47 results about "Radiation impedance" patented technology

The invention relates to a method and a system for adapting a loudspeaker to a specific listening position relative to the loudspeaker according to which method and system the acoustic power radiated by the loudspeaker is corrected by means of a correction filter inserted in the signal path through the loudspeaker, the response of said correction filter being determined by comparison between the a quantity characterising the radiated acoustic power measured at an actual listening position and a similar quantity measured at a reference listening position. According to a specific embodiment of the invention said characterising quantities are the radiation resistances measured at the actual listening position and the reference listening position respectively.

A multi-band antenna system for a portable communications device (e.g. a PC Card wireless modem) is disclosed. The multi-band antenna system comprises a dipole antenna, a reactive circuit, and transmission means coupled between the reactive circuit and the dipole antenna. For signals having frequencies within a first frequency band (e.g. the CDMA 0.86 GHz band), the reactive circuit operates as a trap, i.e. as a substantially high impedance, which enables a radiation impedance of a monopole formed by the presence of the trap to be coupled directly into the feed system (e.g. a diplexer) of the antenna system. The dipole antenna is configured and dimensioned to receive signals within a second frequency band (e.g. the PCS 1.92 GHz band). Second frequency band signals received by the dipole antenna are conducted through the signal conductor of the transmission means to the feed system substantially unimpeded by the reactive circuit. The multi-band antenna system may further include a diversity antenna, which may be configured so that it is polarized orthogonal the to dipole antenna.

A transmission line includes transmission lines parallel and perpendicular, respectively, to a flat portion of a reflector, and the parallel transmission line and the flat portion form a first strip line and the perpendicular transmission line and a conductive plate similarly form a second strip line. Radiators and the transmission line have a radiation impedance and a characteristic impedance, respectively, both set at 150 Ω when the antenna's output terminal has a reference impedance of 75 Ω. If the parallel transmission line has a midpoint serving as the output terminal of the antenna this portion's receiving current is divided in two so that an impedance of half that of the strip line can be provided and a coaxial cable can directly be connected to the transmission line. A matcher or a mixer is not included in the antenna, and matching and mixing losses can be prevented.

An antenna includes inductance elements that are magnetically coupled together, an LC series resonant circuit that includes one of the inductance elements and capacitance elements, and an LC series resonant circuit that includes another of the inductance elements and capacitance elements. The plurality of LC series resonant circuits are used to radiate radio waves and are used as inductances of a matching circuit that matches an impedance when a power supply side is viewed from power supply terminals and a radiation impedance of free space.

A transmission line includes transmission lines parallel and perpendicular, respectively, to a flat portion of a reflector, and the parallel transmission line and the flat portion form a first strip line and the perpendicular transmission line and a conductive plate similarly form a second strip line. Radiators and the transmission line have a radiation impedance and a characteristic impedance, respectively, both set at 150Ω when the antenna's output terminal has a reference impedance of 75Ω. If the parallel transmission line has a midpoint serving as the output terminal of the antenna this portion's receiving current is divided in two so that an impedance of half that of the strip line can be provided and a coaxial cable can directly be connected to the transmission line. A matcher or a mixer is not included in the antenna, and matching and mixing losses can be prevented.

An antenna system and related method are disclosed for an electrically small antenna of variable geometry capable of a harmonically pure resonant radiation pattern over a broadband coverage of frequency selection. One geometrical embodiment comprises a multiple loop antenna system is configured to radiate a switched signal via the multiple antenna elements to inhibit transmission of any of the harmonics of the signal. An additional geometrical embodiment comprises a cylindrical shell with one or more interior center conductors to overcome radiation resistance and radiate a signal pattern of desirable toroidal shape free from undesirable harmonics.

The invention belongs to the field of underwater acoustic test technology base, and mainly relates to a near-field acoustic tomography measurement method for the mutual radiation impedance of an underwater acoustic array. The method includes the following steps: obtaining near-field acoustic field information of a radiated acoustic field of an acoustic array through laser tomography measurement; processing the obtained acoustic field information by using a near-field acoustic holographic transformation technology; dividing the complex vibration velocity into blocks according to the position ofeach array element to obtain the complex vibration velocity of the source surface of each array element; calculating the complex acoustic pressure of the source surface of each array element and theradiated acoustic pressure generated by the array element in the surface positions of the other array elements; and carrying out calculation based on the classic acoustic array mutual radiation impedance theory. The beneficial effects are as follows: the shortcomings of the common intrusive acoustic array mutual radiation test method are overcome by a non-contact test method; the problem that there is no method for accurately testing the mutual radiation impedance of an underwater acoustic array at low frequency and high power is solved; a mutual radiation model is provided for the velocity control of an underwater acoustic array; and a powerful technical guarantee is provided for the design and development of a low-frequency and high-power acoustic array.

