摘要:
A microwave power limiter for generating an output RF signal of substantially constant power level in response to an input RF signal of varying power level comprises a single gate field effect transistor (FET). The FET is biased such that the RF power output variation is small compared to the input power variation in the saturation region. A number of FET cascaded stages may be utilized to reduce this power output variation. A small signal amplifier including a number of FET cascaded stages may be employed in the limiter to increase the power level to that gain or drive level compatible with the saturated FET stages.
摘要:
A microwave frequency discriminator using a one port active device amplifier including a circulator for coupling an input RF signal of substantially constant power level into the amplifier and an output RF signal out from the amplifier. The discriminator further comprises input and output matching networks connected to the circulator and a detector for generating a D.C. signal as a function of the incoming signal frequency. The input and output impedance matching networks are formed to provide selected impedance conditions to the amplifier such that the power-frequency response of the amplifier varies substantially linearly approximating a frequency discriminator characteristic throughout a predetermined frequency bandwidth.
摘要:
A microwave power limiter for generating an output RF signal of substantially constant power level in response to an input RF signal of varying power level comprises a dual gate field effect transistor (FET). The FET is biased such that the RF power output variation is small compared to the input power variation in the saturation region. A number of FET cascaded stages may be utilized to reduce this power output variation. A small signal amplifier including a number of FET cascaded stages may be employed in the limiter to increase the power level to that gain or drive level compatible with the saturated FET stages.
摘要:
A reliable and mass-producible microelectromechanical (MEMS)-based microwave intracranial pressure sensing device for use with a portable microwave monitor and methods for non-invasively monitoring intracranial pressure with this device are provided.
摘要:
A low conductivity, first conductivity type epitaxial layer is formed on a substrate of high conductivity, first conductivity type semiconductor material. Conductivity modifiers of second conductivity type are then implanted into the epitaxial layer so as to create a PN junction in the epitaxial layer. The substrate is next thinned, and conductivity modifiers of first conductivity type are implanted into the thinned surface so as to form a very high conductivity layer at the thinned surface.
摘要:
A method of making an Impatt diode capable of operating at millimeter wave frequencies in which an epitaxial layer of the thickness desired for the diode is deposited on a substrate. Conductivity modifiers are implanted into the epitaxial layer to form one active region and a high conductivity region between the one active region and the surface of the epitaxial layer. A heat sink which also serves as a handle is formed on the epitaxial layer. The substrate is removed and conductivity modifiers are implanted into the other side of the epitaxial layer to the other active region and a high conductivity region between the other active region and the other surface of the epitaxial layer. After the implants the epitaxial layer is annealed. After the first implants the epitaxial layer may be annealed by either thermal or laser annealing. However, after the second implants the epitaxial layer must be laser annealed.
摘要:
A medical probe device comprising a catheter having a stylet guide housing with at least one stylet port in a side thereof and stylet guide means for directing a flexible stylet outward through at least one stylet port and through intervening tissue to targeted tissue. The stylet comprises an electrical central conductor which is enclosed within an insulating or dielectric sleeve surrounded by a conductive layer terminated by an antenna to selectively deliver microwave or radio frequency energy to target tissue. One embodiment includes the electrical conductor being enclosed within a non-conductive sleeve which itself is enclosed within a conductive sleeve in a coaxial cable arrangement to form a microwave transmission line terminated by an antenna. Another embodiment includes a resistive element near the distal end of the stylet which couples the center electrode to an outer conductor to generate joulian heat as electromagnetic energy is applied, such as an RF signal.
摘要:
A medical probe device comprising a catheter having a stylet guide housing with at least one stylet port in a side thereof and stylet guide means for directing a flexible stylet outward through at least one stylet port and through intervening tissue to targeted tissue. The stylet comprises an electrical central conductor which is enclosed within an insulating or dielectric sleeve surrounded by a conductive layer terminated by an antenna to selectively deliver microwave or radio frequency energy to target tissue. One embodiment includes the electrical conductor being enclosed within a non-conductive sleeve which itself is enclosed within a conductive sleeve in a coaxial cable arrangement to form a microwave transmission line terminated by an antenna. Another embodiment includes a resistive element near the distal end of the stylet which couples the center electrode to an outer conductor to generate joulian heat as electromagnetic energy is applied, such as an RF signal.
摘要:
A medical probe apparatus comprising a catheter having a stylet guide housing with at least one stylet port in a side thereof and stylet guide means for directing a flexible stylet outward through at least one stylet port and through intervening tissue to targeted tissues. The stylet guide has an integrated circuit or semiconductor apparatus at the distal end thereof to generate electromagnetic radiation directly at the point of the desired target tissue. The stylet includes at least one semiconductor or integrated circuit radiation emitter adapted for electromagnetic radiation when electrically energized. An elongated electrical insulator includes proximal and distal ends adapted to be introduced into a body opening, such as the urethra. First and second elongated electrical conductors are electrically isolated by the insulator. The distal ends of the electrical conductors are connected to the semiconductor, so that electrical energy coupled to the proximal ends of the conductors energizes the semiconductor to cause radiation. In a particular embodiment of the invention, the semiconductor radiation emitter(s) is (are) a laser(s). In another embodiment, it is a microwave oscillator or integrated circuit. In yet another embodiment, two types of semiconductor radiator emitters are located distally on the catheter, and each type is connected to one of the electrical conductors. According to one aspect of the invention, a third conductor may be connected in common to both types of semiconductor radiation emitters. The stylet may include an antenna to aid in coupling radiation from a semiconductor radiation emitter to the surrounding tissue. The stylet may also include an axial aperture adapted for use with a guide filament.
摘要:
An improved assembly for steering and orienting a functional element at the distal end of a catheter tube holds the functional element with its major axis aligned with the axis of the catheter tube for convenient steering to a tissue site. The mechanism can also pivot the functional element in response to an external force to orient the major axis of the functional element generally parallel to the plane of the tissue site, without bending the catheter tube.