초록 ▼

A catheter shaft carries a coaxial cable, the terminal end of which contains a dipole antenna with opposing first and second helical elements. The first and second helical elements originate from a common connection to an outer conductor of the coaxial cable. The first and second helical elements ar

A catheter shaft carries a coaxial cable, the terminal end of which contains a dipole antenna with opposing first and second helical elements. The first and second helical elements originate from a common connection to an outer conductor of the coaxial cable. The first and second helical elements are formed by winding flat wire around an outer insulator of the coaxial cable near a terminal end of the coaxial cable. A variable, controllable impedance is connected between an inner conductor of the coaxial cable and a point on the second helical element where the resistive component of the antenna's impedance matches the characteristic impedance of the coaxial cable. The impedance match minimizes reflective losses of the antenna, thereby maximizing power transferred to the antenna. The antenna has an effective electrical length which is equal to one-half the wavelength of the radiation emitted, independent of the physical length of the antenna. The antenna also has a radiation length which can be adjusted by varying the number in pitch and turns of the flat wire and the location of the impedance matching point.

대표청구항 ▼

[ What is claimed is:] [1.] A method for treating benign prostatic hyperplasia comprising:inserting a microwave antenna-containing catheter shaft into a urethra so as to position the microwave antenna adjacent a prostatic region of the urethra, the antenna connected to a variable impedance device;pr

[ What is claimed is:] [1.] A method for treating benign prostatic hyperplasia comprising:inserting a microwave antenna-containing catheter shaft into a urethra so as to position the microwave antenna adjacent a prostatic region of the urethra, the antenna connected to a variable impedance device;providing a drive signal to the antenna to apply a radio frequency emission to tissue surrounding the urethra, the radio frequency emission causing molecular excitation of tissue surrounding the urethra sufficient to heat the tissue; andadjusting the variable impedance device, while providing the drive signal, as a function of a reflected power component of the antenna.