High Power Handling Capacity Research Articles

Broadband Continuous Transverse Stub (CTS) Array Antenna for High-Power Applications.

A continuous transverse stub (CTS) array antenna with broad bandwidth and high-power handling capacity is proposed in this paper. The technologies of multi-step impedance matching and T-shaped electromagnetic band-gap (EBG) loading are utilized, which improved the antenna operating frequency bandwidth. An H-plane lens horn is used to feed the CTS array. As a result, a good bandwidth capability of more than 32% is achieved, with a gain variation less than 3.0 dB. The measured sidelobe level (SLL) is below -18 dB in the entire frequency range. Moreover, the power handling capacity of the antenna is more than 80 MW and can reach the GW level after arraying, which indicates that this antenna has application potential in the high-power microwave (HPM) field.

A High-Power and Broadband GaN SPDT MMIC Switch Using Gate-Optimized HEMTs

A high-power, broadband monolithic microwave integrated circuit (MMIC) single-pole double-throw (SPDT) switch is designed with gate-optimized high-electron-mobility transistors (HEMTs) using AlGaN/Gallium nitride (GaN) technology. The foot length of the gate is varied from 200 to 250 nm, and the head length is varied from 500 to 750 nm in the T-gate structure to optimize the radio frequency (RF) performance. The SPDT switch is designed in a series–shunt–shunt topology using gate topology as a design parameter. The switch has achieved an insertion loss better than 0.75 dB throughout the 3.5–13.5-GHz bandwidth. It can transmit 30-W output power at 0.1-dB compression point and handle 47.5-dBm input power at <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${P}_{\textrm{1\,dB}}$</tex-math> </inline-formula> . The isolation is above 25 dB, and the return loss is better than 11 dB. With its low insertion and high power-handling capacity in broadband, the SPDT switch shows state-of-the-art performance for high-power communication systems and radar applications.

An L-Band Leaky-Wave Array Antenna for High-Power Microwave Applications

This work seeks a novel design for a compact leaky-wave array antenna for high-power microwave (HPM) applications. The leaky-wave antenna is made of a rectangular waveguide with closely spaced non-resonant slots in the broad-wall of the waveguide. By this means, more slots can be set within a unit length and less energy will radiate from each slot, then higher power-handling capacity can be achieved. An L-band leaky-wave waveguide antenna centered at 1.57 GHz is designed and experimentally studied. The results show that the radiation efficiency of the antenna is 97% and the power-handling capacity of a single waveguide exceeds 1.3 GW. In addition, a 5-waveguide array antenna is also designed. The antenna array has an aperture efficiency of 76.6% and the beam scanning range can reach ±40° in H-plane, which would be suitable for many HPM applications.

Compact, High Power Capacity, and Low Insertion Loss Millimeter-Wave On-Chip Limiting Filter With GaAs PIN Technology

In this paper, a collaborative design of compact, high-power capacity, and low insertion loss millimeter-wave limiting filter using gallium arsenide (GaAs) PIN technology is presented. Parallel topology is employed to distribute the PIN diodes of the first stage of limiting circuit for high power handling capacity. In order to reduce the circuit size, the filtering function structure is incorporated into the limiter. Four transmission zeros (TZs) are introduced to improve the out-of-band suppression performances of the limiting filter. By utilizing the inductive short-circuited stub, a parallel resonator is introduced to exhibit the passband characteristic. Semi-lumped and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -type topologies are employed to reduce the size of the conventional quarter-wavelength transmission line and introduce several TZs within the stopband. An on-chip limiting filter sample is fabricated by the GaAs PIN process and occupies an area of only <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1.1\times 0.9$ </tex-math></inline-formula> mm2. It is measured with the insertion loss of 1.67 dB at the center frequency of 35 GHz, the stopband suppression of better than 20 dB, and the tolerable input power of greater than 40 dBm. Compared with the traditional designs, good features of high-power capacity, low insertion loss, and miniaturization are obtained with the presented on-chip limiting filter.

Realization of a wide steering end-fire facet optical phased array using silicon rich silicon nitride.

