High-power Narrowband Research Articles

An efficient mode conversion configuration in relativistic magnetron with axial diffraction output

Relativistic magnetron with diffraction output, also known as magnetron with axial extraction, is a favorite in exploring the most compact narrow band high power microwave source. For further improving power conversion efficiency and radiation pattern without diminishing the compactness, this paper proposed an efficient mode conversion configuration in an S-band π-mode operating relativistic magnetron with diffraction output. The whole device has a total length of 290mm and a maximum diameter of 260mm. In three-dimensional particle-in-cell (PIC) simulation, an optimized outcome that the power conversion efficiency can reach 43% corresponding to 4.2GW output and the radiation pattern is similar to TE11 mode is achieved.

High power narrowband 589nm frequency doubled fibre laser source

We demonstrate high-power high-efficiency cavity-enhanced second harmonic generation of an in-house built ultra-high spectral density (SBS-suppressed) 1178 nm narrowband Raman fibre amplifier. Up to 14.5 W 589 nm CW emission is achieved with linewidth Delta nu(589) < 7 MHz in a diffraction-limited beam, with peak external conversion efficiency of 86%. The inherently high spectral and spatial qualities of the 589 nm source are particularly suited to both spectroscopic and Laser Guide Star applications, given the seed laser can be easily frequency-locked to the Na D(2a) emission line. Further, we expect the technology to be extendable, at similar or higher powers, to wavelengths limited only by the seed-pump-pair availability.

Susceptibility of CMOS IC Devices Under Narrow-Band High Power Electromagnetic Waves by Magnetron

We investigated the damage effects of CMOS IC devices manufactured using three different technologies under narrow-band high power electromagnetic (NB-HPEM) waves by magnetron. The output of NB-HPEM waves was controlled from 0 to 1 kW, and the narrow-band operating frequency was 2, 460±50 MHz. The NB-HPEM waves were propagated into a closed-ended standard rectangular waveguide for 1 s. During our investigation, six different semiconductor technologies (three CMOS AND, and three CMOS NAND devices) were tested. The CMOS IC devices showed two types of damage i) malfunction, which means that no physical damage occurred in the system and after a reset, the system returned to normal function, and ii) destruction, which means that the system incurred physical damage, and operation could not be recovered without hardware repair. We increased the electric field, and the HCT and HC series of CMOS AND and NAND devices underwent reversible malfunctions. Furthermore, the HCT and HC series of CMOS AND and NAND devices were not destroyed at the maximum electric field (E max = 23.938 kV/m). However, only the AC series of CMOS AND and NAND devices underwent reversible malfunctions and experienced permanent destruction at much higher fields. The surfaces of the destroyed CMOS devices were removed and the chip conditions were investigated with a microscope. The microscopic analysis of the damaged devices showed component and bondwire destruction such as breakthroughs and melting due to thermal effects. Our results are expected to provide fundamental data for interpreting the combined failure mechanism of digital IC devices in an intentional electromagnetic environment.

Multipoint Fiber-Optic Hot-Spot Sensing Network Integrated Into High Power Transformer for Continuous Monitoring

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> A multipoint fiber-optic temperature sensor network integrated inside a power transformer for continuous monitoring of hot-spots on windings, cellulose insulations, and oil, is demonstrated and tested. The temperature sensors are based on proprietary encapsulated fiber Bragg grating (FBG) sensors and the optical interrogation unit uses a special designed narrowband high power broadband fiber source. The fiber-optic sensing network is integrated into a 20 MVA, 345/<formula formulatype="inline"><tex>$\surd 3$</tex></formula> kV <formula formulatype="inline"><tex>$-20$</tex></formula> kV power transformer (CORE type) having 12 temperature sensing points, distributed over several physical locations inside the transformer (windings, cellulose insulators, magnetic circuit, and cooling oil entrance and exit). </para>

Susceptibility of Microcontroller Devices due to Coupling Effects Under Narrow-Band High Power Electromagnetic Waves by Magnetron

We investigated the malfunction and destruction characteristics of microcontroller devices under narrow-band high power electromagnetic (NB-HPEM) wave by magnetron. NB-HPEM wave was rated at a microwave output of 0 to 1000 W at a frequency of 2460 ± 50 MHz, and was radiated from an open-ended standard rectangular waveguide (WR-340) to free space. The influence of different reset, clock, data, and power supply line lengths was tested. The variation of the lines length was done with flat cables. The susceptibility of the tested microcontroller devices was in general, strongly influenced by clock, reset, and power supply line length, and was only slightly influenced by data line length. Furthermore, as the line length was increased, the malfunction threshold decreased as expected, because more energy was coupled to the devices. The surfaces of the destroyed microcontroller devices were removed and the chip conditions were investigated with a microscope. The microscopic analysis of the damaged devices showed component and bondwire destruction such as breakthroughs and melting due to thermal effects. Our results are expected to provide fundamental data for interpreting the combined mechanism of microcontroller devices in an intentional microwave environment.

