APPLICATION NOTE
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THERMAL ANALYSIS OF MICROWAVE HEATING OF ASPHALT MIXTURES BY HORN ANTENNA USING HFWORKS
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Microwave and RF heating have been widely exploited in industrial processing such as drying, curing, vulcanizing, etc. One of the most useful applications of RF heating is the thermal maintenance of road structures especially for Asphalt mixtures pavement to treat the occurred damages. The proposed RF heating design is based on a rectangular Asphalt sample exposed to a coaxial feed pyramidal horn antenna operating at the frequency range of [700 MHz – 1300MHz]
The return loss 2D plot results demonstrate a good agreement between the HFWorks and measurements for the working frequency band when the horn antenna is air radiating. The measured bandwidth for  is 56%. The next 2D and 3D plots are showing the polar gain pattern results:
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Figure 1 - Return loss results versus frequency
Figure 2 - a)- 3D polar plot and b)- 2D chart plot -Phi=0 deg of gain pattern at 850 MHz
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MW heating process of Asphalt mixture is adopted now for an excitation power set to 800 Watt at the same range of frequency. Electromagnetic and heat transfer equations are coupled together and allowed to obtain the following results.
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Figure 3 - Cross sectional view plot across Asphalt sample of Electric field distribution for Pin=800 W
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Figure 4 displays the Volume loss density inside the Asphalt. A Steady state thermal analysis is coupled to the Electromagnetic study to estimate the temperature profile inside the heated sample. The obtained result of the temperature distribution is illustrated in the Figure 5.
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Figure 4 - Cross section Volume loss density plot inside the Asphalt density for Pin=800Watt at 850 MHz
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Figure 5 - Temperature distribution across the Asphalt sample
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