Abstract: A microwave electrothermal thruster (MET) and its control system is disclosed and claimed. The MET control system uses a dielectric resonator oscillator (DRO) in series with a GaN MMIC-based Solid State Power Amplifier (SSPA) to generate microwave energy, transfer it to a thrust chamber, and heat a propellant that exits a nozzle, providing thrust. The control system uses feedback to provide autonomous control of the MET. A wide variety of propellants may be used, including, for example, hydrazine, ammonia, and water.

Abstract: In some of these approaches, a first fingerprint of a first user is stored in a memory and the transmission of an activation code is authorized. Subsequently, the first fingerprint is re-sensed and authenticated and a second fingerprint of a second user is responsively sensed and stored. The activation code is transmitted to the moveable barrier operator upon subsequent authenticating of the second fingerprint. Subsequently, the second fingerprint is re-sensed and authenticated and a third fingerprint of a third user is responsively sensed and stored. The activation code is transmitted to the moveable barrier operator upon subsequent authenticating of the third fingerprint.

Abstract: The presence of a first human fingerprint at the fingerprint scanner. The first human fingerprint is analyzed to determine whether the first human fingerprint has been previously learned by the barrier movement operator. When the first human fingerprint is determined to be previously learned, a first command is sent to actuate a moveable barrier operator. Within a predetermined time period after the first human fingerprint has been determined to be previously learned, the presence of a second human fingerprint is sensed at the fingerprint scanner. Without analyzing the second fingerprint, a second command is sent to actuate the moveable barrier operator. The first fingerprint and the second fingerprint may be from the same or different users.