JP5856504B2 - Radiated power detector - Google Patents

Description

  The present invention relates to a radiated power detector capable of detecting the radiated power of a broadcasting antenna.

  2. Description of the Related Art Conventionally, a radiated power detector is known that is disposed in the vicinity of a broadcast antenna and monitors the output state of the radiated power of the broadcast antenna (for example, see Patent Document 1).

  The radiated power detector described in Patent Document 1 is a receiving antenna element formed by forming a wire made of a conductive material in a loop shape, and radiated power received by the receiving antenna element is converted into a DC detection signal and output. And a detection circuit for performing the operation.

JP 2010-190825 A

  Since this type of radiated power detector is installed together with a broadcasting antenna, for example, on the top of a tower-like structure, it is exposed to vibration due to the influence of wind or the like for a long time. And when the function of a radiation power detector is impaired by vibration, the replacement will be difficult.

  Therefore, an object of the present invention is to provide a radiation power detector with improved vibration resistance.

In order to solve the above problems, the present invention is provided in an antenna device including a broadcasting antenna having a central axis in the longitudinal direction and a reflector that reflects radio waves radiated from the broadcasting antenna. A radiated power detector for detecting the radiated power of the broadcasting antenna, the conductive plate disposed so as to be parallel to the reflecting plate , and disposed farther from the broadcasting antenna than the conductive plate An electrical signal generated in the conductive plate by the power radiated from the broadcasting antenna is output from the conductive plate to the ground conductor side. The grounding part and the output part each have a pillar part extending in a direction orthogonal to the conductive plate, and the pillar part of the grounding part and the pillar part of the output part are Face to face , The output section provides a radiation power detector provided near the central axis of said broadcasting antenna than the ground portion.

  The conductive plate may be formed in a circular shape, and the grounding portion and the output portion may be provided at positions facing each other across the center of the conductive plate.

  The grounding unit and the output unit may be provided side by side in a direction orthogonal to the central axis of the broadcasting antenna.

  Further, the conductive plate has first and second cutout portions formed by cutting out the conductive plate from the circular outer edge toward the center portion, and the grounding portion and the output portion are configured as described above. The first and second cutouts may be connected to the conductive plate on the center side.

  The grounding portion and the output portion may be formed by bending a single plate conductive member including a portion to be the conductive plate.

  In addition, the conductive plate may have the same potential as that of a reflection plate provided to face the broadcasting antenna.

  According to the present invention, a radiation power detector with improved vibration resistance can be provided.

It is a figure which shows the structural example of the radio tower in which the radiation power detector and antenna device which concern on embodiment of this invention were installed. The structural example of an antenna apparatus is shown, (a) is a top view, (b) is the sectional view on the AA line of (a). It is an enlarged view which expands and shows the radiation power detector in FIG. 2, and its peripheral part. It is a perspective view of the radiation power detector which abbreviate | omitted some components. It is a circuit diagram which shows the example of the detection circuit mounted in the back surface of the mounting board | substrate, (a) shows an envelope detection circuit, (b) shows a voltage doubler detection circuit, respectively. It is explanatory drawing explaining the procedure of processing and an assembly of a radiated power detection element, (a) is one flat conductive member, (b) is a radiated power detection element, (c) is a circuit board, (D) shows the state in which the radiated power detection element is fixed to the circuit board. (A) is a 3rd base member, (b) is a 2nd base member, (c) is a resin cover, (d) is explanatory drawing which shows a 1st base member, respectively. It is a general view which shows the whole radiation power detector. It is a figure which shows the attachment state which attaches a radiation power detector to the reflecting plate of an antenna apparatus. It is the top view of the electric power coupling | bond part of a radiation power detection element, and the side view of a radiation power detection element. It is a schematic block diagram which shows the structural example of an experimental apparatus. It is a graph which shows the experimental result in the experimental apparatus which concerns on FIG. 11, (a) is the electric power coupling | bonding amount of the electric power coupling part at the time of radiating | emitting an electromagnetic wave from an antenna apparatus, (b) is the case where an electric wave is not radiated | emitted from an antenna apparatus. The power coupling amount of the power coupling unit is shown respectively. (A)-(d) shows the radiation power detection element in the 1st-4th rotation position which changed the direction with respect to the double loop antenna of a radiation power detection element every 90 degrees. (A) shows the power coupling amount at the first to fourth rotational positions, (b) and (c) show the relationship between the frequency and element height of the power coupling amount at the first and second rotational positions, respectively. Show. It is a schematic block diagram which shows the modification of an experimental apparatus. It is a graph which shows the experimental result in the experimental apparatus which concerns on FIG. 15, (a) is the amount of power coupling | bonding of the power coupling part at the time of radiating | emitting an electromagnetic wave from an antenna apparatus, (b) is the case of not radiating | emitting an electromagnetic wave from an antenna apparatus. The power coupling amount of the power coupling unit is shown respectively. It is a figure which shows the 1st modification of a radiation power detection element and a circuit board, (a) is a radiation power detection element, (b) is a circuit board, (c) is a circuit board and a 1st base member, The state where the radiated power detection element is fixed is shown. It is a figure which shows the 2nd modification of a radiation power detection element and a circuit board, (a) is a radiation power detection element, (b) is a circuit board, (c) is a circuit board on a 1st base member, and The state where the radiated power detection element is fixed is shown.

[Summary of embodiment]
The radiated power detector according to the embodiment of the present invention is a radiated power detector capable of detecting the radiated power of a broadcasting antenna, and is parallel to the central axis in the longitudinal direction of the broadcasting antenna. Radiated from the broadcasting antenna, a conductive plate disposed, a ground conductor disposed farther from the broadcasting antenna than the conductive plate, a grounding portion connecting the ground conductor and the conductive plate, and And an output unit that outputs an electric signal generated on the conductive plate by electric power from the conductive plate to the ground conductor side, and the output unit is closer to the central axis of the broadcasting antenna than the ground unit. It is provided.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of a radiation power detector according to the invention will be described with reference to the drawings.

[Embodiment]
FIG. 1 is a diagram illustrating a configuration example of a radio tower in which an antenna device including a radiated power detector according to an embodiment of the present invention is installed.

  The radio tower 1 includes a tower portion 1a that is erected in a vertical direction with respect to the ground, and an antenna portion 1b that is installed above the tower portion 1a. The antenna portions 1b are sequentially installed at different heights. A plurality of antenna device groups 10 to 14 are provided. Each of the plurality of antenna device groups 10 to 14 is configured in a ring shape in which a plurality (for example, 80) of antenna devices are arranged in the circumferential direction.

