Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q1/00—Details of, or arrangements associated with, antennas
  • H01Q1/12—Supports; Mounting means
  • H01Q1/22—Supports; Mounting means by structural association with other equipment or articles
  • H01Q1/24—Supports; Mounting means by structural association with other equipment or articles with receiving set
  • H01Q1/241—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM
  • H01Q1/242—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use
  • H01Q1/243—Supports; Mounting means by structural association with other equipment or articles with receiving set used in mobile communications, e.g. GSM specially adapted for hand-held use with built-in antennas
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q9/00—Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
  • H01Q9/04—Resonant antennas
  • H01Q9/0407—Substantially flat resonant element parallel to ground plane, e.g. patch antenna
  • H01Q9/0421—Substantially flat resonant element parallel to ground plane, e.g. patch antenna with a shorting wall or a shorting pin at one end of the element

Definitions

• the invention relates to a low profile antenna, more particularly, to a low profile antenna, which can reduce the profile height of the patch antenna, which can reduce the SAR value of the antenna and not influence the bandwidth of the antenna.
• the internal antennas gradually replace the exterior antennas used in the existing mobile telephones just because the internal antennas . have the low profile heights (low profile for short), low SAR values (Specific Absorption Ratio, which represents the measured value of the electromagnetic radiation absorbed by people) and so on.
• the internal antennas can be divided into two groups: (1) The microstrip patch antenna without ground connection 7, as shown in FIG. 1, is also named as the half wave microstrip patch antenna. Although this kind of antenna has the perfect antenna effect, it is always used for the large devices such as the base station, the space shuttle, the guided missile and so on due to the larger radiating area required. (2) The microstrip patch antenna with ground connection 8, as shown in FIG.
• PIFA Planar Inverted-F Antenna
• the microstrip patch antenna is a good alternative for use in mobile telephones and in the radio devices in view of their volume/ size firstly because the length of the microstrip antenna is reduced to 1/4 wavelength due to the mapping effect of the PIFA produced by earthing.
• the PIFA has some characters, the most important of which is the relation between its size and its bandwidth because the bandwidth of PIFA is determined by its volume (L(length) ⁇ W(width) ⁇ H(height)) and the height affects the bandwidth very much. Furthermore, the resonance efficiency of the PIFA is determined by its perimeter (namely the length (L)+the width (W)). Accordingly, the resonance efficiency can be regulated via changing its perimeter by means of forming the induced load on the PIFA (such as notching of the plate of the PIFA so as to near the ground plate). Furthermore, the PIFA is also named as the "electric-field antenna", i.e. the resonance efficiency of the PIFA is controlled by the electric field formed by the PIFA.
• bandwidth resonance regions namely multi-frequency antenna
• the bandwidth resonance regions influence each other, that is, when the length of one bandwidth resonance region changes, the others can be influenced. Therefore the PIFA has hi coupling.
• the internal space of the mobile telephone will become narrower as mobile telephones become lighter, thinner, shorter and smaller.
• Methods to reduce the profile height of the PIFA in order to reduce the volume of the PIFA have been investigated.
• a piece of dielectric material, for example, is sandwiched between the PIFA and the ground plate so that the volume of the PIFA is reduced proportionately relative to the dielectric constant of the dielectric material, but the method can result in the situation that the bandwidth of the PIFA is shortened and then the PIFA does not perform as well.
• the external antenna can produce the SAR value exceeding the current standard (FCC: 1.6Mw/g; EU: 2.0Mw/g) while it is in close proximity to the user.
• a remarkable performance characteristic of the PIFA is that its bandwidth can't be directly influenced by the size of the ground plate lying under the PIFA, but it can be influenced by the length of the perimeter (that is, the length +the width) of the ground plate.
• an object of the present invention is to provide a low profile antenna, which can reduce the volume of the patch antenna while at the same time not reducing the bandwidth of the antenna, and which can satisfy the requirements of being low profile and having a low SAR value.
• the present invention provides a low profile antenna including a radiator module and a ground plate.
• the radiator module comprises a radiating surface and a feed-in point located on the radiating surface.
• the ground plate and the radiator module are spaced and stacked one upon the other.
• the feed-in member electrically connected to the feed-in point is formed on the ground plate.
• a slot radiating member is also formed on the ground plate, which comprises a first end lying on the feed-in member, a second end lying on one edge of the ground plate and a slot connecting the two ends.
• FIG. 1 is a schematic illustration of the structure of a known microstrip patch antenna without ground connection
• FIG. 2 is a schematic illustration of the structure of a known microstrip patch antenna with ground connection
• FIG. 3 is a schematic illustration of the low profile antenna according to a first embodiment of the present invention
• FIG. 4 is another specific example of the first embodiment
• FIG. 5 is another specific example of the radiator module according to the first embodiment
• FIG. 6 is another specific example of the slot radiating member according to the first embodiment
• FIG. 1 is a schematic illustration of the structure of a known microstrip patch antenna without ground connection
• FIG. 2 is a schematic illustration of the structure of a known microstrip patch antenna with ground connection
