JP5511351B2 - Loop antenna and multi-element loop antenna including the same - Google Patents

Description

  The present invention relates to a loop antenna capable of supporting multiple bands and a multi-element loop antenna including the same.

Conventionally, a loop antenna has been used as an antenna for a transceiver (see, for example, Patent Document 1).
The loop antenna is configured such that both ends of a cable face each other and are arranged in a loop as a whole. When power is supplied to both ends of the cable, for example, an electromagnetic wave having the entire circumference of the loop as one wavelength is emitted, thereby functioning as a transmission antenna. Further, for example, by receiving an electromagnetic wave having the entire circumference of the loop as one wavelength, it functions as a receiving antenna.

JP 2009-118268 A

However, the loop antenna as described above has a problem that tuning to a plurality of frequencies cannot be obtained with one loop antenna when used in multiple bands.
In addition, in order to use multiple bands, it is necessary to prepare a plurality of loop antennas having different perimeters, and there is a problem that the whole antenna becomes large.

  The present invention has been made in view of such circumstances, and a loop antenna that can be tuned to a plurality of frequencies using only one loop antenna and can be used easily even in multiple bands, and the same. It aims at providing the multi-element loop antenna containing.

In order to solve the above problems, the present invention provides the following means.
The present invention provides a loop antenna in which a cable is arranged in a loop shape, wherein the entire circumference of the loop of the cable is arranged longer, and the entire circumference of the loop than when arranged in the long arrangement. A variable mechanism that changes the entire circumference of the loop by changing the arrangement of the loops in a short arrangement in which the length is short, and the variable mechanism is provided in the loop arranged in the long arrangement. By moving a part of the cable to the offset position offset from the loop, the long arrangement is changed to the short arrangement, and a part of the cable arranged in the offset position in the short arrangement is The short arrangement is changed to the long arrangement by being moved into a loop .

In the present invention, the entire circumferential length of the cable changes between the long arrangement and the short arrangement by the variable mechanism.
Thereby, it is possible to tune to a plurality of frequencies with only one loop antenna, and it can be easily used even with multiple bands.

Further, in the present invention, a part of the cable in the loop arranged in the long arrangement is moved to the offset position by the variable mechanism, changed from the long arrangement to the short arrangement, and arranged in the offset position in the short arrangement. When the cable is moved into the loop, the short arrangement is changed to the long arrangement.
Thereby, the perimeter of a cable can be changed reliably.

  In the present invention, the variable mechanism may include a biasing unit that biases the loop so that the loop is arranged in the long arrangement, and a portion of the cable in the loop arranged in the long arrangement. Pulling against the urging force of the means, moving to the offset position and changing to the short arrangement, holding the cable moved to the offset position by the movement means, and changing to the long arrangement In some cases, a holding / release means for releasing the holding is provided.

In this invention, a part of the cable in the loop arranged in the long arrangement is pulled by the moving means against the urging force of the urging means and moved to the offset position, thereby changing to the short arrangement. Is done. At this time, the cable moved to the offset position is held by the holding / release means.
Thereby, not only can it change reliably by a long arrangement | positioning and a short arrangement | positioning, but each arrangement | positioning can be hold | maintained.

  Further, the present invention is characterized in that it has a support column that supports the loop, and the biasing means is an arcuate elastic member that is provided on the support column and biases the cable in the loop. .

In the present invention, the loop is biased by the arcuate elastic member provided on the support so that the loop is arranged in a long arrangement.
Thereby, it can change reliably from short arrangement | positioning to long arrangement | positioning.

  Further, according to the present invention, the loop is arranged in a triangular shape, the apex of the triangular shape is installed at an upper portion in the length direction of the support column, and the remaining two points of the triangular shape are the upper portion. It is below and below and is installed in the direction which cross | intersects the length direction of the said support | pillar.

  Thereby, a loop is reliably supported by a support | pillar and it can hold | maintain triangular shape.

  Further, according to the present invention, the elastic member is disposed to face one side of the triangular shape, and the cable extends from the one side of the triangular shape to each other side according to elastic deformation of the elastic member. Loop guide members for guiding the elastic members are provided at both ends of the elastic member.

In the present invention, the cable is guided by the loop guide member from one side of the triangle to the other side in accordance with the elastic deformation of the elastic member.
Thereby, it can change smoothly with long arrangement | positioning and short arrangement | positioning.

  In addition, the present invention is characterized in that an auxiliary mechanism is provided for pulling the one side of the triangular shape inward of the loop in accordance with the movement of the cable by the moving means.

