1261680 玖、發明說明： 【發明所屬之技術領域】 本發明係關於-種電磁訊號感測系統，特別係關於一種 具有高感度之電磁訊號感測系統。 【先前技術】 傳統的電場感測元件（例如天線）使用一電纜線傳輸訊 號。然而，由於電纜線本身是導體，因此一待測電磁場會 受傳輪訊號之電纜線干擾。為了解決此一干擾問題，即有 所謂光電式電場感測裝置之開發。 光電式電場感測裝置一般係在鈮酸鋰（LiNb〇3)晶體基材 上成長光波導，並以感測之電場改變行經該光波導之雷射 光強度以形成干涉訊號（參考·· IEEE Transacti〇ns⑽ electromagnetic compatibility，ν〇1· 34，Νο· 4，1992， 。此外，日本Tokln公司亦發表了數篇相關技術 之專利，其内谷主要包括電場感測裝置中之電光轉換器設 计製作及以光纖進行溫度補償等技術（參考·· Ep 〇66446⑽工， EP 0668506A1 及 EP 0668507A1等）。 圖1係一習知之光電式電磁場感測裝置丨〇之示意圖。如圖 1所不，該電磁場感測裝置1 〇係由一個感測天線丨2偵測一待 測電磁場之射頻/微波訊號◦該感測天線12之輸出端係電氣 連接至一電光轉換器30，其中該電光轉換器30包含一鈮酸 鋰Μ體基板14、一光輸入波導1 6、二光強度調變波導1 8、 一光輸出波導20以及設置於該光強度調變波導丨8上方之電 極24及26 。 1 HVC, KX)2 lu PD()070\pD0070.DOC - 6 - 1261680 自一雷射光源42發出之雷射光之行進路線係由一第一光 纖22導入該光輸入波導1 6並分光進入該光強度調變波導丄$ 後，再合併到該光輸出波導20。當該電極24與26之間有電 壓差時，將造成該光強度調變波導1 8之折射率改變，使得 行經二光強度調變波導丨8之雷射光之強度改變（即改變強 度差），因此從該光輸出波導20輸出之雷射光的強度將隨 该電極24與26間之電位差而變化。當該感測天線12感測到 一電磁訊號時，即施加一電壓差在該電極24與26之間以改 變行經二光強度調變波導18之雷射光強度’因此電磁訊號 即可由該電光轉換器30轉換成光訊號，並由該第二光纖28 傳送至光偵測器40,以轉換成電訊號。 由於光電式電磁感測裝置1〇具有非接觸 及非破壞之優1261680 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic signal sensing system, and more particularly to an electromagnetic signal sensing system having high sensitivity. [Prior Art] A conventional electric field sensing element (e.g., an antenna) transmits a signal using a cable. However, since the cable itself is a conductor, an electromagnetic field to be measured is disturbed by the cable of the transmission signal. In order to solve this interference problem, there is a development of a so-called photoelectric electric field sensing device. The photoelectric electric field sensing device generally grows an optical waveguide on a lithium niobate (LiNb〇3) crystal substrate, and changes the intensity of the laser light passing through the optical waveguide to form an interference signal by sensing the electric field (refer to IEEE Transacti). 〇ns(10) electromagnetic compatibility, ν〇1· 34, Νο· 4,1992, in addition, Japan Tokln has also published several patents on related technologies, including the design of electro-optical converters in electric field sensing devices. And the technology of temperature compensation by optical fiber (refer to Ep 〇 66446 (10), EP 0668506A1 and EP 0668507A1, etc.) Fig. 1 is a schematic diagram of a conventional photoelectric electromagnetic field sensing device. As shown in Fig. 1, the electromagnetic field The sensing device 1 is configured to detect an RF/microwave signal of an electromagnetic field to be measured by a sensing antenna 丨2. The output end of the sensing antenna 12 is electrically connected to an electro-optic converter 30, wherein the electro-optical converter 30 includes a lithium niobate bulk substrate 14, an optical input waveguide 16, a two-light intensity modulation waveguide 18, an optical output waveguide 20, and an electrode 2 disposed above the light intensity modulation waveguide 8 4 and 26. 