Abstract:
Disclosed is a probe of an electrical measuring instrument including a handle and at least one loop antenna coupled to the handle. A plane defined by the loop antenna is oriented to face an object to be inspected, to detect electrical characteristics in the vicinity of the object. Enhanced accessibility of the probe with respect to the object to be inspected results in an improvement in the accuracy of measured electrical characteristics information and use convenience of the probe by an inspector.

Description:
CROSS-REFERENCE TO RELATED APPLICATION(S) 
       [0001]    This application claims priority under 35 U.S.C. §119 to Korean Patent Application No. 10-2008-0093593, filed on Sep. 24, 2008 in the Korean Intellectual Property Office (KIPO), the entire contents of which are herein incorporated by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Example embodiments of the present invention relate to a measuring instrument, and, more particularly, to a probe of an electrical measuring instrument to detect electrical characteristics of an object to be inspected. 
         [0004]    2. Description of the Related Art 
         [0005]    Electrical characteristics of electric/electronic fields may be measured by a variety of measuring instruments, for example, a voltmeter, an ammeter, and/or an oscilloscope. Examples of electrical characteristics that may be measured by the aforementioned measuring instruments may include a voltage, a current, an electric field, and/or a magnetic field. Conventional measuring instruments may include a body and a probe electrically connected to the body. The measuring instrument may receive information of an object to be measured via the probe allowing a user to analyze the information. Therefore, the accuracy of the electrical characteristics information and the use convenience of the probe by an inspector are determined in accordance with the ability of the probe to access the object. 
         [0006]    For example, detecting a current flowing through a patterned signal line on a printed circuit board may require that two probes be brought into electrical contact with two positions on the signal line. When it is desired to detect the magnitude of current flowing through the signal line via a detection of a magnetic field around the signal line, the ability of the probe to access an object is important for accurate detection. Accessibility of the probe is important for accurate detection because the detected magnitude of current may change according to a flux of the magnetic field and/or a relative position of the probe. 
       SUMMARY 
       [0007]    Example embodiments of present invention provide a probe for an electrical measuring instrument, which may have enhanced accessibility with respect to an object to be inspected, resulting in an improvement in the accuracy of measured electrical characteristics information and use convenience of the probe by an inspector. 
         [0008]    Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
         [0009]    In accordance with an example embodiment of the present invention, a probe for inspecting an object may include a handle and at least one loop antenna coupled to the handle, wherein a plane defined by the at least one loop antenna is oriented to face the object to be inspected, to detect electrical characteristics in a vicinity of the object. 
         [0010]    In accordance with another example embodiment of the present invention, a probe for inspecting an object may include a handle, and a pair of loop antennas coupled to the handle and arranged parallel to each other in a single plane, the pair of loop antennas defining a plane facing the object to be inspected to detect electrical characteristics in a vicinity of the object. 
         [0011]    In accordance with another example embodiment of the present invention, a probe for inspecting an object may include a handle, a pair of loop antennas coupled to the handle, the pair of loop antennas being arranged parallel to each other in a plane, and a protective member enclosing and protecting the pair of loop antennas, wherein the plane faces the object to be inspected to detect electrical characteristics in a vicinity of the object. 
         [0012]    In accordance with another example embodiment of the present invention, a probe for inspecting an object may include a handle and a pair of loop antennas arranged parallel to each other in a single plane to detect electrical characteristics in a vicinity of the object, wherein the pair of loop antennas are detachably coupled to the handle. 
         [0013]    In accordance with another example embodiment of the present invention, In accordance with example embodiments, a probe for inspecting an object may include a handle, at least one loop antenna coupled to the handle, a protective member enclosing and protecting the at least one loop antenna, and a plurality of shields provided at the protective member to surround the at least one loop antenna to intercept noise. 
         [0014]    In accordance with another example embodiment of the present invention, In accordance with example embodiments, a probe for inspecting an object may include a handle, at least one loop antenna coupled to the handle, and a chock electrically connected to the at least one loop antenna and used to intercept common mode noise. 