The design, fabrication, and characterization of a 16-element optical phased array (OPA) using a high index (n = 3.1) silicon-rich silicon nitride (SRN) is demonstrated. We present one-dimensional beam steering with end-fire facet antennas over a wide steering range of >115° at a fixed wavelength of 1525 nm. A beam width of 6.3° has been measured at boresight, consistent with theory. We demonstrate SRN as a viable material choice for chip-scale OPA applications due to its high thermo-optic coefficient, high optical power handling capacity [negligible two-photon absorption (TPA)], wide transparency window, and CMOS compatibility.

Design and experimental research of a compact directional coupler for X-band relativistic triaxial klystron amplifier.

To realize online measurement of power, frequency, and phase for a modularized relativistic triaxial klystron amplifier in a narrow space, a compact directional coupler with high directivity, high power handling capacity, and large bandwidth has been investigated numerically and experimentally. The method with coupling holes distributed in both the longitudinal and lateral directions is proposed, and the simulation results indicate that when two holes are employed, directivity larger than 20 dB is achieved over a 300MHz bandwidth in the X-band and the maximal electric field strength is controlled to be 198.5kV/cm with 1 GW power injection, while the whole coupler longitude is optimized to be as short as 50mm. High power experiments have been performed with a 10GHz relativistic triaxial klystron amplifier, and the results show that the measured power, frequency, and phase shift of the directional coupler have good agreement with the results obtained in the far-field.

Dual mode dielectric resonator filter with a new source coupling slot approach

In this study, a Ka-band dual-mode dielectric resonator filter is studied. As a new approach, to mount the dielectric resonator on the input coupling slot, a mechanical protrusion is designed. By use of this structure, controlled source coupling and excitation via waveguide can be allowed. Compared with coaxial cable excitation, waveguide excitation allows high power handling capacity and less insertion loss.

A dielectric embedded reflectarray for high-power microwave application.

To solve the problem of the large axial size of high-power microwave (HPM) reflectarray antenna and difficulty in vacuum packaging, a dielectric is introduced in the design of the antenna element. On this basis, a dielectric embedded metasurface reflectarray antenna (DEMRA) with high power handling capacity and wide-range beam scanning capability is proposed and fabricated. Compared with traditional HPM antennas, the DEMRA does not need to be sealed and can work directly in open-air conditions. The DEMRA can realize free regulation of the radiation beam within a cone angle of 90° and has a power handling capacity of 1 GW/m2. As verification, a protype working at 10GHz is fabricated and low-power experiments are carried out. Experimental results are consistent with the simulation, proving that the DEMRA has a bandwidth exceeding 600MHz. During the scanning process, the aperture efficiency is always higher than 48.98%, and the side lobe level remains below -15 dB. At the same time, the cross-polarization component is less than -15 dB, while the main lobe-axis ratio remains within 4.5 dB, confirming its beam scanning capability.

Theoretical and Experimental Investigations on a 90° Compact TM01-TE11 Mode Converter for RBWO

Mode converter is one of the most important devices in the high-power microwave (HPM) applications. To conduct an in-depth research for the orthogonal mode converter, a novel 90° compact TM₀₁-TE₁₁ circular waveguide converter working at 9.7 GHz is proposed in this article. This design innovatively integrates the traditional mode converter with 90° bend techniques based on the mode coupling theory, which ensures a compact structure and high-power handling capacity. Calculated and simulated results illustrate that the maximum conversion efficiency of the converter at central frequency reaches 99.4% when the structure length is 535 mm, and the bandwidth reaches 680 MHz when the conversion efficiency exceeds 95%. For demonstration, a prototype is fabricated, and the corresponding experiments are investigated. According to the S-parameter measurement, it has a high conversion efficiency at central frequency. Meanwhile, the high-power performance is conducted by connecting it with a relativistic backward oscillator (RBWO), and the converter works stably under a maximum output power of 4 GW. The good agreement of the theoretical analyses, simulations, and experimental results indicates the feasibility of the proposed converter.