1 HVC, KX) 2 lu PD() 070\pD0070.DOC - 6 - 1261680 The path of the laser light emitted from a laser source 42 is guided by a first optical fiber 22 into the optical input waveguide 16 And splitting into the light intensity modulation waveguide 丄$, and then merging into the light output waveguide 20. When there is a voltage difference between the electrodes 24 and 26, the refractive index of the light intensity modulation waveguide 18 is changed, so that the intensity of the laser light passing through the two-light intensity modulation waveguide 8 is changed (ie, the intensity difference is changed). Therefore, the intensity of the laser light output from the light output waveguide 20 will vary with the potential difference between the electrodes 24 and 26. When the sensing antenna 12 senses an electromagnetic signal, a voltage difference is applied between the electrodes 24 and 26 to change the intensity of the laser light passing through the two-light intensity modulation waveguide 18. Therefore, the electromagnetic signal can be converted by the electro-optical signal. The device 30 converts the optical signal into an optical signal, and the second optical fiber 28 transmits the optical signal to the optical detector 40 for conversion into an electrical signal. Because the photoelectric electromagnetic sensing device has the advantages of non-contact and non-destructive
不足而無法應用於檢測 微弱之電磁訊號。 【發明内容】 測糸統。 本發明之主要目的係提供一 種具有高感度之電磁訊號感 一種電磁訊號感測系統， 為達成上述目的，本發明揭 ΉΥ(;Ί002Ι DOC' 1261680 ^ 〇 ^ 有至沙一光開關之天線、一可產生一電調制訊 號之δίΐ號產生為、一镇一 j|L 4> 弟田射先源、一電氣連接於該訊號 產生器及該第-雷射光源之驅動器、一連接該第雷射光源 及/光開關之夕模光纖以及一電氣連接於該天線之訊號處 理裝置。該驅動器可根據該電調制訊號致能該第一雷射光 源產生一光調制訊號，而該多模光纖係用以傳送該光調制 Λ號至該光開關。 该天線包含一第一導線段、一設置於該第一導線段上之 第一光開關、一第二導線段以及一設置於該第二導線段上 之第二光開關。該第一光開關將該第一導線段分隔成一第 單7G及一第二單元，該第一單元之長度小於該第二單元 之長度’且該訊號處理裝置係電氣連接於該第一單元。 该訊號處理裝置包含一電氣連接於該天線之電光轉換 為、一第二雷射光源、一連接該第二雷射光源及該電光轉 換器之第一光纖、一光電轉換器、一連接該電光轉換器及 。亥光笔轉換杰之第二光纖以及一電氣連接於該光電轉換器 之電訊號解調器。 【實施方式】 圖2例示本發明第一實施例之電磁訊號感測系統5〇。如圖 2所示’該電磁訊號感測系統50包含一天線60、一可產生一 電調制訊號之訊號產生器54、第一雷射光源58A、一電氣連 接於該訊號產生器54及該第一雷射光源58人之驅動器56、一 電氣連接於該第一雷射光源58A之多模光纖70以及一電氣 連接於該天線60之訊號處理裝置1〇〇。該驅動器56可根據該 1111 11V(j.J〇〇21 〇 ι,ΐ-.iiij, j I,L. pn〇〇70'PD0070.DOC _ ο _ 1261680 電調制訊號致能該第一雷射光源58A而產生一光調制訊號。 該訊號處理裝置1〇〇包含一電氣連接於該天線60之電光 轉換為30、一第二雷射光源58B、一連接該第二雷射光源 5 8B及該電光轉換器3〇之第一光纖22、一光電轉換器肋、一 連接忒電光轉換為30及該光電轉換器8〇之第二光纖28以及 一電氣連接於該光電轉換器8〇之電訊號解調器9〇。較佳 地，該第一光纖22之一端可連接至該第一雷射光源58八，如 此整個電磁訊號感測系統5〇可只使用一單一雷射光源。 該天線60包含一第一導線段62、一設置於該第一導線段 62上之第一光開關66、一第二導線段64以及一設置於該第 二導線段64上之第二光開關68。該第一光開關66將該第一 導線段62分隔成一第一單元62a及一第二單元62B，該第一 單元62A之長度小於該第二單元62B之長度，且該訊號處理 t置1⑼係電氣連接於該第一單元62A。 該多模光纖70係用以將該第一雷射光源58A產生之光調 制訊號分別傳送至該第一光開關66及該第二光開關68。當 該第一光開關66受到該第一雷射光源58A產生之雷射光照 射時’其阻抗將降低以導通該第一導線段62之第一單元62A 及第二單元62B。如此，當該第一光開關66及該第二光開關 68導通時’該天線6〇之第一導線段62及第二導線段64即可 用以感測一電場訊號。該第一光開關66及該第二光開關68 之導通狀態係由該光調制訊號控制，亦即由該訊號產生器 54產生之電調制訊號控制。 當該天線60感測到一外部電場訊號時會產生一感應電訊Insufficient to apply to detecting weak electromagnetic signals. [Summary of the Invention] Measuring system. The main object of the present invention is to provide an electromagnetic signal sensing system with high sensitivity electromagnetic signal. To achieve the above object, the present invention discloses (Ί Ι Ι Ι DOC' 1261680 ^ 〇 ^ has an antenna for the sand optical switch, The δ ΐ ΐ 可 可 可 可 可 一 一 一 | | | | | j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j j An illuminating optical fiber of the light source and/or the optical switch, and a signal processing device electrically connected to the antenna, wherein the driver can generate an optical modulation signal according to the electrical modulation signal to enable the first laser light source, and the multimode optical fiber is used Transmitting