FI114260B - Modular switchgear and portable radio equipment - Google Patents

Description

114260

RADIO MODULAR SWITCHING STRUCTURE AND PORTABLE RADIO DEVICE

The present invention relates to a modular switching structure for a radio device used in the transmission and / or reception of RF signals. The invention also relates to a portable radio device, such as a mobile phone, which includes a modular switching structure for transmitting and / or receiving RF signals.

10 The bandwidth of a small cellular antenna element in a typical mobile phone, for example, in the 900 MHz band is about 10%. Such an antenna element emits only a small part of the total radiation power. Most of the radiation is caused by currents induced by the antenna to the cell phone or circuit board. Thus, the antenna element need not be designed to be radiant. This provides 15 new possibilities for antennas or more precisely to emit radiators especially for cellular phones and other small wavelength radios. The present invention is an implementation arrangement utilizing a modular coupling structure.

20 The theory of mobile phone radiation mechanisms is described in: P. Vainikainen, J. Ollikainen, O. Kivekäs, and I. Kelander, Effect of phone; chassis on handset antenna performance, University of Technology, Radio Laboratory, Report S 240, (ISBN 951-22-4928-6), Espoo, Finland, March • · \ 2000, 13 p. The publication indicates that the required bandwidth • The key to achieving 25 is to provide a sufficiently strong coupling between the cellular antenna and the resonant waveforms of the cellular phone body. . between. This can be accomplished by switching on either the waveform of the body; "Into an electric field, a magnetic field, or both. Since the coupling is typically weak and the effective goodness number determined by the reactive and resistive elements of the coupling structure is typically greater than 20, the impedance of the coupling structure is ··. the reactive portion is significant and must be eliminated in order to achieve proper impedance matching between the switching structure and the circuitry of the radio device. Another problem is the impedance level, which is either very high (capacitive coupling) or low (inductive coupling) and thus requires 35 impedance transformations. Conventionally, these have been achieved, at least in part unintentionally, by the use of elements designed to be resonant (self-resonant) antennas.

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Built-in mobile phone so-called. an internal antenna is disclosed, for example, in EP-A1-0 892 459. The structure disclosed in EP-A1-0 892 459 is a multi-band microstrip antenna consisting of a ground plane short-circuit antenna element. This type of arrangement 5 is not optimal because the design does not seek to maximize coupling. In addition, reactance elimination and impedance conversion are performed as in resonance-type antennas, which results in a large space requirement in an effort to minimize the radiation quality index. As a result, the major weaknesses of known antenna structures are the large size and the complex structure.

It is an object of the present invention to provide an optimal solution for achieving a specific bandwidth utilizing radiation from a frame or a corresponding ground plane. The invention is based on the fact that the coupling and the matching circuit are dimensioned separately both electrically (resistance and reactance) and mechanically (size, shape and position). This can be accomplished by separating a substantially non-resonant electromagnetic coupling structure of substantially electrical or magnetic type and a resonance-type matching circuit implemented by either distributed or centralized high-frequency circuit technology, which in principle has no significant earth connection. Accordingly, the structures of the present invention are characterized in that they include, at least one, substantially non-resonant electromagnetic coupling means for coupling the signals to the waveforms of the body (or the corresponding ground plane) of the radio device and at least one impedance of the matching means. 25 so that the coupling and fitting properties of the structures can be dimensioned separately.

A preferred embodiment of the present invention is characterized in that: • the matching member forms a substantially one-dimensional (1D) transmission line structure or: a circuit structure consisting of centered elements and a coupling member together with the body (or equivalent ground plane); with one dominant wave and several other waveforms.

Another preferred embodiment of the present invention is characterized in that the coupling element consists of at least one capacitive or inductive element having an electrical and / or magnetic field direction coinciding with at least 3114260 electric and / or magnetic field directions of one radiating ground plane waveform.

A third preferred embodiment of the present invention is characterized in that the coupling member on or near the ground plane is in the shape of a surface and a plate-like, spike or multi-parallel link group, loop or multiple-series loop, or aperture or multi-aperture group, or alternatively, the coupling element is implemented by direct galvanic coupling to electrically separated portions of the body 10.

A fourth preferred embodiment of the present invention is characterized in that the matching element consists of at least one high frequency circuit which produces low-loss inductive or capacitive reactances so as to achieve the desired impedance matching with the other RF circuitry of the radio device.

Other preferred embodiments of the present invention are set forth in the claims.

Due to its small size, the adapter member can be flexibly located either inside the body of the radio device, for example on its main circuit board. It can also be • ·; place the body on top of the body in the vicinity of the coupling member or, depending on the situation, partially ·. : or completely inside the connection structure.

The coupling and fitting properties of the structures of the present invention can be optimized individually and thus minimize the size of the structures, which is very important especially for small radio devices such as; mobile phones.