  Thereby, it can change easily with long arrangement | positioning and short arrangement | positioning.

  In the present invention, an offset guide member for guiding the cable from the loop to the offset position is provided, and the cable is guided by the offset guide member and arranged at the offset position or connected to the cable. A winding means for winding the member is provided.

In this invention, the cable or the connecting member arranged at the offset position is wound up by the winding means, and the cable is guided from the loop to the offset position by the offset guide member when the cable is moved at this time. The
Thereby, it can change easily with long arrangement | positioning and short arrangement | positioning.

  In addition, the present invention includes a drive unit that drives the winding unit and a control unit that controls driving of the drive unit.

In the present invention, the drive unit is controlled by the control unit, and the winding means is driven by the drive unit.
As a result, the entire circumference of the loop can be changed quickly and with high accuracy.

  Further, the present invention is characterized in that load means for applying a load to the cable when the cable is moved is provided.

  Thereby, not only can the loop of the cable be firmly held, but also the load due to the holding can be distributed.

  Further, the present invention is characterized in that, in the long arrangement, the entire length of the cable is arranged on the entire circumference of the loop.

  Thereby, the load by the urging force from the urging means can be received by the entire cable, and the holding force of the loop can be increased.

  In addition, the present invention is characterized in that a part of the cable that is conducting in the short arrangement includes an insulation mechanism that is insulated in the long arrangement.

  Thereby, it can be used as an expanded quad only when it is arranged in a long arrangement.

Moreover, this invention is provided with the loop antenna as described in any one of Claim 1-11, It is a multi-element loop antenna characterized by the above-mentioned.

Thereby, there can exist an effect similar to the loop antenna as described in any one of Claims 1-11.

  According to the present invention, it is possible to tune to a plurality of frequencies with only one loop antenna, and it can be used easily even with multiple bands.

It is a whole lineblock diagram showing the loop antenna in a 1st embodiment of the present invention. It is an enlarged view which expands and shows the area | region A shown in FIG. It is explanatory drawing which shows a mode when the cable in the loop antenna of FIG. 1 is arranged by short arrangement | positioning. It is a whole block diagram which shows the loop antenna in the 2nd Embodiment of this invention. It is a whole block diagram which shows the loop antenna in the 3rd Embodiment of this invention. It is a whole block diagram which shows the loop antenna in the 4th Embodiment of this invention. It is a whole block diagram which shows the modification of this invention. It is explanatory drawing which shows notionally the auxiliary mechanism of this invention. It is explanatory drawing which shows notionally the modification of the pulley 6a of FIG. It is explanatory drawing which shows notionally the other modification of the pulley 6a of FIG. It is a block diagram which shows the load means of this invention. It is explanatory drawing which shows notionally the insulation mechanism of this invention. It is explanatory drawing which shows a mode that the insulation connection part in FIG. 12 is distribute | arranged ranging over the pulley which makes a pair. It is a perspective view which shows the multi-element loop antenna in this invention.

(Embodiment 1)
Hereinafter, a loop antenna according to a first embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows a loop antenna as a first embodiment of the present invention.
The loop antenna 1 includes a columnar column 2 made of a member such as aluminum.
The support | pillar 2 can be installed in the ground G so that attachment or detachment is possible via the installation part 2a. And when the support | pillar 2 is installed in the ground G, it will stand from the ground G toward the vertical direction upper direction.
In addition, a pair of pulleys (offset guide members) 6 a disposed to face each other with the center line of the support column 2 interposed therebetween are provided on the upper portion 2 c of the support column 2. The pulley 6a rotates around a rotating shaft 6b extending in the depth direction with respect to FIG. The pulley 6a and the rotating shaft 6b are made of a conductive member such as metal. The pulleys 6a are connected by a conductive connecting plate 6c (shown in FIG. 2) and are electrically connected to each other.
In addition, the upper part 2c means an upper end part (end part on the opposite side to the installation part 2a) in the length direction H of the support column 2.

Further, the support column 2 supports an antenna cable 3. The cable 3 is arranged in a triangular loop shape (delta loop) composed of a bottom side 3a and another side 3b. That is, the triangular vertex 3 c of the cable 3 is arranged on the upper portion 2 c of the support column 2. In the upper part 2c, as shown in FIG. 2, the cables 3 each forming the other side 3b are guided by the pulley 6a and moved to the offset position OF. On the other hand, the cable 3 arranged at the offset position OF is guided by the pulley 6a and moves on the loop. The offset position OF is a position removed from the loop of the cable 3 and is provided inside the loop.
Furthermore, as shown in FIG. 1, the base 3 a is extended in the width direction W orthogonal to the length direction H. That is, the apex 3c of the triangle is arranged on the upper part 2c, and the remaining two points (other points) 3d of the triangle are below the upper part 2c, and from the center line of the column 2 to each other in the width direction W. It is arranged in the position extended symmetrically.