the optical modulation nickname to the optical switch. The antenna includes a first wire segment, a first optical switch disposed on the first wire segment, a second wire segment, and a second wire segment disposed on the second wire segment a second optical switch. The first optical switch divides the first wire segment into a first 7G and a second unit, the length of the first unit is less than the length of the second unit, and the signal processing device is electrically Connected to the first unit. The signal processing device includes an electrical light electrically connected to the antenna, a second laser light source, a first optical fiber connected to the second laser light source and the electro-optical converter, and a photoelectric a converter, a second optical fiber connected to the electro-optical converter, and a black light pen and an electrical signal demodulator electrically connected to the photoelectric converter. [Embodiment] FIG. 2 illustrates an electromagnetic system according to a first embodiment of the present invention. The signal sensing system 5 is shown in FIG. 2. The electromagnetic signal sensing system 50 includes an antenna 60, a signal generator 54 that generates an electrical modulation signal, a first laser light source 58A, and an electrical connection. The signal generator 54 and the first laser light source 58 driver 56, a multimode fiber 70 electrically connected to the first laser source 58A, and a signal processing device 1 electrically connected to the antenna 60. The driver 56 can enable the first laser source 58A according to the 1111 11V (jJ〇〇21 〇ι, ΐ-.iiij, j I, L. pn 〇〇 70'PD0070.DOC _ _ _ 1261680 electrical modulation signal Generate a light modulation signal. The signal processing device The first optical fiber 22, one electrically connected to the antenna 60, 30, a second laser light source 58B, a second laser light source 58B connected to the second laser light source 5 8B, and the first optical fiber 22, a photoelectric converter rib, a second optical fiber 28 connected to the photoelectric converter 8 and an electrical signal demodulator 9 electrically connected to the photoelectric converter 8〇. Preferably, the first One end of an optical fiber 22 can be connected to the first laser light source 58. Thus, the entire electromagnetic signal sensing system 5 can use only a single laser light source. The antenna 60 includes a first wire segment 62, and a The first optical switch 66 on the first wire segment 62, a second wire segment 64, and a second optical switch 68 disposed on the second wire segment 64. The first optical switch 66 divides the first wire segment 62 into a first unit 62a and a second unit 62B. The length of the first unit 62A is smaller than the length of the second unit 62B, and the signal processing is set to 1 (9). Electrically connected to the first unit 62A. The multimode fiber 70 is configured to transmit the optical modulation signals generated by the first laser source 58A to the first optical switch 66 and the second optical switch 68, respectively. When the first optical switch 66 is exposed to the laser light generated by the first laser source 58A, its impedance will decrease to turn on the first unit 62A and the