Abstract:
The present invention provides an electromagnetic wave receiving/transmitting device and the application thereof. The electromagnetic wave receiving/transmitting device of the present invention can effectively receive up to 80 to 500 GHz of terahertz electromagnetic waves. The electromagnetic wave receiving/transmitting device of the present invention further achieves the application of terahertz imaging. The physical package of the electromagnetic wave receiving/transmitting device of the present invention is capable of effectively absorbing external and internal noise of electromagnetic waves to significantly reduce noise, and thereby achieving the application of terahertz imaging.

Description:
FIELD OF THE INVENTION 
     The present invention relates to electromagnetic wave receiving/transmitting devices, and in particular, to terahertz (THz) electromagnetic wave receiving/transmitting devices and applications thereof. In particular, the present invention uses an efficient THz electromagnetic absorber for the housing material, which greatly reduces both the interior and exterior electromagnetic noises, thereby achieving the purpose of THz electromagnetic wave receiving/transmitting and imaging. 
     BACKGROUND OF THE INVENTION 
     Terahertz (THz) waves for electromagnetic radiations is a frequency unit in the range of 0.3 to 3 THz, suitable for applications with frequencies bounded between a high frequency edge (300 GHz) of millimeter wave band and a low frequency edge (3000 GHz) of far-infrared spectral band edge, where the wavelengths corresponding to this frequency range are from 1 mm to 0.1 mm (or 100 μm), respectively. At present, the THz radiation has reached the following consensus internationally: THz is a new radiation source with many unique advantages. THz technology is a very important cross frontier, offering opportunities for new technological innovations, economic developments, and national security applications. Aside from its vast range of applications, the reasons THz technology is attracting widespread attentions is firstly, because the THz spectrum (including the transmission spectrum and the reflection spectrum) of substances contains a wealth of physical and chemical information, therefore this frequency spectrum contains important information of the nature and structures of substances; secondly, because a THz light source has unique transmission and reflection properties compared to traditional light sources. 
     In recent years, thanks to the rapid development of ultrafast laser technology, excitation light source for THz pulse have become more stable and reliable, fueling the grounds for further studies of THz technology. In addition, THz imaging technology has been highly valued by governments, research institutions, universities and other research institutions. In addition to the development of pulsed THz imaging technology, continuous-wave THz imaging technology, including active and passive imaging techniques, are the subjects of extensive research. In particular, THz imaging techniques have been, to some extent, put to use in security detections and security inspections in key sectors. Meanwhile, various kinds of THz radiation sources, detectors, and some elements with critical functions are also being rapidly developed, which laid the foundation for the applications of the THz technology in chemistry, biology, material, petroleum, chemical engineering, communications, and other fields particularly in the military and security. 
     Therefore, there are considerable needs for THz electromagnetic wave systems with built-in high absorption housings, such that these systems effectively transmits/receives THz electromagnetic waves while eliminating the interference from unwanted noises. 
     SUMMARY OF THE INVENTION 
     In view of the background of the invention above, and to address the needs in the industry, the present invention proposes an electromagnetic wave receiving/transmitting device that overcomes the outstanding issues in the conventional art as mentioned above. 
     One objective of the present invention is to provide an electromagnetic wave propagation cavity capable of absorbing stray electromagnetic waves generated from outside as well as inside of the electromagnetic wave propagation cavity, thereby eliminating interferences from the noises and maintaining a high signal-to-noise ratio. 
     Another objective of the present invention is to provide an electromagnetic wave receiving/transmitting device that transmits/receives electromagnetic waves through the electromagnetic wave propagation cavity to a sensing region. The transmitting/sensing region may be integrally formed with the electromagnetic wave propagation cavity inside the electromagnetic wave receiving/transmitting device. As such, high-frequency electromagnetic waves can be effectively detected, and applications for imaging devices are made possible. The structural robustness of the electromagnetic wave receiving/transmitting device is high enough to protect and secure the expensive elements therein. 