  The bottom side 3a is provided with a cylindrical elastic support portion (biasing means, elastic member) 4 facing the bottom side 3a on the outer side of the loop. The elastic support portion 4 is attached to the support column 2 via the attachment portion 10. This elastic support part 4 is extended on a straight line in a natural state (a state in which no external force is applied) before attachment. Then, from the natural state, the elastic support portion 4 is elastically deformed to the base 3a side after the central portion of the elastic support portion 4 in the length direction is attached to the support column 2 via the attachment portion 10. 4 is curved in an arcuate shape. Therefore, the elastic support part 4 is urged | biased so that it may return on a straight line with the restoring force of elastic deformation.

  Pulleys (loop guide members) 4 a made of an insulating member are provided at both ends of the elastic support portion 4. These pulleys 4a are respectively rotated around a rotation shaft 4b extending in the depth direction with respect to FIG. A cable 3 is passed through these pulleys 4a. Thus, the cable 3 is guided from the bottom side 3a to the other side 3b by the pulley 4a, and is guided from the other side 3b to the bottom side 3a. Further, the cable 3 is urged by a restoring force of the elastic support portion 4 so as to be arranged in a long arrangement L described later.

Both ends of the cable 3 are coupled via a coupling ring (cable coupling member) 5. The connection ring 5 is formed in a ring shape and is made of an insulating member. The connection ring 5 is passed through the support column 2 and is slidable in the length direction H of the support column 2. A connection point between the cable 3 and the connection ring 5 is a feeding point 15 that is connected to a coaxial cable (not shown) extending from the transmitter / receiver to be fed.
In addition, a connecting string (connecting member) 14 extending in a long shape is connected to a part of the cable 3 in the length direction. The connecting string 14 is made of an insulating member. The connecting string 14 is attached to the central portion of the cable 3 in the length direction. When the entire length of the cable 3 is on the loop, it is suspended along the support column 2 from the cable 3 arranged at the apex portion 3c. It is supposed to be.

A winding drum (moving means, holding / releasing means, winding means) 12 for winding and releasing the connecting string 14 is provided between the attachment portion 10 and the installation portion 2a in the lower end 2d of the support column 2. It has been.
The take-up drum 12 includes a cylindrical drum body 12a and a handle 12b.
The drum body 12a is rotated only in one direction (the direction in which the connecting string 14 is wound) by the ratchet mechanism, and is driven in the other direction (the wound connection) by driving a release switch (not shown). It also rotates in the direction of feeding the string 14. The handle 12b rotates the drum body 12a.

Here, the long arrangement and the short arrangement will be described.
As shown in FIG. 1, the long arrangement L refers to a position where the entire length of the cable 3 is arranged on the loop of the antenna, and the entire circumference of the loop is shorter than the short arrangement S (shown in FIG. 3). It means the position where the length is long.
On the other hand, the short arrangement S refers to a position where the entire circumference of the loop is shorter than the long arrangement L, as shown in FIG.
The total circumference of the loop refers to the total length of the three sides of the triangle (the base 3a and the pair of other sides 3b).
When the handle 12b is rotated in one direction from the long arrangement L under such a configuration, the cable 3 is pulled downward at the apex portion 3c by winding the connecting string 14, as shown in FIG. The cable 3 is arranged from the long arrangement L to the short arrangement S.

Next, the operation of the loop antenna 1 according to this embodiment configured as described above will be described.
When the loop antenna 1 is used as a transmitting antenna, power is supplied from the transmitter to the feeding point 15 via a coaxial cable (not shown). As a result, an electromagnetic wave having the entire circumference of the loop as one wavelength is emitted.
On the other hand, when the loop antenna 1 is used as a receiving antenna, an electromotive force is generated by receiving an electromagnetic wave having the entire circumference of the loop as one wavelength, and functions as a receiving antenna.