  The plurality of antenna device groups 10 to 14 are supplied with a high-frequency current from a transmission device (not shown) via a main feed line and a branch feed line branched from the main feed line, so that radio waves having different frequencies are mainly horizontal. Radiates in the direction. These antenna device groups 10 to 14 are used for transmitting television waves for terrestrial digital broadcasting from 470 MHz to 770 MHz, for example, and their outputs are 1 kW to 10 kW, for example.

(Configuration of antenna device)
FIG. 2 shows a configuration example of one antenna device 100 constituting, for example, the antenna device group 10, where (a) is a plan view and (b) is a cross-sectional view taken along line AA in (a).

  In the present embodiment, a case will be described in which the antenna apparatus 100 includes a dual loop antenna 21 as a broadcasting antenna. The antenna device 100 includes the double loop antenna 21, a reflection plate 22 that reflects radio waves radiated from the double loop antenna 21, a power feeding unit 23 provided between the reflection plate 22 and the double loop antenna 21, Two support portions 24 that support the loop antenna 21 with respect to the reflection plate 22 and a radiated power detector 3 fixed to the reflection plate 22 are provided.

The double loop antenna 21 is a four-element 4L double loop antenna having first to fourth antenna elements 211 to 214. Twin loop antenna 21 has a central axis C ₁ in the longitudinal direction (vertical direction in FIG. 2), first to fourth antenna elements 211 to 214 along the center axis C ₁ is arranged in a row .

Each of the first to fourth antenna elements 211 to 214 has a shape in which openings of a pair of semicircular conductors face each other. Further, the first antenna element 211 second antenna element 212 is coupled by a coupling line 21a consisting of a pair of parallel conductors to the central axis C _1. Similarly, the second antenna element 212 and the third antenna element 213, and the third antenna element 213 and the fourth antenna element 214 is composed of a central axis _{C 1} parallel pair of conductors coupling line 21b and the coupling They are coupled by a line 21c.

  The coupling line 21 b between the second antenna element 212 and the third antenna element 213 is provided with a power feeding unit 23 for feeding a high-frequency current to the double loop antenna 21. As shown in FIG. 2B, the power feeding section 23 includes a + side power feeding plate 23a and a − side power feeding plate 23b, and both the power feeding plates 23a and 23b form a pair of conductors constituting the coupling line 21b. Each is electrically connected. Both the power feeding plates 23a and 23b are connected to a branch power feeding line (not shown) on the opposite side of the reflecting plate 22 from the double loop antenna 21.

  In addition, the first antenna element 211 and the fourth antenna element 214 are supported by the support plate 24 with respect to the reflection plate 22 at both ends in the longitudinal direction of the twin loop antenna 21.

The reflection plate 22 is made of a plate-like conductor and is provided to face the double loop antenna 21. The reflection plate 22 is, for example, lambda _0/4 between the twin loop antenna 21 (lambda ₀ is the wavelength at the center frequency of the frequency band of the radio waves twin loop antenna 21 transmits) first to at a distance of 4 antenna elements 211 to 214 are arranged in parallel. The reflector 22 is electrically grounded in a state where it is installed in the radio tower 1 (shown in FIG. 1).

A through hole 22a is formed in the reflection plate 22, and the radiated power detector 3 is fixed to the through hole 22a. Through holes 22a, when viewed from the normal direction of the reflector 22, and the second antenna element 212 be between the third antenna element 213, perpendicular to the central axis C ₁ with respect to the coupling line 21b It is formed at a position displaced in the direction (left direction in FIG. 2).

(Configuration of radiation power detector)
FIG. 3 is an enlarged view showing the radiated power detector 3 and its peripheral part in FIG. 2 in an enlarged manner.
FIG. 4 is a perspective view showing the radiated power detector 3 with some components omitted.

  As shown in FIGS. 3 and 4, the radiated power detector 3 includes a radiated power detection element 30 having a power coupling unit 31, an output unit 32, and a ground unit 33, and a conductive metal that is electrically grounded. The circuit board 34 and the resin cover 35 which accommodates the radiation power detection element 30 and the circuit board 34 are provided. In FIG. 3, the outline of the resin cover 35 is indicated by a broken line to indicate the inside. In FIG. 4, the resin cover 35 is not shown.

  The radiated power detection element 30 includes a plate-shaped power coupling portion 31 formed in a circular shape, and a rectangular output portion 32 and a grounding portion 33 formed integrally with the power coupling portion 31. More specifically, the radiated power detection element 30 is formed by bending a single-plate conductive member made of a single conductor including a circular portion serving as the power coupling portion 31, and is orthogonal to the circular portion. The bent portions are the output unit 32 and the grounding unit 33. A method for forming the radiated power detection element 30 will be described later.

Power coupling part 31 is arranged so as to be parallel to the center axis C ₁ and the reflection plate 22 of the twin loop antenna 21 (shown in Figure 1). The power coupling unit 31 is coupled with the double loop antenna 21 to generate power corresponding to the intensity of the radio wave radiated from the double loop antenna 21. The power coupling portion 31 is an example of the conductive plate of the present invention.

  In the present embodiment, the radiated power detection element 30 is made of phosphor bronze containing copper as a main component and containing 3.5% or more and 9.0% or less of tin and 0.03% or more and 0.35% or less of phosphorus. Become. The radiated power detection element 30 may be plated with gold on the surface of phosphor bronze as a base material.

  As shown in FIG. 4, the power coupling portion 31 has a generally circular shape, and includes a first cutout portion 320 and a second cutout portion 330 that are formed by cutting out from the outer edge of the circular shape toward the center O. ing.

  The output unit 32 is connected to the power coupling unit 31 on the inner side (center O side) of the first notch 320. That is, the output part 32 is formed to be bent inside the circular outer edge of the power coupling part 31, and the first cutout part 320 is formed outside the bent part. The output unit 32 outputs an electrical signal generated in the power coupling unit 31 by power coupling with the dual loop antenna 21 from the power coupling unit 31 to the circuit board 34 side.

  The ground portion 33 is connected to the power coupling portion 31 on the inner side (center O side) of the second notch portion 330. That is, the grounding portion 33 is formed to be bent inside the circular outer edge of the power coupling portion 31, and the second cutout portion 330 is formed outside the bent portion. The grounding unit 33 electrically connects the power coupling unit 31 and the circuit board 34.

  As shown in FIGS. 3 and 4, the first notch 320 and the second notch 330 are formed at positions facing each other across the center O of the circular outer edge of the power coupling portion 31. That is, the output unit 32 and the ground unit 33 are formed at positions facing each other across the center O of the power coupling unit 31.

