44results about How to "Gain fluctuation is small" patented technology

The invention discloses a liquid crystal electrical control zero-crossing scanning leaky wave antenna based on comb-line waveguide, which belongs to the technical field of microwave antenna construction. The problems that a conventional electrical control scanning leaky wave antenna based on a varactor and other traditional electric tuning elements difficultly works in a microwave high frequency band and the existing liquid crystal electrical control fixed-frequency scanning leaky wave antenna is difficult to realize zero-crossing scanning and requires a bias circuit which is specially designed are solved. The antenna provided by the invention comprises a top dielectric plate layer, a metal layer, a liquid crystal layer and a bottom waveguide groove. The metal layer is arranged between the top dielectric plate layer and the bottom waveguide groove. A longitudinal groove structure is arranged on the upper surface of a rectangular plate to form the bottom waveguide groove. The metal layer is in a comb-line structure. N periodic slit units are arranged between two columns of comb teeth on the comb-line structure. N periodic slit units comprise two groups of vertical slit columns and a group of transverse slit column. Through periodic transverse slits, the equivalent series inductance of electromagnetic waves spreading between the bottom waveguide groove and the metal layer is increased. Through periodic vertical slits, the equivalent parallel capacitance is increased.

A kind of broadband and broad-beam micro-strip antenna unit adopts keyhole coupling and multi-layer micro-strip technology and made up by four rectangular metal patches whose lengths and widths are parallel and three layers of medium layer. The third metal patch is grounding, and the fourth metal patch is micro-strip transmission line. Metal cylinder crosses a rectangular hole at the middle of metal patch without touching it, and its upper end connects with the second metal patch and its bottom end connects with micro-strip transmission line. Count to get the length and width of the first and second metal patch, the diameter of metal cylinder, length and width of rectangular hole, the thickness of each layer of medium, the length and width of micro-strip transmission line according to user's request. Adjust the place of metal cylinder crossing the rectangular hole according to the resonance frequency and matching instance. The frequency of micro-strip antenna unit is 3% to 10%, the unit standing wave of broadband VSWR is not bigger than 2.5, the width of unit wave arrives to 120 degree and gain undulation inside the taper space is less than 5dB.

The invention discloses a planar annular microstrip slow-wave structure which belongs to the field of microwave electric vacuum technology. The planar annular microstrip slow-wave structure relates to a traveling-wave tube amplifier device. The planar annular microstrip slow-wave structure comprises a dielectric substrate (2) and metal wires (1) on the surface of the dielectric substrate (2). The planar annular microstrip slow-wave structure is characterized in that each metal wire (1) has a periodical structure which is obtained through successively connecting a plurality of annular units with same shape and same dimension. Each annular unit is obtained through joining two open rings which are in mirror symmetry in a vertical direction. Two adjacent annular units are connected at a joining part between the two open rings through a microstrip line. Compared with an existing microstrip slow-wave structure, the planar annular microstrip is advantageous in that a vacuum device with the planar annular microstrip slow-wave structure can be used in a higher operating frequency band on condition of same dimension because of wider cold bandwidth. The planar annular microstrip slow-wave structure provided by the invention has a wide transverse dimension, thereby effectively reducing a requirement for an electronic gun and a focusing magnetic field. The planar annular microstrip slow-wave structure has a relatively high coupling impedance and can perform interaction with an electron beam in a relatively good manner. Therefore the planar annular microstrip slow-wave structure has relatively high potential and is suitable for miniature planar traveling-wave tubes.

The invention discloses a low-profile two-dimensional wide-angle scanning circular polarization phased-array antenna, and aims to provide an antenna structure which is easy to integrate and has good wide-angle scanning gain characteristics and circular polarization characteristics. According to the technical scheme, each 3D structure antenna unit forms an array unit of the two-dimensional wide-angle scanning circular polarization phased-array antenna through metal columns which are arranged between an annular radiator and a circular polarization patch slotting radiator in a circumferential circular array mode; each 3D structure antenna unit is fixed on the two-dimensional layer surface of the upper dielectric plate through a feed column fixedly connected to the lower surface of the circularly polarized slotted patch radiator; the feed column penetrates through the lower dielectric plate, the four 3D structure antenna units are connected with the annular radiator upwards and are connected with the feed base disc downwards, the four adjacent 3D structure antenna units form a 2*2 rectangular arrangement subarray in a touch type feed and 90-degree sequential rotation arrangement mode,and the four feed base discs are delayed by 90 degrees clockwise in sequence for feeding, so that the optimal right-handed circular polarization performance is obtained.

The invention discloses a broadband substrate integrated waveguide (SIW) back cavity slot antenna array adopting an L-shaped slot unit. The antenna array comprises a parallel feed type power divisionnetwork and a plurality of SIW back cavity slot antenna units, each antenna unit is mainly composed of an SIW rectangular resonant cavity and two pairs of L-shaped slot pairs rotationally symmetricalrelative to the center of the resonant cavity, and two L-shaped slots of each of L-shaped slot pairs are arranged face to face. By designing the positions of metalized through holes and metalized blind holes, each antenna unit forms a rectangular SIW isolation cavity with an open long side in a dielectric bonding layer, and the influence of an electromagnetic field leaked in the bonding layer on an antenna array directional diagram and gain is remarkably reduced. The antenna array realized by the invention has the characteristics of wide directional diagram bandwidth, flat in-band gain, narrowbeams in both an azimuth plane and a pitch plane, and low cross polarization electrical level.