As described above, the entire circumference of the loop in the loop antenna 1 needs to be adapted to the wavelength of the electromagnetic wave to be used.
The loop antenna 1 is capable of gradually changing the entire circumference of the loop while maintaining the shape of the loop itself (maintaining a similar shape). The operation for changing the entire circumference of the loop will be described below.
It is assumed that the cable 3 is in the long arrangement L as shown in FIG.
Depending on the electromagnetic wave used, it is necessary to tune to a smaller wavelength.
In this case, when the drum main body 12a is rotated in one direction via the handle 12b, the connecting string 14 is wound up by the drum main body 12a. Thereby, in the upper part 2c, the cable 3 is pulled downward via the connecting string 14. Therefore, as shown in FIG. 3, a part of the cable 3 is guided by the pulley 6 a against the urging force of the elastic support portion 4, moves downward, and is arranged at the offset position OF. That is, the cable 3 moves from the bottom side 3a to the other side 3b via the pulley 4a, and moves from the other side 3b to the offset position OF via the pulley 6a.
At this time, when a part of the cable 3 is pulled downward, both ends of the elastic support portion 4 are pulled upward via the pulley 4a. And the elastic support part 4 is elastically deformed so that a curvature radius becomes still smaller.

As a result, the cable 3 gradually changes from the long arrangement L to the short arrangement S. That is, the entire circumference of the loop is gradually shortened while maintaining the similar triangular shape of the loop. At this time, the cable 3 is urged to return to the long arrangement L by the restoring force of the elastic support portion 4, but the rotation of the drum body portion 12a in the other direction is restricted by the ratchet mechanism of the winding drum 12. , And held in the short arrangement S. From this point, when the handle 12b is further rotated in one direction, the entire circumference of the loop gradually decreases.
Even when arranged in the short arrangement S, since the pulley 6a, the rotating shaft 6b and the connecting plate 6c are made of conductive members, the conduction state between the other sides 3b in the apex portion 3c is maintained.

  On the other hand, in order to return from the short arrangement S to the long arrangement L, the operation may be reversed. That is, a release switch (not shown) of the winding drum 12 is driven to release the drum body 12a. At this time, since the cable 3 is urged so as to return to the long arrangement L by the elastic support portion 4, the cable body 3 is offset while the drum body portion 12a rotates in the other direction and feeds the connecting string 14. It moves from OF to the other side 3b, and moves from the other side 3b to the bottom side 3a. As a result, the cable 3 gradually changes from the short arrangement S to the long arrangement L. In the long arrangement L, the entire length of the cable 3 is all arranged on the loop, and the surplus cable 3 does not exist at the offset position OF.

As described above, according to the loop antenna 1 of the present embodiment, it is possible to tune to a plurality of frequencies by using only one loop antenna by changing the entire circumference of the loop, and it can be used easily even in multiple bands. Can do.
Further, by arranging the cable 3 at the offset position OF, it is possible to absorb the excess cable 3 according to the change in the entire circumference of the loop.
Further, the entire length of the loop can be easily changed by the elastic support portion 4 and the winding drum 12 only by a simple operation of winding and releasing the winding drum 12.
Moreover, the urging force can be applied to the cable 3 by the elastic support portion 4 and can be easily changed between the long arrangement L and the short arrangement S.
Further, since the elastic support portion 4 is provided with the pulley 4a, the cable 3 can be easily moved between the bottom side 3a and the other side 3b, and the entire circumference of the loop can be easily changed. it can.

Further, since the pulley 6a is provided in the upper portion 2c, the cable 3 can be easily moved between the offset position OF and the other side 3b, and the entire circumference of the loop can be easily changed. it can.
Further, when the cable 3 is arranged in the long arrangement L, the entire length of the cable 3 is arranged on the loop, so that the load by the urging force from the elastic support portion 4 can be received by the entire cable 3. The holding force when the loop antenna 1 is installed can be increased. That is, it is possible to prevent the load due to the urging force from the elastic support portion 4 from being concentrated on the take-up drum 12 and to improve durability and stability.

(Embodiment 2)
Next, a second embodiment of the present invention will be described.
FIG. 4 shows a loop antenna 1A as a second embodiment of the present invention.
In FIG. 4, the same components as those shown in FIGS. 1 to 3 are denoted by the same reference numerals, and the description thereof is omitted.
This embodiment and the first embodiment have the same basic configuration, and different points will be mainly described here.

The loop antenna 1A includes a winding drum 12A, a stepping motor (drive unit) 20 that rotationally drives the winding drum 12A, and a control device (control unit) 21 that controls driving of the stepping motor 20. .
The winding drum 12A includes a drum main body 12a, a rotary shaft 12d extending from the drum main body 12a, and a gear 12c provided on the rotary shaft 12d. And if the gear 12c is rotated, the drum main-body part 12a will rotate via the rotating shaft 12d.
The take-up drum 12A is not provided with a ratchet mechanism and is in a rotation-free state.