An information terminal device includes a casing, a wireless board, and an antenna arranged to utilize a plurality of radio systems. The antenna includes a power feeding terminal and a plurality of resonant circuits. The plurality of resonant circuits are arranged to radiate radio waves. The plurality of resonant circuits further define a matching circuit that provides impedance matching between an impedance on a power feeding side as viewed from the power feeding terminal and a radiation impedance of a free space.

The invention provides a method for measuring mutual radiation impedance of a transducer array in a non-anechoic tank and a system thereof. the method comprises the following steps: Step 101, resonant frequency of each transducer in the air and resonant frequency of each transducer in water are measured; Step 102, Q distribution points are selected in the non-anechoic tank and are used for distributing a transducer pair to be measured; Step 103, the transducer pair to be measured is distributed on some point in the distribution points, resistance and reactance of a first transducer under various working conditions are obtained when the first transducer and a second transducer operate at same-phase resonant frequency of the first transducer in the air and in water and at reversed-phase frequencies of the first transducer in the air and in water; Step 104, the above Step 103 is repeated until resistance and reactance measurement of the above transducer pair to be measured at all Q distribution points are completed; and Step 105, mutual radiation resistance and mutual radiation impedance of the transducers to be measured at each point are obtained so as to obtain Q mutual radiation resistances and mutual radiation impedances, and mean value of the Q mutual radiation resistances or mutual radiation impedances is calculated to be respectively used as mutual radiation resistance and mutual radiation impedance of the final measurement.

Apparatus is provided featuring a signal processor or signal processing module configured at least to: receive signaling containing information about a radiation impedance of a piston vibrating a process medium, including a fluid or slurry; and determine a speed of sound or density measurement related to the process medium, based at least partly on the signaling received. The signal processor or signal processing module may determine a speed of sound measurement related to the process medium, based on at least partly on the density of the process medium, including where the density of the process medium is known, assumed or determined by the signal processor or signal processing module, or determine a density measurement related to the process medium, based on at least partly on the speed at which sound travels in the process medium, including where the speed of sound of the process medium is known, assumed or determined by the signal processor or signal processing module.

The present invention relates to a method and an arrangement for optimizing the efficiency of a power amplifier (1) that is utilized for transmission of radio signals in a portable radio communication device, such as a mobile phone. The impedance loading the power amplifier (1) is controlled by a controller (5) in dependence on a transmission power of the portable radio communication device, wherein the radiating impedance of an antenna element (2) loading the power amplifier is controlled in dependence of the desired load impedance. Preferably, the changing of radiating impedance is performed by changing a capacitive coupling between the antenna element and a ground element or by changing the size of the antenna element. Better efficiency and bandwidth are thereby attained.

The invention discloses a novel Bluetooth / WLAN antenna and intelligent equipment. The novel Bluetooth / WLAN antenna comprises a PCB and an antenna component, wherein an antenna clearance area is arranged on the PCB; the antenna clearance area comprises a first clearance area arranged on the upper surface of the PCB and a second clearance area arranged on the lower surface of the PCB; the antenna component comprises a first radiator, a second radiator and a third radiator; the first radiator and the second radiator are arranged inside the first clearance area; a feed part is arranged on the first radiator; the third radiator is arranged inside the second clearance area; the second radiator and the first radiator are coupled to form a first resonance branch; the second radiator and the third radiator are coupled to form a second resonance branch. The antenna disclosed by the invention is small in occupied area, high in design flexibility, high in radiation impedance and good in omni-directivity.

An information terminal device that can support almost all of the frequency bands of a plurality of radio systems is provided. The information terminal device includes a casing, a wireless board (110A), and one of an antenna (1A) and an antenna (1B) so as to employ a plurality of radio systems. One of the antenna (1A) and the antenna (1B) includes a power feeding terminal and a plurality of resonant circuits. The plurality of resonant circuits are used for radiating radio waves. The plurality of resonant circuits are further used for a matching circuit that provides impedance matching between an impedance on a power feeding side as viewed from the power feeding terminal (50 CR ) and a radiation impedance of a free space (377 CR ).

The invention relates to a T-type superpower ultrasonic transducer. The T-type superpower ultrasonic transducer utilizes a longitudinal vibration piezoelectric ceramic vibrator to generate longitudinal vibration, stimulates a metal round vibration disc directly connected with the longitudinal vibration piezoelectric ceramic vibrator to generate the vibration of the same frequency, and radiates sound waves to media. With the help of the conversion of the vibration mode, flexural vibration is generated in the metal round vibration disc, effective conversion of the longitudinal vibration mode and the flexural vibration mode is achieved, uniformity of the radiation sound field of the transducer is greatly improved, radiation area of the transducer can be effectively increased, high-power working is realized, at the same time, radiation impedance of the transducer is improved, acoustic matching of the transducer is improved, and radiation efficiency of the transducer is improved. In addition, due to the fact that the flexural vibration disc has multiple vibration modes, the transducer can work in different vibration modes and radiate ultrasonic waves of different frequencies, and therefore an ultrasonic wave source working in multiple frequencies is formed.