Test Method for Measuring Bit Error Rate of Pulsed Transceivers in Presence of Narrowband Interferers

The popularity of pulse-based transceivers can be attributed to the high information rates that can be achieved in such systems compared to traditional narrowband systems. However, such systems are usually low-power and transmission efficiency is severely affected by the interference signals from other moderate to high-power narrowband transmitters. Hence, during manufacturing, pulse-based systems must be characterized and tested for bit error rate (BER) performance in the presence of narrowband interferers. Usually, at large interference levels, the BER is moderate (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> ) to high (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> ). However, at low interference levels when very few bits are in error, the BER is low (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-6</sup> - 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> ) and testing for the BER becomes time consuming. We propose a new measurement technique employing sinusoidal pulses such that the BER value obtained is significantly large (10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-3</sup> - 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-4</sup> ) even at low interference levels. BER values obtained using sinusoidal pulses are highly correlated to the actual BER values. Hence, the actual BER can be accurately estimated in a much smaller time without actually performing the standard test. This method was implemented in hardware using an Altera field-programmable gate-array development board. From the measurements, BER estimation error was less than 3%. In addition, significant reduction (up to 100 x) in test time was obtained using the proposed method.

Adaptive Prediction and Cancellation Digitization Method for Wideband Multistandard Software Radio Base-Station Receivers

In this study, a new method for digitizing a combination of different analog signals occupying significantly different bandwidths and having a very high dynamic range is proposed and analyzed. Since it is based upon signal-prediction/cancellation principles, it is referred to as adaptive prediction and cancellation digitization (APCD) method and is applied to various families of signals simultaneously received by a multistandard software radio (SWR) base-station receiver. It is shown theoretically and by means of computer simulations that the APCD method can effectively reduce the high dynamic range of the signals before digitization takes place. Hence, the stringent analog-to-digital-converter (ADC) resolution requirements imposed by the operation of such SWR base-station receivers can be significant relaxed. The signal dynamic-range reduction is achieved by applying appropriate signal processing techniques, e.g., autoregressive (AR) and periodic autoregressive (PAR) prediction. Such techniques allow accurate prediction and subsequent cancellation of high-power narrowband signals present among the composite received analog signal. As these signals usually have cyclostationary statistical characteristics, analysis and performance evaluation of AR and PAR predictors, when used to predict cyclostationary signals, were presented. A new adaptive algorithm for implementing the PAR predictor is also proposed, and its validity is justified by theoretical analysis as well as by various performance evaluation results obtained by means of computer simulations

Overview of Four European High-Power Microwave Narrow-Band Test Facilities

This paper presents an overview of the key high-power microwave (HPM) narrow-band source technologies and their related HPM open-area radio-frequency (RF) test capabilities within four European counties (France, Germany, Sweden, and the U.K.). The test facilities are described and a brief description of further developments is given covering both power limitations and recent research interests.

High-power narrowband millimeter waves generated by the electron beam emitted from the plasma focus

High-power narrowband millimeter-wave pulses (P ≈ 1 MW, Δf/ f < 5 x 10 −2 , duration < 600 ps) have been observed at a 1.6 kJ plasma focus. The microwaves are generated in the frequency range 30 GHz < f < 120 GHz by a periodic train of electron bunches emitted from the plasma. The power of the harmonics 2 f and 3 f indicates a width of the electron bunches below 4 ps and a maximum diameter of the beam of 1 mm.

Suppression of stimulated Brillouin scattering during transmission of high-power narrowband laser light in monomode fibre

A method is described for transmitting narrowband laser radiation over long lengths of monomode fibre at high power levels without suffering nonlinear attenuation due to stimulated Brillouin scattering. The technique could be applied to long-distance coherent optical data transmission.

Transmission of narrow band high power laser radiation through optical fibers

Due to nonlinear optical processes, especially stimulated Brillouin scattering and four-wave-mixing, narrow band laser radiation cannot be transmitted unaffected through optical fibers at higher power levels. Threshold conditions for the various orders of generated sidebands and the emission spectrum are theoretically and experimentally investigated with particular emphasis on the reflectivities at the fibers ends. In addition to the increase in spectral width, also a limit of the transmission ratio of 25% at high power level was found.

Efficient oscillator–amplifier dye laser pumped by a frequency-doubled Nd:YAG laser

A high-power high-efficiency narrowband dye laser pumped by a frequency-doubled Nd:YAG laser has been constructed and characterized. The dye laser consists of a Hansch-type oscillator and a simple efficient amplifier. The spectral bandwidth is 0.06 cm(-1) The oscillator efficiency saturates at 16%, the amplifier efficiency at 40%, and the total system efficiency reaches 30% for a total pump energy of 6 mJ.