EP2704251A1 - Anordnung mit einer Vorrichtung mit einer Planarantenne - Google Patents

Anordnung mit einer Vorrichtung mit einer Planarantenne Download PDF

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Publication number
EP2704251A1
EP2704251A1 EP12182491.6A EP12182491A EP2704251A1 EP 2704251 A1 EP2704251 A1 EP 2704251A1 EP 12182491 A EP12182491 A EP 12182491A EP 2704251 A1 EP2704251 A1 EP 2704251A1
Authority
EP
European Patent Office
Prior art keywords
assembly
electrically conductive
housing
antenna element
conductive structure
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP12182491.6A
Other languages
English (en)
French (fr)
Inventor
Tommy Kärrman
Jonas Starck
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ProAnt AB
Original Assignee
ProAnt AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ProAnt AB filed Critical ProAnt AB
Priority to EP12182491.6A priority Critical patent/EP2704251A1/de
Publication of EP2704251A1 publication Critical patent/EP2704251A1/de
Withdrawn legal-status Critical Current

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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
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01Q—ANTENNAS, i.e. RADIO AERIALS
    • H01Q1/00—Details of, or arrangements associated with, antennas
    • H01Q1/44—Details of, or arrangements associated with, antennas using equipment having another main function to serve additionally as an antenna, e.g. means for giving an antenna an aesthetic aspect

