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

The invention provides an electric control scanning waveguide leaky-wave antenna based on liquid crystal, belongs to the technical field of microwave antenna engineering, and aims at solving problems that a conventional electric control scanning leaky-wave antenna based on a varactor and other conventional electrically controlled elements is difficult to work at a microwave high-frequency band, and existing liquid crystal electric control scanning leaky-wave antennas require the special design of a bias circuit. The electric control scanning waveguide leaky-wave antenna comprises a top part dielectric plate layer, a metal layer, an insulation paste layer, a liquid crystal layer and a bottom part waveguide slot. The metal layer is arranged at the lower surface of the top part dielectric plate layer. The metal layer has a leaky-wave structure with etching of periodic transverse seams. Equivalent series inductance of electromagnetic wave is enabled to be increased by the periodic transverse seams when electromagnetic wave is transmitted between the bottom part waveguide slot and the metal layer. The metal layer is provided with N periodic seam units. Seam unit spacing distance p is from lambdag / 2 to lambdag. The seams of the middle part are main radiation units. Seam length l of the main radiation unit is from lambdag / 4 to lambdag / 2. The former four and the latter four seams are auxiliary radiation units.

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 provides an electric control zero crossing scanning waveguide leaky-wave antenna based on liquid crystal, belongs to the technical field of microwave antenna engineering, and aims at solving problems that a conventional electric control scanning leaky-wave antenna based on a varactor and other conventional electrically controlled elements is difficult to work at a microwave high-frequency band, and zero crossing scanning of existing liquid crystal electric control fixed-frequency scanning leaky-wave antennas is not easy to realize and the special design of a bias circuit is required. The electric control zero crossing scanning waveguide leaky-wave antenna comprises a top part dielectric plate layer, a metal layer, an insulation paste layer, a liquid crystal layer and a bottom part waveguide slot. The metal layer is arranged at the lower surface of the top part dielectric plate layer. The metal layer has a leaky-wave structure with etching of periodic transverse seams and longitudinal seams. Equivalent series inductance of electromagnetic wave is enabled to be increased by the periodic transverse seams when electromagnetic wave is transmitted between the bottom part waveguide slot and the metal layer. Equivalent parallel induction of electromagnetic wave is enabled to be increased by the periodic longitudinal seams when electromagnetic wave is transmitted between the bottom part waveguide slot and the metal layer. The metal layer is provided with N periodic seam units and two conduction bands. The N periodic seam units include two groups of longitudinal seam columns and a group of transverse seam columns.

A system and method for operating a power amplifier comprising the steps of determining a first impedance generated by a first amplifier component of the power amplifier, determining a second impedance generated by a second amplifier component of the power amplifier, and, adjusting the first impedance or the second impedance to an optimal impedance condition by altering a current ratio of a current delivered by the first amplifier component and a current delivered by the second amplifier component.

The invention provides a liquid crystal electric control zero crossing scanning leaky-wave antenna based on half-mode pectinate line waveguide, belongs to the technical field of microwave antenna engineering, and solves problems that an electric control scanning leaky-wave antenna of conventional electrically controlled elements is difficult to work at a microwave high-frequency band. The liquid crystal electric control zero crossing scanning leaky-wave antenna comprises a top part dielectric plate layer, a metal layer, a liquid crystal layer and a bottom part waveguide slot. The metal layer is arranged between the top part dielectric plate layer and the bottom part waveguide slot. The bottom part waveguide slot has a longitudinal slot structure arranged at the upper surface of a rectangular plate. The liquid crystal layer is arranged in the longitudinal slot. The metal layer has a half-mode pectinate line waveguide structure. N periodic seam units are arranged between the column of pectinate teeth and the longitudinal edge of the opposite side of a rectangular waveguide frame in a rectangular waveguide frame area. The N periodic seam units include a group s longitudinal seam columns and a group of transverse seam columns. The transverse seam columns are arranged between the longitudinal seam columns and the pectinate teeth. Equivalent series inductance of electromagnetic wave is enabled to be increased by the periodic transverse seams and equivalent parallel induction is enabled to be increased by the periodic longitudinal seams when electromagnetic wave is transmitted between the bottom part waveguide slot and the metal layer.

The invention discloses a planar two-dimensional large-angle scanning antenna array, and relates to the technical field of antennas. The array antenna comprises a first array and a second array, wherein the first array comprises N complementary dipole antennas, the second array comprises M complementary dipole antennas, each complementary dipole antenna comprises a dielectric substrate, a first microstrip patch, a second microstrip patch, a floor, a coaxial feeder and P short-circuit metal posts, the first microstrip patch is arranged on an upper surface of the dielectric substrate, a half opening groove is formed in the first microstrip patch, the second microstrip patch is arranged on an upper surface of the dielectric substrate, the second microstrip patch is perpendicular to the firstmicrostrip patch, the floor is arranged at the bottom of the dielectric substrate, and the coaxial feeder is arranged in the dielectric substrate in a penetrating way. The technical effects of simplestructure, simple arraying mode, low side lobe level during the scanning process and small gain fluctuation are achieved.

