The fundamental electromagnetic wave of a single-wire line in a weakly absorbing medium

An approximate dispersion equation valid over a wide frequency range is obtained from the dispersion equation for the symmetric E ₀₀ wave (the Sommerfeld wave) propagating along a finite-conductance metal wire embedded in a lossy dielectric. The boundaries of this frequency range are determined. A technique is developed for solution of the obtained approximate dispersion equation in the frequency band where the pronounced skin effect is observed. The ratio of the wire radius to the thickness of the skin layer is assumed to be no less than 10. This technique is applied to calculate the longitudinal and transverse propagation constants for 1.0-and 2.5-mm-radii copper wires over the frequency range 0.5 MHz to 1000 GHz.     

Effect of self-phase modulation on group-velocity dispersion measurement technique using PM-AM conversion

A report is made on the effects of self-phase modulation (SPM) on the group-velocity dispersion measurement technique using the conversion of phase-modulated signal into the amplitude-modulated signals (i.e. PM-AM conversion technique). The results show that the modulation frequency should be in the range 0.3-1 GHz to suppress the SPM-induced errors while maintaining reasonable PM-AM conversion efficiency.     

Measurement techniques in microstrip

A novel technique has been developed for measurement of dispersion and wavelength in microstrip transmission line laid down on an Al2O3 substrate. The frequency range so far investigated has been 4?12GHz, although the method could be satisfactorily used at far higher frequencies. The measurement accuracy is better than within 1%. Techniques for producing well matched transitions to any thickness substrate have also been established.     

Millimetre-wave active probe frequency-multiplier for on-wafer characterisation of GaAs devices and ICs

A millimetre-wave active probe quintupler with an output frequency range of 60 to 100 GHz has been developed. The frequency multiplier circuit was implemented in a coplanar waveguide. Using this probe along with the electro-optic sampling technique, on-wafer millimetre-wave vector measurement up to 100 GHz and time-waveform measurement at 77 GHz of test structures on a GaAs substrate have been demonstrated.<>     

A scale model for studying ground penetrating radars

A scale model developed for experimentally studying ground penetrating radars is described. The model is one-third full size and is used with transient signals that have significant frequency content within the range 150 MHz to 1.5 GHz. A unique feature is that the soil in the model is represented by an emulsion, which is mixture of mineral oil, saline solution, and a stabilizing agent. This emulsion is a scale model for red clay soil; it matches the electrical parameters of the clay, including the dispersion in the conductivity, over a ten-to-one frequency range. Typical results measured with the model are discussed. These include the measurement of the electric field transmitted by the radar into the soil and the measurement of radar signatures for pipes of various composition buried in the ground     

Selection of optimum frequencies for atmospheric electric path length measurement by satellite-borne microwave radiometers

Numerical experiments using regressions by leaps and hounds have been performed to determine the optimum frequencies for satellite-borne microwave radiometers to estimate atmospheric electrical path length over the sea. The frequency range 5-40 GHz was searched. The effect of surface wind speed, sea surface temperature, and clouds was considered in the optimum frequency selection. Our analysis indicates thatsim 0.6-cm rms accuracy is possible for one-way path length measurement using a proper pair of frequencies. The best two-channel subset selected by the leaps and bounds technique is [16.0, 21.0] GHz.     

Electromagnetic band gap coupled tri-notched miniaturized ultra-wideband antenna loaded with slot and parasitic strip

An electromagnetic band gap (EBG) coupled miniaturized tri-notched printed ultra-wideband (UWB) monopole microstrip antenna having dimensions of 22 mm × 26 mm × 1.6 mm loaded with a slot in radiating patch and a parasitic strip in the ground plane has been presented. The proposed structure incorporates a square-shaped metallic radiating patch with a square EBG structure adjacent to the microstrip feed line, a U-shaped meandered slot over the radiating element, and a U-shaped parasitic resonator at the ground plane beneath the radiating element, to reject the C-band satellite downlink (3.7 to 4.2 GHz), WLAN frequency band (5.15 to 5.85 GHz), and X-band satellite downlink (7.25 to 7.75 GHz) frequency bands, respectively. The designed antenna operates in the frequency range from 3 to 11.1 GHz, with an impedance bandwidth of 8.1 GHz and a percentage bandwidth of 114%. Modification steps incorporating into the reference antenna to achieve the desired design objectives have been discussed, along with parametric studies. The proposed design has been simulated using Ansys HFSS, and measurement has been taken using standard measurement technique and compared with the simulated results.     

Nonreciprocal wave propagation in multilayer semiconductor films at frequencies up to 200 GHz

Three multilayer gyrotropic thin-film semiconductor waveguides comprising S-I GaAs/AlAs/n-GaAs/AlGaAs in a static magnetic field of 0.15 T have been analyzed over the frequency range of 0-200 GHz. The dispersion diagrams and field distributions show nonreciprocal propagation, and forward waves and backward waves depending on the order in which the films are stacked. Potential applications such as miniature phase shifters and isolators in the frequency range of 50-100 GHz with lengths of the order of micrometers are briefly discussed.     