As shown in FIG. 3, the radiated power detector 3 is arranged such that the output unit 32 is closer to the central axis C ₁ of the twin loop antenna 21 than the ground unit 33. More specifically, the central axis C ₂ of the power coupling unit 31 including the center O of the power coupling unit 31 and passing through the centers in the width direction of the output unit 32 and the ground unit 33 and the central axis C ₁ of the dual loop antenna 21 The crossing angle α is set to 90 °. In other words, in the present embodiment, the output unit 32 and the ground unit 33 of the radiated power detection element 30 are provided side by side with respect to the power coupling unit 31 in a direction orthogonal to the central axis C ₁ of the twin loop antenna 21. Yes.

  As shown in FIG. 4, the output unit 32 includes a column part 32 a that supports the power coupling unit 31 in parallel with the circuit board 34, and a tip part 32 b provided on the tip side of the column part 32 a. The column portion 32 a is bent so as to be orthogonal to the power coupling portion 31. The tip 32b is bent in a direction away from the center O of the power coupling portion 31 so as to be orthogonal to the column portion 32a and parallel to the power coupling portion 31.

  Similarly, the grounding portion 33 includes a column portion 33a that supports the power coupling portion 31 in parallel with the circuit board 34, and a tip portion 33b that is provided on the tip side of the column portion 33a. The column portion 33 a is bent so as to be orthogonal to the power coupling portion 31 and to face the column portion 32 a of the output unit 32. Further, the distal end portion 33 b is bent in a direction away from the center O of the power coupling portion 31 so as to be orthogonal to the column portion 33 a and parallel to the power coupling portion 31. The front end portion 33 b of the ground portion 33 is fixed to the circuit board 34 by a bolt 301 and is electrically connected to the circuit board 34.

  The circuit board 34 is arranged farther from the twin loop antenna 21 than the power coupling portion 31. More specifically, the circuit board 34 is arranged so as to be parallel to the reflecting plate 22, and the normal direction of the reflecting plate 22 rather than the power coupling portion 31 that is also arranged so as to be parallel to the reflecting plate 22. In FIG. 2, the antenna is disposed at a position close to the reflecting plate 22 (a position far from the second and third antenna elements 212 and 213 of the dual loop antenna 21 and the coupling line 21b).

  The circuit board 34 is made of a conductive metal such as copper, and is formed in a disk shape having a thickness greater than that of the power coupling portion 31. The circuit board 34 is formed with a rectangular through hole 34 a at a position corresponding to the tip of the output part 32. The circuit board 34 is an example of a ground conductor in the present invention. The circuit board 34 may be plated with gold on the surface of a conductive metal such as copper as a base material.

  An insulating mounting board 340 made of, for example, an epoxy resin is fixed to the surface of the circuit board 34 opposite to the power coupling portion 31. On the mounting substrate 340, a plurality of electronic components constituting a detection circuit described later are mounted. Further, the tip end portion 32 b of the output portion 32 is fixed to the mounting substrate 340 with a bolt 301 through the through hole 34 a of the circuit substrate 34. The mounting substrate 340 is provided with an unillustrated electrode at a portion facing the tip of the output portion 32, and the output portion 32 is kept in contact with the electrode by being fixed by the bolt 301.

  As shown in FIG. 4, the circuit board 34 is fixed to the first base member 36. The first base member 36 is made of, for example, a conductive metal such as stainless steel, and integrally includes a main body portion 36a on a flat plate and a cylindrical cylindrical portion 36b formed to protrude from the main body portion 36a. Yes. The main body portion 36a has a quadrangular shape, and through holes 36c for fixing the first base member 36 to the reflecting plate 22 are provided at the four corners.

  A plurality of (eight in the present embodiment) fixing holes are provided in the peripheral portion of the circuit board 34, and the circuit board 34 has a plurality of (fixing holes) inserted through the fixing holes. The same number of bolts 301 are fixed to the tip surface of the cylindrical portion 36b. That is, the circuit board 34 is electrically grounded via the reflection plate 22 and the first base member 36.

  Since the circuit board 34 and the power coupling unit 31 are connected by the ground unit 33 as described above, both the power coupling unit 31 and the reflection plate 22 are grounded, and radio waves are radiated from the double loop antenna 21. In a state where it is not performed, the power coupling portion 31 and the reflector 22 are at the same potential.

  FIG. 5 shows an example of a detection circuit composed of electronic components mounted on the back surface of the mounting substrate 340, (a) is a circuit diagram of an envelope detection circuit, and (b) is a circuit diagram of a voltage doubler detection circuit. is there. One of these detection circuits is provided on the back surface of the mounting substrate 340.

As shown in FIG. 5A, the envelope detection circuit includes a pair of input electrodes I ₁₁ and I ₁₂ connected to the radiated power detection element side, and a radio wave of the antenna power corresponding to the input power from the twin loop antenna 21. Is configured to include a pair of output electrodes O ₁₁ and O ₁₂ connected to a network analyzer (not shown) for determining whether or not radiated, a diode D ₁₁ , a resistor R ₁₁ , and a capacitor C _11. ing.

Diode _{D 11} is between the input electrode _{I 11} and the output electrode _{O 11,} the anode input electrode _{I 11} side and is connected to the output electrode _{O 11} side as a cathode. The wiring _{L 11} between the diode _{D 11} and the output electrode _{O 11,} between the lines _{L 12} between the input electrode _{I 12} and the output electrode _{O 12,} resistor _{R 11} and capacitor _{C 11} is in parallel It is connected.

As shown in FIG. 5B, the voltage doubler detection circuit includes a pair of input electrodes I ₂₁ and I ₂₂ connected to the radiated power detection element side, a pair of output electrodes O ₂₁ and O ₂₂ , The first and second capacitors C ₂₁ and C ₂₂ , first and second diodes D ₂₁ and D _22, and a resistor R ₂₁ are included.

Between the input electrode I ₂₁ and the output electrode O ₂₁ , a first capacitor C ₂₁ and a first diode D ₂₁ are connected in series. The diode D ₂₁ has an anode on the input electrode I ₂₁ side connected to the first capacitor C ₂₁ and a cathode connected to the output electrode O ₂₁ . The cathode of the second diode D ₂₂ is connected between the first capacitor C ₂₁ and the diode D _21, and the anode of the second diode D ₂₂ is between the input electrode I ₂₂ and the output electrode O _22. and it is connected to the wiring _{L 22.} Further, a resistor R ₂₁ and a second capacitor C ₂₂ are connected in parallel between the wiring L ₂₁ between the diode D ₂₁ and the output electrode O ₂₁ and the wiring L ₂₂ .

