JP2007267010A

JP2007267010A - Radio eavesdropping preventive device

Info

Publication number: JP2007267010A
Application number: JP2006089377A
Authority: JP
Inventors: Minoru Saiki; 実濟木
Original assignee: Oki Electric Industry Co Ltd
Current assignee: Oki Electric Industry Co Ltd
Priority date: 2006-03-28
Filing date: 2006-03-28
Publication date: 2007-10-11

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio eavesdropping preventive device for preventing the eavesdropping from outdoors of an office building, which may be eavesdropped, without having an effect on the outdoor of the office building. <P>SOLUTION: The radio eavesdropping preventive device includes an eavesdropping preventive electromagnetic wave generating device [1], an antenna unit [2] of the radio LAN eavesdropping preventive device, and an electromagnetic wave transmission cable [3] for connecting the eavesdropping preventive electromagnetic wave generating device [1] and the radio LAN eavesdropping preventive device [2]. In the eavesdropping preventive electromagnetic wave generating device [1], a random signal is modulated, and the demodulated signal is mixed with the electromagnetic wave to generate the mixed signal to the antenna unit [2] of the radio LAN eavesdropping preventive device. The antenna unit [2] of the radio LAN eavesdropping preventive device is composed of a rotary device [4], an antenna [5], and a storm sewage preventive cover [6]. The rotary device [4] is a device for rotating the antenna [5] and has a function of always rotation if the electromagnetic wave is radiated from the electromagnetic wave generating device [1]. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

本発明は、無線の盗聴防止に関し、特に、無線ＬＡＮの盗聴防止を行う装置に関するものである。 The present invention relates to wireless wiretapping prevention, and more particularly to a device for preventing wireless LAN wiretapping.

情報化の進展に伴い、オフィスビル等において電磁波を利用した通信が進んでいる。特に、無線ＬＡＮシステムの普及に応じて、コンピュータの機密保持や盗聴防止等のセキュリティ面から建物内部と外部との電磁遮蔽に対する要求が高まっている。従来の電磁遮蔽の方法は、例えば、特開２００１−２８８８３３号公報に示されるように、建物の構造部材により電磁波を減衰させる方法である。
特開２００１−２８８８３３号公報 With the progress of computerization, communication using electromagnetic waves is progressing in office buildings and the like. In particular, with the widespread use of wireless LAN systems, there is an increasing demand for electromagnetic shielding between the inside and outside of a building from the viewpoint of security such as maintaining confidentiality of computers and preventing eavesdropping. A conventional electromagnetic shielding method is a method of attenuating electromagnetic waves by a structural member of a building as disclosed in, for example, Japanese Patent Application Laid-Open No. 2001-288833.
JP 2001-288833 A

しかしながら、従来の電磁波を減衰させる方法では若干ながらも電磁波の漏洩があり盗聴防止の目的には適さない。また、オフィスビル内で構造部材の変更に伴う工事が発生するため、オフィス活動の中断が発生するという問題が生じる。 However, the conventional method for attenuating electromagnetic waves is somewhat unsuitable for the purpose of preventing eavesdropping because of the slight leakage of electromagnetic waves. In addition, there is a problem in that office activities are interrupted due to the construction that occurs in the office building due to the change of the structural members.

かかる課題を解決するため、本発明による無線盗聴防止装置は、盗聴防止用信号を発生する信号発生部と、前記盗聴防止用信号を電磁波として出力するアンテナ部とを有し、アンテナ部は、３６０度回転する回転部を有し、前記盗聴防止用信号を電磁波として出力するときに、水平方向に対して下部方向に指向性を持たせて出力することを特徴とする。 In order to solve this problem, a wireless tapping prevention device according to the present invention includes a signal generation unit that generates a tapping prevention signal and an antenna unit that outputs the tapping prevention signal as an electromagnetic wave. And having a directivity in the lower direction with respect to the horizontal direction when the signal for preventing eavesdropping is output as an electromagnetic wave.

本発明による無線ＬＡＮ盗聴防止装置および無線ＬＡＮ盗聴防止方法によれば、オフィスビルの屋内に影響を及ぼすことなく、盗聴される可能性のあるオフィスビルの屋外からの盗聴を防止することが可能となる。 According to the wireless LAN eavesdropping prevention device and the wireless LAN eavesdropping prevention method according to the present invention, it is possible to prevent eavesdropping from outside the office building that may be wiretapped without affecting the inside of the office building. Become.