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 four-leaf-clover-shaped broadband circular-polarized planar antenna, relates to the technical field of wireless communication and aims to provide a broadband circular-polarized planar antenna which is high in mechanical reliability, high in processing precision and low in cost. The four-leaf-clover-shaped broadband circular-polarized planar antenna comprises an upper medium substrate, a medium support plate and a lower medium substrate, wherein the medium support plate is glued between the upper medium substrate and the lower medium substrate. The four-leaf-clover-shaped broadband circular-polarized planar antenna further comprises a phase-shift power feeding network arranged on the lower surface of the lower medium substrate, a four-leaf-clover-shaped radiation paster including four metallic pasters, two coupling arms, a metallic floor positioned between the medium support plate and the lower medium substrate, and six short-circuited through holes, among which four are respectively and electrically communicated with the four metallic pasters and the metallic floor, and the other two are respectively and electrically communicated with the two coupling arms and two output ends of the phase-shift power feeding network.

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 andsecond 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 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.

The invention discloses a hemispherical broadband electrified small antenna based on the near-field coupling principle, and belongs to the technical field of antenna design. The antenna consists of outer metal radiation strips, an inner metal radiation strip, a hemispherical dielectric substrate, a grounding plate and a coaxial cable. The outer surface of the dielectric substrate is closely provided with the annular outer metal radiation strips with different lengths at regular intervals in an attached manner. The inner surface of the dielectric substrate is provided with the inner metal radiant strip in a pasted manner. The hemispherical dielectric substrate covers the grounding plate. The antenna adopts a bottom feed mode, an outer conductor of a feeder is connected with the grounding plate, and an inner conductor is connected with a metal strip on the inner surface of the dielectric substrate. The antenna provided by the invention has the advantages of small size and wide bandwidth,and the antenna structure is novel, simple to manufacture and easy to install. The antenna has low profile characteristics, has the advantage of working in a wide frequency range, and can be appliedto application communication, such as satellite navigation and wireless local area networks.

The invention provides a broadband low-noise amplifier with a reconfigurable frequency band, and belongs to the technical field of radio frequency integrated circuits. According to the amplifier, a broadband signal is divided into two frequency band signals through a coupling line structure, so that a circuit can be optimally designed according to the noise, gain and other performance of each section of signal, frequency reconfiguration is achieved through switching of the single-pole double-throw switch, and the amplifier has the advantages of being low in noise, high in gain and reconfigurable in broadband. Meanwhile, the flexibility of circuit design is improved, miniaturization and integration of a communication system are better facilitated, implementation is easy, and good practical value is achieved.

The invention discloses a hemispherical broadband electrified small antenna based on the near-field coupling principle, and belongs to the technical field of antenna design. The antenna consists of outer metal radiation strips, an inner metal radiation strip, a hemispherical dielectric substrate, a grounding plate and a coaxial cable. The outer surface of the dielectric substrate is closely provided with the annular outer metal radiation strips with different lengths at regular intervals in an attached manner. The inner surface of the dielectric substrate is provided with the inner metal radiant strip in a pasted manner. The hemispherical dielectric substrate covers the grounding plate. The antenna adopts a bottom feed mode, an outer conductor of a feeder is connected with the grounding plate, and an inner conductor is connected with a metal strip on the inner surface of the dielectric substrate. The antenna provided by the invention has the advantages of small size and wide bandwidth,and the antenna structure is novel, simple to manufacture and easy to install. The antenna has low profile characteristics, has the advantage of working in a wide frequency range, and can be appliedto application communication, such as satellite navigation and wireless local area networks.

The invention discloses a broadband Doherty power amplifier based on a single parallel resonant block, which includes: a broadband input power splitter; The network is cascaded in sequence; the peak amplifier circuit is mainly composed of the second input matching network, the peak amplifier T2, and the second output matching network; the combined resonant circuit, the combined resonant circuit includes a parallel resonant block, mainly It is formed by connecting the transmission line inductance L1 and the lumped capacitance C1 in parallel; the constraint condition M for selecting the inductance of the transmission line inductance L1 is: when the two ends of the parallel resonant block are connected to the Ropt end load, the amplitude of S11 of the parallel resonant block is not Greater than ‑15dB, and the absolute value of the S21 phase is not greater than 10°. The invention has low insertion loss, compact structure and smaller overall volume, which is beneficial to miniaturized design and saves cost.

