2013/4

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    The Design of Polymer Planar Optical Triplexer with MMI Filter and Directional Coupler
    (Společnost pro radioelektronické inženýrství, 2013-12) Jerabek, Vitezslav; Busek, Karel; Prajzler, Vaclav; Mares, David; Svoboda, Rudolf
    Optical bidirectional WDM transceiver is a key component of the Passive Optical Network of the Fiber to the Home topology. Essential parts of such transceivers are filters that combine multiplexing and demultiplexing function of optical signal (triplexing filters). In this paper we report about a design of a new planar optical multi-wavelength selective system triplexing filter, which combines a multimode interference filter with directional coupler based on the epoxy polymer SU-8 on Si/SiO2 substrate. The optical triplexing filter was designed using the Beam Propagation Method. The aim of this project was to optimize the triplexing filter optical parameters and to minimize the planar optical wavelength selective system dimensions. The multimode interference filter was used for separation of downstream optical signal in designed optoelectronic integrated WDM transceiver. The directional coupler was used for adding of upstream optical signal.
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    Prague's Emission Fourier Transform Microwave Spectrometer - Design and Preliminary Results
    (Společnost pro radioelektronické inženýrství, 2013-12) Kabourek, Vaclav; Cerny, Petr; Piksa, Petr; Studecky, Tomas; Kania, Patrik; Urban, Stepan
    The design, performance and operation of the high resolution microwave spectrometer are described. The spectrometer is based on the Fabry-Perot resonator supplemented by a pulsed supersonic nozzle for adiabatic cooling of the sample. The spectrometer’s high sensitivity and resolution are demonstrated by several examples.
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    IR Thermometer with Automatic Emissivity Correction
    (Společnost pro radioelektronické inženýrství, 2013-12) Dobesch, Ales; Poliak, Juraj
    The paper describes the design and implementation of an infrared (IR) thermometer with automatic emissivity correction. The temperature measurement is carried out by the simple digital thermopile sensor MLX90614. The emissivity correction is based on benefits of diffuse reflecting materials and it uses an IR laser diode in conjunction with a selective amplifier. Moreover, the paper includes the design of the control interface with a graphics LCD. Furthermore, this paper describes the power supply unit with a Li-ion cell controlled by basic integrated circuits.
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    Temperature and Frequency Dependent Empirical Models of Dielectric Properties of Sunflower and Olive Oil
    (Společnost pro radioelektronické inženýrství, 2013-12) Vrba, Jan; Vrba, David
    In this article, a known concept and measurement probe geometry for the estimation of the dielectric properties of oils have been adapted. The new probe enables the~measurement in the frequency range of 1 to 3000 MHz. Additionally, the measurement probe has been equipped with a~heat exchanger, which has enabled us to measure the dielectric properties of sunflower and olive oil as well as of two commercial emulsion concentrates. Subsequently, corresponding linear empirical temperature and frequency dependent models of the dielectric properties of the above mentioned oils and concentrates have been created. The dielectric properties measured here as well as the values obtained based on the empirical models created here match the data published in professional literature very well.
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    Broadband RCS Reduction of Microstrip Patch Antenna Using Bandstop Frequency Selective Surface
    (Společnost pro radioelektronické inženýrství, 2013-12) Yang, Huan-huan; Cao, Xiang-yu; Zheng, Qiu-rong; Ma, Jia-jun; Li, Wen-qiang
    In this article, a simple and effective approach is presented to reduce the Radar Cross Section (RCS) of microstrip patch antenna in ultra broad frequency band. This approach substitutes a metallic ground plane of a conventional patch antenna with a hybrid ground consisting of bandstop Frequency Selective Surface (FSS) cells with partial metallic plane. To demonstrate the validity of the proposed approach, the influence of different ground planes on antenna’s performance is investigated. Thus, a patch antenna with miniaturized FSS cells is proposed. The results suggest that this antenna shows 3dB RCS reduction almost in the whole out-of operating band within 1-20GHz for wide incident angles when compared to conventional antenna, while its radiation characteristics are sustained simultaneously. The reasonable agreement between the measured and the simulated results verifies the efficiency of the proposed approach. Moreover, this approach doesn’t alter the lightweight, low-profile, easy conformal and easy manufacturing nature of the original antenna and can be extended to obtain low-RCS antennas with metallic planes in broadband that are quite suitable for the applications which are sensitive to the variation of frequencies.