         [0015]    In accordance with another example embodiment of the present invention, a method of inspecting an object may include positioning a probe near the object, the probe including a handle and at least one loop antenna coupled to the handle, wherein a plane defined by the at least one loop antenna is oriented to face the object to detect electrical characteristics in a vicinity of the object. 
         [0016]    In accordance with another example embodiment of the present invention, a system for measuring an object may include a probe including a handle and at least one loop antenna coupled to the handle, wherein a plane defined by the at least one loop antenna is oriented to face the object to be inspected to detect electrical characteristics in a vicinity of the object. In accordance with example embodiments, the system for measuring an object may also include a measuring instrument electrically connected to the handle of the probe. 
         [0017]    In accordance with another example embodiment of the present invention, a probe may include a handle and at least one loop antenna coupled to the handle, wherein a plane defined by the loop antenna may be oriented to face an object to be inspected, to detect electrical characteristics in the vicinity of the object. 
         [0018]    The handle and loop antenna may be coupled to each other such that a longitudinal direction of the handle follows a normal direction of the plane of the loop antenna. 
         [0019]    The handle and loop antenna may be coupled to each other such that the longitudinal direction of the handle is tilted by a preset angle from the normal direction. 
         [0020]    The loop antenna may be electrically connected to a measuring instrument via the handle. 
         [0021]    The electrical characteristics may include a magnetic field. 
         [0022]    In accordance with another example embodiment the present invention, a probe may include a handle and a pair of loop antennas coupled to the handle. The pair of loop antennas may be parallel to each other to define a single plane. The plane of the pair of loop antennas may be oriented to face an object to be inspected, to detect electrical characteristics in the vicinity of the object. 
         [0023]    The handle and the pair of loop antennas may be coupled to each other such that a longitudinal direction of the handle follows a normal direction of the plane of the pair of loop antennas. 
         [0024]    The handle and the pair of loop antennas may be coupled to each other such that the longitudinal direction of the handle is tilted by a preset angle from the normal direction. 
         [0025]    The pair of loop antennas may be electrically connected to a measuring instrument via the handle. 
         [0026]    An intermediate position between the pair of loop antennas may be located at a position to be inspected, to detect a magnetic field. 
         [0027]    The pair of loop antennas may have a diagonally symmetrical configuration. 
         [0028]    The electrical characteristics may include a magnetic field. 
         [0029]    In accordance with another example embodiment the present invention, a probe may include a handle and a pair of loop antennas coupled to the handle. The pair of loop antennas may be arranged parallel to each other to define a single plane. The probe may also include a protective member to enclose and protect the pair of loop antennas, wherein the plane of the pair of loop antennas may be oriented to face an object to be inspected, to detect electrical characteristics in the vicinity of the object. 
         [0030]    The protective member may be made of a transparent material. 
         [0031]    The protective member may be made of an opaque material. 
         [0032]    A mark to represent an intermediate position between the pair of loop antennas may be provided at a surface of the protective member. 
         [0033]    The mark may be aligned with an inspecting position of the object, to detect a magnetic field in the vicinity of the object. 
         [0034]    The electrical characteristics may include a magnetic field. 
         [0035]    In accordance with another example embodiment of the present invention, a probe may include a handle and a pair of loop antennas detachably coupled to the handle. The pair of loop antennas may be arranged parallel to each other to define a single plane, wherein the plane of the pair of loop antennas may be oriented to face an object to be inspected, to detect electrical characteristics in the vicinity of the object. 
         [0036]    Any one of a plurality of loop antennas defining different sizes of planes may be selected and coupled to the handle, to detect a magnetic field in the vicinity of the object. 
         [0037]    The probe may further include an electric element electrically connected to the loop antennas to determine frequency characteristics of the loop antennas. 
         [0038]    The electric element may be at least one of a capacitor, a resistor, and an inductor. 
         [0039]    Any one of the plurality of loop antennas having different characteristics values of the electric element may be selected and coupled to the handle so as to detect a magnetic field in the vicinity of the object to be inspected. 
         [0040]    The electrical characteristics may include a magnetic field. 