本発明の第１の実施形態について図面を参照して説明する。 A first embodiment of the present invention will be described with reference to the drawings.

（Ａ）第１の実施形態
（Ａ−１）第１の実施形態の構成
図１は、本発明の第１の実施の形態に係る無線ＬＡＮ盗聴防止装置の構成を示す図である。 (A) First Embodiment (A-1) Configuration of First Embodiment FIG. 1 is a diagram showing a configuration of a wireless LAN wiretapping prevention device according to a first embodiment of the present invention.

図１の無線ＬＡＮ盗聴防止装置の構成は、盗聴防止用電磁波発生装置［１］、無線ＬＡＮ盗聴防止装置のアンテナ部［２］、盗聴防止用電磁波発生装置［１］と無線ＬＡＮ盗聴防止装置［２］とを接続する電磁波伝送用ケーブル［３］で構成される。盗聴防止用電磁波発生装置［１］は、後述、説明される。無線ＬＡＮ盗聴防止装置のアンテナ部［２］は、回転装置［４］、アンテナ［５］、雨水防止カバー［６］で構成される。回転装置［４］は、アンテナ［５］を回転させる装置であり、盗聴防止用電磁波発生装置［１］から電磁波が放射されている時は、常に回転する機能を有する。アンテナ［５］は、指向性が鋭く、側面や後方への電磁波漏洩も少ない利得・ビーム幅以外の周波数特性を持たず、無線ＬＡＮの周波数に利用できる空中線アンテナである。例えば、アンテナ［５］は、パラボラアンテナや八木アンテナ（八木アンテナ）が利用される。防止カバー［６］は、回転装置［４］とアンテナ［５］を雨水から錆びることを防止するものである。防止カバー［６］の側面と底面は、電磁波の減衰量が少ない材質を持つが、防止カバー［６］の上面は、電磁波の減衰量が多い材質を使用している。 The configuration of the wireless LAN wiretapping prevention device of FIG. 1 includes an electromagnetic wave generation device for wiretapping [1], an antenna portion [2] of the wireless LAN wiretapping prevention device, an electromagnetic wave generation device for wiretapping prevention [1] and a wireless LAN wiretapping prevention device 2] and an electromagnetic wave transmission cable [3]. The eavesdropping electromagnetic wave generator [1] will be described later. The antenna unit [2] of the wireless LAN wiretapping prevention device includes a rotating device [4], an antenna [5], and a rainwater prevention cover [6]. The rotating device [4] is a device that rotates the antenna [5], and has a function of always rotating when electromagnetic waves are radiated from the electromagnetic wave generating device [1] for preventing eavesdropping. The antenna [5] is an antenna that can be used for the frequency of the wireless LAN without having the frequency characteristics other than the gain and the beam width with sharp directivity and less electromagnetic leakage to the side and rear. For example, the antenna [5] is a parabolic antenna or a Yagi antenna (Yagi antenna). The prevention cover [6] prevents the rotating device [4] and the antenna [5] from rusting from rainwater. The side surface and the bottom surface of the prevention cover [6] have a material with a small amount of electromagnetic wave attenuation, but the upper surface of the prevention cover [6] uses a material with a large amount of electromagnetic wave attenuation.

図２は、本発明の第１の実施の形態に係る盗聴防止用電磁波発生装置［１］のプロックダイヤグラムを示す図である。 FIG. 2 is a diagram showing a block diagram of the electromagnetic wave generating device [1] for preventing eavesdropping according to the first embodiment of the present invention.

