350results about "Telescopic elements" patented technology

An antenna adapter may be used for mounting an antenna to a vehicle or other object via the object's antenna mount, making antenna theft more difficult. The adapter is therefore configured to both receive the antenna and engage the antenna mount. The antenna adapter includes one or more elements that are configured to assist in removable engagement of the antenna adapter with the antenna, such as a groove and a set screw that screws through the antenna and into the groove of the adapter. The antenna adapter may also include another element that is configured to maintain the antenna at a particular radial orientation with respect to the antenna adapter when engaged therewith.

The invention discloses a plane matrix type high folding and unfolding bionic antenna truss structure with a negative Poisson's ratio effect, and relates to the technical field of space folding and unfolding mechanisms, the plane matrix type high folding and unfolding bionic antenna truss structure comprises a plurality of cell elements and a plurality of cell element connecting rods, transverse cell elements are connected through the cell element connecting rods, and longitudinal cell elements are fixedly connected through adjacent cell element cross beams; the cell element connecting rods are hinged to the cell elements on the two sides respectively, and the cell elements are three-level positioning inwards-concave hexagonal cell elements; the folding and unfolding antenna truss structure is in a folded state during launching, transportation and silent latency and is in an unfolded working state during on-orbit task execution, the high folding and unfolding ratio characteristic of the antenna provides bionic improvement inspiration for various urgent properties such as stealth and size reduction of a satellite antenna structure, the shape of the antenna folding and unfolding array can be changed in a multi-stage mode, and the antenna folding and unfolding array is suitable for large-scale popularization and application. Therefore, the functions of optimal frequency band adjustment, optimal area expansion, switching of different scanning ranges and the like are realized.

The invention is applied to the technical field of communication, and provides an antenna control method and a communication device. The method may be applied to a communication device comprising a primary antenna panel and at least one secondary antenna panel, the primary antenna panel being in a deployed configuration. The method comprises the following steps: acquiring wind speed information; determining whether the form of the auxiliary antenna panel needs to be adjusted according to the wind speed information; and under the condition that the form of the auxiliary antenna panel needs to be adjusted, the form of the auxiliary antenna panel is adjusted. Wherein the form of the auxiliary antenna panel comprises an unfolded form and an ununfolded form, the antenna panel is in the unfolded form when the antenna panel performs signal transmission, and the antenna panel comprises a main antenna panel and the auxiliary antenna panel. According to the method, the form of the auxiliary antenna panel can be flexibly adjusted according to the wind speed information, so that the size of the antenna panel can be increased as much as possible under the condition that the requirement of wind resistance for the size of the antenna panel is met, and the communication capacity and resolution can be improved.

The invention discloses a portable antenna, and relates to the field of measurement and control antennae, the portable antenna comprises an antenna disc, an antenna pedestal and a tripod, the antenna disc, the antenna pedestal and the tripod are sequentially installed from high to low, the tripod comprises a sleeve seat, a central vertical pipe is sleeved with the sleeve seat, and the upper end of the central vertical pipe is fixedly connected with a connecting end plate used for being connected with the antenna pedestal. The supporting legs are overturned outwards to be unfolded, at the moment, the elastic fixing pieces drive the central vertical pipe to ascend, the two supporting arm rods are unfolded together and unfolded to be in the horizontal state, then the supporting arm rods are stretched to be lengthened, the base is fixed to the surface of the connecting end plate, and then the mounting disc is mounted on the upper surface of the door-shaped frame through the bolt connecting pieces. And then a plurality of reflection panels are sequentially installed on the outer side of the installation disc, the feed source cylinder is installed on the installation disc, most of the whole structural component can be disassembled or folded, the storage portability is improved, disassembly and assembly are convenient and rapid, and rapid motorization is achieved.

The invention discloses a mesh antenna metal net zero-constraint splicing method. A metal net is tiled and hung on a working tension applying device, and working tension is applied to the metal net in the transverse direction and the longitudinal direction; in the working tension state, tension control belts are sewn on the edges of the two sides of the metal net in the length direction; lapping two metal nets which need to be spliced and are sewn with the same tension control belts, wherein the sections of the lapping positions are lapped according to the sequence of belt-net-net-belt; sewing two layers of metal nets along the two sides of the tension control belt by adopting composite material sewing lines; and repeating the steps, and sewing all the metal meshes required by the whole antenna reflecting surface in sequence. According to the method, the metal net is spliced by adopting an overlock stitching method, the tension control belt can be detached after splicing is completed, the formed splicing seam is of a net-net structure, the thickness is only 0.07-0.08 mm, the elasticity keeps the original elasticity of the metal net, the net surface tension is more uniform, and the risk that the antenna expansion resistance is increased due to micro shrinkage of the tension control belt at high temperature is effectively eliminated.