When these envelope detection circuits or voltage doubler detection circuits are applied, the input electrodes I ₁₁ and I ₂₁ are connected to the output unit 32 of the radiated power detection element 30 and the input electrodes I ₁₂ and I ₂₂ are connected to the ground unit. 33. The output electrodes O ₁₁ and O ₂₁ are connected to a core wire of a coaxial cable (not shown) that connects the radiated power detector 3 and the network analyzer, for example, and the output electrodes O ₁₂ and O ₂₂ are braided of the coaxial cable. Connected to wire (shielded wire).

  FIG. 6 is an explanatory diagram for explaining processing and assembly procedures of the radiated power detection element 30.

  FIG. 6A shows one flat conductive member 40 before being formed as the radiated power detection element 30. The conductive member 40 is formed by integrally forming a circular portion 41 formed at the central portion and rectangular first and second plate portions 42 and 43 protruding to one side and the other side of the circular portion 41. Yes.

  The circular portion 41 is formed with a pair of slit-like cuts 41a, 41a parallel to each other, and a first plate portion 42 is formed between the pair of cuts 41a, 41a. The circular portion 41 is formed with a pair of slit-like cuts 41b and 41b parallel to each other on the extended lines of the cuts 41a and 41a, and the second plate portion 43 is formed between the pair of cuts 41b and 41b. Is formed. The lengths of the cuts 41a and 41a are longer than the lengths of the cuts 41b and 41b.

  The first plate portion 42 includes a root portion 42a that is mountain-folded with respect to the circular portion 41 at the position of the alternate long and short dash line illustrated in FIG. 6A, and a broken line position illustrated in FIG. 6A with respect to the root portion 42a. It consists of the front-end | tip part 42b by which a valley is folded. Further, the second plate portion 43 includes a root portion 43a that is mountain-folded with respect to the circular portion 41 at the position of the alternate long and short dash line illustrated in FIG. 6A, and a broken line illustrated in FIG. 6A with respect to the root portion 43a. It consists of the front-end | tip part 43b folded at the position of. Through holes 420b and 430b are formed in the tip portions 42b and 43b, respectively.

  FIG. 6B shows the radiated power detection element 30 formed by bending the conductive member 40. The radiated power detection element 30 is formed by forming the circular portion 41 of the conductive member 40 as the power coupling portion 31, the first plate portion 42 as the output portion 32, and the second plate portion 43 as the ground portion 33. Yes. The column part 32a of the output part 32 corresponds to the root part 42a, and the tip part 32b corresponds to the tip part 42b. Further, the pillar portion 33a of the grounding portion 33 corresponds to the root portion 43a, and the tip portion 33b corresponds to the tip portion 43b.

  A through hole 320 b corresponding to the through hole 420 b of the first plate portion 42 is formed at the distal end portion 32 b of the output portion 32. Although not shown, a through hole corresponding to the through hole 430b of the second plate portion 43 is also formed in the distal end portion 33b of the grounding portion 33. The region sandwiched between the pair of cuts 41 a and 41 a becomes the first notch 320 in the radiated power detection element 30, and the region sandwiched between the pair of cuts 41 b and 41 b is the second in the radiated power detection element 30. It becomes the notch part 330 of this.

FIG. 6C shows the circuit board 34 before the radiated power detection element 30 is attached, and a part of the mounting board 340 fixed to the circuit board 34. An electrode 340 a made of a metal foil such as copper is formed on the surface of the mounting substrate 340, and the electrode 340 a is exposed from the rectangular through hole 34 a of the circuit substrate 34. A circular through hole 340b is formed at the center of the electrode 340a. Electrode 340a corresponds to the input electrode _{I 11} or the input electrode _{I 21} of the detection circuit shown in FIG. Further, eight through holes 34 b are formed at equal intervals along the circumferential direction in the outer peripheral portion of the circuit board 34.

  FIG. 6D shows a state in which the radiated power detection element 30 is fixed to the circuit board 34. This fixing is performed by tightening the distal end portion 32b of the output portion 32 to the mounting substrate 340 and the distal end portion 33b of the grounding portion 33 to the circuit substrate 34 by bolts 301, respectively. Further, the distal end portion 32b of the output portion 32 is fixed to the mounting substrate 340, so that the distal end portion 32b is in electrical contact with the electrode 340a.

  FIG. 7 shows the resin cover 35, the second base member 37, and the third base member 38 assembled to the first base member 36 shown in FIG.

  As shown in FIG. 7A, the third base member 38 is made of a metal such as stainless steel, a flat plate portion 38a formed in a flat plate shape, and a cylinder formed to protrude in the normal direction of the flat plate portion 38a. It has the part 38b integrally. The cylindrical part 38b is formed in the center part of the flat plate part 38a, and the inner surface is a through-hole through which a cylindrical part 35a of the resin cover 35 described later is inserted. In addition, through holes 38c are formed at the four corners of the flat plate portion 38a for allowing passage of bolts described later.

  As shown in FIG. 7B, the second base member 37 is made of a metal such as stainless steel, and a flange portion 35b of the resin cover 35 described later is fitted in the central portion of the flat plate portion 37a formed in a flat plate shape. A through-hole 37b to be joined is formed. Four through holes 37 c are formed in the flat plate portion 37 a at positions corresponding to the through holes 38 c of the third base member 38.

  As shown in FIG. 7C, the resin cover 35 is made of a non-conductive resin, and protrudes in the radial direction from the cylindrical portion 35a formed in a bottomed cylindrical shape and the periphery of the opening of the cylindrical portion 35a. It has the formed collar part 35b integrally. A plurality of (two in the present embodiment) drainage through holes 35c are formed in the cylinder portion 35a in parallel along the axial direction of the cylinder portion 35a.

  As shown in FIG. 7D, the first base member 36 has the flat plate-like main body portion 36a and the cylindrical cylindrical portion 36b as described above. The outer diameter of the cylindrical portion 36b is formed slightly smaller than the inner diameter of the cylindrical portion 35a of the resin cover 35, and the resin cover 35 can accommodate the cylindrical portion 36b. Further, the position of the through hole 36 c of the main body 36 a corresponds to the position of the through hole 38 c of the third base member 38 and the through hole 37 c of the second base member 37.