Technique of Broadband Measurements of Frequency Conversion Efficiency for Each Harmonique in Frequency Multipliers up to Terahertz Range

The paper describes technique of quantitative analysis of a millimeter- and submillimeter-wave range multipliers performance in particular the measurement of the frequency conversion efficiency. The output power on each harmonic produced by the multiplier can be measured separately without any changes in the setup even in the case of simultaneous emission of all harmonics including the fundamental in a frequency range up to 1 THz and well above. The measuring technique primarily developed for high resolution microwave spectroscopy is based on absorption of radiation in spectral lines of rarefied sample gas and photo-acoustic method of the absorption detection. Sensitivity independence of the detection method on frequency and well known spectral parameters of the lines provide the technique with broadbandness, high spectral resolution and power measurement reliability. Principal limits of measurable radiation power may vary from nanowatts up to hundreds of watts. The technique permits real time operation convenient, e.g., for multiplier tuning. Practical examples include measurements of harmonic generation efficiency of multipliers of 78-118 GHz fundamental frequency range, and power measurement up to 6-th harmonic of 230 GHz fundamental radiation of phase locked Backward Wave Oscillator (BWO).     

GaAs microwave MOSFET's

GaAs microwave metal-oxide-semiconductor field-effect transistors (MOSFET's) with plasma-grown native oxides as gate insulator have been fabricated using a low-temperature magnetically controlled plasma-oxidation technique. A small-signal enhancement device with the gate length of 2.0 µm has demonstrated useful unilateral power gains in the 2-8-GHz frequency range. A maximum frequency of oscillation in the enhancement device is 13 GHz. This is the highest in all enhancement-mode GaAs devices reported up to this time. A medium-power depletion device with the gate length of 1.8 µm has the maximum frequency of oscillation of 22 GHz. This value is 10 percent larger than that of the best analogous metal-semiconductor field-effect transistor (MESFET). The intrinsic current-gain cutoff frequency for the depletion MOSFET is 4.5 GHz which is 22 percent higher than that of the MESFET. The superiority of the depletion MOSFET in the small-signal microwave performance over the MESFET results from the smaller gate parasitic capacitance in the MOSFET as compared to the MESFET. The depletion MOSFET has produced 0.4-W output power at 6.5 GHz as a Class A amplifier. Quite a large frequency dispersion of transconductance is observed in the enhancement MOSFET at a frequency range between 10 and 100 kHz and attributed to interface states. The effect of the interface states does not severely restrict the microwave-frequency capabilities of the enhancement MOSFET as well as the depletion MOSFET since the interface states are unable to follow the input-signal variations at high frequencies.     

Time-Domain Measurement of Loss and Dispersion (Short Papers)

Time-domain metrology (TDM) techniques are applied to determine loss and dispersion in microstrip and coaxial cable for possible future use in interconnections in the frequency range of 0.4-10 GHz. After a brief presentation of the method, results are given for microstrip, RG/U 58, and RG/U 188A coaxial cable. Good agreement is obtained between measured, computed, and published values. Major advantages of the technique are that unwanted multiple reflections can be excluded from the measurement time window, and errors from interface discontinuities can be evaluated and removed from the final result.     

电流反馈型均一相位噪声正交振荡器

论文提出了一种电源反馈型的全集成正交压控振荡器。得益于反馈电流源的电流调节作用,提出的正交振荡器在整个频率调谐范围之内有着均一的相位噪声 。 此振荡器用65-nm CMOS工艺实现。测试结果表明,该振荡器工作电压为1.2V, 消耗的电流均值是3mA. 频偏1MHz的相位噪声小于 -110dBc/Hz。整个调谐范围内的相位噪声变化小于1dBc/Hz, 这充分证明了电流反馈技术的正确性。     

Calibration of optical modulators by optical down-conversion

A new method for the calibration of intensity modulators and modulated laser diodes at millimeter-wave frequencies is presented. The method uses an integrated-optic modulator as both a mixer and a frequency doubler. To demonstrate the measurement technique an intensity modulator is calibrated over the band 26.5-40 GHz. The measurement system employs no components exceeding 20 GHz (excluding the RF generator), and with relatively minor modifications measurements in excess of 60 GHz are feasible     

