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The directional attenuators are devices with attenuation dependent on direction of propagation of RF energy. A new type of the directional attenuator was developed, designed and tested. The advantages of the new directional attenuators are low cost and low attenuation in forward direction, which is from 1 to 2 dB. The attenuation of designed directional attenuators in backward direction is from 7...
Detectors designing is a key aspect for the development of the new millimeter wave systems. In this paper two detectors in microstrip technology are presented. They use zero bias Schottky diodes to detect signals from low frequency to 40 GHz. High sensibility, flat frequency response and ultrabroadband are the main features of these designs. They are also cheap and easy to mount because they have...
A comprehensive approach to the design of a stripline for EMC testing is given in this paper. The authors attention has been focused on the design items that are most crucial by the achievement of satisfactory value of the VSWR and the impedance matching at the feeding ports in the extended frequency range from 80 MHz to 1000 GHz. For this purpose, the Vivaldi-structure and other advanced structures...
Application of metamaterial left-handed transmission lines to design 180deg power dividers is considered. Design of microstrip and coplanar miniaturized rat-race rings based on artificial left-handed and right-handed transmission line sections is presented. The devices have been implemented as quasi-lumped-element multilayer structures on low-temperature co-fired ceramics. Novel broadband Wilkinson-type...
Paper presents multisixport principle and its benefits above classical sixport. The novel multisixport design is presented in practical example with its parameters as obtained bandwidth and standard deviation of measurement.
The following topics are dealt the following with: microwave measurements; antennas and propagation; industry applications; biological effect; medical applications; metamaterials line; active and passive circuits; electromagnetic compatibility.
Gallium Nitride's superior physical properties, in comparison with other semiconductors, make GaNHEMT active devices a prime candidate in the implementation of next generation transmitters for radar systems, 3G/4G base stations and WiMAX. In this contribution, the characterization, modelling and verification of different families of high efficiency, high- power devices manufactured at SELEX Sistemi...
Since 2001, an Internet textbook of electromagnetic waves and antennas has been developed at the Dept. of Radio Electronics, Brno University of Technology. In the paper, the history of the textbook is reviewed, the latest version of the textbook is described, and the experience of its development and usage are summarized.
This paper provides an overview of planar near- field antenna test systems developed for submillimeter wave applications used for earth observation and radio astronomy. Examples are shown of some of these test systems and methods described to overcome technical restrictions, limiting performance at very high RF frequencies. Aspects like thermal structural change, RF cable phase instability and scanner...
This paper is focused on the Gaussian beam properties in the turbulent atmosphere. At first the optical wireless link is briefly introduced and the atmospheric transmission media is presented. The atmospheric turbulences are introduced and laser beam geometry is analyzed. For the Gaussian beam in the turbulent atmosphere we can calculate correlation between influenced laser beam and ideal Gaussian...
The subject of this paper is to provide a comparison of 3D EM field simulation results of 0603 size SMD resistors with corresponding real data obtained by precise vector measurements. The simulated results were obtained by 3D EM field simulator CST Microwave Studio with time-domain solver. The comparison is shown on a design of an optimized 50 Omega load composed of a common SMA flange connector and...
Controlled attenuators are key elements in a phased array's beam forming network and generally in all those systems requiring accurate control of the RF signal's amplitude and phase. Therefore the realisation of constant- phase digital attenuators is essential to obtain advanced system performance. A reactive element has been inserted in the traditional T topology digital attenuator to obtain equiphase...
Requirements on computer networks speed are steadily increasing. Unfortunately it is not possible to use a classic fiber optic backbone networks in all areas due to very high cost of this system. High altitude platform system offers communication on long distance with a great degree of flexibility. In combination with free space optics it provides low cost solution with high rate-speed. However as...
The paper reports the properties of AlGaN/GaN HEMT fabricated on sapphire substrate. Using 2 mum length of gate electrode 6.67 GHz transition frequency as well as 24.5 GHz maximum frequency of oscillation was achieved. Small-signal model was identified. The transistor transconductance is in the range of 170 mS/mm. However the transistor was intended for structure and technology verification, it could...
This paper presents a possible application of an artificial dielectric substrate. The substrate is fabricated as a 2D array of metallic posts separated from the top conductor by a thin dielectric slab. The effective permittivity of a microstrip line fabricated on this substrate depends on the dimensions of the posts, the permittivity of a dielectric material filling the space between the posts, and...
3-D EM simulator based equivalent circuit of a single layer capacitor (SLC) mounted on 50 Omega microstrip line of Arlon CuClad233 substrate was derived. The circuit corresponds to substrate thickness ranging from 0.254 mm to 1.270 mm and frequency range 45 MHz + 26 GHz. Values of equivalent circuit components determined by equations are dependent on substrate thickness.
In this paper two modified structures of multi- layered broadband 3 dB/'90deg coupled line couplers are proposed. The first structure is a broadside coupled stripline coupler with corrugated ground plane. The second investigated structure is a modified micro strip-slotline coupler. In comparison to basic configurations of couplers the improvement of operation bandwidth for proposed structures is achieved...
The general principle of an ultra-wideband (UWB) amplifier design in the planar structure using the common available monolithic amplifier is proposed in this paper. The structure of the amplifier is designed in order to accomplish the conditions of the transmission of UWB impulses (flat gain and constant group delay over FCC approved frequency band) with a minimum distortion. The roll-of stage is...
A new topology of high performance pHEMT distributed power amplifier is presented. An adjustable inter-stage cascaded matching network between two non-identical transistors is proposed. The superiority of the topology as indicated by the theoretical discussion is verified through simulation. Gain and PAE of 24 dB and 45+56%, respectively while output power of 32 dBm (plusmn2 dB) for frequency ranges...
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