     Still another objective of the present invention is to provide an electromagnetic wave receiving/transmitting device that can be applied to reflective and/or transmissive electromagnetic wave imaging method(s). Arranging at least one high-frequency electromagnetic wave emitter and the electromagnetic wave receiving/transmitting device on the same side or opposite sides enables reflective or transmissive imaging methods, respectively, thus offering high design flexibility. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  and  FIG. 1B  is an exploded view of an electromagnetic wave receiving/transmitting device in accordance with the present invention; 
         FIG. 2A  is an exploded view of a pushed-out electromagnetic wave receiving/transmitting device in accordance with the present invention; 
         FIG. 2B  is an exploded view of a pushed-in electromagnetic wave receiving/transmitting device in accordance with the present invention; 
         FIG. 3A  is an isometric view of a pushed-out electromagnetic wave receiving/transmitting device in accordance with the present invention; 
         FIG. 3B  is an isometric view of a pushed-in electromagnetic wave receiving/transmitting device in accordance with the present invention; 
         FIG. 4  is a schematic diagram illustrating a physical package for an electromagnetic wave receiving/transmitting device in accordance with the present invention; 
         FIG. 5A  is a schematic diagram illustrating reflective electromagnetic wave reception/transmission in accordance with the present invention; and 
         FIG. 5B  is a schematic diagram illustrating transmissive electromagnetic wave reception/transmission in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention is directed to an electromagnetic wave receiving/transmitting device. In order to facilitate a thorough understanding of the present invention, detailed structures and their elements and steps of methods are provided in the following descriptions. It should be apparent that the present invention can be practiced without the specific details well known to those with ordinary skilled in the art of electromagnetic wave reception and transmission. On the other hand, well-known structures and their elements are not described in detail to prevent imposing unnecessary limits to the present invention. In addition, in order to provide a clear description and for those with ordinary skill in the art to understand the contents of the present invention, various elements in the diagrams are not drawn to scale; the sizes of some may be exaggerated relative to others; and some details that are not relevant to the present invention are completely omitted for conciseness. Reference will be made in details to preferred embodiments of the present invention below. The present invention may be generally practiced in other embodiments, and the scope of the present invention is not limited as such, but rather defined by the appended claims. 
     According to a first embodiment of the present invention, as shown in  FIGS. 1A ,  1 B and  2 A, the present invention provides an electromagnetic wave receiving/transmitting device  100 , which includes: a first base  110 A, a second base  110 B, a first sensing section  130 A, a second sensing section  130 B, a front lens  141 , a back lens  142 , an electromagnetic wave reception processing element  143 . Referring to  FIG. 1A , the aforementioned first base  110 A includes: a first propagation housing space  111 A, a first sensing section housing space  112 A, a first front opening  113 A, a first back opening  114 A, a first sensing opening  115 A, a first front securing groove  116 A, a first back securing groove  117 A, a first base sensing section latch  118 A, and at least one first base tenon  121 A. The aforementioned first sensing section  130 A includes: a first identifying housing space  131 A, a first sensing section front opening  132 A, a first sensing section back opening  133 A, and at least one first sensing section stop latch  134 A. 
     According to this embodiment, the aforementioned second base  110 B includes: a second propagation housing space  111 B, a second sensing section housing space  112 B, a second front opening  113 B, a second back opening  114 B, a second sensing opening  115 B, a second front securing groove  116 B, a second back securing groove  117 B, a second base sensing section latch  118 B, and at least one second base mortise  121 B. The aforementioned second sensing section  130 B includes: a second identifying housing space  131 B, a second sensing section front opening  132 B, a second sensing section back opening  133 B, and at least one second sensing section stop latch  134 B. 
     According to this embodiment, the first propagation housing space  111 A is positioned at one end of the first base  110 A, whereas the first sensing section housing space  112 A is positioned at the other end of the first base  110 A. The first propagation housing space  111 A and the first sensing section housing space  112 A are connected with each other. The first front opening  113 A is positioned at one end of the first base  110 A and the first propagation housing space  111 A, whereas the first sensing opening  115 A is positioned at the other end of the first base  110 A and the first sensing section housing space  112 A, and the first back opening  114 A is positioned at a location where the first propagation housing space  111 A and the first sensing section housing space  112 A are connected. The first front securing groove  116 A is positioned at the first front opening  113 A, and the first back securing groove  117 A is positioned at the first back opening  114 A. The first base sensing section latch  118 A is positioned at the first sensing opening  115 A. 
