Browsing by Author "Stander, Tinus"

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    Compact high-power broadband absorptive filters using slotted waveguide harmonic pads
    (The Institution of Engineering and Technology - IET, 2014-06) Stander, Tinus; Meyer, Petrie; Van der Walt, Pieter Willem; Electrical and Electronic Engineering
    A compact high-power broadband absorptive filter is designed by cascading a slotted waveguide harmonic pad with a wide stop-band reflective filter. Absorption is achieved by coupling a surface current standing wave to absorptive external auxiliary waveguides through a cascade of transversal broad-wall slots in rectangular waveguide
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    Etched ring absorbing waveguide filter based on a slotted waveguide antenna response
    (Wiley, 2008-04) Stander, Tinus; Meyer, Petrie; Electrical and Electronic Engineering
    A cascade of resistively loaded etched rings in waveguide is proposed to act as the load in a balanced FMCW Reflected Power Canceller topology using a slotted waveguide array antenna. A synthesis technique using derived equivalent circuit models, is presented and tested.
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    High-power broadband absorptive waveguide filters
    (Stellenbosch : University of Stellenbosch, 2009-12) Stander, Tinus; Meyer, P.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.; University of Stellenbosch. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.
    ENGLISH ABSTRACT: This dissertation presents a synthesis method for broadband high-power absorptive microwave lters by cascading a wide stop-band wa e-iron lter with an absorptive harmonic pad. The classical image impedance synthesis methods for wa e-iron lters are updated to allow for non-uniform boss patterns, which enable control over both the stop-band attenuation and pass-band re ection of the lter. By optimising an accurate circuit model equivalent, computationally intensive numerical EM optimisation are avoided. The nonuniform wa e-iron lter achieves the same electrical speci cation as similar lters in literature, but in a smaller form factor. The prototype presented displays less than -21 dB in-band re ection over 8.5 - 10.5 GHz, with stop-band attenuation in excess of 50 dB over the harmonic bands 17 - 31.5 GHz and 30 dB over the 34 - 42 GHz. The prototype is designed to handling 4 kW peak power incident in the transmitted band, and is 130 mm in length. Minimal full-wave tuning is required post-synthesis, and good agreement is found between synthesised and measured responses. Additionally, a completely novel oblique wa e-iron boss pattern is proposed. For the absorptive harmonic pad, transversal broadwall slots in rectangular waveguide, coupling to an absorptive auxiliary guide, are investigated in the presence of standing wave surface current distributions. An accurate circuit model description of the cascaded structure is developed, and optimised to provide a required level of input match in the presence of an arbitrary re ective lter. Using numerical port parameter data of the wa eiron lter, a harmonic pad is developed that provides -12.5 dB input re ection match across the band 17 - 21 GHz with up to 1 kW peak incident power handling capability, yet is only 33 mm in length. Again, good agreement is found between synthesised and measured responses of the cascaded structure.