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Ultra-high frequency (UHF) partial discharge sensors are widely used for conditioning monitoring and defect location in insulation system of high voltage equipment. Designing sensors for specific applications often requires an iterative process of manufacturing, testing and mechanical modifications. This paper demonstrates the use of finite-difference time-domain (FDTD) technique as a tool to predict the frequency response of UHF PD sensors. Using this approach, the design process can be simplified and parametric studies can be conducted in order to assess the influence of component dimensions and material properties on the sensor response. The modelling approach is validated using gigahertz transverse electromagnetic (GTEM) calibration system. The use of a transient excitation source is particularly suitable for modeling using FDTD, which is able to simulate the step response output voltage of the sensor from which the frequency response is obtained using the same post-processing applied to the physical measurement.

A microstrip parallel coupled line bandpass filter is designed in UHF range and the filter size is reduced by microstrip hairpin structure. The FR4 substrate is used as base material of the filter. The filter is analyzed by both ADS and CST design studio in the frequency range of 500 MHz to 650 MHz. The Bandwidth is found 13.27% with a center frequency 570 MHz. Simulation from both ADS and CST shows a very good agreement of performance of the filter.

The possible environmental impacts of cellular base stations are operational and biological. The operational effects comprise Electro-Μagnetic Interference (EMI), lightning alterations and aesthetic degradation. Both thermal and non-thermal biological effects depend on the absorption of UHF radiofrequencies used. We measured, calculated and estimated the impact zones. The results are: (a) The lightning lethal zone equal to the antenna height, (b) the EMI impact in a zone up to 40m and (c) the ICNIRP’s limits exceed to a zone of 8∼20m into the antenna’s radiation pattern (for 2G GSM and 3G UMTS station). Finally we conclude the adverse effects must not expected in a zone of more than 150m from the radiated antenna, whereas, there is possibility of stochastic effects in intermediate distances (20/40-150m).

Inductive Output Tube (IOT) is an amplifier that usually operates in UHF range. It is an electron tube whose basic structure is similar to conventional vacuum devices. This device is widely used in broadcast applications but is now being explored for scientific applications also specifically, particle accelerators and fusion plasma heating purposes. The paper describes the design approach of a spherical gridded electron gun of a 500 MHz, 100 kW CW power IOT. The electron gun structure has been simulated and optimized for operating voltage and current of 40kV and 3.5 A respectively. The electromagnetic analysis of this spherical electron gun has been carried out in CST and TRAK codes.

In most particle accelerators RF power is a decisive design constraint due to high costs and relative inflexibility of current electron beam based RF sources, i.e. Klystrons, Magnetrons, Tetrodes etc. At VHF/UHF frequencies the transition to solid state devices promises to fundamentally change the situation. Recent progress brings 1 Watt per Euro cent installed cost within reach. We present a Silicon Carbide semiconductor solution utilising the Solid State Direct Drive{trade mark, serif} [1-3,7,8] technology at unprecedented efficiency, power levels and power densities. The proposed solution allows retrofitting of existing RF accelerators and opens the route to novel particle accelerator concepts.

Using the ZHAireS Monte Carlo code, we show that the Fourier-spectrum of the radio emission of inclined air showers can have a sizable intensity up to the GHz frequency range. At these frequencies only a significantly reduced volume of the shower around the axis contributes coherently to the signal observed on the ground, which is mainly due to the geomagnetic and charge excess mechanisms. At ground level, the maximum emission at high frequencies is concentrated in a ring-like elliptical region defined by the intersection with the ground of a Cherenkov cone with its vertex at shower maximum. The frequency-spectrum of inclined showers, when observed at positions close to the ring-like maximum emission region, is in broad agreement with the pulses detected by the ANITA experiment, making the interpretation that they are due to ultrahigh energy cosmic ray atmospheric showers consistent with our simulations. These results are also relevant for ground-based radio experiments aiming at detecting molecular bremsstrahlung radiation in the GHz range - an entirelly different emission mechanism which is not included in ZHAireS simulations - since they present an important background for such experiments.