     According to this embodiment, the first identifying housing space  131 A is positioned at the first sensing section  130 A. The first sensing section front opening  132 A is positioned at one end of the first sensing section  130 A, whereas the first sensing section back opening  133 A is positioned at the other end of the first sensing section  130 A. The first sensing section stop latch  134 A is positioned at the first sensing section back opening  133 A, wherein the first sensing section  130 A can be latched into the first sensing section housing space  112 A. Moreover, the first sensing section  130 A is moveable relative to the first sensing section housing space  112 A, and the first base sensing section latch  118 A and the first sensing section stop latch  134 A abut against each other in order to stop the first sensing section  130 A from moving out of the first sensing section housing space  112 A. The at least one first base tenon  121 A is positioned at either sides of the first front opening  113 A, the first back opening  114 A, the first sensing opening  115 A, and the first base  110 A. 
     According to this embodiment, the second propagation housing space  111 B is positioned at one end of the second base  110 B, whereas the second sensing section housing space  112 B is positioned at the other end of the second base  110 B. The second propagation housing space  111 B and the second sensing section housing space  112 B are connected to each other. The second front opening  113 B is positioned at one end of the second base  110 B and the second propagation housing space  111 B, whereas the second sensing opening  115 B is positioned at the other end of the second base  110 B and the second sensing section housing space  112 B, and the second back opening  114 B is positioned at a location where the second propagation housing space  111 B and the second sensing section housing space  112 B are connected. The second front securing groove  116 B is positioned at the second front opening  113 B, and the second back securing groove  117 B is positioned at the second back opening  114 B. The second base sensing section latch  118 B is positioned at the second sensing opening  115 B. 
     According to this embodiment, the second identifying housing space  131 B is positioned at the second sensing section  130 B. The second sensing section front opening  132 B is positioned at one end of the second sensing section  130 B, whereas the second sensing section back opening  133 B is positioned at the other end of the second sensing section  130 B. The second sensing section stop latch  134 B is positioned at the second sensing section back opening  133 B, wherein the second sensing section  130 B can be latched into the second sensing section housing space  112 B. Moreover, the second sensing section  130 B is moveable relative to the second sensing section housing space  112 B, and the second base sensing section latch  118 B and the second sensing section stop latch  134 B abut against each other in order to stop the second sensing section  130 B from moving out of the second sensing section housing space  112 B. The at least one second base mortise  121 B is positioned at either sides of the second front opening  113 B, the second back opening  114 B, the second sensing opening  115 B, and the second base  110 B. 
     According to this embodiment, as shown in  FIGS. 2A to 3B , the first base  110 A, the second base  110 B, the first sensing section  130 A, the second sensing section  130 B are joined together through the first base tenons  121 A and the second base mortises  121 B. Furthermore, with the structures of the first base tenons  121 A and the second base mortises  121 B, the two bases can be engaged while preventing side leakage of the propagating electromagnetic waves. The front lens  141  is secured between the first front securing groove  116 A and the second front securing groove  116 B. The back lens  142  is secured between the first back securing groove  117 A and the second back securing groove  117 B. The electromagnetic wave reception processing element  143  is secured between the first identifying housing space  131 A and the second identifying housing space  131 B. The electromagnetic wave receiving/transmitting device  100  further includes at least one emitting element combined onto the electromagnetic wave receiving/transmitting device  100  for emitting electromagnetic waves in the range of 80˜550 GHz to properly illuminate the subject, and the range of electromagnetic waves received/propagated by the electromagnetic wave receiving/transmitting device  100  is between 80 to 550 GHz. 
     According to this embodiment, the material of the first base  110 A and the second base  110 B includes a filler and a polymer. The filler may include graphite, carbon particles, silver, conductive particles, dyes and pigments. The percentage by weight of the filler to the total weight of the first base  110 A and the second base  110 B is between 0.5 to 15 wt. %. The polymer may include expanded polypropylene, expanded polystyrene, and polyurethane foam. The percentage by weight of the polymer to the total weight of the first base  110 A and the second base  110 B is between 85 to 99.5 wt. %. The material of the first base  110 A and the second base  110 B is an electrically conductive expanded polypropylene. The electrically conductive expanded polypropylene includes carbon particles of a weight percentage between 13 to 15 wt. %. Moreover, the material of the first base  110 A and the second base  110 B exhibits properties such as high absorption rate, low refractive index, high mechanical strength, and high chemical stability. 
