Classifications

• • 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
  • H01Q9/30—Resonant antennas with feed to end of elongated active element, e.g. unipole
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C7/00—Orthodontics, i.e. obtaining or maintaining the desired position of teeth, e.g. by straightening, evening, regulating, separating, or by correcting malocclusions
  • A61C7/12—Brackets; Arch wires; Combinations thereof; Accessories therefor
  • A61C7/20—Arch wires
  • A61C7/22—Tension adjusting means
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61C—DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE
  • A61C7/00—Orthodontics, i.e. obtaining or maintaining the desired position of teeth, e.g. by straightening, evening, regulating, separating, or by correcting malocclusions
  • A61C7/12—Brackets; Arch wires; Combinations thereof; Accessories therefor
  • A61C7/28—Securing arch wire to bracket
  • A61C7/30—Securing arch wire to bracket by resilient means; Dispensers therefor
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/30—Arrangements for providing operation on different wavebands
  • H01Q5/307—Individual or coupled radiating elements, each element being fed in an unspecified way
  • H01Q5/342—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes
  • H01Q5/357—Individual or coupled radiating elements, each element being fed in an unspecified way for different propagation modes using a single feed point
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01Q—ANTENNAS, i.e. RADIO AERIALS
  • H01Q5/00—Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
  • H01Q5/30—Arrangements for providing operation on different wavebands
  • H01Q5/378—Combination of fed elements with parasitic elements

Definitions

• the present invention relates to a dual band antenna, and more particularly, to a dual band antenna in which it can transmit and receive signals of the L-band ranging from of 1.45 to 1.48 GHz and the UHF (Ultra High Frequency) band ranging from 470 to 740 MHz at the same time.
• L-band ranging from of 1.45 to 1.48 GHz
• UHF Ultra High Frequency
• DVB-H Digital Video Broadcasting-Handheld
• T- DMB Transmission-Digital Multimedia Broadcasting
• the standards use similar frequency bands, and standards that used different frequencies use similar frequency bands in consideration of the compatibility.
• the DVB-H standard used the VHF-m band ranging from 174 to 230 MHz
• the UHF-IV/V band ranging from 470 to 830 MHz
• the L-band ranging from 1.452 to 1.492 GHz
• T-DMB generally used the VHF band.
• the use of the L-band has increased for the compatibility with the DVB-H.
• the UHF band has a very wide bandwidth.
• the UHF-IV/V band has a bandwidth of approximately 56%, which is significantly greater than a PCS bandwidth (1.75 to 1.87 GHz) corresponding to at most 7%.
• a PCS bandwidth (1.75 to 1.87 GHz
• an object of the present invention has been made to overcome the above-mentioned problems occurring in the prior art, and it is an object of the present invention to provide a dual band antenna having a miniaturized size while covering both the UHF band and the L-band.
• the present invention an easily tunable dual band antenna in which the frequency of each band can be controlled independently.
• an antenna comprising: a first radiator having one end connected to a feed element; and a second radiator disposed substantially in parallel with the first radiator and spaced apart from the first radiator by a predetermined distance, the second radiator having one end grounded.
• the first radiator and the second radiator may operate as monopole antennas with respect to different resonant frequencies.
• a change in a length of the first radiator and a change in a length of the second radiator may have an effect on different resonant frequencies substantially independently.
• the predetermined distance may be set such that the first radiator and the second radiator are coupled electromagnetically and also operate as substantially independent radiators.
• a width of the first radiator may be set to be smaller than that of the second radiator such that the first radiator and the second radiator are coupled electromagnetically and also operate as substantially independent radiators.
• a stub is formed at the one end of the first radiator so as to be projected toward both sides.
• a width of the stub may be set such that the first radiator and the second radiator are coupled electromagnetically and also operate as substantially independent radiators.
• an antenna comprising: a first radiator having one end connected to a feed element; and a second radiator disposed substantially in parallel with the first radiator and spaced apart from the first radiator by a predetermined distance, the second radiator having one end grounded.