The stepping motor 20 includes a motor main body 20a, a rotary shaft 20b extended from the motor main body 20a, and a gear 20c provided on the rotary shaft 20b. The stepping motor 20 functions as a holding / release means for holding / releasing the cable 3.
The gear 20c is meshed with the gear 12c, and by driving the motor main body 20a, the drum main body 12a is rotated in one direction and the other through the gears 20c and 12c.
The control device 21 includes a control unit 21d that controls the overall operation, and a plurality of input buttons (input units) 21a, 21b, and 21c connected to the control unit 21d.
When the input buttons 21a, 21b and 21c are pressed by the operator, the input buttons 21a, 21b and 21c output instruction signals corresponding to the respective buttons.
The control unit 21d reads the instruction signals output from the input buttons 21a, 21b, and 21c, and outputs a drive signal corresponding to each instruction signal to drive the stepping motor 20. Thereby, the drum main body 12a stops at a predetermined rotation position set in advance.

With this configuration, when the operator presses the input button 21a, the input button 21a outputs an instruction signal for a frequency of 3.8 MHz. Then, the control unit 21d reads the instruction signal, drives the stepping motor 20, and stops the rotation position of the drum main body 12a at a predetermined rotation position set in advance. Thereby, the total circumference of the loop is adjusted to be 1λ with respect to 3.8 MHz.
Further, when the operator presses the input buttons 21b and 21c, the entire circumference of the loop is adjusted to 1λ with respect to 5.0 MHz and 7.0 MHz, respectively, in the same manner as described above.

  As described above, according to the loop antenna 1 in the present embodiment, it is possible to change the entire circumference of the loop quickly and with high accuracy only by operating the control device 21.

(Embodiment 3)
Next, a third embodiment of the present invention will be described.
FIG. 5 shows a loop antenna 1B as a third embodiment of the present invention.
In FIG. 5, the same components as those shown in FIGS. 1 to 4 are denoted by the same reference numerals, and the description thereof is omitted.
This embodiment and the first embodiment have the same basic configuration, and different points will be mainly described here.

The pulley 6a and the rotating shaft 6b in this embodiment are attached so as to be movable along the length direction H of the support column 2 by a slide mechanism (not shown). Furthermore, the pulley 6a and the rotating shaft 6b are urged upward (outward of the loop) H1 by a coil spring (biasing means) 30 fixed to the upper end of the column 2.
The pulley 4 a and the rotating shaft 4 b are attached to a support portion 33 extending in a plate shape via a coil spring (biasing means) 31. That is, the pulley 4a and the rotating shaft 4b are attached to the support portion 33 in a state in which it can slide in the width direction W. The coil spring 31 urges the pulley 4a and the rotating shaft 4b in the width direction (outward of the loop) W1 and W2, respectively. That is, the cable 3 is biased by the coil springs 30 and 31 so as to be in the long arrangement L.
The support portion 33 is made of a member such as aluminum, and is attached to the support column 2 via the attachment portion 32.
Further, both ends of the cable 3 are connected by an insulating connecting member (not shown).

Under such a configuration, when the drum body 12a is rotated in one direction via the handle 12b in the state of being arranged in the long arrangement L, the cable 3 is resisted against the urging force of the coil springs 30 and 31. The total circumference gradually decreases. That is, in the upper part 2c, the cable 3 is pulled downward and moved to the offset position OF, whereby the pulleys 6a and 4a and the rotating shafts 6b and 4b slide inward of the loop. Then, the entire circumference of the cable 3 gradually decreases while maintaining the similar shape of the triangle. Thereby, the cable 3 is changed from the long arrangement L to the short arrangement S.
On the other hand, in order to return from the short arrangement S to the long arrangement L, a release switch (not shown) of the winding drum 12 may be driven and operated in the reverse manner.

  Thereby, there can exist an effect similar to the said 1st and 2nd embodiment.

(Embodiment 4)
Next, a fourth embodiment of the present invention will be described.
FIG. 6 shows a loop antenna 1C as a fourth embodiment of the present invention.
In FIG. 6, the same components as those shown in FIGS. 1 to 5 are denoted by the same reference numerals, and the description thereof is omitted.
The basic configuration of this embodiment is the same as that of the third embodiment, and here, different points will be mainly described.

