Experiment Study On Frequency-Dispersion Response Of Wideband EM Wave Over Inhomogeneous Medium

The process of wideband electromagnetic wave propagation in geologic mediums occur frequency-dispersion phenomenon. Frequency-dispersion phenomenon is not only disadvantage but also advantage. By physical experiment studying on frequency-dispersion response of wideband electromagnetic wave over different medium in the thesis, it offers practical experience in using frequency-dispersion phenomenon. The main achievements of the thesis are as follows:1. Physical model experiment studying indoorConstruct wideband (100KHz--2.8GHz) electromagnetic wave signal analyzing system base on NI company's key hardware and software of high frequency signal transmitting and receiving. Simulate high resistance medium by forty-three concrete modules (100cmxl0cmx50cm) continuously arranged and low resistance medium by three cast iron modules (same scale). Transmit and receive electromagnetic wave at the height of 55cm over the model. Measure each module reflective intensity of 0.5GHz, 1.0GHz, 1.5GHz electromagnetic wave in the condition of non-overcast and overcast water layer of 15 cm thickness. By analyzing and computing observe data, the main conclusion of the experiment indoor are as follows:(1) On non-overcast water layer, for concrete modules, reflective intensity of frequency 1.0GHz is less 51.98% than reflective intensity of frequency 0.5GHz, and reflective amplitude frequency-dispersion rate is 1.0396/GHz between 1.0GHz and 0.5GHz ; reflective intensity of frequency 1.5GHz is less 41.97% than reflective intensity of frequency 1.0GHz, and reflective amplitude frequency-dispersion rate is 0.8394/GHz between 1.5GHz and 1.0GHz . Concrete modules' frequency-dispersion of reflective amplitude variety non-linear . For cast iron modules, reflective intensity of frequency 1.0GHz is less 43.73% than reflective intensity of frequency 0.5GHz, and reflective amplitude frequency-dispersion rate is 0.8746/GHz between 1.0GHz and 0.5GHz ; reflective intensity of frequency 1.5GHz is less 38.55% than reflective intensity of frequency 1.0GHz, and reflective amplitude frequency-dispersion rate is 0.7710/GHz between 1.5GHz and 1.0GHz . Cast iron modules' frequency-dispersion of reflective amplitude variety non-linear, too. Low resistance cast iron modules' the value of frequency-dispersion is less than high resistance concrete modules' in the same frequency difference. The attenuation of reflective intensity become weaker in the high frequency band than in low frequency band.(2) On overcast water layer, for concrete modules, reflective intensity of frequency 1.0GHz is less 59.92% than reflective intensity of frequency 0.5GHz, and reflective amplitude frequency-dispersion rate is 1.1984/GHz between 1.0GHz and 0.5GHz ; reflective intensity of frequency 1.5GHz is less 38.91% than reflective intensity of frequency 1.0GHz, and reflective amplitude frequency-dispersion rate is 0.7782/GHz between 1.5GHz and 1.0GHz . For cast iron modules, reflective intensity of frequency 1.0GHz is less 48.79% than reflective intensity of frequency 0.5GHz, and reflective amplitude frequency-dispersion rate is 0.9758/GHz between 1.0GHz and 0.5GHz ; reflective intensity of frequency 1.5GHz is less 31.79% than reflective intensity of frequency 1.0GHz, and reflective amplitude frequency-dispersion rate is 0.6358/GHz between 1.5GHz and 1.0GHz . Because of the overcast water layer, the value of frequency-dispersion in the low frequency band become stronger, however, the value of frequency-dispersion in the high frequency band become weaker.2. Physical model experiment studying localMeasure the different frequency of 0.1 GHz, 0.4 GHz, 0.9 GHz reflective intensity of the cast iron pipe embodied in soil of 100 cm depth by TerraSIRch SIR-3000 Ground Probe Radar system.By analyzing and computing observe data, for cast iron pipe, reflective intensity of frequency 0.4GHz is less 0.1423% than reflective intensity of frequency 0.1GHz, and reflective amplitude frequency-dispersion rate is 0.004745/GHz between 0.4GHz and 0.1GHz ; reflective intensity of frequency 0.9GHz is less 0.4487% than reflective intensity of frequency 0.4GHz, and reflective amplitude frequency-dispersion rate is 0.008974/GHz between 0.9GHz and 0.4GHz . Cast iron pipe frequency-dispersion of reflective amplitude variety non-linear, and The attenuation of reflective intensity become stronger in the high frequency band than in low frequency band.