         [0041]    In accordance with another example embodiment of the present invention, a probe may include a handle, at least one loop antenna coupled to the handle, a protective member to enclose and protect the at least one loop antenna, and a plurality of shields provided at the protective member to surround the at least one loop antenna and used to intercept noise to be introduced into the at least one loop antenna. The plane defined by the loop antenna may be oriented to face an object to be inspected, to detect electrical characteristics in the vicinity of the object. 
         [0042]    Each of the plurality of shields may have a loop shape. 
         [0043]    In accordance with another example embodiment of the present invention, a probe may include a handle, at least one loop antenna coupled to the handle, and a chock electrically connected to the at least one loop antenna and used to intercept common mode noise to be introduced via the loop antenna. The plane defined by the loop antenna may be oriented to face an object to be inspected, to detect electrical characteristics in the vicinity of the object. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0044]    These and/or other aspects and advantages of the example embodiments of the present invention will become apparent and more readily appreciated from the following description of the example embodiments, taken in conjunction with the accompanying drawings of which: 
           [0045]      FIG. 1  is a view showing probes according to example embodiments of the present invention; 
           [0046]      FIG. 2  is a view showing a detection of a magnetic field using a probe shown in  FIG. 1 ; 
           [0047]      FIG. 3  is a partial section view of a printed circuit board taken along III-III′ in  FIG. 2 , showing a detection of a magnetic field using the probe shown in  FIG. 2 ; 
           [0048]      FIG. 4  is a view showing probes according to other example embodiments of the present invention; 
           [0049]      FIG. 5  is a view showing a detection of a magnetic field using a probe shown in  FIG. 4 ; 
           [0050]      FIG. 6  is a partial section view of a printed circuit board taken along VI-VI′ in  FIG. 5 , showing a detection of a magnetic field using the probe shown in  FIG. 5 ; 
           [0051]      FIG. 7  is a view showing a probe according to another example embodiment of the present invention; 
           [0052]      FIG. 8  is a view showing a probe according to another example embodiment of the present invention; 
           [0053]      FIG. 9  is a view showing a probe according to another example embodiment of the present invention; 
           [0054]      FIG. 10  is a view showing a probe according to another example embodiments of the present invention; 
           [0055]      FIG. 11  is a view showing a probe according to another example embodiments of the present invention; 
           [0056]      FIG. 12  is a view showing a probe according to another example embodiment of the present invention; and 
           [0057]      FIG. 13  is a view showing a probe according to another example embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0058]    Example embodiments of the present invention will now be described more fully with reference to the accompanying drawings, in which example embodiments of the present invention are shown. The invention may, however, be embodied in different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the sizes of components may be exaggerated for clarity. 
         [0059]    It will be understood that when an element or layer is referred to as being “on”, “connected to”, or “coupled to” another element or layer, it can be directly on, connected to, or coupled to the other element or layer or intervening elements or layers that may be present. In contrast, when an element is referred to as being “directly on”, “directly connected to”, or “directly coupled to” another element or layer, there are no intervening elements or layers present. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. 
         [0060]    It will be understood that, although the terms first, second, etc. may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers, and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, and/or section from another element, component, region, layer, and/or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section without departing from the teachings of the example embodiments. 
         [0061]    Spatially relative terms, such as “beneath”, “below”, “lower”, “above”, “upper”, and the like, may be used herein for ease of description to describe one element or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly. 
         [0062]    Example embodiments of the present invention described herein will refer to plan views and/or cross-sectional views by way of ideal schematic views. Accordingly, the views may be modified depending on manufacturing technologies and/or tolerances. Therefore, example embodiments of the present invention are not limited to those shown in the views, but include modifications in configuration formed on the basis of manufacturing processes. Therefore, regions exemplified in figures have schematic properties and shapes of regions shown in figures exemplify specific shapes or regions of elements, and do not limit the example embodiments of the present invention. 
         [0063]    Reference will now be made in detail to the example embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. 
         [0064]    Hereinafter, example embodiments of the present invention will be described with reference to  FIGS. 1 to 13 . 