• FIG. 3 is a schematic illustration of the low profile antenna according to a first embodiment of the present invention
• FIG. 4 is another specific example of the first embodiment
• FIG. 5 is another specific example of the radiator module according to the first embodiment
• FIG. 6 is another specific example of the slot radiating member according to the first embodiment
• FIG. 7 is another specific example of the slot radiating member according to the first embodiment
• FIG. 8 is another specific example of the slot radiating member according to the first embodiment
• FIG. 9 is another specific example of the slot radiating member according to the first embodiment
• FIG. 10 shows the state of the current distribution in the radiator and the ground plate when the slot radiating member according to the first embodiment is in operation
• FIG. 11 shows the state of the current distribution in the radiator and the ground plate when the radiator module according to the first embodiment is in operation
• FIG. 12 shows the measure results of the SWR of the first embodiment
• FIG. 13 shows that the slot radiating member according to the first embodiment covered with a piece of dielectric material; deposited with a layer of metallic material
• FIG. 15 is a schematic illustration of the low profile antenna according to a second embodiment of the present invention.
• FIG. 3 shows a first embodiment of the low profile antenna 1.
• the low profile antenna 1 includes a radiator module 2 and a ground plate 3, and in the embodiment the low profile antenna 1 is given an example of one in the small radio communication device (such as the mobile telephone).
• the ground plate 3 is a copper foil formed on one side of an insulating base board (such as a printed circuit board) 30, and a feed-in member 31 connected to a signal transmission line (not shown) is located on the ground plate 3.
• the feed-in member 31 and the ground plate 3, which are isolated from each other, are mounted on the insulating base board 30.
• the radiator module 2 and the ground plate 3 are opposite and spaced, and the radiator module 2 is posited upon the ground plate 3, which comprises a radiating surface 20, a feed-in point 21 and a earthing point 22 located on the radiating surface 20.
• the radiating surface 20 is a generally rectangular metallic planar plate. It is sometimes referred to as a patch antenna.
• the radiating surface 20 is often attached to an insulating base plate (not shown) and then is stacked above the ground plate 3 in order to prevent distortion.
• the feed- in point 21 is electrically connected with the feed-in member 31 on the ground plate 3 in order that the signals outputted by the feed-in member 31 are sent to the radiating surface 20 to radiate or that the signals received by the radiating surface 20 are sent to the feed-in member 31.
• the earthing point 22 is electrically connected with the ground plate 3 in order that the radiator module 2 comes into being a PIFA, that is, an electric field antenna.
• the surface area of the radiating surface 20 of the radiator module 2 is required to be equal to 1/4 wavelength of the resonance frequency (about half the surface area of a patch antenna without ground connection) due to the connection between the earthing point devices, such as mobile telephones.
• FIG. 4 Another embodiment is shown in FIG. 4.
• the radiator module 4 When the radiator module 4 is used in larger radio communication devices (that is, where reduced volume/size is not a priority), the radiator module 4 comes into being a patch antenna without ground connection while it isn't electrically connected to the ground plate 3 (that is, no earthing point posited). At this rate, the area of the radiating surface 40 of the radiator module 4 must be about two times of the area of the radiating surface 20 of the radiator module 2.
• the resonance efficiency of the radiator module 2 is determined by the perimeter (namely the length (L) +the width (W)) of the radiating surface 2, so the length and the width of the radiating surface 2 should be designed in order that the radiating surface 20 can happen to resonate at 1900Hz ( in high frequency region).
• the resonance efficiency of the radiating surface 20 can be regulated by means of forming an induced load on the radiating surface 20 (such as notching a slot 23 extending inward from the edge on the radiating surface 20) and forming the capacitive load on the radiating surface 20 (such as forming a bending part 24 bending downward towards the ground plate 3 so as to near the ground plate 3 on one edge of the radiating surface 20).
• the bandwidth of the radiator module 2 is determined by its volume, that is, the product of the surface area and the height (that is, the distance H between the radiating surface 20 and the ground plate 3) of the radiating surface 20 (L(length) ⁇ W(width) ⁇ H(height)) and the variety of the height (H) affects the bandwidth very much.
• the present invention is charactered that a slot radiating member 6 is formed on the ground plate 3, which comprises a first end 61 close to the feed-in member 31, a second end 62 lying on one edge 33 of the ground plate 3 and a slot 63 connecting the first end 61 and the second end 62.
• the slot antenna similar to the magnetic field antenna is formed on the ground plate 3 and its shape and structure are designed so that it can produce the resonance at 900Hz (in low frequency region).
• the low profile antenna is double-frequency antenna which can work at both two different frequency regions including the high frequency region and the low frequency region (1900MHz and 900MHz) due to the radiator module 2 and the slot radiating member 6 formed on the ground plate 3. by designing properly its shape and structure. As shown in FIG.
• the slot 64 of the slot radiating member 6 is formed into a continuously winding jagged shape.
• the slot radiating member 6 is formed into an L shape, that is, the first end 61 extends outward along the direction perpendicular to the slot 63 to form a first branch arm 65.