Solar PV Fed DC Microgrid: Applications, Converter Selection, Design and Testing

In this research article, major applications which use solar PV fed DC microgrid for either their routine operation or gain additional advantages over existing electrical power architecture are elaborated. The role of power converters in interfacing the input with the required output is highlighted. The advantages of solar PV fed DC microgrid are demonstrated by designing and testing a non-isolated high gain high power (HGHP) DC-DC converter to meet the DC distribution voltage level. The proposed converter is synthesized by using hybrid combination of three-phase interleaved boost converter (IBC) with voltage lift technique along with coupled inductors (CIs) and voltage multiplier cell (VMC). The proposed concept is practically demonstrated and the adopted design techniques are validated using simulation and experimentation. The proposed converter with 60V/1.1kV, 100kHz and 3kW rating operates at 92.3% full-load efficiency under practical conditions. Due to the gain extension techniques adopted, the switches used in the proposed converter are subjected to a voltage stress which is only 36% of the output voltage. Due to interleaving technique, the input current ripple and the current stress on the switches are only 15% and 33% of the input current respectively. Key performance parameters of this converter are thoroughly investigated and benchmarked with some state-of-the art converters to appreciate the salient features of the presented converter. The ability to yield higher voltage gain at safe duty ratio, high power handling capacity, low voltage and current stresses on the power switches are the main advantages of the proposed converter.

A Power Management Scheme for Grid-connected PV Integrated with Hybrid Energy Storage System

The penetration of renewable energy sources (RESs) in the distribution system becomes a challenge for the reliable and safe operation of the existing power system. The sporadic characteristics of sustainable energy sources along with the random load variations greatly affect the power quality and stability of the system. Hence, it requires storage Systems with both high energy and high power handling capacity to coexist in microgrids. An efficient energy management structure is designed in this paper for a grid-connected PV system combined with hybrid storage of supercapacitor and battery. The combined supercapacitor and battery storage system grips the average and transient power changes, which provides a quick control for the DC-link voltage, i. e., it stabilizes the system and helps achieve the PV power smoothing. The average power distribution between the power grid and battery is done by checking the state of charge (SOC) of a battery, and an effective and efficient energy management scheme is proposed. Additionally, the use of a supercapacitor lessens the current stress on the battery system during unexpected disparity in the generated power and load requirement. The performance and efficacy of the proposed energy management scheme are justified by simulation studies.

Novel Reconfigurable Full-Metal Cavity-Backed Slot Antennas Using Movable Metal Posts

Novel design concept of reconfigurable full-metal cavity-backed slot antennas (CBSAs) using movable metal posts is proposed in this article. It is found that the cavity mode with purely directional electric field is only affected by the metal post to be placed in parallel to its electric field. Thus, two orthogonal cavity modes TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">101</sub> and TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">011</sub> can be perturbed by two respective metal posts so as to independently tune the resonant frequencies of these two modes. Electromagnetic energy of the cavity modes can be radiated out through the slots on the top wall of the cavity. In this context, reconfigurable slot antennas with different functionalities, such as single-band, dual-band, dual-mode wideband, the tunable frequency with constant bandwidth, and tunable bandwidth with constant frequency, are thus constituted to demonstrate its attractive design feasibility. The frequency-reconfigurable cavity-back slot antenna with movable metal posts is proposed for the first time. The utilization of the metal posts allows us to achieve a continuous frequency tuning property, while the full-metal structure of the proposed antenna holds a high power-handling capacity and a high radiation efficiency. In final, a prototype of the dual-mode wideband slot antenna is designed, fabricated, and tested to reveal its total efficiency higher than 88% and stable radiation pattern over the tuning band. Good agreement between the measured and the simulated results well validates the presented design concept.

Low-Sidelobe Cavity-Backed Slot Antenna Array With Simplified Feeding Structure for Vehicular Communications

In this article, low-sidelobe cavity-backed slot antenna array with simplified feeding structure for vehicular communication is proposed. Conventional low-sidelobe antennas were realized using power dividing network to obtain the in-phase and nonuniform-amplitude excitation, which causes complicated antenna's structure and design. To tackle these challenges, a simplified feeding method without using power dividing network is introduced to design the low-sidelobe slot antenna array. The slots at the top walls serve as the radiation elements, and the slots are directly fed by the electric field of the cavity mode. Nonuniform amplitude is obtained by simply modifying the slots' sizes and positions, while the in-phase excitation of the elements is remained. The nonuse of power dividers brings out a simpler antenna structure than conventional full-metal waveguide-based antennas. Besides, the full-metal structure introduces a high power-handling capacity. Then, two linear arrays with 1 × 4, 1 × 7 elements and a planar array with 5×4 elements are presented to show the design feasibility. Finally, the 5 × 4 antenna array is fabricated and measured, which can achieve 18.2 dBi gain, -20 dB sidelobe level, 94% radiation efficiency, and -42 dB cross-polarization. Good agreement between measurement and simulation verifies the feasibility of the proposed design concept.

