In a communication control device in which an antenna electrode having an antenna connected thereto, a power supply circuit, and a communication circuit are mounted on a mounting board, the antenna electrode is disposed at one corner portion on a principal surface of the mounting board, the communication circuit is disposed on a side of a first side of the principal surface that shares the corner portion, and the power supply circuit is disposed on a side of a second side facing the first side. Further, a first signal path connecting the antenna electrode and the communication circuit extends along the first side, and a second signal path connecting the antenna electrode and the power supply circuit extends along a third side that shares the corner portion and is perpendicular to the first side.

According to a first aspect of the present invention, there is provided a duplexer for a radio frequency antenna, comprising: a radio frequency signal transmitter port arranged for connection to a radio frequency signal transmitter; a radio frequency signal receiver port arranged for connection to a radio frequency signal receiver; a switch arranged selectively to adopt either one of: a first state which connects the transmitter port to a common input/output port of the switch arranged for connection to a radio frequency antenna; and a second state which connects the receiver port to the common input/output port; a switch control unit arranged to monitor radio frequency power at the common input/output port and to receive a transmission gate signal; wherein the switch control unit is arranged to control the switch to adopt the first state upon receipt of the transmission gate signal, and, subsequently, to control the switch to adopt the second state when the monitored radio frequency power falls below a threshold level.

A system comprising a temperature controlled device, a primary energy source, and either or both of an electronic device and an electro-mechanical device. One or both of the electronic device and an electro-mechanical device include a secondary energy source, a switching device, a measuring device, and optionally a controller. The temperature controlled device is connected to the secondary energy source when the temperature controlled device is turned on. The measuring device measures a predetermined condition, and the switching device switches from the secondary energy source to the primary energy source when the temperature controlled device achieves the predetermined condition. The predetermined condition is achieved in about 60 seconds or less.

A high frequency circuit module includes a variable inductance circuit portion and a reactance circuit portion. The variable inductance circuit portion is connected between an antenna port and ground. The variable reactance circuit is connected between the antenna port and a front-end port. The variable inductance circuit portion includes a first inductor, a second inductor, and a switch. The first inductor is connected between the antenna port and the ground. The second inductor and the switch are connected in series, and this series circuit is connected in parallel to the first inductor.

Disclosed is a modular voice amplification system for a protective mask that allows connection of a single amplifier assembly to masks of varying configurations through minimal adjustment of the system. Adapter plates in the form of mounting brackets are provided, each of which is configured for attachment to the single amplifier assembly, but is individually configured for attachment to protective masks of varying configurations through differing attachment mechanisms provided on each adapter plate.

Disclosed is a modular voice amplification system for a protective mask that allows connection of a single amplifier assembly to masks of varying configurations through minimal adjustment of the system. Adapter plates in the form of mounting brackets are provided, each of which is configured for attachment to the single amplifier assembly, but is individually configured for attachment to protective masks of varying configurations through differing attachment mechanisms provided on each adapter plate.

A communication device includes a communication circuit capable of switching a reception or a transmission of a desired frequency signal through an antenna. The circuit includes an oscillator that oscillates a first frequency signal according to the desired frequency signal at a receiving time, a first divider that outputs a second frequency signal obtained by dividing the first frequency signal into two, a second divider that outputs a third frequency signal obtained by dividing the second frequency signal into two, a first mixer that mixes the reception signal received through the antenna and the first frequency signal and outputs an intermediate frequency signal, a second mixer that mixes the intermediate frequency signal and the third frequency signal and outputs a baseband signal, a third mixer capable of mixing the output from the first divider and the output from the second divider, and a filter circuit that eliminates a signal component of the frequency of an output signal from the third mixer from the reception signal at the receiving time.