The invention provides a multi-folding type unfolding device of a phased-array antenna and an assembling and working method of the multi-folding type unfolding device, and belongs to the field of space product structure and mechanism design. The problem that the unfolding capacity of an existing multi-fold unfolding type phased-array antenna is limited is solved. The multi-folding type unfolding device comprises a phased-array antenna unfolding part, an unfolding locking mechanism and a pressing and releasing mechanism, the side edge of the phased-array antenna unfolding part is connected with a main frame of a satellite through the unfolding locking mechanism, a plurality of pressing points are arranged on the phased-array antenna unfolding part, each pressing point is connected with the satellite through the pressing and releasing mechanism, and the phased-array antenna unfolding part is connected with the satellite through the pressing and releasing mechanism. The phased-array antenna unfolding part and the satellite bottom plate are both provided with phased-array antenna sub-arrays, the unfolding locking mechanism comprises a tightening arm, a top hinge and a root hinge, the top hinge is installed on the side face of the phased-array antenna unfolding part, and the root hinge is installed on the side face of a main frame of a satellite. The multi-folding unfolding device is mainly used for multi-folding unfolding of the phased-array antenna.

The invention provides an unfolding device of a satellite-borne phased-array antenna and an assembling and working method of the unfolding device, and belongs to the technical field of space product structure and mechanism design. The problem that the unfolding capacity of an existing unfolding type phased-array antenna is limited is solved. The unfolding device comprises a phased-array antenna unfolding part, unfolding locking mechanisms and a pressing releasing mechanism, in a pressing state, the phased-array antenna unfolding part is located below a satellite bottom plate, and the side edge of the phased-array antenna unfolding part is connected with a main frame of a satellite through the unfolding locking mechanisms which are symmetrically arranged; a plurality of pressing points are arranged on the phased-array antenna unfolding part, each pressing point is connected with a satellite through a pressing releasing mechanism, phased-array antenna sub-arrays are arranged on the phased-array antenna unfolding part and a satellite bottom plate, and the unfolding locking mechanism comprises an unfolding arm, an unfolding arm support, a torsion spring and a locking hook. The two ends of the two unfolding arms are rotationally connected with the two ends of the two unfolding arm supports. The satellite-borne phased-array antenna unfolding device is mainly used for unfolding satellite-borne phased-array antennas.

The present invention relates to a portable frequency jammer. The portable frequency jammer includes a host and an antenna module, the host includes a housing and at least one functional module provided in the housing, the at least one functional module is used to generate an interference signal within at least one frequency band; the antenna module is positioned outside the housing and integrally connected to the housing, the antenna module includes at least one antenna, and the at least one antenna is communicatively connected to the at least one functional module respectively. Since the antenna module of the portable frequency jammer in the present invention is provided outside the housing and integrally connected to the host, there is no need to repeatedly disassemble and assemble the antenna, thus having the advantages of saving time and labor and having a fast response speed.

The invention discloses an automatic unfolding parabolic antenna with a flexible surface and a fixed surface combined, and belongs to the field of antennas. The antenna comprises a center body, a reflecting surface, a folding driving mechanism, an annular adjusting mechanism, an auxiliary surface, an auxiliary surface supporting structure and a feed source, wherein a feed source supporting cylinder plays a role in overall supporting. Wherein the fixed surfaces and the flexible surfaces are arranged at intervals to form an antenna reflecting surface, when the system works, the folding driving mechanism adopts an electric unfolding and folding mode to realize full-automatic unfolding and folding actions of the reflecting surface, and after the antenna is unfolded, the surface shape precision of the flexible surfaces can be adjusted through the annular adjusting mechanism. The invention provides a flexible and fixed surface combined reflecting surface structure form for the first time, and full-automatic unfolding and folding of the whole reflecting surface are realized. A traditional manual assembly mode is broken through, the maneuvering performance of the large-diameter vehicle-mounted antenna is effectively improved, the antenna opening time is shortened to be within 15 minutes, and the position precision of the antenna when the antenna is unfolded again is guaranteed while the maneuvering performance is improved.