Definitions

  • This invention relates to an assembly comprising a device with a planar antenna.
  • stand-alone devices for measuring some physical parameter can be deployed somewhere in the field and report measurements only via such a radio interface, making them easy to deploy even in places difficult to access.
  • radio frequencies can be used for the radio interface.
  • comparatively low frequency bands such as VHF (Very High Frequency)
  • VHF Very High Frequency
  • planar antennas with slits to increase the electrical length of the antenna.
  • the required frequency may be transmitted since the electrical length of the antenna element can be increased up till the minimum half wavelength while still being able to fit the antenna in a relatively small housing.
  • a further problem with devices that make use of such a described antenna arises when such devices are connected to some kind of sensor to measure for instance a physical parameter in an electrically conducting, box-like structure.
  • the antenna directly or indirectly share a common printed circuit board with circuits that are in contact with the sensor and further is operated on a comparatively low frequency, such a sensor can have a negative effect on the antenna efficiency.
  • a main object is consequently to propose a device with a planar antenna with an improved efficiency.
  • the solution to this problem according to the invention is to use an electrically conducting surface of a structure where a housing of the device is mounted, as a part of the radiating structure. In this way - thinking out of the box so to speak - the antenna of the device can be significantly increased in size by employing the outer electrically conductive structure 6 as a part of the antenna.
  • the assembly additionally also solves the problem of antenna efficiency in connection with such devices having an antenna and which are also in contact with a sensor, a sensor that is at least partly introduced inside an electrically conducting box.
  • the antenna element of the device is galvanically connected to the electrically conducting box to make the electrically conducting box a part of the resulting antenna.
  • the connection of the antenna element to the electrically conducting box effectively short-circuits the sensor radio-wise in relation to the antenna element. Therefore, the printed circuit board is practically not a part of the resulting antenna and thus there is a much lower energy transfer to the sensor from the antenna element without the need for any additional components or measures.
  • a possible device with a housing 5 enclosing an antenna element 2 that is to be used at a relatively long wavelength compared to the size of the device is illustrated in fig. 1 .
  • the housing 5 of the device is, as an example, shown mounted on a box-like structure.
  • a solution to the problem of operating an antenna at a frequency implying a wavelength that is comparably long in relation to the size of a housing 5 of a device including the antenna can be seen in fig. 2 .
  • planar antenna element 2 is made larger by folding twice in the box. In this way, the effective antenna surface becomes larger and therefore the efficiency of the antenna can be improved. Also, since the antenna is larger, the electric length of the antenna can be made longer permitting to send radio waves with a lower frequency/greater wavelength.
  • the device with the housing 5 is depicted without a top cover in fig. 2 for simplicity of interpreting the figure. In reality, when deploying the device, it would also comprise a top cover to make the housing 5 completely enclose the antenna element and other electrical components inside the device to protect them. This is also true for the other figures of this application.
  • fig. 3 It is an assembly 1 comprising an electrical device having a housing 5 comprising at least partly an electrically non-conductive material. Inside the housing 5 is located a planar antenna element 2 connected by a transmission line 3 to a radio circuit (not shown in the figure). The planar antenna element (2) further is connected to an electrically conducting connection member (9) which penetrates the housing (5)
  • radio waves can be emitted by the antenna element 2 and propagate through the housing 5.
  • the assembly can be seen to further comprise an electrically conductive structure 6, having an electrically conductive outer surface 7.
  • the housing 5 of the electrical device is configured to be mechanically fastened to the electrically conductive structure 6 and the antenna element 2 inside the housing 5 is configured to be situated at least partly in parallel with the outer surface 7 of the electrically conductive structure 6 and to be in electrical connection with the outer surface 7 via the electrically conducting connection member 9 such that the electrically conductive structure 6 forms a radiating part when the antenna element 2 inside the housing 5 is excited by a radio signal from the radio circuit (not shown).
  • this assembly increases the size of the radiating area of the assembly, compared to what is possible to contain in the device housing 5 alone, by employing the outer electrically conductive structure 6 as a radiating part of the antenna. Thereby, the efficiency of the assembly can be improved. It should be noticed that this antenna only has one excitation point and that the antenna element and the electrically conductive structure together forms one antenna. Thus, this assembly is not a system with two separate antennas excited with two different signals.
  • the housing 5 When the assembly 1 is to be used to transmit a radio signal, the housing 5 would be fastened to the electrically conductive structure 6 and the antenna element 2 would be situated at least partly in parallel with said outer surface 7 and would be in electrical connection with the outer surface of the electrically conductive structure 6 via the connection member 9, as shown in fig. 3 .
  • the housing of the device could be fastened to the electrically conductive structure 6 with the connection member 9.
  • both the fastening of the device housing 5 to the electrically conductive structure 6 and the electrical connection of the antenna element 2 to the electrically conductive structure 6 can be effected with one and the same element 9, making the assembly 1 a bit less complicated. This is the case in fig. 3
  • the electrically conductive structure could have an electrically conductive outer surface 7 with an area that is larger than an outer surface area 8 of the housing 5, which outer surface area 8 of the housing 5 is the largest outer surface area 8 of said housing 5. That is to say that the electrically conducting structure has an outer surface that is larger than what is possible to contain in the housing 5.
  • the outer surface of the electrically conducting structure is therefore larger than the largest possible surface of an antenna element 2 contained inside the housing 5. This significantly increases the size of the radiating part of the antenna, compared to what is possible to contain in the housing 5 alone, such that a better efficiency is attained compared with what is available when the radiating part is contained in the housing 5. Therefore, in the case of a relatively small housing 5, compared to the resonating wavelength, a comparably large electrically conductive structure can compensate the size of the housing to provide an antenna that never-the-less has an acceptable efficiency.
  • the electrical conductive outer surface 7 could have a physical extent that is equal to or less than 1 ⁇ 2 wavelengths of a resonating wavelength of the assembly.
  • the surface 7 has a physical extent that is equal to or longer than 0.1 wavelengths of a resonating wavelength of the assembly.
  • the antenna element 2 could for instance be formed by a printed circuit board 10. If at least a part of the antenna element 2 is flexible it could be bent 11 in the vicinity of where it connects to the connection member 9, as seen in fig. 3 . This is a convenient way of connecting the antenna element 2 to the electrically conducting structure while at the same time keeping the rest of the antenna element 2 at greater distance from the housing wall adjacent to the electrically conducting structure, as shown with the double arrow in fig. 3 .
  • a plan view of the assembly 1 with, among others, the electrical device with he planar antenna element 2, the transmission line 3, the housing 5 of the electrical device, the electrically conductive structure 6 and the electrically conducting connection member 9 is visible.
  • the antenna element 2 could be rigid and separated by a sleeve 12 from a bottom 13 of the device housing 5 in contact with the electrically conductive structure 6, as illustrated in fig 5 .
  • the required distance of the antenna element 2 to the bottom 13 and the electrically conductive structure 6 could then be ensured while at the same time a single connection member 9, for instance a screw 9, could be used to connect it to the electrically conducting structure 6.
  • the sleeve 12 may serve as a separating element only or additionally also as an electrically conducting element to connect the antenna element 2 to the electrically conductive structure 6 electrically.
  • some other object may serve to provide the electrical contact between the antenna element 2 and the electrically conducting structure 6, for instance a spring 9 as seen in fig. 6 .
  • the spring does not function to provide a support onto which the antenna element 2 may rest as was the case with the sleeve 12. Instead, the spring is compressed between the antenna element 2 and the bottom 13 of the device housing 5 as seen in fig. 6 where the antenna element 2 is resting on posts 14 and is holding the spring in compressed electrical contact with the electrically conductive structure 6.
  • any other suitable electrical element may of course be used to provide the electrical contact between the antenna element 2 and the electrically conductive structure 6.
  • the radio circuit 4 would be located in the housing 5. However, it is also possible that the radio circuit 4 is located elsewhere and the transmission line 3 would enter the housing 5 through a wall of the same (not shown in any figure).
  • the radio circuit 4 When the radio circuit 4 is located in the housing 5, it is also possible to have the antenna element 2 and the radio circuit 4 located on the same printed circuit board. It reduces the count of components of the assembly 1 but may make the antenna more expensive if the PCB of the radio circuit 4 must use a multi layer design, rather than a two sided board that is enough for the antenna itself.
  • a schematic illustration of the antenna element 2 and the radio circuit 4 located on the same printed circuit board is shown schematically in figure 5 . A single board can be seen in this sectioned side view.
  • the antenna element 2 is configured to connect to the connection member 9 at a distance of less or equal to 0.1 wavelengths of a resonating wavelength of the assembly from a point 15 where the transmission line 3 connects to the antenna element 2 (see for instance fig. 3 ). This is due to the fact that the electrical length of the antenna element 2 often is about 0,25 wavelengths.
  • the most distant part of the antenna element, seen from the point 15 where the transmission line connects to the antenna element - the excitation point of the antenna - has a higher electrical field strength and the part closer to the excitation point, has a lower electrical field strength and a higher current density and magnetic field.
  • connection member 9 it is beneficial to connect connection member 9 at a point closer to the excitation point, so that the current is transferred from the antenna element through the connection 9 to the electrically conductive structure 6 (for instance a metal box).
  • the best connection point for transferring the current from antenna and structure 6 is located within a distance less than 0.1 wavelengths from the excitation point of the antenna.
  • the electrically conductive structure 6, where the housing 5 of the device is fastened is box-like and the assembly 1 can further comprise an electrically conducting sensor 16 that at least partly is introduced inside the electrically conductive structure 6, see fig. 7 .
  • the sensor is denoted by a dashed line, reference numeral 16 is really pointing to the electrical line connecting to the sensor.
  • the sensor can for instance be intended to register a physical parameter that is to be reported via a radio interface enabled by the assembly 1.
  • a sensor is in this context understood to encompass any kind of sensor or measuring transducer that can be used to measure a quantity of some sort and report the measurement to some other entity. It may also encompass an electrical line transmitting a measurement from the sensor.
  • electrically conductive means that some part of the sensor is electrically conductive at some frequency.
  • the sensor would be in connection with a printed circuit board, in order to report any measurements.
  • the printed circuit board, to which measurements from the sensor would be communicated would also be in connection with the radio circuit, in order to enable the measurements to be communicated wirelessly via the antenna element 2. It is not necessarily so that the radio circuit must be hosted on the PCB where the measurements from the sensor 16 are collected, but they must be in some kind of contact in order for such measurements to ultimately be communicated via the antenna element 2.
  • the sensor may funnel some of the radio energy to the inside of the electrically conductive box where it is effectively dissipated as heat.
  • the antenna element 2 is galvanically connected to the electrically conducting box. Without this connection to the electrically conducting box, the sensor effectively becomes a part of the radiating antenna. Having the antenna element directly connected to the electrically conductive box kind of short circuits the sensor in the sense that it does not any longer electrically form part of the antenna.
  • the assembly 1 according to the invention could for instance be used in the VHF (Very High Frequency) band, making it a VHF antenna.
  • VHF Very High Frequency
  • 169 MHz frequency band could be used in some countries for different applications.
  • the electrically conductive structure 6 could be a gas flow meter chamber to which the device housing 5 with the antenna element 2 would be attached to complete the assembly 1.
  • the electrically conductive structure 6, can be made of metal such as aluminium or steel. However, other, electrically conductive materials are also possible and there is really only a need for the surface of the electrically conductive structure 6 to be electrically conductive. Thus, a design with a non-conductive material, coated with an electrically conductive coating is also possible. Such a coating could be metallic or even an electrically conductive synthetic material.
EP12182491.6A 2012-08-30 2012-08-30 Anordnung mit einer Vorrichtung mit einer Planarantenne Withdrawn EP2704251A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP12182491.6A EP2704251A1 (de) 2012-08-30 2012-08-30 Anordnung mit einer Vorrichtung mit einer Planarantenne