         [0065]      FIG. 1  is a view showing probes according to example embodiments of the present invention. More particularly,  FIG. 1A  shows a probe  102 , wherein a rectangular loop antenna  102   a  may be coupled to a handle  102   b .  FIG. 1B  is a front view of the probe  102 , and  FIG. 1C  is a side view of the probe  102 . The handle  102   b  of the probe  102  may have a pen shape, allowing an inspector to grip the probe  102  as one would hold a pen. The handle  102   b  may be coupled to the loop antenna  102   a  in such a manner that a longitudinal direction of the handle  102   b  may follow an approximately normal direction of a rectangular plane defined by the loop antenna  102   a . More specifically, the handle  102   b  may be coupled to the loop antenna  102   a  by a slight tilt angle from the normal direction of the rectangular plane of the loop antenna  102   a . With this coupling manner, when the inspector moves the probe  102  to a position to be inspected, the inspector may accurately locate the loop antenna  102   a  at the inspecting position while confirming the inspecting position as well as a position of the loop antenna  102   a . Further, gripping the probe  102  like a pen may cause the plane of the loop antenna  102   a  to face downward, thereby allowing the entire loop antenna  102   a  to be brought near a surface of an object to be inspected (for example, a Printed Circuit Board (PCB)). That is, the inspector may be able to detect a magnetic field after moving the loop antenna  102   a  to an inspection position by gripping the probe  102  as one would hold a pen. 
         [0066]    In another example embodiment of the present invention, the longitudinal direction of the handle  102   b  may be completely perpendicular to the plane of the loop antenna  102   a . In another example embodiment of the present invention, the loop antenna  102   a  and handle  102   b  may be in a straight line. Specifically, the shape of the handle and the coupling manner between the handle and the loop antenna may be determined to allow the plane of the loop antenna to be parallel to a surface of an object to be inspected. 
         [0067]    In addition,  FIG. 1D  shows a probe  104  wherein a circular loop antenna  104   a  may be coupled to a handle  104   b .  FIG. 1E  is a front view of the probe  104 , and  FIG. 1F  is a side view of the probe  104 . Similar to the previously described probe  102 , the inspector grips the probe  104  as one would hold a pen. 
         [0068]    In all the example embodiments of the present invention disclosed herein, a metal constituting the loop antenna of the probe may be made as thin as possible. In the example embodiments of the present invention, measurement of current is based on detection of a magnetic field (commonly denoted by H) and therefore, the effect of an electric field (commonly denoted by E) may be minimized for accurate measurement of the magnetic field. For this, the metal of the loop antenna may be made as thin as possible. 
         [0069]      FIG. 2  is a view showing a detection of a magnetic field using the probe  102  shown in  FIG. 1 . As shown in  FIG. 2 , one-end of the handle  102   b  of the probe  102  may be electrically connected to a measuring instrument  202 . In  FIG. 2 , when current for transmission of electrical signals flows through a patterned signal line  206  printed on a printed circuit board  204 , a magnetic field  208  is created around the signal line  206  by the current flow. If the loop antenna  102   a  is located in the magnetic field  208 , an electromotive force may be generated in the loop antenna  102   a . The measuring instrument  202  may detect and display the magnitude of current flowing through the signal line  206  based on the magnitude of the electromotive force. In  FIG. 2 , an arrow  210  represents the direction of current flowing through the signal line  206 . Also, the magnetic field  208  has a magnetic line direction as shown in  FIG. 2 . 
         [0070]    The printed circuit board  204  may require a ground line  212  as well as a power line. The ground line  212  may be provided at one surface of the printed circuit board  204  opposite to the other surface at which the signal line  206  is provided. If current flows through the signal line  206 , the current may also flow through the ground line  212 . Accordingly, a slight magnetic field may be created throughout the printed circuit board  204  owing to the current flowing through the ground line  212 . If the loop antenna for detection of a magnetic field is oriented perpendicular to the printed circuit board  204 , rather than being horizontal thereto, the loop antenna may detect a magnetic field created from the ground line  212  as well as the magnetic field  208  created from the signal line  206 , resulting in deterioration in the detection accuracy of a magnetic field. However, in the example embodiments of the present invention disclosed herein, the loop antenna may be oriented horizontal (parallel) to the printed circuit board  204  upon detection of a magnetic field, and may not be affected by the magnetic field created from the ground line  212 . Accordingly, the example probes may achieve an improvement in the detection accuracy of a magnetic field. 