second unit 62B of the first wire segment 62. Thus, when the first optical switch 66 and the second optical switch 68 are turned on, the first wire segment 62 and the second wire segment 64 of the antenna 6 can be used to sense an electric field signal. The conduction states of the first optical switch 66 and the second optical switch 68 are controlled by the optical modulation signal, that is, by the electrical modulation signal generated by the signal generator 54. When the antenna 60 senses an external electric field signal, an inductive telecommunications is generated.
HUl|IVG\l002IC)uK；!l!!ifi4'.,PD00701 PD0070.DOC 1261680 號’而該感應電訊號將由該第一光開關66及該第二光開關 6 8根據該光調制訊號調制後，施加於該電光轉換器3 〇上。 自該第二雷射光源58B發出之雷射光由該第一光纖22導入 該光輸入波導16，並分光進入該光強度調變波導丨8。而根 據該光調制訊號調制後之感應電訊號則藉由該電極24與26 載入行經該光強度調變波導18之雷射光。亦即原本不具任 何訊號之雷射光將被載入經過調制之感應電訊號後再合併 到該光輸出波導20。 載入该感應電訊號之雷射光由該第二光纖28傳送至該光 電轉換器80，用以將該雷射光之光訊號轉換成一電訊號並 傳送至該電訊號解調器90。該電訊號解調器9〇根據該訊號 產生器54之電調制訊號解調來自該光電轉換器8〇之電訊 號’並由該電磁訊號感測系統5〇之輸出端52輸出由該天線 60感測之外部電場訊號的頻率及振幅。如此，該電光轉換 态30之鈮酸鋰晶體基材14本身之雜訊將可經由感測訊號之 调制/解調而去除，以提昇該電磁訊號感測系統5〇之整體感 度。 圖3例不本發明第二實施例之電磁訊號感測系統丨丨〇。相 較於圖2之電磁訊號感測系統5〇，該電磁訊號感測系統n〇 係採用一具有二光開關122、124之環形天線120，其中該光 開關122、124係分別設置於該環形天線12〇之二自由末端。 该裱形天線1 20係藉由該光開關丨22、1 24電氣連接於該電光 轉換器30之電極24及26，而該光開關丨22、124則由該多模 光纖70耦合於該第一雷射光源58八，以接收該光調制訊號。 -10- i m丨|_ ㈤卿瞻7〇取 1261680 相較於圖2之天線60可用以感測一外部電場，當該光開關 122及124導通時，該環形天線12〇可用以感測一外部磁場。 圖4例示本發明第三實施例之電磁感測系統15〇。相較於 圖2之電磁感測系統50,圖4之電磁感測系統ι5〇係使用一天 線陣列160及一雷射光源陣列170，且另包含一位址產生器 152及一多工器154。該天線陣列160係由複數個天線6〇構 成’而該雷射光源陣列1 70係由複數個雷射光源5 8 A構成。 該位址產生器152可產生一位址訊號（代表某一雷射光源 58A )，該多工器154則根據該訊號產生器54之電調制訊號 及該位址產生器1 52之位址訊號致能該位址訊號所代表之 雷射光源5 8 A以產生該光調制訊號，進而調制連接於該雷射 光源58A之天線60以感測一待測電場訊號。藉由該位址產生 器1 52及該多工器1 54切換控制該複數個天線6〇，該電磁訊 號感測系統150可測得該天線陣列150所在地之電場分佈。 同理’該電磁訊號感測系統1 5 0亦可採用一由複數個圖3所 示之環形天線120構成之天線陣列以量測磁場分佈。 傳統之调制/解调技術使用2個相位敏感偵測器（phase sensitive detector，PSD)搭配一低通濾波器或1個相位敏感 偵測器、一鎖相放大器以及一低通濾波器（參考： htt^l//www. srsys.com/downloads/PDFs/ApplicationNotes/A bmUAs_.pdf)。下文即以2個相位敏感偵測器搭配一低通濾 波器建構前述實施例之電訊號解調器90。 假設待測之電磁訊號的頻率為com，該第一雷射光源58A 之光調制訊號的頻率為cos，則由該天線60偵測到之電磁訊 H: H U ^ H YG\I00： I OVi, ί; ； Ijlj 111, Γ λ pD0070\ P D0070. DOC -11 - 1261680 號為 VmSin(comt+em)xVsSin(cost+es)。如果一待測元件（即微 波源）之參考成5虎為VmrSin(omt + 0mr)，光調制訊號之參考訊 號（即該訊號產生器54之電調制訊號）為vsrSin(cost+0sr)，則 5亥天線6 (H貞測到之電磁訊號經由兩級相位敏感價測器（或 一相位敏感偵測器與一鎖相放大器）分別以微波源之參考 訊號及光調制訊號之參考訊號解調可得輸出訊號為： V。-VmSin(〇)mt+em)xVsSin(cost+es)xVmrSin(c〇mt+0mr)xVsrSin(HUl|IVG\l002IC)uK;!l!!ifi4'.,PD00701 PD0070.DOC 1261680' and the inductive signal will be modulated by the first optical switch 66 and the second optical switch 68 according to the optical modulation signal Applied to the electro-optical converter 3 〇. The laser light emitted from the second laser light source 58B is guided from the first optical fiber 22 to the optical input waveguide 16, and is split into the light intensity modulation waveguide 丨8. The inductive signal modulated according to the optical modulation signal is loaded with the laser light passing through the light intensity modulation waveguide 18 by the electrodes 24 and 26. That is, the laser light that originally did not have any signal will be loaded into the modulated inductive signal and then merged into the optical output waveguide 20. The laser light loaded into the inductive signal is transmitted from the