The article presents a study on the prediction quality of the ITS HF Propagation application suite: VOACAP (Voice of America Coverage Analysis Program), ICEPAC (Enhanced Profile Ionospheric ...Communications Circuit Analysis and Prediction Program) and REC533 (ITU Recommendation RS 533) for point to point connections of the NVIS (Near Vertical Incidence Sky-wave) type. The simulation results were compared to the measurements obtained on a NVIS direction carried out in Romania and with the measurement results obtained and published by Walden in 1 for a NVIS network established in the UK. Compared with the measurement data obtained in Romania, the results predicted by the three applications have achieved average values of the correlation factors. These low values regarding the quality of a predictive application are due to the short observation period of the ionospheric channel. In these circumstances, REC533 achieved the lowest mean value of the standard deviations compared to VOACAP and ICEPAC. Regarding the measurement results published by Walden, the three applications have achieved strong values. These results lead to high values of the coefficient of determination, ensuring a very good power of prediction. REC533 provided the most correlated values and the lowest average value of standard deviations. The results provided by ICEPAC and VOACAP are highly correlated for each month under review. Of the three applications analysed, the best predictions were obtained by REC533.
Surface passivation of high-resistivity silicon (HRS) by amorphous silicon thin-film deposition is demonstrated as a novel technique for establishing HRS as a microwave substrate. Metal-oxide-silicon ...(MOS) capacitor measurements are used to characterize the silicon surface properties. An increase of the quality factor (Q) of a 10-nH spiral inductor by 40% to Q=15 and a 6.5-dB lower attenuation of a coplanar waveguide (CPW) at 17 GHz indicate the beneficial effect of the surface passivation for radio frequency (RF) and microwave applications. Regarding CPW attenuation, a nonpassivated 3000-/spl Omega//spl middot/cm substrate is equivalent to a 70-/spl Omega//spl middot/cm passivated substrate. Surface-passivated HRS, having minimum losses, a high permittivity, and a high thermal conductivity, qualifies as a close-to-ideal radio frequency and microwave substrate.
This letter describes a recent HF/VHF radio signal measurement campaign carried out in a small urban reservation of the Atlantic Rainforest at Rio de Janeiro, Brazil. Motivation came from the lack of ...detailed reports on this type of work, considering the Brazilian forest scenarios. The collected data are presented in the form of path loss versus distance and frequency and are compared to Tamir's model. Good adherence was observed between measurements and calculated values from the reference model, despite the relatively short distances, with mean errors no greater than 3.0 dB and standard deviations less than 4.3 dB.
La transmission radioélectrique à longue distance dans la bande HF permet de couvrir de vastes zones géographiques à l’aide d’infrastructures légères et mobiles. Elle est donc bien adaptée pour ...établir des communications lors d’opérations militaires ou pour le déploiement rapide d'un réseau de communication agile lors d'opérations humanitaires. Dans ce contexte, il est important de pouvoir localiser les émetteurs inconnus par l’analyse des signaux électromagnétiques de communication. L’objectif de la thèse est de développer une technique de géolocalisation alternative et complémentaire, intitulée Time Difference of Arrival (TDoA), qui a rarement été étudiée dans le cas de la propagation ionosphérique. Dans un premier temps, l'algorithme de géolocalisation HF basé sur la technique TDoA est adapté et optimisé par des simulations paramétriques. Les résultats de simulation montrent que l'augmentation du nombre de récepteurs entraîne une amélioration significative de la précision de géolocalisation. Afin d'étudier la faisabilité de mise en oeuvre d'un système de géolocalisation HF basé sur la technique TDoA, plusieurs récepteurs HF pilotable à distance ont été développés à partir de modules de radio logicielle, et un réseau national de récepteurs a été déployé en France. Un concept original de sondage de canal croisé est proposé et décrit mathématiquement. Il permet d’évaluer les différences de durée de propagation entre les signaux reçus sur deux récepteurs synchronisés distincts. Les résultats expérimentaux collectés montrent qu'il est possible de localiser les émetteurs HF dans des conditions favorables avec une erreur de géolocalisation relative comprise entre 0,1 et 10% de la distance réelle au sol. Les données collectées lors de la campagne de mesure sont analysées de manière statistique afin d’évaluer la performance de l'algorithme de géolocalisation et de définir les paramètres les plus pertinents à prendre en compte pour déployer cette technique dans une approche opérationnelle.