• the antenna resonates in a first resonant frequency, a second resonant frequency and a third resonant frequency that is a multiple frequency of the first resonant frequency.
• the first resonant frequency and the second resonant frequency may be included in the same frequency band.
• the first radiator and the second radiator may operate as monopole antennas with respect to the first resonant frequency and the second resonant frequency, respectively.
• a change in a length of the first radiator and a change in a length of the second radiator may have an influence on the first resonant frequency and the second resonant frequency, respectively, substantially independently.
• the predetermined distance may be set such that the first radiator and the second radiator are coupled electromagnetically and also operate as substantially independent radiators in the first resonant frequency and the second resonant frequency, respectively.
• the first resonant frequency and the second resonant frequency may exist in an UHF (Ultra High Frequency) band and the third resonant frequency may exist in a L-band, and the predetermined distance may be set in the range of 6 mm to 10 mm.
• a width of the first radiator may be set to be smaller than that of the second radiator such that the first radiator and the second radiator are coupled electromagnetically and also operate as substantially independent radiators in the first resonant frequency and the second resonant frequency, respectively.
• a stub is formed at the one end of the first radiator so as to be projected toward both sides and influencing an antenna characteristic near the third resonant frequency.
• a width of the stub may be set such that the first radiator and the second radiator are coupled electromagnetically and also operate as substantially independent radiators in the first resonant frequency and the second resonant frequency, respectively.
• an apparatus including an antenna and configured to transmit or receive a radio signal, the antenna comprising: a first radiator having one end connected to a feed element; and a second radiator disposed substantially in parallel with the first radiator and spaced apart from the first radiator by a predetermined distance, the second radiator having one end grounded.
• the dual band antenna having a miniaturized size while covering both the UHF band and the L-band using two separated radiators can be obtained.
• the antenna can be tuned easily since the frequency of each band can be controlled independently.
• FIG. 1 is a lateral view of a dual band antenna according to an embodiment of the present invention
• FIG. 2 is a front view of the dual band antenna according to an embodiment of the present invention.
• FIG. 3 is a graph showing the relationship between the length of a first radiator and the reflection coefficient in an implementation example of the present invention
• FIG. 4 is a graph showing the relationship between the length of a second radiator and the reflection coefficient in an implementation example of the present invention
• FIG. 5 is a graph showing the relationship between the width of the first radiator and the reflection coefficient in an implementation example of the present invention
• FIGS. 6, 7 and 8 are graphs showing the relationship between the predetermined distance between radiators and the reflection coefficient in an implementation example of the present invention.
• FIG. 9 is a graph showing the relationship between the width of a stub and the reflection coefficient in an implementation example of the present invention.
• FIG. 10 is a graph showing the standing- wave ratio of another implementation example of the present invention.
• FIG. 11 is a graph showing current distributions of another implementation example of the present invention. Best Mode for Carrying Out the Invention
• the term “dual band antenna” does not refer to an antenna having two resonant frequencies, but refers to an antenna that is able to transmit and receive signals of two specific frequency bands.
• the term “dual band antenna” is used in this specification, it is to be understood that the antenna can have three or more resonant frequencies and, in the case where the antenna is used in bands other than specific frequency bands such as the UHF band and the L-band, the antenna can be used in a single band or three or more bands even though it is the same antenna.
• connection refers to coupling of two constituent elements in such a way to communication with each other electronically and another constituent element may also be included if an electronic communication path is formed between the constituent elements.
• FIG. 1 is a lateral view of a dual band antenna according to an embodiment of the present invention.
• the dual band antenna of the present embodiment includes a first radiator 10 connected to a feed element 30 and a second radiator 20 connected to a ground plane 40. Further, the first radiator 10 and the second radiator 20 are spaced apart from each other at a predetermined distance D and disposed substantially in parallel.
• the first radiator 10 substantially operates a monopole antenna
• the second radiator 20 is feed through electromagnetic coupling with the first radiator 10 and also operates as the monopole antenna.