The loops in this embodiment are arranged in a square shape. That is, the two vertices of the quadrilateral are arranged on the top and bottom of the column 2, and the remaining two points are arranged at positions extending symmetrically in the width direction W from the center line of the column 2.
In the present embodiment, a pulley 36 a and a rotating shaft 36 b made of an insulating member are provided below the support 2. The pulley 36 a and the rotating shaft 36 b are attached to the support column 2 through a coil spring (biasing means) 35 so as to be slidable in the length direction H. The coil spring 35 urges the pulley 36a and the rotating shaft 36b downward (outward of the loop) H2. That is, the cable 3 is biased so as to be in the long arrangement L by the coil springs 30, 31, and 35.
Then, the cable 3 is passed through the pulleys 6a, 4a, and 36a, so that the shape of the loop is held in a square shape.
Note that both ends of the cable 3 are connected by an insulating connecting member (not shown).

In such a configuration, when the drum body 12a is rotated in one direction via the handle 12b in the state of being arranged in the long arrangement L, the cable is resisted against the urging force of the coil springs 30, 31, and 35. The total circumference of 3 gradually decreases. That is, in the upper portion 2c, the cable 3 is pulled downward and moved to the offset position OF, whereby the pulleys 6a, 4a, 36a and the rotating shafts 6b, 4b, 36b slide inward of the loop. Then, the entire circumference of the cable 3 is gradually reduced while maintaining the quadrangular similarity. Thereby, the cable 3 is changed from the long arrangement L to the short arrangement S.
On the other hand, in order to return from the short arrangement S to the long arrangement L, a release switch (not shown) of the winding drum 12 may be driven and operated in the reverse manner.

  Accordingly, not only can the total circumference of the loop be gradually changed without using the arcuate elastic support portion 4, but the loop can be held in a square shape.

  In the first to third embodiments, the shape of the loop is a triangle and a quadrangle. However, the shape is not limited to this, and the shape can be changed as appropriate. For example, like the loop antenna 1D shown in FIG. 7, the slidable loop 41a and the rotating shaft 41b, which are urged outward by the coil spring (biasing means) 40, are increased in the circumferential direction of the loop. Can be octagonal. That is, it can be changed to a polygonal shape. Furthermore, by increasing the loop 41a and the rotating shaft 41b in the circumferential direction of the loop, it can be made close to a circular shape.

In the first to fourth embodiments, an auxiliary mechanism 43 can be further provided as shown in FIG.
The auxiliary mechanism 43 includes an auxiliary connection line 41 that connects the winding drum 12 and the connection ring 5, an auxiliary pulley 42 a, and a rotating shaft 42 b.
One end of the auxiliary connecting line 41 is wound around the winding drum 12, and the other end is fixed to the connecting ring 5.
The auxiliary pulley 42 a guides the auxiliary connecting line 41 to the winding drum 12 and the connecting ring 5.
Under such a configuration, when the drum body 12a is rotated in one direction, the auxiliary connecting wire 41 is wound up, and the connecting ring 5 is raised by the guide of the auxiliary pulley 42a. That is, the coupling ring 5 is raised in synchronization with (in synchronization with) the rotation of the drum body 12a in one direction.
Thereby, the force by winding up the drum main body 12a can be directly transmitted to the connecting ring 5 without going through the cable 3, and the connecting ring 5 can be easily moved up and down.

In the first to fourth embodiments, instead of the pulley 6a, a guide piece (offset guide member) 2e may be provided at the upper end of the column 2 as shown in FIG. The guide piece 2 e extends in a curved shape outward in the radial direction of the support column 2, and guides the cable 3.
In addition, as shown in FIG. 10, a cylindrical metal column (offset guide member) 45 may be provided instead of the pulley 6 a.
According to such a modification, the cable 3 can be guided with a simpler configuration.

In the first to fourth embodiments, a lock mechanism (loading means) 50 for locking the movement of the cable 3 can be further provided as shown in FIG.
The lock mechanism 50 includes a lock main body 51 in which a pair of lock pieces 51 a are rotatably connected by a fulcrum part 54. The lock piece 51a is formed in a gentle crank shape. Inside the lower end of the lock piece 51a, a coil spring 53 that urges the lower ends of the lock pieces 51a outward in the width direction W is provided. A pressing portion 52 is provided outside the lock piece 51a. The pressing portion 52 is extended inward in the radial direction of the support column 2 by a switch (not shown), and presses the lock piece 51 a inward in the radial direction against the urging force of the coil spring 53.
The cable 3 is arranged between the outer wall at the upper end of the lock piece 51a and the inner wall of the support column 2.

