Browsing by Author "Voipio, Veli-Erkki"
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Item Culvert pipe resonance(Presses Universitaires de Rennes, 2021-07-01) Voipio, Veli-Erkki; Department of Electronics and NanoengineeringResonant frequency in the target is revealed using a Gopher antenna designed by the author for the measurements. Deconvolution is applied after conventional pre-processingItem The Gopher Antenna - A New Efficient Design for Ground Penetrating Radar(2019) Voipio, Veli-Erkki; Department of Electronics and NanoengineeringIn this article, we propose a new design we call the “Gopher antenna”: a patch antenna structure which does not require a resistive load and is therefore more efficient than the current ground-penetrating radar (GPR) antennas. When tested, it works well in a GPR application as low as approximately -25 dB of the application’s original transmit power. The Gopher antenna also meets the general requirements for the GPR antennas: a received wide spectrum and a good impulse response. Departing from the common designs (bow-tie dipoles and horn/Vivaldi structures), the Gopher antenna is a patch-antenna structure consisting of a quarter-wave feeder and a parasitic half-wave patch with no resistive load. The Gopher antenna has a directive radiation pattern, a good impulse response without distortion, a reasonable cross-polarization ratio, and a good radiated spectrum also when placed on the ground.Item GPR trace integral as a postprocessing tool(2022-08-02) Voipio, Veli-Erkki; Department of Electronics and NanoengineeringThe receiving antenna produces an approximate derivative from the signal. Thus one could think that a time domain integral of the received signal corresponds better to the reflected signal in the ground. This processing method is explored using a real field data example which was collected with the Gopher antenna designed by the author. Cross-correlation and deconvolution are applied after the integral as further processing in the example case.Item Tilted GPR beam in the ground(2020-06-14) Voipio, Veli-Erkki; Department of Electronics and NanoengineeringIn this presentation, I introduce the idea of a tilted beam in GPR. Tilting is now possible due to the relatively narrow beam of my Gopher antenna. The use of a neoprene filling allows for a smooth coupling between the antenna and the ground.