second optical fiber 28 to the photo-electric converter 80 for converting the optical signal of the laser light into an electrical signal and transmitting it to the electrical signal demodulator 90. The electrical signal demodulator 9 解调 demodulates the electrical signal ' from the photoelectric converter 8 according to the electrical modulation signal of the signal generator 54 and outputs the output 52 of the electromagnetic signal sensing system 5 from the antenna 60. The frequency and amplitude of the external electric field signal sensed. Thus, the noise of the lithium niobate crystal substrate 14 of the electro-optical conversion state 30 can be removed by modulation/demodulation of the sensing signal to enhance the overall sensitivity of the electromagnetic signal sensing system 5 . Fig. 3 illustrates an electromagnetic signal sensing system of the second embodiment of the present invention. Compared with the electromagnetic signal sensing system 5 of FIG. 2, the electromagnetic signal sensing system uses a loop antenna 120 having two optical switches 122 and 124, wherein the optical switches 122 and 124 are respectively disposed on the ring. The antenna 12 has two free ends. The scorpion antenna 120 is electrically connected to the electrodes 24 and 26 of the electro-optic converter 30 by the optical switches 丨22, 224, and the optical switch 丨22, 124 is coupled to the multimode fiber 70 by the A laser source 58 is received to receive the light modulation signal. -10- im丨|_ (5) Qing Zhan 7 126 1261680 Compared with the antenna 60 of FIG. 2 can be used to sense an external electric field, when the optical switches 122 and 124 are turned on, the loop antenna 12 〇 can be used to sense one External magnetic field. Fig. 4 illustrates an electromagnetic sensing system 15A of a third embodiment of the present invention. Compared with the electromagnetic sensing system 50 of FIG. 2, the electromagnetic sensing system ι5 of FIG. 4 uses an antenna array 160 and a laser light source array 170, and further includes an address generator 152 and a multiplexer 154. . The antenna array 160 is constructed by a plurality of antennas 6 ’ and the laser source array 170 is composed of a plurality of laser sources 5 8 A. The address generator 152 can generate a bit address signal (representing a certain laser source 58A), and the multiplexer 154 is based on the electrical modulation signal of the signal generator 54 and the address signal of the address generator 1 52. The laser light source 58 8A represented by the address signal is enabled to generate the light modulation signal, thereby modulating the antenna 60 connected to the laser light source 58A to sense an electric field signal to be tested. The plurality of antennas 6 are switched by the address generator 1 52 and the multiplexer 1 54. The electromagnetic signal sensing system 150 can measure the electric field distribution of the antenna array 150. Similarly, the electromagnetic signal sensing system 150 can also employ an antenna array composed of a plurality of loop antennas 120 as shown in Fig. 3 to measure the magnetic field distribution. Traditional modulation/demodulation techniques use two phase sensitive detectors (PSDs) with a low-pass filter