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP12182491.6A EP2704251A1 (de) 2012-08-30 2012-08-30 Anordnung mit einer Vorrichtung mit einer Planarantenne

Publications (1)

Publication Number Publication Date
EP2704251A1 true EP2704251A1 (de) 2014-03-05

Family

ID=47048956

Family Applications (1)

Application Number Title Priority Date Filing Date
EP12182491.6A Withdrawn EP2704251A1 (de) 2012-08-30 2012-08-30 Anordnung mit einer Vorrichtung mit einer Planarantenne

Country Status (1)

Country Link
EP (1) EP2704251A1 (de)

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6731920B1 (en) * 2000-03-31 2004-05-04 Matsushita Electric Industrial Co., Ltd. Portable telephone apparatus and control method thereof
US20060017626A1 (en) * 2004-07-12 2006-01-26 Anand Kannan Antenna module for mobile phone
FR2888068A1 (fr) * 2005-07-01 2007-01-05 Agnes Jullian Dispositif permettant de rendre communicants des elements de mobiliers urbains
US20110254741A1 (en) * 2010-04-16 2011-10-20 Katsunori Ishimiya Wireless communication device with housing member that functions as a radiating element of an antenna

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6731920B1 (en) * 2000-03-31 2004-05-04 Matsushita Electric Industrial Co., Ltd. Portable telephone apparatus and control method thereof
US20060017626A1 (en) * 2004-07-12 2006-01-26 Anand Kannan Antenna module for mobile phone
FR2888068A1 (fr) * 2005-07-01 2007-01-05 Agnes Jullian Dispositif permettant de rendre communicants des elements de mobiliers urbains
US20110254741A1 (en) * 2010-04-16 2011-10-20 Katsunori Ishimiya Wireless communication device with housing member that functions as a radiating element of an antenna

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