         [0071]      FIG. 3  is a partial section view of the printed circuit board  204  taken along III-III′ in  FIG. 2 , showing detection of a magnetic field using the probe  102 . When magnetic lines of the magnetic field  208  created by the current flowing through the signal line  206  are perpendicular to the plane of the loop antenna  102   a , the largest electromotive force is generated. Accordingly, as shown in  FIG. 3 , upon detection of a magnetic field (current), the inspector may place the loop antenna  102   a  close to the surface of the printed circuit board  204  immediately near the signal line  206  such that magnetic lines of the magnetic field  208  are perpendicular to the plane of the loop antenna  102   a.    
         [0072]      FIG. 4  is a view showing probes according to other example embodiments of the present invention. More particularly,  FIG. 4A  shows a probe  402  wherein a pair of rectangular loop antennas  402   a , which may be arranged in parallel to define a single plane, may be coupled to a handle  402   b .  FIG. 4B  is a front view of the probe  402 , and  FIG. 4C  is a side view of the probe  402 . The handle  402   b  of the probe  402  may have a pen shape, allowing an inspector to grip the probe  402  as one would hold a pen. The handle  402   b  may be coupled to the pair of loop antennas  402   a  in such a manner that a longitudinal direction of the handle  402   b  may follow an approximately normal direction of the rectangular planes of the loop antennas  402   a . More specifically, the handle  402   b  may be coupled to the loop antennas  402   a  by a slight tilt angle from the normal direction of the planes of the loop antennas  402   a . With this coupling manner, when the inspector moves the probe  402  to a position to be inspected, the inspector can accurately locate the loop antennas  402   a  at the inspecting position by easily confirming the inspecting position as well as positions of the loop antennas  402   a . Further, gripping the probe  402  like a pen may cause the planes of the loop antennas  402   a  to face downward, thereby allowing the loop antennas  402   a  to easily be brought into contact with an object to be detected (for example, a Printed Circuit Board (PCB)). The inspector may be able to detect a magnetic field after locating the loop antennas  402   a  at a position to be inspected by gripping the probe  402  as one would hold a pen. Alternatively, the longitudinal direction of the handle  402   b  may be perpendicular to the planes of the loop antennas  402   a.    
         [0073]    In addition,  FIG. 4D  shows a probe  404  wherein a pair of circular loop antennas  404   a  may be coupled to a handle  404   b .  FIG. 4E  is a front view of the probe  404 , and  FIG. 4F  is a side view of the probe  404 . Similar to the previously described probe  402 , the inspector grips the probe  404  as one would hold a pen. 
         [0074]      FIG. 5  is a view showing a detection of a magnetic field using the probe  402  shown in  FIG. 4 . As shown in  FIG. 5 , one end of the handle  402   b  of the probe  402  may be electrically connected to a measuring instrument  502 . In  FIG. 5 , when current for transmission of electrical signals flows through a patterned signal line  506  printed on a printed circuit board  504 , a magnetic field  508  is created around the signal line  506  by the current flow. If the loop antennas  402   a  are located in the magnetic field  508 , an electromotive force is generated in the loop antennas  402   a . The measuring instrument  502  may detect and display the magnitude of current flowing through the signal line  506  based on the magnitude of the electromotive force. That is, the probe  402  of the present embodiment may detect a magnetic field around the signal line  506 , and may detect current flowing through the signal line  506  based on the magnetic field. In  FIG. 5 , an arrow  510  represents the direction of current flowing through the signal line  506 . Also, the magnetic field  508  has a magnetic line direction as shown in  FIG. 5 . 
         [0075]      FIG. 6  is a partial section view of the printed circuit board  504  taken along VI-VI′ in  FIG. 5 , showing a detection of a magnetic field using the probe  402 . When magnetic lines of the magnetic field  508  created by the current flowing through the signal line  506  are perpendicular to the planes of the loop antennas  402   a , the largest electromotive force is generated. Accordingly, as shown in  FIG. 6 , upon detection of a magnetic field (current), the inspector may place the loop antennas  402   a  close to a surface of the signal line  506  immediately above the signal line  506  such that magnetic lines of the magnetic field  508  around the signal line  506  are perpendicular to the respective planes of the pair of loop antennas  402   a.    