3-D Absorptive Energy-Selective Structures

In this article, an absorptive energy-selective structure (ESS) based on a 3-D structure mounted with p-i-n limiter diodes is proposed for achieving high-power electromagnetic protection and low reflection at the same time. Two separate transmission and absorption paths are constructed by the 3-D structure. They are activated and bypassed, respectively, under a low-power incidence with turned-off diodes generating a high-efficiency transmission window and out-of-band absorption. On the contrary, the diodes are turned on and the structure is then short-circuited under a high-power incidence, leading to high shielding effectiveness and low reflection. To demonstrate the design concept, an absorptive ESS operating at 3 GHz is designed. Cuboid absorbing material with high power-handling capacity is employed to absorb the undesired incident signals. A stepped-impedance resonator structure is constructed as the transmission path to reduce the profile of the 3-D structure. Equivalent circuit models are derived to explain the operating principle and to deduce the design guidelines. Furthermore, the absorptive ESS is fabricated and tested achieving a good agreement between simulated and measured results. High-efficiency transmission with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | > -0.7 dB under the low-power incidence, high shielding effectiveness with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">21</sub> | <; -40 dB under the high-power incidence, and low reflection with |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> | <; -10 dB are achieved at the operating frequency.

A Ku-Band Compact Disk-Beam Relativistic Klystron Oscillator Operating at Low Guiding Magnetic Field

The disk-beam relativistic klystron oscillator (DB-RKO) with the radial-line high frequency structure is one of the attractive high power microwave (HPM) sources due to its specific virtues of weak space-charge effect, high power handling capacity and strong electron collection ability. However, such a device generally exhibits a bulky volume in the radial direction, retarding its actual applications in some compact occasions. Besides, it usually saturates slowly because of the insufficient beam-wave coupling strength. For this purpose, a compact DB-RKO with a rapid saturation process is proposed and physically designed in this paper. By compressing the axial width of the electron beam drift tube suitably, the beam-wave coupling strength is enhanced clearly and the saturation process is accelerated significantly. The whole beam-wave interaction structure is shortened with a radial length of about 5 cm. Besides, in order to increase the device compactness further, an improved magnetic-excited method is presented to enhance the magnetic field in the diode area by introducing a pair of soft-magnets. Furthermore, with the guiding of a low magnetic field of 0.4 T, the compact DB-RKO is experimentally demonstrated to be capable of generating Ku-band HPM radiations with a peak power of 810 MW, a power conversion efficiency of 28%, a center frequency of 14.19 GHz and a pulse duration of about 27 ns. The proposed DB-RKO is promising for the package of the permanent magnets which are preliminarily designed in this paper.

Design and preliminary experiment of a disk-beam relativistic klystron amplifier for Ku-band long-pulse high power microwave radiation

Spatial coherent combination of multiple high power microwave (HPM) sources is considered as a promising scheme to improve the equivalent radiation power of the HPM system dramatically. Relativistic klystron amplifier (RKA) is one of the most suitable sources for the coherent power combination owing to its specific capabilities of stable microwave frequency and controllable phase. However, the RKAs operating at high frequency-band are severely limited by the problems of the intense space-charge effect and radio frequency breakdown. The radial-line HPM sources driven by the disk-shape electron beam may provide the potential to alleviate this issue due to its attractive features of the weak space-charge effect, the high power handling capacity, and the strong electron collection ability. In this paper, a disk-beam relativistic klystron amplifier (DB-RKA) is proposed and physically designed aiming to generate long-pulse HPM radiation at Ku-band. The physical idea, design principles, and simulation results are presented in detail. In a preliminary experiment, the disk-shape intense electron beam is well focused with an axial-width of 1.2 mm by an improved magnetic-excited method. Furthermore, the DB-RKA is demonstrated to be capable of generating Ku-band HPMs typically with peak power of 320 MW, pulse duration of 100 ns, and gain of 42 dB.