Next, the operation of the lock mechanism 50 will be described.
When a switch (not shown) is driven, the pressing portion 52 extends inward in the radial direction of the support column 2 and presses the lock piece 51a inward in the radial direction against the urging force of the coil spring 53. Therefore, the lower end portions of the lock pieces 51 a move in a direction approaching each other, and the upper end portions move in directions away from each other via the fulcrum portion 54. And the outer wall of an upper end part contacts the inner wall of the support | pillar 2, and also presses the inner wall of the support | pillar 2 to radial direction outward. At this time, since the cable 3 is disposed between the outer wall of the upper end portion and the inner wall of the support column 2, the movement of the cable 3 is locked and the loop is firmly held.
On the other hand, when the switch (not shown) is released, the pressing portion 52 is returned outward in the radial direction. The lower end portion of the lock piece 51 a moves radially outward by the biasing force of the coil spring 53, and the upper end portion moves radially inward via the fulcrum portion 54. Therefore, the outer wall at the upper end and the inner wall of the support column 2 are separated, and the cable 3 is unlocked.
Thereby, not only can the loop of the cable 3 be firmly held, but the load caused by the holding can be distributed to other than the winding drum 12 and the stepping motor 20.

  The load means can also be realized by increasing the number of windings of the cable 3 around the pulley 6a and the metal column 45. That is, by doubling the winding, a load is applied to the movement of the cable 3 and not only the loop of the cable 3 can be firmly held, but also the load caused by the holding can be other than the winding drum 12 and the stepping motor 20. Can be dispersed.

In the first to fourth embodiments, an insulating mechanism 66 may be provided as shown in FIGS. The insulating mechanism 66 includes a long insulating connecting portion 65 that connects the cables 3. The insulating connecting portion 65 is made of an insulating member and insulates the cable 3.
In such a configuration, as shown in FIG. 12, when a part of the cable 3 is disposed at the offset position OF, the other side 3b of the loop is interposed via the pulley 6a, the rotating shaft 6b, and the connecting plate 6c. Conduct each other. On the other hand, as shown in FIG. 13, when the entire length of the cable 3 is arranged on the loop, the insulating connecting portion 65 is arranged across the pair of pulleys 6a. At this time, since the cable 3 is insulated by the insulating connecting portion 65 and the cable 3 is also insulated from the pulley 6a via the insulating connecting portion 65, the cable 3 is insulated at the apex portion 3c.
Thereby, only when it is arranged in the long arrangement L, it can be used as an expanded quad.
In addition, what is necessary is just to adjust with the matching device to the change of the impedance by insulation.

In the first to fourth embodiments, a single loop antenna is used. However, as shown in FIG. 14, a plurality of these antennas can be provided and used as a multi-element loop antenna 60. is there.
Similarly, a metal support column 62 is provided on the metal column 61 in the orthogonal direction, and loop antennas 1, 1 a, 1 b, and 1 c are provided on the support column 62.
Specifically, the loop antenna 1 functions as a second waveguide, the loop antenna 1a functions as a first waveguide, the loop antenna 1b functions as a radiator, and the loop antenna 1c functions as a reflector.
The loop antennas 1, 1 a, 1 b, and 1 c have the same configuration except for the entire circumference of the loop in the long arrangement L.
Further, the support column 62 is formed in a cylindrical shape, and a plurality of members having different diameters are connected in a slidable state. Therefore, the mutual distance between the loop antennas 1, 1a, 1b, 1c can be changed.
As a result, not only one loop antenna but also a multi-element loop antenna 60 can be used, and convenience can be improved. In addition, since the support 61 is provided on the ground, lightning surge can be released to the ground G from the antennas 1, 1 a, 1 b, and 1 c through the support pillar 62 and the support 62 even if there is a lightning strike or the like. .
The multi-element loop antenna 60 shown in FIG. 14 is composed of four loop antennas, but is not limited to this, and the number of loop antennas can be changed as appropriate (for example, two, three, five, etc.). , 6 etc.).
Further, the interval between the respective loop antennas can be appropriately changed. Furthermore, the loop antennas do not have to be arranged in parallel with each other. For example, it may be composed of two loop antennas, and the apex portions 3c of the two loop antennas may be arranged closer to each other than the bases 3a.