The invention discloses a fixed surface deployable antenna. The antenna comprises a center body, a lifting mechanism, an outer ring panel group and a locking assembly. The center body has a first end and a second end in an axial direction. The outer ring panel set comprises a plurality of arc-shaped panel units, each arc-shaped panel unit is hinged to the fixed disc through an overturning base, the outer surface of each arc-shaped panel unit is connected with the movable disc through an inclined supporting rod, one end of each inclined supporting rod is connected with the movable disc through a first universal hinge, and the other end of each inclined supporting rod is connected with the movable disc through a second universal hinge. The first lifting device drives the movable disc to move in the direction away from or close to the fixed disc, the arc-shaped panel unit can rotate clockwise or anticlockwise, and therefore the fixed surface expandable antenna has the unfolded state and the folded state. The size of the outer envelope in the folded state meets the railway / highway transportation requirement, the time used in the unfolding and folding process is short, disassembly and assembly are not needed, and therefore precision errors caused by disassembly and assembly are avoided.

The invention discloses an interference elimination device for a router antenna, which relates to the technical field of routers and comprises a clamp mechanism. According to the interference elimination device for the router antenna, through the design of a clamp mechanism, in the process that a clamping plate clamps the surface of a router, a supporting rod extrudes a third spring on the inner side of a clamp shell, so that the damping and buffering effects are achieved, the clamping pressure of parts is reduced, damage to objects is avoided, and therefore the service life of the parts is prolonged; secondly, the supporting rods are contracted according to the appearance of the router, so that the supporting rods can be conveniently attached to the surface of the object, the clamping and attaching effect is improved, a certain anti-skid effect is achieved, the circular plates are made of silicone grease materials, heat conduction is enhanced, the overall heat dissipation efficiency is improved, the heat dissipation effect of equipment is kept, and the service life of the equipment is prolonged. Meanwhile, the contact area of the circular plate is small, space is reserved in the router clamping process, and the heat dissipation effect of equipment is prevented from being affected.

The invention relates to the technical field of satellite communication antennas, in particular to a terminal antenna for Tiantong satellite communication, which comprises a shell and a terminal, the signal transceiving mechanism comprises a signal antenna; the telescopic mechanism comprises a telescopic column and a limiting frame; the control module comprises an oil pump, controls the signal antenna to automatically stretch and contract by setting a satellite received signal strength value, realizes automatic adjustment of a signal receiving area of the signal antenna, avoids complex manual adjustment steps, optimizes an operation process, can perform auxiliary cooling on the interior of the terminal through hydraulic oil, prolongs the working time of the terminal, and improves the working efficiency of the terminal. After the signal antenna stretches out and draws back in place, the signal antenna is locked through the arranged limiting frame, auxiliary positioning is achieved, meanwhile, the device adapts to all diameter size parts of the signal antenna, the application scene is wide, and when the signal antenna stretches out, automatic locking and limiting of the limiting frame on the signal antenna are achieved through the rotating cylinder and the moving ring.

The present invention relates to a folding device for an antenna element layer, which comprises two first truss beams; two second truss beams; a support cross beam, including support legs and a cross beam main body; a telescopic driving mechanism arranged on the cross beam main body; a first link mechanism, including two first links, two second links and two first linkage rods; one ends of the two first links are hinged to one end of the cross beam main body, the middle parts of the first links are respectively hinged to the middle parts of the second links, and the hinge points between the first links and the second links are also respectively hinged to the second truss beams, the other ends of the first links are respectively hinged to one ends of the first linkage rods, and the other ends of the first linkage rods are respectively hinged to the first truss beams; one ends of the two second links are hinged to the telescopic driving mechanism. For the above folding device of the antenna element layer, when the antenna element layer needs to be repaired or is not in use, the telescopic driving mechanism drives the first link mechanism to fold up, and the folding device of the antenna element layer folds, which is convenient for maintenance and storage.

