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Antennas with metamaterial radomes
Martínek, Luděk ; Tkadlec, Roman (referee) ; Pítra, Kamil (advisor)
This thesis deals with microstrip antennas covered by the metamaterials. First, are described planar antennas, their problems and the emergence of surface waves. Surface waves can cause unwanted coupling among particular parts of the structure and can degrade its parameters. The problem can be solved using an electromagnetic band gap structure (EBG). These periodic structures are able to suppress surface waves in different frequency bands. It is shown how the EBG structure in the function superstate improve directivity and antenna gain. Radiation conventional microstrip antenna with metallo-dielectric EBG superstrate and with the purely dielectric double-layer superstrate is described. The both structures are designed and simulated in CST Microwave Studio program. Further is described the antenna radiation with so-called mushroom structure and metallo-dielectric EBG superstate. The structure is again designed and simulated in CST MWS program. Finally, there are two structures with metallo-dielectric superstate implemented and measured.
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Pulse Generator for GPR
Martínek, Luděk ; Dušek, Martin (referee) ; Šebesta, Jiří (advisor)
This thesis deals with the question of ground penetrating radar. At first it considers the electromagnetic field and its mathematical description. Then it covers measurement of electromagnetic pulses and their processing of sub-surface ground penetrating radar. . In this thesis is also described the involvement of pulse generator with several transistors operating in avalanche breakdown. Individual transistors are compared in time domain. The received waveform is then selected the best transistor for the final generator. Then is proposed solution for the final pulse generator and its implementation. For impulsive generator is also designed and constructed increasing the DC-DC voltage converter. Finally, it is necessary to measure the time behavior of the output pulse generator.
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Pulse Generator for GPR
Martínek, Luděk ; Dušek, Martin (referee) ; Šebesta, Jiří (advisor)
This thesis deals with the question of ground penetrating radar. At first it considers the electromagnetic field and its mathematical description. Then it covers measurement of electromagnetic pulses and their processing of sub-surface ground penetrating radar. . In this thesis is also described the involvement of pulse generator with several transistors operating in avalanche breakdown. Individual transistors are compared in time domain. The received waveform is then selected the best transistor for the final generator. Then is proposed solution for the final pulse generator and its implementation. For impulsive generator is also designed and constructed increasing the DC-DC voltage converter. Finally, it is necessary to measure the time behavior of the output pulse generator.
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Antennas with metamaterial radomes
Martínek, Luděk ; Tkadlec, Roman (referee) ; Pítra, Kamil (advisor)
This thesis deals with microstrip antennas covered by the metamaterials. First, are described planar antennas, their problems and the emergence of surface waves. Surface waves can cause unwanted coupling among particular parts of the structure and can degrade its parameters. The problem can be solved using an electromagnetic band gap structure (EBG). These periodic structures are able to suppress surface waves in different frequency bands. It is shown how the EBG structure in the function superstate improve directivity and antenna gain. Radiation conventional microstrip antenna with metallo-dielectric EBG superstrate and with the purely dielectric double-layer superstrate is described. The both structures are designed and simulated in CST Microwave Studio program. Further is described the antenna radiation with so-called mushroom structure and metallo-dielectric EBG superstate. The structure is again designed and simulated in CST MWS program. Finally, there are two structures with metallo-dielectric superstate implemented and measured.
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