In the first to fourth embodiments, the entire length of the cable 3 is arranged on the loop in the long arrangement L. However, the present invention is not limited to this, and the entire circumference of the cable 3 is appropriately set. It can be changed. That is, even in the long arrangement L, a part of the cable 3 may be arranged at the offset position OF.
Further, although the offset position OF is provided inside the loop, the present invention is not limited to this and may be provided outside the loop.
Further, the entire circumference of the loop may be changed by moving the surplus cable 3 along the loop without providing the offset position OF.
In addition, although the elastic support portion 4 and the coil springs 30, 31, 35, and 40 are provided, the present invention is not limited to this and may be biased by an electromagnetic mechanism such as a magnet or a solenoid.
The cable 3 may be one in which the conducting wire is covered with an insulating material, or one in which the conducting wire is exposed (wire).
In addition, although the triangular vertex 3c is arranged in the upper portion 2c, the present invention is not limited to this. For example, the rotational position of the triangle on the paper surface of FIGS. 1 to 7 can be changed as appropriate. For example, a triangle may be arranged at a position rotated 90 degrees or 180 degrees on the paper surface of FIGS.
In addition, although the feeding point 15 is provided on the base 3a of the triangle, the position is not limited to this, and the position thereof can be changed as appropriate. For example, you may provide in the other side 3b, the vertex part 3c, or the other point part 3d.
Needless to say, the first to fourth embodiments and various modifications can be freely combined.
The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 1 Loop antenna 2 Support | pillar 2c Upper part 3 Cable 4 Elastic support part (Biasing means, elastic member)
4a Pulley (loop guide member)
6a Pulley (offset guide member)
12 Winding drum (moving means, holding / releasing means, winding means)
14 Connection string (connection member)
20 Stepping motor (drive unit)
21 Control device (control unit)
30 Coil spring (biasing means)
31 Coil spring (biasing means)
35 Coil spring (biasing means)
40 Coil spring (biasing means)
43 Auxiliary mechanism 50 Lock mechanism (loading means)
60 Multi-element loop antenna 66 Insulation mechanism L Long arrangement OF Offset position S Short arrangement

Claims (12)

A loop antenna with a cable arranged in a loop,
The arrangement of the loop is changed between a long arrangement in which the entire circumference of the loop of the cable is arranged longer and a short arrangement in which the entire circumference of the loop is arranged shorter than when arranged in the long arrangement. By providing a variable mechanism that changes the entire circumference of the loop,
The variable mechanism is
By moving a part of the cable in the loop arranged in the long arrangement to an offset position offset from the loop, the long arrangement is changed to the short arrangement,
A loop antenna , wherein a part of a cable arranged at the offset position in the short arrangement is moved from the short arrangement to the long arrangement by moving the cable into the loop. The variable mechanism is
Biasing means for biasing the loop so as to be arranged in the long arrangement;
A moving means for pulling a part of the cable in the loop arranged in the long arrangement against the urging force of the urging means and moving the cable to the offset position to change to the short arrangement;
The loop antenna according to claim 1, further comprising: holding / release means for holding the cable moved to the offset position by the moving means and releasing the holding when changing to the long arrangement. A strut supporting the loop;
The loop antenna according to claim 2, wherein the biasing means is an arcuate elastic member that is provided on the support column and biases a cable in the loop. The loop is arranged in a triangular shape,
The triangular apex is installed in the upper part of the length of the column;
4. The loop antenna according to claim 3, wherein the remaining two points in the triangular shape are disposed below the upper portion and in a direction intersecting with the length direction of the support column. The elastic member is disposed opposite one side of the triangular shape;
The loop guide member for guiding the cable from the one side of the triangular shape to each of the other sides according to elastic deformation of the elastic member is provided at both ends of the elastic member. 4. The loop antenna according to 4.   The loop antenna according to claim 5, further comprising an auxiliary mechanism that pulls the one side of the triangular shape inward of the loop in accordance with the movement of the cable by the moving means. An offset guide member is provided for guiding the cable from the loop to the offset position;
The winding device which winds up the cable guided by the offset guide member and arranged at the offset position or the connection member connected to the cable is provided. The loop antenna as described in one. A drive unit for driving the winding means;
The loop antenna according to claim 7, further comprising a control unit that controls driving of the driving unit.   The loop antenna according to any one of claims 4 to 8, further comprising load means for applying a load to the cable when the cable is moved.   The loop antenna according to any one of claims 1 to 9, wherein, in the long arrangement, the entire length of the cable is arranged on the entire circumference of the loop.   The loop according to any one of claims 1 to 10, wherein a part of the cable that conducts in the short arrangement includes an insulation mechanism that is insulated in the long arrangement. antenna.   A multi-element loop antenna comprising the loop antenna according to any one of claims 1 to 11.

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