The utility model discloses a 5G antenna with a good protection effect, and relates to the technical field of 5G antennas. The antenna extension device comprises a base, a sliding block is slidably connected to the interior of the base, an installation groove is formed in the sliding block, a circuit board is fixedly connected to the interior of the installation groove, and a terminal is welded to one end of the circuit board. The motor rotates to drive the threaded rod to rotate so as to drive the sliding block to move, so that the antenna connected to the sliding block through the terminal can move backwards, and the antenna enters from one side of the circular arc along the guide groove and extends out from the other side, so that the antenna can extend out of the interior of the traversing machine body. According to the fancy flight antenna, the influence on the flight performance due to unstable signals caused by the overlong antenna in the fancy flight process is avoided, and meanwhile, the technical problems that the antenna needs to be well protected, and the length of the antenna needs to be adjusted are solved.

A narrow-band dipole antenna module comprising: a housing comprising a base having an opening defined therein, and a hollow post extending [A1] from the opening and having a plurality of antenna openings defined therein; a circuit assembly configured for insertion into the housing comprising: an input printed circuit board having transmit and receive connectors thereon; a matching printed circuit board having lumped element matching components and a plurality of terminal blocks thereon; a pair of coaxial feed lines connected between the input and matching printed circuit boards, each having a coil formed therein such that the feed lines act as a balun; and at least one rigid support member connected between the input and matching printed circuit boards such that when the circuit assembly is inserted into the housing the terminal blocks are adjacent the antenna openings; and a plurality of antenna elements configured to be connected to the terminal blocks.

The application discloses an over-constrained cross type deployable parabolic cylindrical antenna support structure and particularly relates to the technical field of aerospace. The application comprises a plurality of arc surface deployable units, cylindrical deployable units and a motion control device, the arc surface deployable units are deployed to form an arc-shaped support surface, the cylindrical deployable units are deployed to form a linear support surface, and the motion control device is used for controlling the cylindrical deployable units to drive the arc surface deployable units to be deployed or contracted. The technical scheme of the application aims to provide a reference value for the structural design of a large-scale deployable parabolic cylindrical antenna, realizes the support of the deployable parabolic cylindrical antenna, and is beneficial to the structural design of the deployable parabolic cylindrical antenna.

The utility model discloses an assembly assembly dotting frock, including work table, the top of work table is sequentially provided with feeding station, assembly station, pre -dotting station, dotting station and material collecting box, and the inside of work table is provided with through groove, and one side of through groove is provided with mounting panel, and the top of through groove is provided with material shifting board, and the side of mounting panel is provided with linear slide rail, and material shifting board passes through sliding block and is installed on linear slide rail, and one side of material shifting board is sequentially provided with first material shifting dog, second material shifting dog, third material shifting dog and fourth material shifting dog, and the utility model discloses through with antenna mast from feeding station sequentially after assembly station, pre -dotting station and dotting station, then, fall into the inside of material collecting box, realized the automatic integration of antenna mast feeding, assembly, dotting and collection, reduced the consumption of human resources, improved production efficiency.

The utility model discloses a telescopic satellite antenna support frame, which comprises a fixed frame detachably connected with the back surface of a satellite antenna; the side slope end of the triangular table is detachably connected with the fixing frame; the top end of the connecting block is detachably connected with the bottom end of the triangular table; the telescopic grabbers are of semi-arc-shaped structures, the telescopic grabbers are detachably arranged on the side face of the connecting block, and the three telescopic grabbers are evenly arranged on the side face of the connecting block. According to the telescopic satellite antenna supporting frame, the problems that an existing supporting leg cannot be adjusted and is inconvenient to install when being suitable for different terrains are solved.

The present invention provides a curved elastic deployable rod-type film structure, which includes: a mounting body, a mounting plate provided on the end surface of the mounting body, a rotating shaft provided at the center of the mounting plate; a guide mechanism, which forms a preset track with the rotating shaft; a curved rod, one end of which is connected to the rotating shaft, and the other end of which extends radially outward from the center of the mounting plate or winds and contracts inward from the edge of the mounting plate along the preset track during the rotation of the rotating shaft; a film, which is connected to the curved rod, and when the curved rod extends radially outward from the center of the mounting plate, the film gradually unfolds to a curved state; when the curved rod winds and contracts inward from the edge of the mounting plate, the film gradually contracts to a folded state; and a limiting mechanism, which includes a fixing column, an extrusion member, and an elastic member. Compared with conventional planar deployable film structures at the current stage, the present invention not only improves its flexibility of use, but also improves the directional reflectivity, communication quality, signal transmission efficiency, rigidity, and stability of the film after deployment.