• the slot radiating member 6 is formed into an F shape, that is, the middle part of the slot 63 extends at the same side with and generally parallel to the first branch arm 65 to form a second branch arm 66 besides the said first branch arm 65.
• FIG. 7 the slot radiating member 6 is formed into an L shape, that is, the first end 61 extends outward along the direction perpendicular to the slot 63 to form a first branch arm 65.
• the slot radiating member 6 is formed into an F shape, that is, the middle part of the slot 63 extends at the same side with and generally parallel to the first branch arm 65 to form a second branch arm 66 besides the said first branch arm 65.
• the slot radiating member 6 is formed into an E shape, that is, the part of the slot 63 close to the second end 62 extends at the same side with and generally parallel to the second branch arm 66 to form a third branch arm 67 besides the said first branch arm 65 and the said second branch arm 66.
• Each of the branch arms may be of the same length, or may be of different lengths.
• the losing bandwidth of the radiator module 2 which is produced by reducing the profile height can be compensated via forming the slot radiating member 6 on the ground plate 3 so as to resolve the problem that the bandwidth is shortened along with reducing height.
• the bandwidth of the radiator module 2 isn't reduced while its volume is reduced besides that a low transformation frequency region of the low profile antenna is increased, and it can measure up and satisfy the object of further reducing the volume of the current PIFA.
• FIG. 10 shows the measure results of the low profile antenna 1 when the slot radiating member 6 is formed into an F style slot as shown in FIG. 8. It can be known from the figure radiating member 6 and the first branch arm 65 to diffuse to the whole ground plate 3 so that the peak value of the SAR is reduced. It can be known from the measure results as shown in FIG.
• the low profile antenna works in high frequency region (that is, the radiator module 2), it can prevent the electromagnetic wave radiating along the direction to the ground (that is, the direction to the people), and the SAR value is held in a set range, just because the radiator module 2 is shielded with the ground plate 3 under it similar to the traditional inner antenna structure with the ground plate.
• FIG.12 shows the results received by measuring the SWR (Standing Wave Ratio) value of the low profile antenna 1 when the slot radiating member 6 is formed into an F style slot as shown in FIG. 8. It can be know from the FIG.12 that the low profile antenna 1 has perfect SWR value and the bandwidth in the high and low frequency region (900MHz and 1900MHz).
• a piece of dielectric material 70 is positioned on the slot radiating member 6 of the ground plate 3 (referring to FIG. 1), that is, between the radiator module 2 and the slot radiating member 6 in order to further reduce the volume of the radiator module 2.
• the volume of the radiator module 2 is reduced proportionately relative to the dielectric constant of the dielectric material 70 (that is, the height of the radiator module 2), and then it can compensate the losing bandwidth of the radiator module 2 produced by providing the dielectric material 70 via regulating the shape and the structure of the slot radiating member 6.
• the embodiment may be further designed that a metallic layer 71 is placed partly on the surface of the dielectric material 70 to improve the direction performance of the electromagnetic field of the slot radiating member 6, so that the electromagnetic field produced by the slot radiating member 6 is more concentrated and the SAR value is reduced and the radiating efficiency is increased.
• FIG. 15 shows a second embodiment of the low profile antenna according to the present invention, the only difference of which compared with the first embodiment is that the radiator module 5 isn't a patch, but rather, is a monopole antenna.
• One end of the radiator module 5 is equipped with a earthing point 51 electrically connected to the ground plate 3, and a feed-in point 52 located at a position which is spaced at a proper distance to the earthing point 51 is electrically connected to the feed-in member 31 on the ground plate 3 so as to form a PIFA. It can compensate for reduced bandwidth produced by reducing the height of the radiator module 5 and can realize the many advantages which are member 6 on the ground plate 3.
• the low profile antenna according to the present invention can produce the necessary resonance in the low frequency region (900MHz) by forming the slot radiating member 6 on the ground plate 3 and it can compensate for the reduced bandwidth of the radiator modules 2 and 5 operating in the high frequency region (1900MHz) which is produced by reducing the profile height via providing the slot radiating member 6. It likewise does not affect the resonance frequencies of the radiator modules 2,5 and the slot radiating member 6 due to regulating their respective shapes and structures because that the low and high frequency antennas of the low profile antenna 1 are respectively formed into the individual modules.
• radiator modules 2,5 can further reduce the heights of the radiator modules 2,5 to increase its ability to reduce its profile while not influencing the bandwidths of the radiator module 2,5 by means of covering a piece of dielectric material 50 upon the slot radiating member 6 and properly regulating the slot radiating member 6.
• a layer of metallic material 52 is placed partly on the surface of the dielectric material 50 to improve the direction performance of the slot radiating member 6, so that the radiating efficiency of the slot radiating member 6 is further increased and the SAR value is reduced.

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• Computer Networks & Wireless Communication (AREA)
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Cited By (22)

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Citations (3)

• 2004
  • 2004-04-29 CN CN 200410037401 patent/CN1691415B/zh not_active Expired - Fee Related
• 2005
  • 2005-04-29 WO PCT/US2005/014824 patent/WO2005109567A1/en active Application Filing

Patent Citations (3)

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