• the length of each radiator decides the resonant frequency of the antenna.
• the two radiators are connected to each other electromag- netically unlike the conventional monopole antenna, the length of the antenna can become 1/4 or less of a wavelength and the size of the antenna can be miniaturized.
• the predetermined distance D between the radiators 10, 20 is set to electromag- netically couple the radiators 10, 20 and also maintain the coupling degree of the two radiators to a minimum level. Specifically, when the predetermined distance D is too short, electromagnetic coupling between the radiators becomes too strong and therefore the second radiator 20 does not perform radiation independently, thus failing in a dual band characteristic. In contrast, when the predetermined distance D is too long, electromagnetic coupling between the radiators is weakened and therefore the second radiator 20 cannot be feed effectively, thus failing in dual band and wideband characteristics. For this reason, the predetermined distance D is preferably set to elec- tromagnetically couple the radiators 10, 20 and also enable independent radiation. Quantitative description of the predetermined distance D is given later on. Meanwhile, as the two radiators 10, 20 operate as the monopole antennas independently, the respective resonant frequencies can be controlled independently.
• FIG. 2 is a front view of the dual band antenna according to an embodiment of the present invention.
• the first radiator 10 extends in a substantially band form and has a length Ll.
• the second radiator 20 also extends in a substantially band form and has a length L2.
• the lengths Ll and L2 can be decided freely according to a frequency at which the antenna will be operated, but Ll is preferably greater than L2 in the present embodiment.
• the first radiator 10 is feed directly and substantially operates as the monopole antenna, thus generating resonance in a multiple frequency.
• a first resonant frequency by the first radiator 10 As the length Ll is set to be greater than the length L2, a first resonant frequency by the first radiator 10, a second resonant frequency by the second radiator 20 and a third resonant frequency (i.e., the multiple frequency of the first resonant frequency) can be obtained in this sequence and a dual band can be implemented. Further, by making small the difference between the first resonant frequency and the second resonant frequency, a wideband characteristic can be obtained by the two resonant frequencies.
• a width Wl of the first radiator 10 can be set to be smaller than that of the second radiator 20.
• the first radiator 10 and the second radiator 20 are coupled electromagnetically while independently operating as the radiators, so that a dual band can be implemented as described above.
• a stub 12 which has a shape projected toward both sides, can be formed at one end of the first radiator 10.
• the stub 12 is a constituent element added for impedance matching of the first radiator 10. Further, the stub 12 has an effect on the resonant characteristic in the third frequency (the multiple frequency) of the first radiator 10. As the size L3 of the stub 12 increases, the electrical length of the first radiator 10 increases, so the resonant characteristic in the third frequency can be improved. However, if the size L3 of the stub 12 is increased, electromagnetic coupling with the second radiator 20 is increased, thus degrading characteristics in the second resonant frequency. It is therefore necessary for the size L3 of the stub 12 to have a critical value.
• FIG. 3 is a graph showing the relationship between the length of the first radiator and the reflection coefficient in the present implementation example.
• the antenna of the implementation example has a first resonant frequency of about 500 MHz, a second resonant frequency of about 700 MHz and a third resonant frequency of about 1.5 GHz.
• the resonant frequency was moved toward a low frequency as the length Ll of the first radiator was increased. This is because the first radiator operates as the monopole antenna. Meanwhile, a change in the length Ll of the first radiator greatly changed the first and third resonant frequencies, but not greatly changed the second resonant frequency.
• the first radiator which is directly feed and operates as the monopole antenna as described above, has an influence on the radiation of the first resonant frequency and the third resonant frequency (i.e., the multiple resonant frequency of the first resonant frequency).
• FIG. 4 is a graph showing the relationship between the length of the second radiator and the reflection coefficient in an implementation example of the present invention. From FIG. 4, it can be seen that a change in the length L2 of the second radiator largely changed the second resonant frequency, but rarely changed the first and third resonant frequencies. It is understood that the second radiator, which is coupled and directly feed, operates as the monopole antenna and therefore resonates in the second resonant frequency.