         [0076]    The probe  402  having the pair of loop antennas  402   a  may detect a magnetic field created at both sides of the signal line  506 . Representing the magnitude of electromotive force generated by the magnetic field around the signal line  506 , as shown in the lower part of  FIG. 6 , it can be appreciated that the electromotive force becomes the largest at both sides of the signal line  506 . Accordingly, if an intermediate position of the pair of loop antennas  402   a  is located immediately above the signal line  506 , the respective loop antennas  402   a  are naturally located at both sides of the signal line  506 , thereby enabling detection of the largest magnetic field around the signal line  506 , resulting in a significant improvement in the detection accuracy of a magnetic field. 
         [0077]    In addition, as shown in  FIG. 6 , the loop antennas  402   a  may have opposite flux directions to each other. Specifically, a magnetic flux passes upward from the printed circuit board  504  through any one of the pair of loop antennas  402   a , and passes downward toward the printed circuit board  504  through the other loop antenna  402   a . Therefore, as shown in  FIG. 4 , the loop antennas  402   a  may be spiraled in opposite directions, (i.e. are symmetrical in opposite diagonal directions), thereby detecting all magnetic fluxes generated toward opposite directions from each other at both sides of the signal line  506 . This configuration is similar to the pair of circular loop antennas  404   a  shown in  FIG. 4D . 
         [0078]      FIG. 7  is a view showing a probe according to another example embodiment of the present invention. As shown in  FIG. 7 , a pair of loop antennas  702   a  may be coupled to a handle  702   b  of a probe  702  and the pair of loop antennas  702   a  may be enclosed and protected by a protective member  702   c . The protective member  702   c , may, for example, be made of a transparent synthetic resin. Because the loop antennas  702   a  may have a relatively thin thickness, the loop antennas  702   a  may be easily damaged by external shock or may be contaminated by contaminants. Therefore, the protective member  702   c  may be provided to enclose the loop antennas  702   a  thereby protecting the loop antennas  702   a  from external shock and contamination. 
         [0079]    To assure accurate detection of a magnetic field, a signal line  706  may be located midway between the pair of loop antennas  702   a  (see the above description of  FIG. 6 ). For this, using the transparent protective member  702   c  to visually confirm the signal line  706  and loop antennas  702   a  allows the inspector to adjust a position of the loop antennas  702   a  to align an intermediate position between the pair of loop antennas  702   a  with the signal line  706 . 
         [0080]      FIG. 8  is a view showing a probe according to another example embodiment of the present invention. As shown in  FIG. 8 , a pair of loop antennas  802   a  may be coupled to a handle  802   b  of a probe  802  and the pair of loop antennas  802   a  may be enclosed and protected by a protective member  802   c , which may be made of, for example, transparent synthetic resin. A plurality of loop-shaped shields  802   d  may be arranged at a lower surface of the protective member  802   c  around the loop antennas  802   a , to intercept noise generated by unwanted magnetic fields. In the case of a complicated arrangement of a plurality of signal lines, there is a risk in that detecting a magnetic field of a target position around one signal line is hindered by a magnetic field around a neighboring signal line. The shields  802   c  may minimize or eliminate the effect of an unwanted magnetic field. 
         [0081]      FIG. 9  is a view showing a probe according to another example embodiment of the present invention. As shown in  FIG. 9 , a pair of loop antennas  902   a  may be coupled to a handle  902   b  of a probe  902  and the pair of loop antennas  902   a  may be enclosed and protected by a protective member  902   c , which may be made of, for example, synthetic resin. A resistor  902   d  may be installed between opposite distal ends of the loop antennas  902   a  as coupling ends with the handle  902   b . The resistor  902   d  may cause constant frequency characteristics, for example, a constant flat s-parameter of the loop antennas  902   a , thereby improving the detection accuracy of a magnetic field of the loop antennas  902   a . Example embodiments of the present invention are not limited to the use of a resistor to change electrical characteristics of the probe, for example, the resistor  902   d  may be replaced with at least one of a capacitor and an inductor. 