The invention relates to an antenna structure and an antenna array. The antenna structure comprises a radiation unit; the grounding unit is arranged opposite to the radiating unit; the first supporting structure is connected with the grounding unit and the radiating unit and comprises at least one elastic piece and a first supporting unit connected with the elastic piece and the radiating unit, and one end, far away from the first supporting unit, of the elastic piece is connected with the grounding unit. According to the invention, the radiation unit and the grounding unit are connected through the supporting structure composed of the elastic member and the supporting unit, so that the formed antenna structure has the longitudinal telescoping capability, the rebound rate is high, and the stability is high.

The invention discloses a horn antenna device with a reconfigurable wave beam and a using method thereof, and belongs to the technical field of antennae, and the horn antenna device comprises a wave same module which is relatively and fixedly arranged at the tail end of the horn antenna device; the three-axis telescopic framework is connected to the front end of the wave-same module, and the three-axis telescopic framework is at least composed of a transverse electric control telescopic component, a longitudinal electric control telescopic component and a depth direction electric control telescopic component and is used for changing the aperture and the depth size of the horn antenna; the distance feedback device is arranged at the oral surface position of the three-axis telescopic framework and is used for detecting in real time and feeding back the actual oral surface size to the control extension set; and the control extension set is electrically connected with the transverse electric control telescopic component, the longitudinal electric control telescopic component, the depth direction electric control telescopic component and the distance feedback device. The wave beam reconfigurable horn antenna device is simple and small in structure and high in structural strength, can expand various frequency bands and gains, and has high development and use potential.

The present invention provides a shortwave array antenna and a vehicle-mounted communication system, and relates to the field of communication technology. The shortwave array antenna provided by the present invention includes: a logarithmic periodic antenna, a dual three-wire loaded dipole antenna and a bracket; the logarithmic periodic antenna is located above the dual three-wire loaded dipole antenna, and the logarithmic periodic antenna and the dual three-wire loaded dipole antenna are respectively installed on the bracket. The logarithmic periodic antenna is used to achieve medium and long-distance communication, and the dual three-wire loaded dipole antenna is used to achieve short-distance communication, thereby achieving both short-distance and long-distance communication capabilities. In addition, the shortwave array antenna can be mounted on a vehicle platform, can achieve high gain and broadband, meet the effective and reliable communication requirements of short, medium and long distances, and can also move in real time to meet the needs of rapid deployment in specific areas, and can effectively solve the problem of insufficient short-distance communication resources in hot spots.

The present invention discloses a double-throw convergence antenna, comprising a support rod, wherein the bottom of the support rod is fixedly connected to a base, the top of the base is threadedly connected to a fixing screw, one side of the support rod is threadedly connected to an adjusting screw, the inside of the support rod is movably connected to a spring, the top of the support rod is movably connected to a telescopic rod, the top of the telescopic rod is fixedly connected to an antenna body, the outer side of the telescopic rod is fixedly connected to a fixing sleeve, both sides of the fixing sleeve are fixedly connected to a mounting frame, one side of the mounting frame is movably connected to a bolt, the mounting frame is fixedly connected to a bracket by the bolts, and one side of the bracket is fixedly connected to a metal shielding plate. The flexibility of the double-throw convergence antenna is improved by arranging the telescopic rod, so that the staff can adjust the focusing angle of the antenna at will according to the needs, and the phenomenon of missing signals or unstable received signals of the antenna is avoided by arranging the metal shielding plate, the guide plate and the metal vibrator, thereby improving the strength of the antenna received signal.

The invention discloses a telescopic mechanism for preventing vibration of a hectometer-level ring column antenna, and relates to the field of mechanical structure design. The invention aims to solve the problem that a connecting structure for relieving large-amplitude vibration of an antenna is added between the outside of the antenna and a satellite platform in the prior art and is large and heavy, so that the injection and stability of a satellite are influenced. Each limiting protective cover telescopic mechanism comprises two telescopic connecting rod mechanisms of the same structure and a 1 / 4 arc satellite limiting protective cover. The two telescopic connecting rod mechanisms are arranged side by side and are in sliding connection with the outer arc wall of the 1 / 4 arc satellite limiting shield; the four 1 / 4 arc satellite limiting shields are spliced into a circle through a locking mechanism and are embraced on an antenna; explosive bolts are arranged on the locking mechanisms and are used for exploding to break connection between every two adjacent limiting protective cover telescopic mechanisms; when all the telescopic connecting rod mechanisms retract synchronously, a space is reserved between the antenna and the fairing, and when all the telescopic connecting rod mechanisms stretch synchronously, all the telescopic connecting rod mechanisms are supported on the fairing. The invention is used for preventing antenna vibration.