During the Convective and Orographically‐induced Precipitation Study (COPS), lidar dark bands were observed by the Univ. of BASILicata Raman lidar system (BASIL) on several IOPs and SOPs (among others, 23 July, 15 August, 17 August). Dark band signatures appear in the lidar measurements of particle backscattering at 355, 532 and 1064 nm and particle extinction at 355 and 532 nm, as well as in particle depolarization measurements. Lidar data are supported by measurements from the University of Hamburg cloud radar MIRA 36 (36 GHz), the University of Hamburg dual‐polarization micro rain radars (24.1 GHz) and the University of Manchester Radio UHF clear air wind profiler (1.29 GHz). Results from BASIL and the radars are illustrated and discussed to support in the comprehension of the microphysical and scattering processes responsible for the appearance of the lidar dark band and radar bright band.

As is known each sea‐going vessel is equipped with navigation, communication and other radio engineering facilities that serve to secure the safety of navigation and are chiefly operated at UHF‐wave band. In developing these systems and calculating the energy potential for a necessary coverage range one should be well aware of the radio signal attenuation processes on a propagation path. The key parameter of this path is the (radio) wave attenuation factor V and its distance dependence V(R). A diversity of factors influencing the radio signal attenuation over the oceanic expanses, especially well pronounced and quite stable tropospheric ducts, and the lack of experimental data were the compelling reasons why the researchers of the Institute for Radiophysics and Electronics, NASU, had spent many years on comprehensive radiophysical investigations carried out in different regions of the Atlantic, Indian, Arctic and Pacific Oceans. The experimental data obtained allow creating the database of radio wave attenuation factor V.

CPI continues its role as a leading supplier of state‐of‐the‐art, high‐power microwave tubes; from linear beam, velocity‐ and density‐modulated devices, to high frequency gyro‐devices. Klystrons are the device‐of‐choice for many high‐power microwave applications, and can provide multi‐megawatts to multi‐kilowatts of power from UHF to W‐band, respectively. A number of recent and on‐going developments will be described. At UHF frequencies, the inductive output tube (IOT) has replaced the klystron for terrestrial NTSC and HDTV broadcast, due to its high efficiency and linearity, and is beginning to see use in scientific applications requiring 300 kW or less. Recent advances have enabled use well into L‐band.CPI has developed a number of multiple‐beam amplifiers. The VKL‐8301 multiple‐beam klystron (MBK) was built for the TESLA V/UV and x‐ray FEL projects, and is a candidate RF source for the International Linear Collider (ILC). We have also contributed to the development of the U.S. Naval Research Laboratory...

Invented in 1938, at the same time as the klystron, it took the Inductive Output Tube (IOT) more than 40 years to surface as a useful device. Its progress after that event was rapid. Though plagued by teething problems in the beginning, it has since replaced the klystron as a TV amplifier in UHF, and it holds its own against the solid‐state competition in that application. The IOT also shows much promise as a high‐power amplifier, but early developments in this direction have remained solitary events so far. The paper discusses the causes and the potential of the device for future high‐power applications.

Capturing, decoding, and displaying telemetry from orbiting spacecraft in real time, in the classroom, is an excellent way of introducing space science to students. At this time there are a number of orbiting satellites carrying amateur radio (OSCAR) actually sending back telemetry. Further satellites are planned in the near future with real opportunities for true pioneering science. Signals from these spacecraft are downlinked on frequencies that can be received on regular vhf/uhf scanner radio receivers. Excluding the Personal Computer, a simple telemetry capturing ground station can be set up for less than $500.00 in equipment costs.This paper provides an introduction as to how this can be done using readily available low cost equipment. General topics discussed cover telemetry, the spacecraft themselves. Ground station hardware topics include receiving antennas, radio receivers, and modems. Software topics discussed include the software used to track the spacecraft and the software used to both decode...

This paper presents the design and performance of high power Y junction circulators in coaxial and waveguide design. The design procedure is based on field theoretical simulations of the ferrite resonator. The temperature behavior of the ferrite material is analyzed. High temperature gradients are the limiting factors for high power applications. An overview about the today limits is given. Coaxial circulators can handle more than 250 kW CW input power, while waveguide circulators handle more than 1 MW CW, the circulator output shortened at any phase, respectively. These devices preferrable used within the UHF and VHF bands typically have insertion losses less than 0.1 dB and isolation losses of more than 20 dB (±3% bandwidth).