     According to a second embodiment, as shown in  FIG. 4 , the present invention includes a physical package  400  for an electromagnetic wave receiving/transmitting device. The physical package  400  for an electromagnetic wave receiving/transmitting device includes an electromagnetic wave propagation cavity  410  and a sensing region  430 . The electromagnetic wave propagation cavity  410  is formed from a surrounding wall  420 . The surrounding wall  420  is capable of absorbing electromagnetic waves external to the package and the stray electromagnetic waves in the electromagnetic wave propagation cavity  410 . One end of the electromagnetic wave propagation cavity  410  is an electromagnetic wave incident port  410 A, while the other end of the electromagnetic wave propagation cavity  410  is an electromagnetic wave exit port  410 B, wherein the electromagnetic wave incident port  410 A is a first opening  400 C of the physical package  400 . In addition, the sensing region  430  is situated behind the electromagnetic wave exit port  410 B and connected with the electromagnetic wave propagation cavity  410  for receiving the electromagnetic waves propagated through the electromagnetic wave exit port  410 B. The sensing region  430  is formed by the extension of the surrounding wall  420 . 
     According to this embodiment, the material of the physical package  400  for an electromagnetic wave receiving/transmitting device and its surrounding wall  420  includes a filler and a polymer. The filler may include graphite, carbon particles, silver, conductive particles, dyes and pigments, and the percentage by weight of the filler to the total weight of the physical package  400  and its surrounding wall  420  is between 0.5 to 15 wt. %. Furthermore, the polymer may include expanded polypropylene, expanded polystyrene and polyurethane foam. The percentage by weight of the polymer to the total weight of the surrounding wall is between 85 to 99.5 wt. %. The material of the surrounding wall is an electrically conductive expanded polypropylene. The electrically conductive expanded polypropylene includes carbon particles of a weight percentage between 13 to 15 wt. %. 
     The material of the aforementioned physical package  400  and its surrounding wall  420  has low refractive index. Preferably, its refractive index is about 1.0, so it not only minimizes internal reflections but also absorbs both the external electromagnetic waves and the stray electromagnetic waves generated inside the electromagnetic wave propagation cavity, thereby eliminating interference from noises in the electromagnetic wave propagation cavity and effectively propagating high-frequency electromagnetic waves while maintaining a high signal-to-noise ratio. 
     The aforementioned material includes a foamed structure and a filler at a specific ratio, thus exhibiting high mechanical strength. Meanwhile, the aforementioned material also has high chemical stability, so when used as a packaging material, it can protect the internal elements of the electromagnetic wave receiving/transmitting device of the present invention from physical or chemical detriment or both. 
     According to the descriptions above, the packaging material proposed by the present invention has properties of high absorption rate, low refractive index, high mechanical strength and high chemical stability, and compared to normal materials, it is particularly suitable for use as a packaging material for the electromagnetic wave receiving/transmitting device of the present invention. 
     According to this embodiment, the physical package  400  further includes a first outer casing  400 A and a second outer casing  400 B. The outer walls of the first outer casing  400 A and the second outer casing  400 B are conformally formed and sealed, while the inner walls of the first outer casing  400 A and the second outer casing  400 B are conformally formed as the surrounding wall  420 . The appearance of the outer walls of the first outer casing  400 A and the second outer casing  400 B can be nonlinear or uneven in order to prevent side leakage of electromagnetic waves. The joining surfaces between the outer walls of the first outer casing  400 A and the second outer casing  400 B further include matching concave/convex features for fastening purpose as well as preventing side leakage of electromagnetic waves. 
