerating structure is needed for the linearization of the longitudinal phase space. In order to determine the maximum sustainable gradients in normal conducting RF powered particle beam accelerators with extremely low probability of RF breakdown, investigations are in progress for using short accelerating structures in the Ka-band regime. We here report an electromagnetic design of a compact linearizer standing wave (SW) accelerating structure. The cavity has a length of about 8 cm and operates on the π -mode at 35.982 GHz, which is the third harmonic with respect to the Linac frequency (11.994 GHz). The accelerating gradient is 100 MV/m and the cavity geometry is optimized in order to minimize the surface peak electric field.
TL;DR: In this paper, a low-cost and low-profile $Ka$ -band passive phasedarray antenna (PAA) using continuously tunable substrate-integrated waveguide (SIW) phase shifter is presented.
Abstract: A low-cost and low-profile $Ka$ -band passive phased-array antenna (PAA) using continuously tunable substrate-integrated waveguide (SIW) phase shifter is presented in this article. The phase shifting mechanism is based on perturbing the electric field of the slotted SIW (SSIW) line by putting a high dielectric constant slab over the slot of SIW. A systematic approach based on a simple transmission line (TL) circuit model which can support different modes is developed as a fast method for design optimization. It provides insightful physical understanding of the operating mechanism of the proposed phase shifter. In addition, a fully verified TL model of the $1\times 4$ SIW PAA is presented and used to predict and optimize the overall reflection coefficients and radiation patterns at different scanning angles. The TL circuit model is verified by full-wave simulations. As a design example, a $1\times 4$ SIW-based phased-array is designed, fabricated, and measured to validate phase shifter performance and capabilities. The prototype exhibits a continuous beam scanning range from −20° to +20° covering the whole operating band of 29–31 GHz.
TL;DR: In this article, a polarization converter is proposed for triband simultaneous microwave transmission in ${X}$, Ku, and Ka bands, which converts the incident linearly polarized (LP) waves into transmitted circular polarized (CP) waves in three frequency bands.
Abstract: In this letter, a polarization converter is proposed for triband simultaneous microwave transmission in ${X}$ , Ku , and Ka bands. It converts the incident linearly polarized (LP) waves into transmitted circular polarized (CP) waves in three frequency bands. The unit cell of the converter is composed of ultrathin bilayered metasurface having a thickness of about $\lambda $ /40, patterned with a square ring and five squares conductor patches diagonally intersecting each other. The step-by-step design guideline for LP-to-CP conversion is presented with a converter example whose operational bands are 7.317–9.58, 25.45–31.4, and 35.37–42.167 GHz. To verify the design, a sample consisting of $20\times20$ elements is fabricated using a standard printed circuit board (PCB) fabrication process and tested inside the anechoic chamber. Close agreement between the simulated and measured results depicts the validity and reliability of the proposed design.