The application relates to the technical field of aerospace equipment, in particular to a stretchable release mechanism for separating a lunar soil penetration projectile communication antenna, which comprises a main body, the main body comprising a first mounting surface and a second mounting surface, the first mounting surface being arranged obliquely to the second mounting surface; an antenna oscillator arranged on the first mounting surface and provided with a locking ring for locking the antenna oscillator; a super-elastic conductive member sleeved on the second mounting surface; and a fuel line release mechanism arranged on the super-elastic conductive member, one end of the fuel line release mechanism being connected with the locking ring and the other end being connected with one end of the second mounting surface away from the first mounting surface. The arrangement of the fuel line release mechanism avoids the risk of failure of the stretchable release mechanism for separating the lunar soil penetration projectile communication antenna.

An antenna for charging and measurement may comprise: a telescopic support installed at a lower portion of an aerial vehicle and configured to contract when the aerial vehicle lands on a wireless station and extend when the aerial vehicle takes off from the wireless station; and an antenna coil part deformed into a spiral shape when the telescopic support is contracted so that the wireless station receives wireless power and deformed into a conical shape when the telescopic support is extended to measure a radio signal.

The invention discloses a portable frequency interferometer and a wireless signal shielding system. The portable frequency interferometer comprises an interferometer host used for generating a radio interference signal; the at least one antenna assembly is used for transmitting the radio interference signal; and a movable connecting piece. The interferometer host is movably connected with the at least one antenna assembly through the movable connecting piece, so that the antenna assembly can move relative to the interferometer host, and the antenna assembly and the interferometer host can be fixed. According to the portable frequency interferometer, the antenna assembly is movably connected to the interferometer host, integration of the antenna assembly and the interferometer host is achieved, the overall size of the portable frequency interferometer is more compact, miniaturization of the portable frequency interferometer is facilitated, and the appearance of the portable frequency interferometer is simpler and more attractive.

The utility model discloses a posture monitoring communication antenna, which relates to the technical field of communication antenna equipment and comprises a sucker seat, an antenna telescopic rod arranged at the top of the sucker seat, a reflecting plate arranged at the top of the sucker seat, a plurality of reflecting strips matched with the reflecting plate arranged at the top of the reflecting plate, and a connecting rod arranged between the reflecting strips and the antenna telescopic rod. A positioning pin is arranged at the bottom of the reflecting strip, holes matched with the positioning pin are formed in the surface of the reflecting strip and the top of the reflecting plate, the multi-stage telescopic rod serves as an antenna, the length of the antenna can be changed, one side of the antenna is shielded by a housing composed of the reflecting strip and the reflecting plate, the signal receiving and transmitting direction of the antenna is accurate, and the antenna is more compact. And the antenna telescopic rod can be stretched and extended, the reflection strip is separated from the reflection plate in the extension process, the radiation area for signal sending and receiving is increased, the height is increased after the whole structure is completely unfolded, the height and the receiving area of the antenna can be adjusted without assistance of external equipment.

The utility model, which relates to the technical field of the length-adjustable mobile phone antenna, discloses a length-adjustable mobile phone antenna comprising a connecting assembly, a rotating assembly and a receiving assembly. The connecting assembly comprises a connecting block, a groove is formed in one side of the connecting block, and a thread is formed in one side of the connecting block; the rotating assembly comprises a fixed block, a rotating ball is arranged on one side of the fixed block, and a movable rod is arranged on one side of the fixed block; the receiving assembly comprises a movable block, one side of the movable block is provided with a circular groove, one side of the movable block is provided with an adjustable antenna, the length of the adjustable antenna can be adjusted according to needs to receive signals, one side of the connecting block is provided with a rotating ball, and the rotating ball is rotatably connected with the connecting block. And the angle of the fixed block connected with the fixed block can be adjusted without being limited to a fixed position.