  The radiation power detector 3 is assembled by attaching a circuit board 34 having the radiation power detection element 30 shown in FIG. 6D fixed to the cylindrical portion 36b of the first base member 36 with a plurality of bolts 301 (shown in FIG. 4). The cylindrical portion 36b, the circuit board 34, and the radiated power detection element 30 are accommodated in the resin cover 35, and the second base member 37 and the third base member 38 are overlapped in this order. Is done.

  FIG. 8 shows the entire radiated power detector 3 in which the resin cover 35, the second base member, and the third base member 38 are assembled to the first base member 36.

  The main body portion 36a of the first base member 36, the second base member 37, and the flat plate portion 38a of the third base member 38 are formed in a rectangular shape having a common long side and short side in plan view. ing. Further, the flange 35b of the resin cover 35 is accommodated in the through hole 37b of the second base member 37, and the flange 35b is moved in the axial direction by the first base member 36 and the third base member 38. Is regulated and held.

(Attaching the radiated power detector to the reflector)
FIG. 9 is a diagram illustrating a state in which the radiated power detector 3 assembled as described above is attached to the reflection plate 22 of the antenna device 100.

  The radiated power detector 3 is assembled to the reflector 22 in a state where a metallic cylindrical member 39 having a bent tip is fixed. The cylindrical member 39 is used to draw out a coaxial cable (not shown) for transmitting an output signal of a detection circuit constituted by electronic components mounted on the back surface of the mounting board 340 to a network analyzer.

  The radiation power detector 3 can be attached to and detached from the reflection plate 22 from the back side of the reflection plate 22 in consideration of the ease of work in the radio tower 1 (shown in FIG. 1).

  That is, from the back side of the reflecting plate 22 (the side opposite to the side where the double loop antenna 21 is provided) to the through hole 22a of the reflecting plate 22, the tip of the resin cover 35 of the radiated power detector 3 is disposed below the through hole 35c. The first to third base members 36 to 38 are fixed to the back side of the reflection plate 22. The through hole 22a of the reflecting plate 22 is formed larger than the outer diameter of the cylindrical portion 38b of the third base member 38, and the radiated power detector 3 has the outer peripheral surface of the cylindrical portion 38b of the third base member 38 penetrating therethrough. It is fixed so as to face the inner peripheral surface of the hole 22a. The first to third base members 36 to 38 are fixed to four bolts 302a (only two are shown in FIG. 9) whose head is fixed to the front side of the reflector 22 and the first base member 36. It is performed by screwing with the nut 302b in contact.

(Dimension of radiated power detection element)
FIG. 10 shows a plan view of the power coupling portion 31 of the radiated power detection element 30 and a side view of the radiated power detection element 30.

The power coupling portion 31 is formed with a first notch portion 320 and a second notch portion 330 by notching a part of a circular outer edge having a diameter D. The diameter D is 30.0 mm, for example. The width W of the first notch 320 and the second notch 330 is, for example, 10.0 mm. Further, the cut length L ₁ of the first cutout portion 320 is, for example, 10.8 mm, and the cut length L ₂ of the second cutout portion 330 is, for example, 5.1 mm.

Thus, the length _{L 1} of the cuts of the first notch 320, second notch 330 of the cuts greater than the length _{L 2,} the length _{L 1} is more than twice the length _{L 2} Is set to the length of The total dimension of the length L ₁ and the length L ₂ is set larger than the radius (D / 2) of the power coupling portion 31.

  The thickness t of the power coupling portion 31 is, for example, 0.3 mm. Further, the height H of the power coupling unit 31 from the circuit board 34 (shown in FIG. 4) (hereinafter, this height is referred to as “element height”) is, for example, not less than 5 mm and not more than 20 mm.

(Experimental result of radiated power detection element)
FIG. 11 shows the antenna device 100 to which the radiated power detector 3 to be tested is attached, the first to fourth radiating antenna devices 101 to 104 arranged in the periphery thereof, the antenna device 100 and the first to first antennas. A distributor 6 that distributes and supplies a high-frequency current to the four radiating antenna devices 101 to 104, a first port 51 that supplies a high-frequency current to the distributor 6, and an output signal that receives an output signal from the radiated power detector 3. 2 shows a configuration example of an experimental apparatus including a network analyzer 5 having two ports 52.

  The first to fourth radiating antenna devices 101 to 104 are configured in the same manner as the antenna device 100 described above, except that the radiated power detector 3 is not attached. That is, the antenna device 100 and the first to fourth radiating antenna devices 101 to 104 each include the twin loop antenna 21 having the same shape, and have common characteristics such as directivity and gain.

The antenna device 100 and the first to fourth radiating antenna devices 101 to 104 are arranged in the circumferential direction along two concentric circles C ₀₁ and C ₀₂ having different diameters. The diameter of the outer concentric circle C ₀₁ is 7.0 m, for example, and the difference in diameter d between the concentric circle C ₀₁ and the concentric circle C ₀₂ is 30 cm, for example.

On the concentric circle C ₀₁ , the antenna device 100 and the third and fourth radiating antenna devices 103 and 104 are arranged so that the antenna device 100 is located at the center. Further, on the concentric circle C _02, the first radiation antenna device 101 is arranged at a position sandwiched between the antenna device 100 and the third radiating antenna device 103, the antenna device 100 and the fourth radiation antenna device A second radiating antenna device 102 is arranged at a position sandwiched by 104.

  A high frequency current is supplied to the antenna device 100 and the first to fourth radiating antenna devices 101 to 104 via branch feeders 61 to 65 connected to the output side of the distributor 6. A high frequency current is supplied from the first port 51 of the network analyzer 5 to the input side of the distributor 6 through the main power supply line 60.

  A coaxial cable 300 is connected to the radiated power detector 3 attached to the antenna device 100, and an output signal of the radiated power detector 3 is input to the second port 52 of the network analyzer 5 via the coaxial cable 300. The

  By the experimental apparatus configured as described above, the signal intensity of the output signal of the radiated power detector 3 when the radio wave is radiated from the antenna apparatus 100 and the first to fourth radiating antenna apparatuses 101 to 104, and the antenna apparatus By comparing the signal intensity of the output signal of the radiated power detector 3 when radio waves are radiated from the first to fourth radiating antenna devices 101 to 104 except 100, the detection accuracy of the radiated power detector 3 is increased. evaluate.

  That is, the signal intensity when the radio wave is radiated from the antenna apparatus 100 and the signal intensity when the radio wave is not radiated from the antenna apparatus 100 are compared. If the difference is large, the radio wave radiation from the antenna apparatus 100 is emitted. The state can be detected with high accuracy. On the other hand, when there is no significant difference in signal intensity due to the wraparound of radio waves radiated from the first to fourth radiating antenna devices 101 to 104 other than the antenna device 100, the antenna device 100 by the radiated power detector 3 is used. Therefore, it is impossible to accurately detect the radiation state of the radio waves from.