         [0082]      FIG. 10  is a view showing a probe according to another example embodiment of the present invention. As shown in  FIG. 10 , a handle  1002   b  may be formed with coupling holes  1002   c  and any one of various sizes of loop antennas  1002   a ,  1004   a  and  1006   a  may be selectively coupled to the handle  1002   b  via the coupling holes  1002   c . If an inspector selects a desired size of loop antennas  1002   a ,  1004   a  or  1006   a  as necessary, the selected loop antennas may be coupled to the handle  1002   b  via the coupling holes  1002   c , completing the probe  1002 . Generally, signal lines printed on a printed circuit board may contain various widths and intervals. If large size loop antennas  1002   a  are used with a printed circuit board having a narrow width of signal lines and a narrow interval between neighboring signal lines, there is a risk of detecting a magnetic field around an undesignated signal line. Accordingly, when signal lines have a narrow width and narrow interval therebetween, a small size of loop antennas  1006   a  may be selected to enable more accurate detection of a magnetic field. Although not shown in  FIG. 10 , the loop antennas  1002   a ,  1004   a  or  1006   a  may be enclosed and protected by the protective member  702   c  as shown in  FIG. 7 . 
         [0083]      FIG. 11  is a view showing a probe according to another example embodiment of the present invention. As shown in  FIG. 11 , a handle  1102   b  may be formed with coupling holes  1102   c . Various kinds of loop antennas  1102   a ,  1104   a  and  1106   a , having different resistance values, may be provided and selectively coupled to the handle  1102   b  via the coupling holes  1102   c . If the inspector selects a desired resistance value of loop antennas  1102   a ,  1104   a  or  1106   a  as necessary, the selected loop antennas may be coupled to the handle  1102   b  via the coupling holes  1102   c , completing the probe  1102 . The loop antennas  1102   a ,  1104   a  or  1106   a  may have a resistor  1102   d ,  1104   d  or  1106   d  that may have a resistance value suitable for a desired s-parameter. Accordingly, selective use of the loop antennas  1102   a ,  1104   a  or  1106   a  may enable more accurate detection of a magnetic field. Although not shown in  FIG. 11 , the loop antennas  1102   a ,  1104   a  or  1106   a  may be enclosed and protected by the protective member  702   c  as shown in  FIG. 7 . 
         [0084]      FIG. 12  is a view showing a probe according to another example embodiment of the present invention. As shown in  FIG. 12 , a pair of loop antennas  1202   a  coupled to a handle  1202   b  of a probe  1202  may be enclosed and protected by a protective member  1202   c , which is made of, for example, opaque synthetic resin. The loop antennas  1202   a  may have a relatively thin thickness and may be easily damaged by external shock or may be contaminated by contaminants. Therefore, the protective member  1202   c  may enclose and protect the loop antennas  1202   a  from external shock and contamination. 
         [0085]    To assure accurate detection of a magnetic field, a signal line  1206  may be located midway between the pair of loop antennas  1202   a  (see the above description of  FIG. 6 ). For this, a mark  1202   d  representing an intermediate position between the pair of loop antennas  1202   a  may be provided at a surface of the opaque protective member  1202   c . Upon detection of a magnetic field using the probe  1202 , the inspector may locate the probe  1202  above the signal line  1206  such that the mark  1202   d  is aligned with the signal line  1206 , enabling accurate detection of a magnetic field. 
         [0086]      FIG. 13  is a view showing a probe according to another example embodiment of the present invention. As shown in  FIG. 13 , a common mode chock  1302   d  may be installed at upper ends of a pair of loop antennas  1302   a . The common mode chock  1302   d  may intercept common mode noise to be introduced via the loop antennas  902   a , improving detection accuracy of a magnetic field of the loop antennas  1302   a . By adjusting electrical characteristics of the common mode chock  1302   d  (for example, the number of coil turns, etc.), selective interception of low-frequency noise or high-frequency noise may be possible. 
         [0087]    Although a few example embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.