• the first and third resonant frequencies can be controlled substantially by the length Ll of the first radiator independently and the second resonant frequency can be controlled substantially by the length L2 of the second radiator independently. Desired characteristics can be accomplished by controlling the resonant frequencies independently.
• FIG. 5 is a graph showing the relationship between the width Wl of the first radiator and the reflection coefficient in an implementation example of the present invention. From FIG. 5, it can be seen that as the width Wl of the first radiator increases, the reflection coefficient of about 700 MHz is increased and a resonant characteristic in the second resonant frequency disappears. This is because electromagnetic coupling of the first and second radiators is increased as the width Wl is increased as described above, which makes it impossible independent radiation of the second radiator. Thus, an adequate width has to be decided in consideration of fabrication requirements of an antenna and required characteristics.
• FIGS. 6, 7 and 8 are graphs showing the relationship between the predetermined distance D between radiators and the reflection coefficient in an implementation example of the present invention.
• the predetermined distance D is 6 mm or less as shown in FIG. 6, the reflection coefficient in the second resonant frequency was increased and the dual band and wideband characteristics were weakened.
• the predetermined distance D increases from 6 mm to 10 mm as shown in FIG. 7, reflection loss in the second resonant frequency was reduced and the dual band and wideband characteristics were enhanced.
• the predetermined distance D exceeds 10 mm as shown in FIG. 8
• reflection loss in the second resonant frequency was increased and the dual band and wideband characteristics were weakened.
• FIG. 9 is a graph showing the relationship between the width L3 of the stub and the reflection coefficient in an implementation example of the present invention.
• a change in the width L3 of the stub did not induce a change in the resonant frequency, but as the width L3 of the stub increased, the reflection coefficient in the third resonant frequency was reduced and therefore the bandwidth was expanded.
• the reflection coefficient in the second resonant frequency was degraded due to increased electromagnetic coupling between the radiators, so that the characteristics were degraded.
• the width L3 appropriate for applications must be selected considering this trade-off relationship.
• FIG. 10 is a graph showing the standing- wave ratio of another implementation example of the present invention.
• the present implementation example has the first and second resonant frequencies in 500 MHz and 700 MHz, respectively, and therefore has the standing- wave ratio of 2 or less in the wideband of the UHF band in 470 MHz to 740 MHz.
• the present implementation example has the third resonant frequency in 1465 MHz (i.e., about three times of the first resonant frequency 500 MHz) and has the standing- wave ratio of 2 or less in the L-band ranging from 1450 MHz to 1480 MHz.
• a dual band antenna covering both the UHF band and the L-band could be obtained.
• the antenna of the implementation example including attached elements such as casings for protecting the radiators, was 121 x 11 x 10 mm in dimension and implemented the wideband and dual band characteristics with a very small size when compared with the conventional monopole antenna.
• FIG. 11 is a graph showing current distributions of another implementation example of the present invention.
• FIG. 1 l(a) shows current distributions in the first resonant frequency of 500 MHz, wherein the first radiator 10 had current distributions similar to that of a 1/4 wavelength monopole antenna.
• FIG. 1 l(b) shows current distributions in the second resonant frequency of 700 MHz, wherein the second radiator 20 had current distributions similar to that of a 1/4 wavelength monopole antenna.
• FIG. 11 (c) showing current distributions in 1465 MHz, the first radiator 10 operated as a 3/4 wavelength monopole antenna in the third resonant frequency.

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• Health & Medical Sciences (AREA)
• General Health & Medical Sciences (AREA)
• Dentistry (AREA)
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• Life Sciences & Earth Sciences (AREA)
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• Oral & Maxillofacial Surgery (AREA)
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• 2007
  • 2007-01-04 KR KR1020070000826A patent/KR100867128B1/ko not_active IP Right Cessation
  • 2007-12-26 WO PCT/KR2007/006810 patent/WO2008082132A1/en active Application Filing

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