The invention provides a method and a device for stabilizing the gain of a wireless communication receiver. According to the invention, bias circuits of a transconductance amplifier and a mixer circuit are designed, set and adjusted, independent compensation is carried out on the transconductance amplifier, combined compensation is carried out on a mixer and a trans-impedance amplifier, and different compensation circuit structures are selected according to the characteristics of each unit, so that the fluctuation of respective gain under PVT (process angle, voltage and temperature) is reduced, and the overall gain fluctuation is reduced.

The invention discloses a broadband multi-patch antenna, which includes sequentially arranged from top to bottom: a first layer structure, including a top layer multi-patch structure; a second layer structure, including a substrate integrated resonant cavity, and a substrate integrated resonant cavity The top is provided with a top middle groove and two side grooves, the bottom is provided with a bottom middle groove, and the two side grooves are arranged on both sides of the top middle groove and are symmetrical about the top middle groove; the third layer structure, including the feed structure, is used for Feed and couple the signal into the substrate integrated resonant cavity through the bottom middle slot, thereby exciting the mode signal, which radiates through the two side slots and couples with the first mode of the top multi-patch structure, At the same time, the mode signal is also coupled to the first mode and the second mode of the top multi-patch structure through the top middle groove. The invention can generate three effective radiation working modes to further expand the working bandwidth of the antenna, and can also realize efficient cavity-backed slot radiation to reduce gain fluctuation in the antenna band.

The invention relates to a common-caliber three-frequency multi-mode horn antenna, which belongs to the field of electronic science and technology. It consists of OMT, corrugated excitation section, optical wall horn section, and L-band feed section. The orthogonal mode coupler is located at the lowermost end of the antenna; the corrugated excitation segment is located above the OMT, the input end of the corrugated excitation segment is connected to the output end of the OMT, and the output port of the corrugated excitation segment is connected to the input end of the optical wall horn segment; the optical wall The horn section is located above the corrugated excitation section; the L-band feeding section is connected to the side wall of the light-wall horn section through a coupling port; the present invention adopts an orthogonal mode coupler to realize the S and C-band feeding, wherein the C-band passes through the straight-through port. Feeding, the S-band is fed through the coupling port on the sidewall, and the polarizations of the two ports are orthogonal. The high-order mode of the S / C band is excited by the partial corrugated excitation section with double groove depth, and the optical wall horn section is connected to form a multi-mode horn, which improves the polarization isolation of the S / C band and the beam equalization of the pattern, and reduces the In-band gain fluctuation, the performance is better than the optical arm horn antenna.

The invention discloses a planar ring microstrip slow wave structure, belongs to the field of microwave electric vacuum technology, and relates to a traveling wave tube amplifier. It includes a dielectric substrate (2) and a metal wire (1) located on the surface of the dielectric substrate (2), characterized in that the metal wire (1) is a periodic structure formed by sequentially connecting a plurality of annular units with the same shape and size, Each annular unit is formed by butting two split rings with upper and lower mirror planes symmetrical, and two adjacent annular units are connected by a microstrip line at the junction of the two split rings. Compared with the existing microstrip slow wave structure, the present invention has wider cold bandwidth, so the vacuum device adopting the structure of the present invention can be used in a higher operating frequency band under the same size; the planar ring microstrip slow wave provided by the present invention The structure has a wide lateral dimension, which can effectively reduce the requirements on the electron gun and focusing magnetic field; and has a high coupling impedance, which can better interact with the electron beam, so it is a kind of small The slow wave structure of planar traveling wave tube.

The invention discloses a four-leaf-clover-shaped broadband circular-polarized planar antenna, relates to the technical field of wireless communication and aims to provide a broadband circular-polarized planar antenna which is high in mechanical reliability, high in processing precision and low in cost. The four-leaf-clover-shaped broadband circular-polarized planar antenna comprises an upper medium substrate, a medium support plate and a lower medium substrate, wherein the medium support plate is glued between the upper medium substrate and the lower medium substrate. The four-leaf-clover-shaped broadband circular-polarized planar antenna further comprises a phase-shift power feeding network arranged on the lower surface of the lower medium substrate, a four-leaf-clover-shaped radiation paster including four metallic pasters, two coupling arms, a metallic floor positioned between the medium support plate and the lower medium substrate, and six short-circuited through holes, among which four are respectively and electrically communicated with the four metallic pasters and the metallic floor, and the other two are respectively and electrically communicated with the two coupling arms and two output ends of the phase-shift power feeding network.

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 thefact 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 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.