or a phase-sensitive detector, a lock-in amplifier, and a low-pass filter (reference: Htt^l//www.srsys.com/downloads/PDFs/ApplicationNotes/A bmUAs_.pdf). Hereinafter, the telecommunication demodulator 90 of the foregoing embodiment is constructed by using two phase sensitive detectors together with a low pass filter. Assuming that the frequency of the electromagnetic signal to be measured is com, and the frequency of the light modulation signal of the first laser source 58A is cos, the electromagnetic signal H detected by the antenna 60 is: HU ^ H YG\I00: I OVi, ί; ; Ijlj 111, Γ λ pD0070\ P D0070. DOC -11 - 1261680 is VmSin(comt+em)xVsSin(cost+es). If the reference of the device to be tested (ie, the microwave source) is VmrSin (omt + 0mr), and the reference signal of the optical modulation signal (ie, the electrical modulation signal of the signal generator 54) is vsrSin(cost+0sr), then 5 Hai antenna 6 (H贞 measured electromagnetic signal is demodulated by reference signal of microwave source and reference signal of optical modulation signal via two-stage phase sensitive price detector (or a phase sensitive detector and a lock-in amplifier) The available output signals are: V.-VmSin(〇)mt+em)xVsSin(cost+es)xVmrSin(c〇mt+0mr)xVsrSin(
At+Osr) =VmVmrVsVsr(.i/2Cos(2Qmt+0m-emr)+l/2Cos(0m-emr))(-l/ 2Cos(20st +θ5-θ sr)+l/2Cos(0s-0sr)) 该輸出訊號若再經一低通濾波器，則可得該低通濾波器 之輸出訊號為：voD=i/4vmvmrvsvsrc〇s(em-emr)c〇s(es-esr)。 由此可知，該低通濾波器（即該電訊號解調器9〇)之輸出訊號 v〇D與該天線60偵測到之電磁訊號的振幅乂⑺成正比。 在雜訊方面，由於一般放大器之頻寬（即使是窄頻帶放大 器）約為數百赫玆，在這個頻帶中因放大而引進的寬帶雜訊 可能比待測訊號大，易於蓋掉微弱之待測訊號。然而’，本 發明藉由感測訊號之調制/解調，只有與微波源或光調制訊 號之參考訊號具有相同調制頻率的成分會被解調出來，因 而被放大的頻寬可以小於0·01赫玆，#寬頻雜訊可已差到 1〇〇倍。因此，從該天線60之後各級，包括該電光調制器％、 電導線與電子S件所產生或偶合進來的雜訊大都會被低通 濾、波器渡掉，尸'有與調制頻率相同的訊號會被擷取出來， 因而可提昇該電磁訊號感測系統50之整體感度。 Ι11ΑΗΥΟ'ΙΟϋ21ιΛ!Κ；ί^|'.LAPD0070\PD0070.DOC -12- 1261680 相較於習知技藝因該電光轉換器3G之㈣鐘晶體基㈣ 本身之雜訊而無法應用於量測微弱電磁訊號，本發明之電 磁訊號感測系統50藉由感測訊號之調制/解調，以去除該^ 光轉換器30之銳酸鐘晶體基材14本身之雜訊，因此該電: 訊號感測系統50之感度可大幅地提昇而可應用於量測微型 元件與整合模組之微弱電磁特性。 本發明之技術内容及技術特點巳揭示如上，然而熟悉本 項技術之人士仍可能基於本發明之教示及揭示而作種種不 背離本發明精神之替換及修飾。因此，本發明之保護範圍 應不限於實施例所揭示者，而應包括各種不背離本發明之 替換及修飾，並為以下之申請專利範圍所涵蓋。 【圖式簡要說明】 圖1係一習知之光電式電磁場感測裝置之示意圖； 圖2例示本發明第一實施例之電磁訊號感測系統； 圖3例示本發明第二實施例之電磁訊號感測系統；以及 圖4例示本發明第三實施例之電磁訊號感測系統。 【元件符號說明】 10 電磁場感測裝置 12 天線 14 鈮酸鋰晶體基板 16 光輸入波導 18 光強度調變波導 20 光輸出波導 22 第一光纖 24 電極 26 電極 28 第二光纖 30 電光轉換器 40 光偵測器 42 雷射光源 50 電磁訊號感測系統At+Osr) =VmVmrVsVsr(.i/2Cos(2Qmt+0m-emr)+l/2Cos(0m-emr))(-l/ 2Cos(20st +θ5-θ sr)+l/2Cos(0s-0sr) If the output signal passes through a low pass filter, the output signal of the low pass filter is: voD=i/4vmvmrvsvsrc〇s(em-emr)c〇s(es-esr). It can be seen that the output signal v〇D of the low-pass filter (ie, the signal demodulator 9〇) is proportional to the amplitude 乂(7) of the electromagnetic signal detected by the antenna 60. In terms of noise, since the bandwidth of a general amplifier (even a narrowband amplifier) is about several hundred Hz, the broadband noise introduced by amplification in this frequency band may be larger than the signal to be tested, and it is easy to cover the weak test. Signal. However, in the present invention, by the modulation/demodulation of the sensing signal, only components having the same modulation frequency as the reference signal of the microwave source or the optical modulation signal are