时间拉伸光子多普勒测速技术研究

在瞬态高速测速场景中,目标物体在几十ns时间内能加速到几~几十km/s,因此光子多普勒测速系统中电学数模转换器件带宽要求达到GHz甚至上百GHz。时间拉伸光子多普勒测速系统利用飞秒激光时间拉伸特性,在光域中完成信号降频处理,降低了光电信号探测器件和电学数模转换器件带宽压力。提出了改进的时间拉伸光子多普勒测速系统,飞秒脉冲经过第一级色散器件充分展宽铺满整个时域,避免了速度信号的采样间断;信号解调上采用误差补偿算法对频移信号进行补偿,减小了因为位移引入的系统误差,从而增加了有效记录时间。实验使用纳秒激光驱动铝膜产生高速飞片,测试了文中测速系统在记录时间1.2 μs内的实验效果。实验使用重频50 MHz飞秒光源,第一级和第二级色散器件分别使用200 km和100 km单模光纤,构成比例因子2/3。最终实验表明系统将3.6 GHz的多普勒频移信号降低为2.4 GHz,通过与光子多普勒测速系统进行结果比对,实验动态误差小于5%。该系统将能够应用于多种动高压技术加载飞片场景下的速度进行测量,为瞬态高速测量领域提供了新的测量手段。     

Effect of a magnetic wall and a conducting plane on the characteristics of magnetostatic waves in an in-plane-magnetized ferrite plate

The dispersion relations for an in-plane-magnetized ferrite plate with an arbitrary combination of magnetic-wall or perfectly conducting plane boundary conditions imposed at a distance from the plate’s surfaces are compared. A rule is formulated so that a dispersion relation for one of the structures can be used to derive the equation for any other structure. The isofrequency and dispersion characteristics of magnetostatic waves in a metal/ferrite/magnetic-wall structure are investigated. It is found that, in this case, the waves are characterized not only by a unidirectional propagation over the entire range of their existence (～5 GHz) but also by the presence of a nearly straight section of the dispersion curve (～2 GHz). In this structure, volume waves, surface waves, and waves with an amplitude that is constant over the plate thickness are seen to exist within the same frequency interval.     

基于偏振调制器和单模光纤的微波瞬时频率测量研究

提出了一种基于偏振调制器(PolM)实现微波信号 的瞬时频率测量(IFM)方法并进行了实验验证。它采用PolM同时实现相位调制和强度调制, 利用1个光源和1段单模光纤(SMF)保持光路中功率稳定,通 过光纤的色散将微波信 号频率映射到功率上,最后经过光电探测器(PD)探测并计算出两路电信号的功率比。这个功 率比一一对应于输入的微 波信号频率,最终能够测得所输入的微波信号频率。实验结果表明,它不仅可以实现1～12GHz宽带范围 内IFM,测量精度可以达到0.2GHz,而且能够同时保证 所测量的微波信号频率的系统误差小,稳定度好。     

A Dipole Excited Ultrawideband Dielectric Rod Antenna With Reflector

A novel very compact ultrawideband dielectric rod antenna with metallic reflector is presented. The desired HE11 mode on the rod is excited by a biconical dipole fed by a broadband tapered microstrip line balun. The input reflection remains below -10 dB from 3 up to 20 GHz. The antenna exhibits a flat gain larger than 7 dBi over the whole ultrawideband frequency range from 3 to 10 GHz approved by the Federal Communication Commission. An almost constant transient performance over a wide azimuth angle of plusmn40deg is obtained with small dispersion.     

Impedance Measurements of Microwave Lumped Elements from 1 to 12 GHz

The impedance measurement of small, microwave lumped elements of the order of 1 mm has been extended up to 12 GHz by a technique in which the frequency and Q of a resonant transmission line are perturbed by the connection of a lumped element. With the use of low-loss resonant coaxial lines, the technique has been applied to the measurement of lumped-element capacitors ranging from 0.4 to 3.6 pF and inductors ranging from 1.1 to 4.3 nH. Conductor Q values for capacitors as high as 1700 at 1.4 GHz and 100 at 12 GHz have been measured and estimates of dielectric Q values for capacitors of over 5000 have been obtained. Single-turn 1.1-nH inductor Q's of 40 at 1 GHz and 90 at 7 GHz have also been measured. The capacitors and single-turn inductors are found to have constant C and L values up to 12 GHz.     

半导体激光器芯片3dB带宽的测量

提出一种测量半导体激光器芯片频率响应的方法并建立了一套测试系统,通过校准完全剔除了夹具的影响.该方法简单、精确、实用性强.在理论上,该测试系统的测量范围只由测量仪器所决定.在实验中,测量了带宽为7.5GHz和10GHz的芯片,并与其他方法的测量结果进行了比较,表明该方法测量精度达到实用的要求,同时具有简单、易于操作的优点.     

半导体激光器芯片3dB带宽的测量

提出一种测量半导体激光器芯片频率响应的方法并建立了一套测试系统,通过校准完全剔除了夹具的影响.该方法简单、精确、实用性强.在理论上,该测试系统的测量范围只由测量仪器所决定.在实验中,测量了带宽为7 5GHz和10GHz的芯片,并与其他方法的测量结果进行了比较,表明该方法测量精度达到实用的要求,同时具有简单、易于操作的优点.