盗聴防止用電磁波発生装置［１］のプロックダイヤグラムは、ランダム信号発生部［１１］、ＦＭ変調部［１２］、ＰＬＬ［１３］、周波数混合部［１４］、電カ増幅部［１５］で構成される。ランダム信号発生部［１１］は、白色雑音とならない無意味なデータをランダムに発生させ、ＦＭ変調部［１２］へ出カする。ＦＭ変調部［１２］は、ランダム信号発生部［１１］の信号を入カとして、無線ＬＡＮで使われる電波形式へ変調され、周波数混合部［１４］へ出カする。ＰＬＬ［１３］は、無線ＬＡＮで用いられる周波数の電磁波を生成して、周波数混合部［１４］へ出カする。周波数混合部［１４］は、ＦＭ変調部［１２］で変調された周波数とＰＬＬ［１３］で生成された無線ＬＡＮで用いられる周波数を混合させ、電カ増幅部［１５］へ出カする。電カ増幅部［１５］は、周波数混合部［１４］から出カされる電磁波を増幅する機能を有する。電カ増幅部［１５］は、電磁波伝送用ケーブル［３］を経由してアンテナ［５］と接続されている。アンテナ［５］は、増幅された電磁波を出力する。 The block diagram of the electromagnetic wave generation device [1] for preventing eavesdropping includes a random signal generation unit [11], an FM modulation unit [12], a PLL [13], a frequency mixing unit [14], and an electric power amplification unit [15]. Is done. The random signal generation unit [11] randomly generates meaningless data that does not become white noise, and outputs it to the FM modulation unit [12]. The FM modulation section [12] receives the signal from the random signal generation section [11], modulates it into a radio wave format used in the wireless LAN, and outputs it to the frequency mixing section [14]. The PLL [13] generates an electromagnetic wave having a frequency used in the wireless LAN, and outputs it to the frequency mixing unit [14]. The frequency mixing unit [14] mixes the frequency modulated by the FM modulation unit [12] and the frequency used by the wireless LAN generated by the PLL [13], and outputs the mixed signal to the power amplification unit [15]. The electric power amplification unit [15] has a function of amplifying the electromagnetic wave output from the frequency mixing unit [14]. The power amplification unit [15] is connected to the antenna [5] via the electromagnetic wave transmission cable [3]. The antenna [5] outputs an amplified electromagnetic wave.

図３は、本発明の第１の実施の形態に係る無線ＬＡＮ盗聴防止装置の設置例を示す図である。 FIG. 3 is a diagram illustrating an installation example of the wireless LAN tapping device according to the first embodiment of the present invention.

通常、無線ＬＡＮ盗聴防止装置のアンテナ部［２］は、建物［２１］に支えられた支柱ポール［２２］で建物の屋外に固定される。盗聴防止用電磁波発生装置［１］は、建物［２１］に設置され電磁波伝送用ケーブル［３］を通じて、建物の屋外にある無線ＬＡＮ盗聴防止装置のアンテナ部［２］と接続される。第１の電磁的シールド領域（セル）［２３］は、アンテナ［５］を中心とした領域となり、無線ＬＡＮ盗聴防止装置のアンテナ部［２］から放射される電磁波の到達範囲を示す。第２の電磁的シールド領域［２４］は、アンテナ［５］を中心とした領域となり、第１の電磁的シールド領域（セル）［２３］より小さい領域である。第２の電磁的シールド領域［２４］は、回転装置［４］（：図１）より回転されたアンテナ［５］（：図１）の指向特性から無線ＬＡＮ盗聴防止装置のアンテナ部［２］を頂点とする円錐型の範囲を示し、無線ＬＡＮ盗聴防止装置のアンテナ部［２］から放射される電磁波は、到達されない。 Normally, the antenna unit [2] of the wireless LAN tapping prevention device is fixed to the outside of the building by a support pole [22] supported by the building [21]. The electromagnetic wave generating device [1] for preventing wiretapping is connected to the antenna unit [2] of the wireless LAN wiretapping preventing device located outside the building through an electromagnetic wave transmission cable [3] installed in the building [21]. The first electromagnetic shield area (cell) [23] is an area centered on the antenna [5], and indicates the reach of electromagnetic waves radiated from the antenna section [2] of the wireless LAN tapping prevention apparatus. The second electromagnetic shield area [24] is an area centered on the antenna [5] and is smaller than the first electromagnetic shield area (cell) [23]. The second electromagnetic shield area [24] is formed by the antenna section [2] of the wireless LAN tapping prevention device based on the directivity of the antenna [5] (: FIG. 1) rotated by the rotating device [4] (: FIG. 1). An electromagnetic wave radiated from the antenna unit [2] of the wireless LAN tapping prevention device is not reached.