demodulated, and thus the amplified bandwidth can be less than 0·01. Hertz, #Broadband noise can be as much as 1〇〇. Therefore, from the subsequent stages of the antenna 60, the noise generated or coupled by the electro-optic modulator %, the electric wires and the electronic S-pieces are mostly passed through the low-pass filter and the wave device, and the body has the same modulation frequency. The signal is extracted and the overall sensitivity of the electromagnetic signal sensing system 50 can be improved. Ι11ΑΗΥΟ'ΙΟϋ21ιΛ!Κ; ί^|'.LAPD0070\PD0070.DOC -12- 1261680 Compared to the conventional technique, the noise of the (4) crystal base (4) of the electro-optical converter 3G cannot be applied to the measurement of weak electromagnetic The signal, the electromagnetic signal sensing system 50 of the present invention removes the noise of the sharp acid crystal substrate 14 of the optical converter 30 by the modulation/demodulation of the sensing signal, so the electric: signal sensing The sensitivity of the system 50 can be greatly improved and can be applied to measure the weak electromagnetic characteristics of the micro components and the integrated modules. The technical content and technical features of the present invention are disclosed above, but those skilled in the art may still make various substitutions and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be construed as being limited by the scope of the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view of a conventional photoelectric electromagnetic field sensing device; FIG. 2 illustrates an electromagnetic signal sensing system according to a first embodiment of the present invention; FIG. 3 illustrates a second embodiment of the present invention. The measuring system; and FIG. 4 illustrates an electromagnetic signal sensing system according to a third embodiment of the present invention. [Explanation of component symbols] 10 Electromagnetic field sensing device 12 Antenna 14 Lithium niobate crystal substrate 16 Optical input waveguide 18 Light intensity modulation waveguide 20 Optical output waveguide 22 First optical fiber 24 Electrode 26 Electrode 28 Second optical fiber 30 Electro-optical converter 40 Light Detector 42 laser source 50 electromagnetic signal sensing system
Η ： HU' H\ Cf 10U210 !,ciI!lji! i, l： \PD007()\PD0070. DOC 1261680 52 輸出端 56 驅動器 58B 第二雷射光源 62 第一導線段 62B 第二單元 66 第一光開關 70 多模光纖 90 電訊號解調器 110 電磁訊號感測糸統 122 光開關 150 電磁訊號感測糸統 154 多工器 170 雷射光源陣列 訊號產生器 第一雷射光源 天線 第二單元 第二導線段 第二光開關 光電轉換器 訊號處理裝置 環形天線 光開關 位址產生器 天線陣列 雷射光源陣列 H IUJ H YG 1002 10 V，；；i!l!i i I.L PD0070 PD0070.DOC - 14Η : HU' H\ Cf 10U210 !,ciI!lji! i, l: \PD007()\PD0070. DOC 1261680 52 Output 56 Driver 58B Second Laser Light Source 62 First Wire Segment 62B Second Unit 66 First Optical Switch 70 Multimode Fiber 90 Signal Demodulator 110 Electromagnetic Signal Sensing System 122 Optical Switch 150 Electromagnetic Signal Sensing System 154 Multiplexer 170 Laser Source Array Signal Generator First Laser Source Antenna Second Unit Second wire segment second optical switch photoelectric converter signal processing device loop antenna optical switch address generator antenna array laser light source array H IUJ H YG 1002 10 V,;;i!l!ii IL PD0070 PD0070.DOC - 14