  12 is a graph showing experimental results in the experimental apparatus shown in FIG. 11, and FIG. 12A is a power coupling unit when radio waves are radiated from the antenna apparatus 100 and the first to fourth radiating antenna apparatuses 101 to 104. (B) shows the power coupling amount of the power coupling unit 31 when the radio wave is radiated from only the first to fourth radiating antenna devices 101 to 104, respectively, in decibel values. is there. In these graphs, the horizontal axis represents the frequency of the radio wave radiated from each antenna device, and the vertical axis represents the power coupling amount of the power coupling unit 31 at each frequency. Further, the amount of power coupling was measured by setting the element height H of the radiated power detection element 30 to 5 mm, 10 mm, and 20 mm.

  As shown in FIG. 12A, the power coupling amount of the power coupling unit 31 increases as the element height H increases (as the power coupling unit 31 approaches the double loop antenna 21). Further, the higher the element height H, the higher the frequency dependency in the power coupling amount. That is, the higher the element height H, the more easily the power coupling amount changes with frequency.

  Further, as shown in FIG. 12B, when the emission of the radio wave from the antenna device 100 is interrupted, the power coupling amount becomes small at any element height H. Even in a state in which no radio wave is radiated from the antenna device 100, the frequency dependence of the power coupling amount increases as the element height H increases, as in FIG.

  Here, it is desirable that the frequency dependence of the power coupling amount is low. If the frequency dependency is high, it is necessary to adjust the threshold value of the power coupling amount for determining whether or not radio waves are radiated from the antenna device 100 according to the frequency of radio waves radiated from the antenna device 100. In addition, in the state where the antenna device 100 is installed in the radio tower 1 (shown in FIG. 1), this determination is correctly performed based on radio waves from other antenna device groups that emit radio waves having different frequencies. This is because there may be no case.

  From the experimental results shown in the graphs of FIGS. 12 (a) and 12 (b), the lower the element height H, the lower the frequency dependency. When the element height H is 5 mm, in the frequency band of 500 MHz to 600 MHz, It can be seen that whether or not radio waves are radiated from the antenna device 100 can be determined using, for example, 50 dB as a threshold value.

  In addition, lowering the element height H contributes to improvement of vibration resistance of the radiated power detection element 30. That is, by reducing the element height H, the radiated power detection element 30 becomes more rigid, and even when the antenna device 100 is installed in the radio tower, it is possible to exhibit the expected performance over a long period of time. .

  13 and 14 show the relationship between the direction of the radiated power detection element 30 with respect to the double loop antenna 21 and the amount of power coupling, and FIGS. 13A to 13D show the radiated power detection element 30 with respect to the double loop antenna 21. FIG. 14A shows the power coupling amount at each rotational position, and FIGS. 14B and 14C show the radiated power detection element 30 at each rotational position whose direction is changed every 90 °. The relationship between the frequency of the power coupling amount at the rotational position shown in a) and (b) and the element height H is shown.

In the first rotational position shown in FIG. 13 (a), the central axis C ₂ of the power coupling part 31 through the center in the width direction of the center O include and output unit 32 and the ground portion 33 of the power coupling part 31, bi The radiated power detection element 30 is arranged such that the intersection angle α with the central axis C ₁ of the loop antenna 21 is 90 °, and the output unit 32 is closer to the central axis C ₁ than the ground unit 33.

Figure 13 in a second rotational position shown in (b), a parallel to the center axis C ₁ of the central axis C ₂ and twin loop antenna 21 of the power coupling part 31, the output unit 32 is the third antenna element 213 side The radiated power detection element 30 is arranged so that the grounding portion 33 is on the second antenna element 212 side.

In the third rotational position shown in FIG. 13 (c), the central axis C ₂ of the power coupling part 31, a cross angle α is 90 ° between the center axis C ₁ of the twin loop antenna 21, the ground portion 33 is output The radiated power detection element 30 is arranged so as to be closer to the central axis C ₁ than the part 32, that is, so that the output part 32 is farther from the central axis C ₁ than the ground part 33.

13 In the fourth rotational position (d), the parallel and the central axis C ₁ of the central axis C ₂ and twin loop antenna 21 of the power coupling part 31, the output unit 32 and the second antenna element 212 side The radiated power detection element 30 is arranged so that the ground portion 33 is on the third antenna element 213 side.

  In the graph showing the power coupling amount at each rotational position of the radiated power detecting element 30 shown in FIG. 14A, the power coupling amount at the first rotational position in FIG. 13 (b) shows the power coupling amount at the second rotational position on the horizontal axis (2), and FIG. 13C shows the power coupling amount at the third rotational position on the horizontal axis (3). The amount of power coupling at the fourth rotational position in d) is shown in (4) on the horizontal axis. The element height H of the radiated power detection element 30 at each rotational position was 22 mm.

  As shown in this graph, the power coupling amount at the first rotational position is higher than the power coupling amounts at the second rotational position and the fourth rotational position. The amount of power coupling at the second rotational position is equal to the amount of power coupling at the fourth rotational position. Further, the power coupling amount at the third rotational position is lower than the power coupling amounts at the second rotational position and the fourth rotational position. From this experimental result, the output unit 32 is provided closer to the twin loop antenna 21 than the ground unit 33, which is higher than the case where the output unit 32 is provided farther from the double loop antenna 21 than the ground unit 33. It can be seen that the amount of power coupling can be obtained.

  FIG. 14B shows the result of measuring the power coupling amount at the first rotational position of the radiated power detection element 30 in the frequency band of 500 MHz to 600 MHz when the element height H is 12 mm, 17 mm, and 22 mm. ing. FIG. 14C shows the result of measuring the amount of power coupling at the second rotational position of the radiated power detection element 30 under the same conditions as in FIG.

  As shown in FIGS. 14B and 14C, at any element height H and at any frequency, the power coupling amount at the first rotational position exceeds the power coupling amount at the second rotational position. . Further, in the first rotation position, the change width of the power coupling amount with respect to the fluctuation of the element height H is smaller than that in the second rotation position. From this experimental result, by providing the output unit 32 closer to the twin loop antenna 21 than the ground unit 33, a high power coupling amount can be obtained and the dependency of the power coupling amount on the element height H is low. It can be seen that the high H can be lowered.