Long-range radio transmission in the HF band can cover large geographical areas using light and mobile equipment. It is therefore well suited for communications during military operations orfor the rapid deployment of an agile communication network during humanitarian operations. In this context, it is important to determine the geographic location of the transmitters by analyzing the electromagnetic communication signals. The aim of the thesis is to develop an alternative, complementary geolocation technique, entitled Time Difference of Arrival (TDoA) that has rarely been studied in the case of ionospheric propagation. As a first step, HF geolocation algorithm based on TDoA is setup and analyzed by parametric software simulations. Simulation results demonstrate that increasing the number of receivers leads to a significant improvement in the geolocation accuracy. In order to study the feasibility of a practical HF geolocation system based on TDoA, multiple remotely controllable HF receivers are designed using software defined radio (SDR) modules and a country wide operational receiver network is deployed in France. A concept of cross-channel sounding along with its mathematical description is proposed to evaluate the propagation duration differences between the signals captured by two distinct receivers. Preliminary experimental results show that it is possible to locate the HF transmitters under favorable conditions with a relative geolocation error ranging from about 0.1 to 10% of the actual ground distance. Data captured during the large scale measurement campaign are analyzed statistically to evaluate the performance of the geolocation algorithm and define parameters that could be considered in an operational approach.
This paper presents an overview of RF calibration and pad de-embedding techniques, discusses limitations and demonstrates methods for accuracy improvement applicable for the characterization of ...advanced BiCMOS HBTs. The impact of the reference plane location is discussed. Numerous experiments with different device geometries showed that the in-situ (on-wafer) calibration yields the most accurate results. For a probe-tip calibration, a multiple-dummy de-embedding is crucial to improve measurement accuracy. A comparison with the compact model (HICUM V2.30) confirmed the findings.
Coplanar waveguide (CPW) and thin film microstrip (TFMS) lines integrating porous ultra low-
k as inter-metal dielectric layers (
k
=
2.5) and copper as metal, are for the first time experimentally ...measured up to 110
GHz and under different temperature conditions, up to 200
°C. The extracted attenuation and propagation coefficients of those transmission lines are compared to simulations performed with MAGWEL software, a frequency domain 3-D Maxwell solver. Based on the characterization results some guidelines related to interconnect design are presented for future applications.
We report on negative differential transconductance (NDT) effect in Y-branch nanojunctions which leads to small-signal nonreciprocity of the device for certain biasing schemes. We present the dc ...analysis of the device from which we identify the bias regions where NDT effect occurs. We compare experimental dc measurements with results of Monte Carlo simulations, which yields very good qualitative and quantitative agreement. We perform a high-frequency analysis of the NDT effect up to 110 GHz which shows that the effect discussed is still present at such high frequencies
With the dimensions scaling down at each new technology node, introduction of porous dielectric materials is required to reduce the interconnect capacitance. Nevertheless, these materials are very ...prone to damage during integration, thus increasing their
K-value (2.5 as deposited for the 45
nm node) in the final circuit. In order to characterize these effects, high-frequency measurements and electromagnetic simulations were carried out on specific microstrip structures. Taking into account typical circuit characteristics, time-domain extraction of delay values and crosstalk levels were then performed, enabling a precise analysis of moisture uptake effects from a performance point of view.
Room-temperature dc and broad-band high-frequency (HF) to dc conversion measurements of a double Y-branch junction (YBJ) are presented and discussed. Nonlinear dc characteristics of the devices at ...room temperature are observed and HF to dc conversion up to 40 GHz at room temperature is presented. The HF to dc conversion efficiency degradation is found to be partly due to losses in interconnects feeding the device. A small-signal equivalent circuit of the YBJ is proposed in order to verify the frequency dependence of intrinsic elements.
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