ここで、第１の電磁的シールド領域（セル）［２３］と第２の電磁的シールド領域（セル）［２４］は、アンテナ［５］の指向性により定まり、、無線ＬＡＮ盗聴防止装置のアンテナ部［２］から放射される電磁波は、第１の電磁的シールド領域（セル）［２３］と第２の電磁的シールド領域（セル）［２４］との間に、盗聴を防止したい信号の領域を包含するように出力される。また、無線ＬＡＮ盗聴防止装置のアンテナ部［２］から放射される電磁波において、アンテナから放射される幅の領域は、便宜上直線にて表しているが、実際は、アンテナの利得パターンに依存した領域となる。 Here, the first electromagnetic shield region (cell) [23] and the second electromagnetic shield region (cell) [24] are determined by the directivity of the antenna [5], and the antenna of the wireless LAN wiretapping prevention device is used. The electromagnetic wave radiated from the part [2] is a signal region that is desired to prevent wiretapping between the first electromagnetic shield region (cell) [23] and the second electromagnetic shield region (cell) [24]. Is output to include. In addition, in the electromagnetic wave radiated from the antenna unit [2] of the wireless LAN wiretapping prevention device, the region of the width radiated from the antenna is represented by a straight line for the sake of convenience, but actually, the region depending on the gain pattern of the antenna Become.

無線ＬＡＮＡＰ［２５］は、無線ＬＡＮのアクセスポイントである。無線ＬＡＮＡＰ［２５］は、電磁波の放射出カを柔軟に調整する事が可能であり、建物［２１］の屋外への電磁波到達をできるだけ少なくするよう電磁波の放射出力を調整して設置される。無線ＬＡＮアクセスポイントの電波到達範囲［２６］は、無線ＬＡＮＡＰ［２５］から放射される電磁波の到達範囲を示す。 The wireless LAN AP [25] is a wireless LAN access point. The wireless LAN AP [25] can adjust the radiation output of the electromagnetic wave flexibly, and is installed by adjusting the radiation output of the electromagnetic wave so as to minimize the arrival of the electromagnetic wave to the outside of the building [21]. . The radio wave reachable range [26] of the wireless LAN access point indicates the reachable range of electromagnetic waves radiated from the wireless LAN AP [25].

（Ａ−２）第１の実施形態の動作
第１の実施形態の動作は、図１〜図３を用いて説明される。 (A-2) Operation of First Embodiment The operation of the first embodiment will be described with reference to FIGS.

まず、建物［２１］（：図３）の内部にある盗聴防止用電磁波発生装置［１］（：図１、図３）のランダム信号発生部［１１］（：図２）からランダムなデータが発生し出カされると、ランダムなデータは、ＦＭ変調部［１２］（：図２）にて、無線ＬＡＮで使われる電波形式に変調され、ＰＬＬ［１３］（：図２）にて生成された無線ＬＡＮの周波数で用いられる電磁波と周波数混合部［１４］（：図２）に混合され、電カ増幅部［１５］（：図２）にて盗聴防止用電磁波として増幅生成される。 First, random data is received from the random signal generator [11] (: FIG. 2) of the electromagnetic wave generator for wiretapping [1] (: FIG. 1 and FIG. 3) inside the building [21] (: FIG. 3). When generated, the random data is modulated into a radio wave format used in the wireless LAN by the FM modulator [12] (: FIG. 2) and generated by the PLL [13] (: FIG. 2). The electromagnetic wave used at the frequency of the wireless LAN mixed with the frequency mixing unit [14] (: FIG. 2) is amplified and generated as an electromagnetic wave for preventing wiretapping by the electric power amplification unit [15] (: FIG. 2).

生成された盗聴防止用電磁波は、電磁波伝送用ケーブル［３］（：図１、図３）を伝送して、建物［２１］（：図３）の屋外に設置される無線ＬＡＮ盗聴防止装置のアンテナ部［２］（：図１、図３）の回転装置［４］（：図１）へ到達して、アンテナ［５］（：図１）へ到達する。この時、回転装置［４］（：図１）は、回転して無線ＬＡＮ盗聴防止用電磁波をアンテナ［５］（：図１）から放射しながらアンテナ［５］（：図１）を回転させる。 The generated electromagnetic wave for eavesdropping is transmitted through an electromagnetic wave transmission cable [3] (: FIG. 1 and FIG. 3), and the wireless LAN eavesdrop prevention device installed outdoors in the building [21] (: FIG. 3). The antenna unit [2] (: FIGS. 1 and 3) reaches the rotating device [4] (: FIG. 1) and reaches the antenna [5] (: FIG. 1). At this time, the rotating device [4] (: FIG. 1) rotates and rotates the antenna [5] (: FIG. 1) while radiating the electromagnetic wave for preventing wireless LAN eavesdropping from the antenna [5] (: FIG. 1). .

回転してるアンテナ［５］（：図１）から放射される盗聴防止用電磁波は、第１の電磁的シールド領域（セル）［２３］（：図３）の電磁波到達範囲を形成する。 The eavesdropping electromagnetic wave radiated from the rotating antenna [5] (: FIG. 1) forms an electromagnetic wave reachable range of the first electromagnetic shield region (cell) [23] (: FIG. 3).