FIG. 15 is an example in which the arrangement of the antenna device 100 and the first to fourth radiating antenna devices 101 to 104 in the experimental apparatus is changed. In the experimental apparatus shown in FIG. 11, the antenna device 100 and the third and fourth radiating antenna devices 103 and 104 are arranged on the outer concentric circle C ₀₁ , and the first and second antenna devices are arranged on the inner concentric circle C ₀₂ . Although the radiation antenna devices 101 and 102 are disposed, in this experimental apparatus, the first and second radiation antenna devices 101 and 102 are disposed on the outer concentric circle C ₀₁ and the antenna device is disposed on the inner concentric circle C _02. 100, and third and fourth radiating antenna devices 103 and 104 are arranged. Since the other configurations are the same, common components are denoted by the same reference numerals, and redundant description is omitted.

  16 is a graph showing the relationship between the frequency measured with the configuration of the experimental apparatus shown in FIG. 15 and the amount of power coupling. FIG. 16A shows the antenna apparatus 100 and the first to fourth radiating antenna apparatuses 101 to 104. (B) shows the power coupling amount of the power coupling unit 31 when only the first to fourth radiation antenna devices 101 to 104 are radiated. Are shown respectively.

  As shown in FIGS. 16A and 16B, there is a clear difference in the amount of power coupling between the case where radio waves are radiated from the antenna device 100 and the case where radio waves are not radiated. The nature is low.

(Operation and effect of the present embodiment)
According to the present embodiment described above, the following operations and effects can be obtained.

(1) Since the output unit 32 of the radiated power detection element 30 is disposed closer to the center axis C ₁ of the loop antenna 21 than the ground unit 33, the output unit 32 is further away from the center axis C ₁ than the ground unit 33. The element height H of the radiated power detection element 30 can be lowered as compared with the case of arranging in this way. Therefore, the vibration resistance of the radiated power detection element 30 can be improved. Further, in this embodiment, since the arranged side by side with the output portion 32 and the ground portion 33 in a direction perpendicular to the central axis C ₁ of the loop antenna 21, to be maximize the effect of lowering the element height H it can.

(2) Since the power coupling portion 31 of the radiated power detection element 30 is formed in a circular shape, and the output portion 32 and the ground portion 33 are formed at positions facing each other across the center of the power coupling portion 31, the output portion 32 and The power coupling portion 31 can be supported in a balanced manner by the ground portion 33, and the vibration resistance of the radiated power detection element 30 can be improved.

(3) First and second cutout portions 320 and 330 are formed in the power coupling portion 31, and the output portion 32 and the grounding portion 33 are connected to the power coupling portion on the center side of the cutout portions 320 and 330 with respect to the power coupling portion 31. 31, the size of the circuit board 34 to which the radiated power detection element 30 is fixed can be reduced, and the power coupling portion 31 is supported between the outer edge and the center of the circuit board 34. The vibration resistance can be improved.

(4) Since the radiated power detection element 30 is formed by bending the single-plate conductive member 40, it is not necessary to combine a plurality of members, the radiated power detection element 30 can be easily formed, and the radiated power detection element 30 is lightweight. Can be Further, in the present embodiment, since the radiated power detection element 30 is formed of phosphor bronze having a high spring property, it is possible to suppress the occurrence of breakage in the bent portion formed by bending.

(5) Since the power coupling unit 31 of the radiated power detection element 30 is grounded by the ground unit 33 and has the same potential as the reflection plate 22, the radiation of the loop antenna 21 by attaching the radiated power detector 3 to the reflection plate 22. The influence on the characteristics can be suppressed.

  The embodiment of the present invention has been described above. However, the present invention is not limited to this. For example, the present invention can be modified as shown below.

(Modification 1)
FIG. 17A shows a radiated power detection element 70 according to a first modification. The radiated power detection element 70 includes a power coupling portion 71 formed of a circular conductive plate in which the first and second cutout portions 720 and 730 are formed, and a center O of the power coupling portion 71 of the first cutout portion 720. The output unit 72 is connected to the power coupling unit 71 on the side, and the ground unit 73 is connected to the power coupling unit 71 on the center O side of the second notch 730.

  The output part 72 has a column part 72a extending in a direction orthogonal to the power coupling part 71, and a tip part 72b formed in parallel to the power coupling part 71 on the tip side of the column part 72a. The grounding portion 73 includes a column portion 73a that faces the column portion 72a and extends in a direction orthogonal to the power coupling portion 71, and a tip portion 73b that is formed in parallel to the power coupling portion 71 on the tip end side of the column portion 73a. Have A through hole (only the through hole 720b of the front end portion 72b is shown) is formed in each of the front end portion 72b and the front end portion 73b.

  The notch length of the second notch part 730 (the distance from the outer edge of the power coupling part 71 to the column part 72a when there is no notch of the power coupling part 71) is the notch length of the first notch part 720. The length is set to be the same as the length (the distance from the outer edge of the power coupling portion 71 to the column portion 73a when the power coupling portion 71 is not cut out). That is, the ratio of the size of the second notch portion 730 to the power coupling portion 71 rather than the ratio of the size of the second notch portion 330 to the power coupling portion 31 in the radiated power detection element 30 shown in FIG. Is getting bigger.

  FIG. 17B shows a circuit board 34A to which the radiated power detection element 70 is fixed. In addition to the eight through holes 34b formed on the outer peripheral portion of the circuit board 34A, a through hole 34c for fixing the grounding portion 73 is formed on the inner side of the circuit board 34A than the through holes 34b. ing. Other configurations are the same as those of the circuit board 34 shown in FIG.

  FIG. 17C shows a state in which the circuit board 34A is fixed to the first base member 36 and the radiated power detection element 70 is fixed to the circuit board 34A. As shown in this figure, after the circuit board 34A and the radiated power detection element 70 are assembled to the first base member 36, the resin cover 35, the second base member 37, and the third base member 38 (all are shown in the figure). 7) is assembled to constitute a radiated power detector.

(Modification 2)
FIG. 18A shows a radiated power detection element 80 according to a second modification. In addition to the first notch 820 formed corresponding to the output part 82 and the second notch 830 formed corresponding to the grounding part 83, the power coupling part 81 of the radiated power detection element 80 includes: Radially cut out third to eighth cutout portions 811 to 816 are formed.

  The output part 82 has a column part 82a orthogonal to the power coupling part 81 and a tip part 82b formed in parallel with the power coupling part 81 on the tip side of the column part 82a. A column part 83a orthogonal to 81, and a tip part 83b formed in parallel with the power coupling part 81 on the tip side of the column part 83a. A through hole (only the through hole 820b of the front end part 82b is illustrated) is formed in the front end part 82b and the front end part 83b.