The invention discloses a CMOS radio frequency receiving front end with a wide temperature work gain automatic control function. The front end comprises a radio frequency single end-difference converting circuit, a local oscillator single end-difference converting circuit, a Gilbert frequency mixing circuit, a variable gain amplifier, an output driving circuit, a band gap reference based current bias circuit and a gain automatic control circuit. The radio frequency single end-difference converting circuit and the local oscillator single end-difference converting circuit respectively convert input single-end receiving signals and local oscillator signals into difference signals, the difference output driving the Gilbert frequency mixing circuit is connected with the variable gain amplifier, then difference-single end conversion is carried out through the output driving circuit, and finally intermediate frequency output is performed. The current bias circuit outputs five paths of reference currents from Iref1 to Iref5 respectively to the tail current tube circuits of the Gilbert frequency mixing circuit, the variable gain amplifier, the output driving circuit and the gain automatic control circuit for current biasing.

The invention discloses a broadband Doherty power amplifier based on a single parallel resonance block. The broadband Doherty power amplifier comprises a broadband input power divider; a carrier amplification circuit, which is mainly formed by sequentially cascading a phase shift network, a first input matching network, a carrier amplifier T1 and a first output matching network; a peak value amplifying circuit, which is mainly formed by sequentially cascading a second input matching network, a peak value amplifier T2 and a second output matching network; and a combined resonance circuit, whichcomprises a parallel resonance block and is mainly formed by connecting a transmission line inductor L1 and a lumped capacitor C1 in parallel, wherein the constraint condition M selected for the inductance value of the transmission line inductor L1 is that when the two ends of the parallel resonance block are connected with terminating loads with the impedance of Ropt, the S11 amplitude of the parallel resonance block is not larger than -15 dB, and the absolute value of the S21 phase is not larger than 10 degrees. The broadband Doherty power amplifier is low in insertion loss, compact in structure, smaller in overall size, beneficial to miniaturization design and capable of saving cost.

The invention discloses a frequency polarization reconfigurable patch antenna. The antenna includes a dielectric substrate, the upper surface of the dielectric substrate is provided with a metal patch, The lower surface of the dielectric substrate is provided with a ground plane, and the antenna further comprises three groups of ground via holes arranged in the dielectric substrate, wherein the ground via holes connect the metal patch and the ground plane, and the antenna further comprises two pairs of controllable perturbation parts arranged on the metal patch, wherein the three groups of ground via holes and the two pairs of controllable perturbation parts are connected with switches respectively. The antenna can work at different frequencies by changing the states of three groups of ground via holes. The antenna has three different polarization characteristics: linear polarization, left-handed circular polarization and right-handed circular polarization, and satisfies better polarization characteristics, better standing wave characteristics, small gain fluctuation, low profile, small volume, simple implementation and easy integration.

The invention relates to a multistage fibre amplifier having a first amplifying fibre (EDFI) and at least one further amplifying fibre (EDF2) connected in series, and also a pump source (2D), a first pump signal (AI) being fed to the first amplifying fibre (EDFI) and a further pump signal (A2) being fed to the further amplifying fibre (EDF2). The multistage fibre amplifier is distinguished by the fact that the further pump signal (A2) is fed to the further amplifying fibre (EDF2) via a power-dependent attenuation element (ZFED). The attenuation element (ZFED) is formed in such a way that, as the pump power increases, small further pump signals are attenuated to a greater extent than large further pump signals. The power-dependent attenuation of the pump signal (A2) fed to the further amplifying fibre primarily results in improvements in the noise figure of the multistage amplifier.; A method for adapting the pump power of the multistage fibre amplifier according to the invention is furthermore specified. This involves a modified feedforward control which advantageously compensates for the delays brought about by the additional fibre on changes in the input signal power. An improved dynamic behaviour of the multistage fibre amplifier is achieved by means of the method according to the invention.

The invention discloses a method for designing a special-shaped curved surface conformal array antenna of a vehicle-carrying platform, and aims to provide an antenna design method capable of remarkably reducing the array height and realizing full-airspace measurement and control communication under a vehicle-mounted platform. The method is implemented by the following steps of: establishing an xyzthree-dimensional rectangular coordinate system according to a parabolic, spherical and cylindrical surface special-shaped curved surface array flow pattern, dividing the special-shaped curved surface conformal array flow pattern into a paraboloid part, a partial spherical surface part and a cylindrical surface part, and connecting the lower part of a paraboloid with a cylindrical surface in an arc transition manner to obtain a special-shaped curved surface array flow pattern formed by parabolic, spherical and cylindrical surfaces; on the basis of the special-shaped curved surface array flowpattern, constructing an antenna subarray according to the rule of half-wavelength uniform arrangement of antenna units in the antenna sub-array, and establishing a special-shaped curved surface antenna array based on a curved surface sub-array level; and then taking curved surface subarrays as basic units, and arranging the antenna subarrays on the special-shaped curved surface conformal array according to an equal-area region center arrangement rule to obtain the special-shaped curved surface antenna array based on the curved surface subarray level.