このとき、建物［２１］（：図３）の内部にある無線ＬＡＮＡＰ［２５］（：図３）から放射された無線ＬＡＮの電磁波の一部となる電波到達範囲［２６］（：図３）における第１の領域［２７］（：図３）は、第２の電磁的シールド領域［２４］（：図３）に包含されるため、建物の内部は盗聴防止用竜磁波に影響されることなく無線ＬＡＮの送受信を行うことができる。 At this time, the radio wave arrival range [26] (: FIG. 3) which becomes a part of the electromagnetic wave of the wireless LAN radiated from the wireless LAN AP [25] (: FIG. 3) inside the building [21] (: FIG. 3). ) Is included in the second electromagnetic shield area [24] (: FIG. 3), the interior of the building is affected by eavesdropping dragon waves. Wireless LAN can be transmitted and received without any problem.

一方、建物［２１］（：図３）の内部にある無線ＬＡＮＡＰ［２５］（：図３）から放射された無線ＬＡＮの電磁波の一部となる電波到達範囲［２６］（：図３）における第２の領域［２８］（：図３）は、第１の電磁的シールド領域（セル）［２３］（：図３）に包含されるため、ＦＭ変調の特性から電界強度の強い盗聴防止用電磁波に妨害され無線ＬＡＮの受信ができない。また、第１の電磁的シールド領域（セル）［２３］（：図３）から外の範囲では建物［２１］（：図３）の内部にある無線ＬＡＮＡＰ［２５］（：図３）から放射された無線ＬＡＮの電磁波が到達しないため無線ＬＡＮの受信ができない。 On the other hand, the radio wave arrival range [26] (: FIG. 3) that becomes part of the electromagnetic wave of the wireless LAN radiated from the wireless LAN AP [25] (: FIG. 3) inside the building [21] (: FIG. 3) Since the second region [28] (: FIG. 3) in FIG. 3 is included in the first electromagnetic shield region (cell) [23] (: FIG. 3), wiretapping prevention with strong electric field strength is obtained from the characteristics of FM modulation. Wireless LAN cannot be received due to interference with industrial electromagnetic waves. Further, in a range outside the first electromagnetic shield area (cell) [23] (: FIG. 3), from the wireless LAN AP [25] (: FIG. 3) inside the building [21] (: FIG. 3). Since the radiated electromagnetic wave of the wireless LAN does not reach, the wireless LAN cannot be received.

つまり、建物の屋外である電磁的シールド領域（セル）［２３］（：図３）とその外では、無線ＬＡＮＡＰ［２５］（：図３）から放射された無線ＬＡＮの電磁波を受信することができないため、無線ＬＡＮの盗聴をすることができない。 That is, the electromagnetic shielding area (cell) [23] (: FIG. 3) outside the building and the outside receive electromagnetic waves of the wireless LAN radiated from the wireless LAN AP [25] (: FIG. 3). Cannot wiretap the wireless LAN.

（Ａ−３）第１の実施形態の効果
以上のように、無線ＬＡＮ盗聴防止装置から無線ＬＡＮアクセスポイントより放射される周波数と同一の妨害波を放射する事により、建物の屋内では無線ＬＡＮの電磁波が到達できるため通信ができ、建物の屋外では屋内の無線ＬＡＮアクセスポイントより漏洩する電磁波は無線ＬＡＮ盗聴防止装置から放射される電磁波に妨害され電磁的シールド領域外に漏洩しないため建物の屋外にある電磁的シールド領域内及び電磁的シールド領域外で盗聴することができない。よって、オフィスビルの屋内に影響を及ぼすことなく盗聴される可能性のあるオフ７スビルの屋外からの盗聴を防止することができると言う効果が得られる。 (A-3) Effect of First Embodiment As described above, by emitting the same interference wave as the frequency radiated from the wireless LAN access point from the wireless LAN eavesdropping prevention device, the wireless LAN can be used indoors in the building. Since electromagnetic waves can reach, communication is possible. Outside the building, electromagnetic waves leaking from the indoor wireless LAN access point are disturbed by electromagnetic waves radiated from the wireless LAN wiretapping prevention device and do not leak outside the electromagnetic shield area. An eavesdropping cannot be performed within a certain electromagnetic shield area and outside the electromagnetic shield area. Therefore, it is possible to prevent an eavesdropping from the outside of an off-seven building that may be wiretapped without affecting the inside of the office building.