  FIG. 18B shows a circuit board 34B to which the radiated power detection element 80 is fixed. The circuit board 34 </ b> B has first to eighth through holes 341 to 348 formed in the outer peripheral portion along the circumferential direction. The electrode 340a of the mounting board 340 is exposed from the through hole 34a formed in the circuit board 34B.

  FIG. 18C shows a state in which the circuit board 34B is fixed to the first base member 36 with bolts 301, and the radiated power detection element 80 is fixed to the circuit board 34B.

  As shown in FIGS. 18A to 18C, the third to fifth cutout portions 811 to 813 of the radiated power detection element 80 are formed at positions corresponding to the second to fourth through holes 342 to 344. The sixth to eighth notches 814 to 816 are formed at positions corresponding to the sixth to eighth through holes 346 to 348. That is, when viewed from the normal direction of the circuit board 34B, the second to fourth through holes 342 to 344 are visible through the third to fifth notches 811 to 813, and the sixth to fifth The sixth to eighth through holes 346 to 348 are visible through the eight notches 814 to 816.

  Therefore, when the circuit board 34B is assembled to the first base member 36, a tool for tightening the bolt 301 can be inserted from the third to fifth cutout portions 811 to 813, and the bolt 301 can be tightened.

(Other variations)
Although the case where the antenna device 100 includes the four-element double-loop antenna 21 has been described in the above embodiment, the present invention is not limited to this, and a two-element double-loop antenna may be used. Alternatively, two two-element twin loop antennas may be arranged along the central axis direction. Even in this case, the element height H of the radiated power detection element 30 can be lowered by arranging the radiated power detector 3 so that the output unit 32 is closer to the center axis of the double loop antenna than the ground unit 33. .

  Moreover, not only a double loop antenna but a dipole antenna can also be used. In this case, the extending direction of the pair of elements of the dipole antenna is the longitudinal direction of the antenna, and the central axis of the pair of elements is the central axis of the antenna.

  As mentioned above, although embodiment of this invention and its modification were demonstrated, embodiment and modification which were described above do not limit the invention which concerns on a claim. In addition, it should be noted that not all combinations of features described in the embodiments or the modifications are essential to the means for solving the problems of the invention.

DESCRIPTION OF SYMBOLS 1 ... Radio tower, 1a ... Tower part, 1b ... Antenna part, 3 ... Radiation power detector, 5 ... Network analyzer, 6 ... Divider, 10-14 ... Antenna device group, 21 ... Double loop antenna, 21a-21c ... Coupling line, 22 ... reflecting plate, 22a ... through hole, 23 ... feeding portion, 23a, 23b ... feeding plate, 24 ... supporting portion, 30 ... radiant power detection element, 31 ... power coupling portion (conductive plate), 32 ... output Part, 32a ... pillar part, 32b ... tip part, 33 ... grounding part, 33a ... pillar part, 33b ... tip part, 34, 34A, 34B ... circuit board, 34a, 34b, 34c ... through hole, 35 ... resin cover, 35a ... cylindrical portion, 35b ... collar portion, 35c ... through hole, 36 ... first base member, 36a ... main body portion, 36b ... cylindrical portion, 36c ... through hole, 37 ... second base member, 37a ... flat plate portion , 37b, 37c ... through holes, 3 ... third base member, 38a ... flat plate part, 38b ... cylindrical part, 38c ... through hole, 39 ... cylindrical member, 40 ... conductive member, 41 ... circular part, 42,43 ... plate part, 42a, 43a ... root Part, 42b, 43b ... tip part, 61-65 ... branch feeding line, 51 ... first port, 52 ... second port, 60 ... main feeding line, 70 ... radiated power detection element, 71 ... power coupling part ( Conductive plate), 72 ... Output portion, 72a ... Column portion, 72b ... Tip portion, 73 ... Ground portion, 73a ... Column portion, 73b ... Tip portion, 80 ... Radiation power detection element, 81 ... Power coupling portion (conductive plate) , 82 ... output section, 82a ... pillar section, 82b ... tip section, 83 ... grounding section, 83a ... pillar section, 83b ... tip section, 100 ... antenna apparatus, 101 ... antenna apparatus for radiation, 101-104 ... first to first Fourth radiating antenna device, 211 to 214, antenna element 300 ... Coaxial cable, 301 ... Bolt, 302a ... Bolt, 302b ... Nut, 320 ... First notch, 320b ... Through hole, 330 ... Second notch, 340 ... Mounting substrate, 340a ... Electrode, 340b ... Through holes, 341 to 348 ... first to eighth through holes, 420b, 430b ... through holes, 720 ... first notch, 730 ... second notch, 720b ... through hole, 811 to 816 ... third ~ 8th notch, 820 ... first notch, 820b ... through hole, 830 ... second notch, α ... intersection angle

Claims (6)

A radiated power detector for detecting a radiated power of the broadcast antenna, provided in an antenna device having a broadcast antenna having a longitudinal central axis and a reflector for reflecting radio waves radiated from the broadcast antenna Because
A conductive plate arranged to be parallel to the reflecting plate ;
A grounding conductor disposed away from the broadcasting antenna than the conductive plate;
A grounding portion connecting the grounding conductor and the conductive plate;
An output unit that outputs an electric signal generated in the conductive plate by the electric power radiated from the broadcasting antenna from the conductive plate to the ground conductor side;
The grounding part and the output part each have a pillar part extending in a direction orthogonal to the conductive plate, and the pillar part of the grounding part and the pillar part of the output part face each other.
The output unit is a radiated power detector provided closer to the central axis of the broadcasting antenna than the ground unit.   The radiated power detector according to claim 1, wherein the conductive plate is formed in a circular shape, and the grounding portion and the output portion are provided at positions facing each other across the center of the conductive plate.   The radiated power detector according to claim 1, wherein the grounding unit and the output unit are provided side by side in a direction orthogonal to the central axis of the broadcasting antenna.   The conductive plate has first and second cutouts formed by cutting out from the circular outer edge toward the center, and the grounding part and the output part are the first and second cutouts. The radiated power detector according to any one of claims 1 to 3, wherein the radiated power detector is connected to the conductive plate on the center side of a portion.   The radiated power detector according to claim 1, wherein the grounding unit and the output unit are formed by bending a single plate conductive member including a portion to be the conductive plate.   The radiated power detector according to any one of claims 1 to 5, wherein the conductive plate has the same potential as that of a reflecting plate provided to face the broadcasting antenna.

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