     According to this embodiment, the electromagnetic wave receiving/transmitting device further includes a lens assembly  450 . The lens assembly  450  is provided in the electromagnetic wave propagation cavity  410  of the physical package  400 . The aforementioned lens assembly  450  further includes: an incident lens  450 A located at the electromagnetic wave incident port  410 A for guiding the electromagnetic waves into the electromagnetic wave propagation cavity  410 ; and an outgoing lens  450 B located at the electromagnetic wave exit port  410 B for guiding the electromagnetic waves out of the electromagnetic wave propagation cavity  410  and into the sensing region  430 . The electromagnetic wave propagation cavity  410  has a conical shape, wherein the electromagnetic wave incident port  410 A is bigger than the electromagnetic wave exit port  410 B, and the sizes and shapes of the incident lens  450 A and the outgoing lens  450 B are conformal to the electromagnetic wave incident port  410 A and the electromagnetic wave exit port  410 B, respectively. 
     According to this embodiment, the electromagnetic wave receiving/transmitting device further includes a sensing assembly  470 . The sensing assembly  470  is provided in the sensing region  430  for sensing the electromagnetic waves coming out of the electromagnetic wave exit port  410 B to facilitate electromagnetic wave imaging. The sensing assembly  470  further includes a carrier  470 A for carrying a sensing analyzing element. The carrier  470 A is able to modify the imaging focal length by displacement movements. The direction of the displacement movement of the aforementioned carrier  470 A is the same as the incident direction of the electromagnetic waves. The aforementioned sensing region  430  further includes a displacement opening  430 A. The displacement opening  430 A is a second opening  400 D of the physical package, wherein the displacement opening  430 A is provided at an opposite location to the electromagnetic wave incident port  410 A of the physical package, so as to allow the carrier  470 A to carry out displacement movements for adjusting the imaging focal length in the displacement opening  430 A. 
     According to this embodiment, the physical package  400  further includes at least one electromagnetic wave emitting unit  480  for emitting electromagnetic waves of frequencies between 80˜550 GHz. The electromagnetic wave emitting unit  480  can be mounted on the outer surface of the physical package  400 , and the frequency range of electromagnetic waves received by the electromagnetic wave receiving/transmitting device is between 80 to 550 GHz. 
     According to a third embodiment of the present invention, as shown in  FIG. 4 , the present invention provides an electromagnetic wave imaging method, which includes: generating an electromagnetic wave in the range of 80 to 550 GHz by at least one electromagnetic wave emitting unit  480 . Then, the electromagnetic wave illuminates on objects to be measured, M and N, at specific locations, forming a projected electromagnetic wave. Next, the projected electromagnetic wave is guided through the electromagnetic wave incident port  410 A into the electromagnetic wave propagation cavity  410  to form an incident electromagnetic wave. The projected electromagnetic wave includes the electromagnetic wave generated by the electromagnetic wave emitting unit in addition to other external stray electromagnetic waves. The electromagnetic wave propagation cavity is formed from the surrounding wall  420 . The surrounding wall  420  is capable of absorbing the external electromagnetic wave and the stray electromagnetic waves in the electromagnetic wave propagation cavity  410 , allowing the incident electromagnetic wave to form a captured electromagnetic wave, wherein the electromagnetic wave incident port  410 A further includes the incident lens  450 A for guiding the external electromagnetic wave into the electromagnetic wave propagation cavity  410 , wherein the electromagnetic wave propagation cavity  410  has a conical shape, and the electromagnetic wave incident port  410 A is larger than the electromagnetic wave exit port  410 B. 
     According to this embodiment, the captured electromagnetic wave is guided out of the electromagnetic wave exit port  410 B of the electromagnetic wave propagation cavity  410  to a sensing region  430 . The sensing region  430  is connected with the electromagnetic wave propagation cavity  410  to receive the captured electromagnetic wave, and the sensing region  430  is formed by the extension of the surrounding wall  420 , wherein the electromagnetic wave exit port  410 B further includes the outgoing lens  450 B that optimizes the guiding of the captured electromagnetic wave from the electromagnetic wave propagation cavity  410  into the sensing region. 
     According to this embodiment, the incident electromagnetic wave is detected and analyzed to form an image by a sensing imaging device  470 , wherein the sensing imaging device  470  is provided in the aforementioned sensing region  430 . The sensing imaging device is capable of performing displacement movements in the sensing region to adjust the focus, wherein the direction of the displacement movement is the same as the incident direction of the electromagnetic wave. 