CMOS series-shunt single-pole double-throw transmit/receive switch and low noise amplifier design for internet of things based radio frequency identification devices

The incompatibility between current RFID standards has led to the need for universal and Wi-Fi compatible RFID for IoT applications. Such a universal RFID requires an SPDT and an LNA to direct and amplify the received raw signal by the antenna. The SPDT suffers from low isolation, high insertion loss and low power handling capacity whereas the LNA suffers from bulky die area, lesser Q factor, limited tuning flexibility etc. because of passive inductor usage in current generation of devices. In this research, nano-CMOS inductorless SPDT and LNA designs are proposed. The SPDT adopts a series-shunt topology along with parallel resonant circuits and resistive body floating in order to achieve improved insertion loss and isolation performance whereas the LNA design is implemented with the gyrator concept in which the frequency selective tank circuit is formed with an active inductor accompanied by the buffer circuits. The post-layout simulation results, utilizing 90nm CMOS process of cadence virtuoso, exhibit that our SPDT design accomplishes 0.83dB insertion loss, a 45.3dB isolation, and a 11.3dBm power-handling capacity whereas the LNA achieves a peak gain of 33dB, bandwidth of 30MHz and NF of 6.6dB at 2.45GHz center frequency. Both the SPDT and LNA have very compact layout which are 0.003mm 2 and 127.7 μm 2 , respectively. Such SPDT and LNA design will boost the widespread adaptation of Wi-Fi-compatible IoT RFID technology.

Design of a millimeter wave helical reflectarray antenna with high power handling capacity

A millimeter-wave high-power handling capacity circularly polarized shared-aperture transceiver reflectarray antenna is proposed and designed. The short helical reflection antenna is proposed to be the reflectarray element. The 360° phase shift can be achieved by rotating the helical element. A flat-top shaped beam shared-aperture transceiver array antenna feed is designed to improve the efficiency and power capacity of the reflectarray antenna. The reflectarray with the aperture size of 49.5 × 49.5 mm2 is designed and simulated. The full-wave simulation results show that at center frequency of 30 GHz, the gain of the antenna is 22.5 dB with the efficiency of 57.8%, and the axis ratio is 0.8 dB. In the range of 26 to 34 GHz, the reflection coefficient is lower than -17.8 dB, with the relative bandwidth of 26.7%. The 1-dB gain bandwidth is 19.4%. Under air condition, the power capacity of the element antenna is 898 W, and the power capacity of the reflectarray antenna is 19.2 kW.

A Compact and Broadband Directional Coupler for High-Power Radio Frequency Applications

In this letter, a compact and broadband directional coupler is proposed for high-power radio frequency applications in the frequency band of 5–150 MHz. The coupler is composed of a suspended semiflexible coaxial cable and a series of equalizers composed of lumped components. Such design exhibits excellent performance in high power handling capacity (~kW), high directivity (~35 dB), low return loss (>20 dB), and flat coupling coefficient (45 ± 1.3 dB).

Field distribution and dispersion characteristics of a coaxial oversized slow wave structure with deep corrugation operating on high-order mode

Compared with the traditional slow wave structure (SWS) with a fundamental mode, the oversized SWS with deep corrugation operating in a high-order mode has a higher power handling capacity and lower beam density. However, for the new structures, the traditional Floquet harmonic expansion method is not applicable in analyzing the dispersion characteristics of the slow wave structure. In this paper, we present a new analysis method based on the mode matching method, which is suitable for the arbitrary depth of corrugation of SWS. Besides, as the field matches at the corrugated surface of inner and outer conductors, the method is applicable whether the conductors are corrugated or uniform. The method is validated by software simulation. The calculation results of the software verify the correctness of the theory and show that the theoretical calculation is more convenient. By the method we present, the dispersion characteristics, field distribution, and coupling impedance are theoretically derived and analyzed.