Features of Antenna-Applicator for Functional Studies of the Human Brain

In the article, the characteristics of antenna-applicators (AA) for the contact microwave radiometers are analyzed. The bow-tie AA (in which the near-field and transition regions better match with the feeder in a wide frequency band) is preferred for monitoring the brain microwave radiation. Modelling these bow-tie AA with contact pins was conducted. The simulation results have confirmed that the increase in length of the pins up to 5 mm reduces the characteristic impedance similar to that of flat AA. Meanwhile, increased thickness of the vibrator does not degrade receiving properties of the AA. The modelling results are confirmed by laboratory studies that have examined the characteristics of the bow-tie AA with pins and flat AA without pins. It is shown that the introduction of designed AA with pins significantly reduced the impact of hair on the matching of the AA and body. In the study of changes in the characteristics of AA for 30 min, the change rate matching such antennas with the brain tissue changes by less than two times compared with that matching AA without pins.