     According to this embodiment, as shown in  FIG. 5A , the electromagnetic wave imaging method of the present invention is a reflective electromagnetic wave imaging method. The electromagnetic wave emitting unit  480  and the electromagnetic wave incident port  410 A are on the same side X2 of the reference coordinate axis Y1-Y2 shown in  FIG. 5A . The electromagnetic wave of the electromagnetic wave emitting unit  480  is emitted along the direction from X2 to X1, and is reflected by the different objects to be measured M and N to form a reflected electromagnetic wave. The reflected electromagnetic wave is reflected along the direction from X1 to X2 into the electromagnetic wave propagation cavity  410 . In other words, the electromagnetic wave emitting unit  480  and the electromagnetic wave incident port  410 A are on opposite directions along which electromagnetic waves propagate, wherein the reflected electromagnetic wave is the projected electromagnetic wave. The different objects to be measured, namely M and N, may be on the same measuring location, such that one surrounds the other or their locations overlap. For example, M is larger than N in size, and M surrounds N. The same measuring location means that the objects are on the same reference coordinate axis Y1-Y2. The reflective electromagnetic wave imaging method of the present invention is able to detect and analyze the incident electromagnetic wave using the sensing imaging device  470  in order to form images of different intensities for different objects to be measured M and N. 
     According to this embodiment, as shown in  FIG. 5B , the electromagnetic wave imaging method of the present invention is a transmissive electromagnetic wave imaging method. The electromagnetic wave emitting unit  480  and the electromagnetic wave incident port  410 A are on the two sides X1 and X2 of the reference coordinate axis Y1-Y2 shown in  FIG. 5B . The electromagnetic wave of the electromagnetic wave emitting unit  480  is emitted along the direction from X1 to X2, and forms a transmissive electromagnetic wave from the different objects to be measured M and N. The different objects to be measured M and N can be on the same measuring locations. The transmissive electromagnetic wave is transmitted along the direction from X1 to X2 into the electromagnetic wave propagation cavity  410 . In other words, the electromagnetic wave emitting unit  480  and the electromagnetic wave incident port  410 A are on the same direction along which electromagnetic waves propagate, wherein the transmissive electromagnetic wave is the projected electromagnetic wave. The same measuring location means that the objects are on the same reference coordinate axis Y1-Y2. The transmissive electromagnetic wave imaging method of the present invention is able to sense and analyze the incident electromagnetic wave using the sensing imaging device  470  in order to form images of different intensities of the different objects to be measured M and N. 
     According to this embodiment, with reference to  FIGS. 5A and 5B , the present invention may also have a plurality of the electromagnetic wave emitting units  480  provided at different specific locations, allowing both reflective and transmissive imaging methods to be performed at the same time. 
     According to this embodiment, the packaging material of the aforementioned surrounding wall  420  includes a filler. The filler may include graphite, carbon particles, silver, conductive particles, dyes and pigments. The percentage by weight of the filler to the total weight of the surrounding wall is between 0.5 to 15 wt. %. The packaging material of the surrounding wall includes a polymer, which may further include expanded polypropylene, expanded polystyrene and polyurethane foam. The percentage by weight of the polymer to the total weight of the surrounding wall is between 85 to 99.5 wt. %. The material of the surrounding wall is an electrically conductive expanded polypropylene. The electrically conductive expanded polypropylene includes carbon particles of a weight percentage between 13 to 15 wt. %. Moreover, the material of the surrounding wall  420  exhibits low refractive index. Preferably, its refractive index is about 1.0; Therefore, it not only minimizes internal reflections, but also absorbs both the external electromagnetic waves and the stray electromagnetic waves generated inside the electromagnetic wave propagation cavity, thereby eliminating interference from noises in the electromagnetic wave propagation cavity and effectively propagating high-frequency electromagnetic waves while maintaining a high signal-to-noise ratio. 
     In summary, it is apparent that, in light of the description of the above embodiments, various modifications and variations of the present invention are possible. Therefore, the present invention should be interpreted under the scope of the appended claims. In addition to the above detailed description, the present invention can also be widely embodied in other embodiments. The above descriptions are merely provided to illustrate preferred embodiments of the present invention, and are not intended to limit the claims of the present invention in any way. Any equivalent changes or modifications made without departing from the spirit of the present invention should be construed as being included in the following claims.