Abstract: An axial fan has an inner-rotor motor which includes a drive end, a non-drive end and a shaft which extends axially from the drive end; and an impeller which includes a cylindrical impeller cup and a number of impeller blades that extend radially from the impeller cup. The impeller cup has an open upstream end and a closed downstream end which is connected to the shaft. In operation, the motor spins the impeller to generate an airflow in a direction from the non-drive end of the motor to the drive end of the motor. The impeller cup is configured to receive the motor therein and surround the drive end of the motor but not the non-drive end of the motor. As a result, the non-drive end of the motor is exposed to the airflow during operation of the fan.

Abstract: A fan comprises a fan housing which includes a shroud having an upstream end that defines an inlet of the fan housing, a motor which is connected to the fan housing, and an impeller which is connected to the motor. The impeller includes an impeller hub and a number of impeller blades which extend radially outwardly from the impeller hub. The shroud includes a cylindrical micro-perforated panel (“MPP”) liner which extends axially from proximate the inlet to proximate the impeller.

Abstract: A method and apparatus for cancelling interference of an interfering transmit signal. The method includes the steps of (a) transmitting an RF transmit signal from a transceiver, (b) optically modulating the RF transmit signal, (c) optically modulating a RF receive signal; (d) demodulating an optical signal back to an RF signal using an optical-electrical balanced receiver and directing to the transceiver, and (e) demodulating the optical transmit signal back to RF transmit signal.