（Ｂ）他の実施形態
本発明は、無線ＬＡＮアクセスポイントの電波到達領域の範囲を狭めることを特徴とするものであるので、盗聴防止用電磁波発生装置とアンテナの周波数を変更することにより、屋内ＰＨＳ、ワイヤレスマイク、ワイヤレス電話機の盗聴防止装置にも適用可能である。 (B) Other Embodiments Since the present invention is characterized in that the range of the radio wave access area of the wireless LAN access point is narrowed, by changing the frequency of the electromagnetic wave generator for eavesdropping and the antenna, The present invention can also be applied to an eavesdropping prevention device for PHS, wireless microphone, and wireless telephone.

本発明の第１の実施の形態に係る無線ＬＡＮ盗聴防止装置の構成を示す図である。It is a figure which shows the structure of the wireless LAN tapping prevention apparatus which concerns on the 1st Embodiment of this invention. 本発明の第１の実施の形態に係る盗聴防止用電磁波発生装置のプロックダイヤグラムを示す図である。It is a figure which shows the block diagram of the electromagnetic wave generator for wiretapping prevention which concerns on the 1st Embodiment of this invention. 本発明の第１の実施の形態に係る無線ＬＡＮ盗聴防止装置の設置例を示す図である。It is a figure which shows the example of installation of the wireless LAN tapping prevention apparatus which concerns on the 1st Embodiment of this invention.

Explanation of symbols

１・・・盗聴防止用電磁波発生装置。
２・・・無線ＬＡＮ盗聴防止装置のアンテナ部。
３・・・電磁波伝送用ケーブル。
４・・・回転装置。
５・・・アンテナ。
６・・・雨水防止カバー。
１１・・・ランダム信号発生部。
１２・・・ＦＭ変調部。
１３・・・ＰＬＬ。
１４・・・周波数混合部。
１５・・・電カ増幅部。
２１・・・建物。
２２・・・支柱ポール。
２３・・・第１の電磁的シールド領域（セル）。
２４・・・第２の電磁的シールド領域（セル）。
２５・・・無線ＬＡＮＡＰ。
２６・・・無線ＬＡＮアクセスポイントの電波到達範囲。
２７・・・第１の通信領域。
２８・・・第２の通信領域。 1 ... Electromagnetic wave generator for wiretapping prevention.
2 ... Antenna portion of the wireless LAN wiretapping prevention device.
3 ... Cable for electromagnetic wave transmission.
4 ... Rotating device.
5: Antenna.
6 ... Rainwater prevention cover.
11: Random signal generator.
12: FM modulation section.
13 ... PLL.
14: Frequency mixing section.
15: Electric power amplification section.
21 ... Building.
22 ... Pole pole.
23: First electromagnetic shield region (cell).
24: Second electromagnetic shield region (cell).
25: Wireless LAN AP.
26: Radio wave coverage of the wireless LAN access point.
27: First communication area.
28: Second communication area.

Claims

A signal generator for generating an eavesdropping prevention signal;
An antenna unit that outputs the signal for preventing eavesdropping as an electromagnetic wave,
The antenna unit is
Having a rotating part that rotates 360 degrees;
A wireless eavesdropping prevention apparatus characterized in that, when outputting the eavesdropping prevention signal as an electromagnetic wave, it is output with directivity in a lower direction with respect to a horizontal direction.

The wireless eavesdrop prevention device according to claim 1,
The signal generator is
A random signal generator for generating a random signal;
A modulation unit that modulates the random signal and outputs a modulation signal;
An electromagnetic wave generator for generating electromagnetic waves;
A wireless wiretapping prevention device comprising: a frequency mixing unit that mixes the modulation signal and electromagnetic waves and outputs a mixed signal.

The wireless eavesdrop prevention device according to claim 1,
A cover for accommodating the antenna portion and the rotating portion;
The cover is
A wireless eavesdropping prevention device, characterized in that a side surface and a bottom surface of the cover are made of a material having a smaller amount of electromagnetic wave attenuation than the upper surface of the cover.

The wireless eavesdrop prevention device according to claim 1,
The directivity is between a first region centered on the antenna portion and a second region centered on the antenna portion that is smaller than the first region so as to include a signal region where it is desired to prevent eavesdropping. A wiretapping prevention device characterized in that the wiretapping prevention signal is output as an electromagnetic wave.