title: Electric-field distribution near rectangular microstrip radiators for hyperthermia heating: theory versus experiment in water.
abstract: A rectangular microstrip antenna radiator is investigated for its near-zone radiation characteristics in water. Calculations of a cavity model theory are compared with the electric-field measurements of a miniature nonperturbing diode-dipole E-field probe whose 3 mm tip was positioned by an automatic three-axis scanning system. These comparisons have implications for the use of microstrip antennas in a multielement microwave hyperthermia applicator. Half-wavelength rectangular microstrip patches were designed to radiate in water at 915 MHz. Both low (epsilon r = 10) and high (epsilon r = 85) dielectric constant substrates were tested. Normal and tangential components of the near-zone radiated electric field were discriminated by appropriate orientation of the E-field probe. Low normal to transverse electric-field ratios at 3.0 cm depth indicate that the radiators may be useful for hyperthermia heating with an intervening water bolus. Electric-field pattern addition from a three-element linear array of these elements in water indicates that phase and amplitude adjustment can achieve some limited control over the distribution of radiated power.
authors.affiliation: Department of Physics, Wheaton College, IL 60187.
authors.forename: H R
authors.initials: HR
authors.lastname: Underwood
authors.forename: A F
authors.initials: AF
authors.lastname: Peterson
authors.forename: R L
authors.initials: RL
authors.lastname: Magin
mesh_terms: D000388:Air; D004553:Electric Conductivity / Q000502:physiology; D004560:Electricity; D004574:Electromagnetic Fields; D004867:Equipment Design; D006979:Hyperthermia, Induced / Q000295:instrumentation* / Q000379:methods; D008872:Microwaves / Q000627:therapeutic use; D008962:Models, Theoretical; D014867:Water
chemical_list: D014867:Water