The present invention will now be described in more detail by way of example with reference to the following drawings:

Figures 1a, 1b and 1c are block diagrams of possible topologies of the :: structures according to the present invention;

Figure 2 illustrates a matching arrangement of a capacitive coupling structure,

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Fig. 3 shows the frequency response of a reflection coefficient of a prototype of a compact coupling member according to Fig. 2,

Figure 4 shows another example of a 5 modular switching structure for a 900 MHz band in a mobile phone,

Figure 5 shows the frequency response of the reflection coefficient of the structure of Figure 4,

Figure 6 shows the frequency response of the radiation efficiency 10 of the structure of Figure 4.

The topology of the modular switching structure is shown in the block diagram of Figure 1.

It consists primarily of three blocks such that the matching circuit 1 represents one-dimensional (1D) circuit technology and the coupling element 2 and the waveforms 3 of the housing (or 15 circuit boards) together represent three-dimensional (3D) electromagnetic technology.

The coupling elements can be either capacitive (plate, spike, capacitive aperture), inductive (loop, inductive aperture) or combinations thereof,]: *: 20 so that the directions of their electric and / or magnetic fields coincide with the electric and / or magnetic field of the body waveform with the direction. Connectivity and bandwidth can be maximized by properly positioning the element. : to the maximum of the waveform field and by increasing the (electrical) volume of the element by increasing the size and / or distance of the capacitive plate to the body or the like ··. 25 by increasing the area or number of loop or aperture elements.

At a general level, the design of switching structures has been described in the literature on switching techniques for electromagnetic waveguides. Examples of these include: R. E. Collin, Foundations, · for Microwave Engineering, McGraw-Hill Kogakusha, Tosho Printing Co., 30 Tokyo, Japan, 1966, p. 183-197.

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The matching circuit can be implemented by any known high frequency circuit technology such as centered elements, microstrip or coaxial wires, which can perform low loss inductive or capacitive reactances. Fig. 2 shows the implementation of the matching of the capacitive plate element 5 by a short-circuited microstrip cable 4. The matching structure may also consist of several stages. In this case, higher bandwidths can be achieved following the known design principles of broadband matching circuits 5114260. For example, the fitting structure can be positioned between the coupling element and the body of the radio device to minimize the size of the entire structure.

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In Figure 2, Gr, Ch is mainly the radiation conductance caused by the body currents of the device, Cc is the capacitance of the coupling element 5, Zc, sreff and tan are the parameters of the microstrip line 4 used in the matching circuit. The total length of the microstrip line is d, and nd determines the position of the line entry point 10 and thus also the admittance level of the input admittance Yjn, m.

As shown in Figure 1, the modular arrangement of the present invention allows the use of a plurality of small switching elements and matching circuits, thereby providing multiple discrete frequency bands such as transmission and reception bands used in frequency duplex systems or even multiple subbands for different frequency channels. If necessary, it is also possible to implement switching structures for dual and multi-frequency systems such as GSM900 / GSM1800, in which the frequency bands used are typically further apart than the above transmission and T: 20 reception bands for a single radio system.

• t • ·. ·. According to the present invention, ·. '- tunable (e.g. electrically tunable) matching circuits may be used in the switching elements. As shown in Fig. 1b • ·, more than one matching circuit unit can be connected to one switching element unit. As shown in Fig. 1c, according to the present invention ·· ', one coupling element can be divided into several smaller elements. For example, they can then be better adapted to the geometry of the radio device. Such a plurality of switching means is coupled to at least one matching circuit unit. Any combination of the topologies of Figures 1b and 1c: 30 is also possible.

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The modular switching element arrangement can realize significantly: .v smaller structures than, for example, conventional internal microstrip type antennas or PIFAs (Planar Inverted F-Antenna). This facilitates, for example, the implementation of typical 35 antenna systems, such as diversity systems, in space-constrained environments such as mobile phones.

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Conventional internal cellular antennas, such as PIFAs, typically require at least two contacts on the circuit board (input peak and short circuit) of the device. By replacing the antenna with a capacitive modular switching structure, the number of contacts can be reduced to one, which makes the structure mechanically more reliable and can reduce production costs.

The structures of the present invention can be used to minimize local SARs (Specific Absorption Rate). This is due, for example, to the high impedance of the capacitive coupling element and thus to low currents in the structure. SAR can also be minimized by appropriately designing the design and location of high-power switching elements. Similarly, the design and positioning of lower power coupling members may be more freely designed based on other considerations. The position and type of elements can also be selected to minimize the impact of the user's body on the element fit and efficiency. For example, it is well known that the effect of dielectric loading is greater on capacitive elements than on inductive elements.

Example 1 *" " . As a practical example, Fig. 3 shows the measured reflection coefficient (pin, m in Fig. 2, S11 in Fig. 3) of a structure similar to Fig. 2 as a function of frequency. The size of the base plate is 100 mm x 40 mm (length x width). Connection element, ··. size is 20mm x 20mm x 4mm (length x width x height). Measured, ··. The impedance bandwidth (Lretn ^ 6 dB) is Br = 7.6% (86 MHz) at a center frequency of fc = 1.13 GHz.

* * ·, / Example 2: 30 Figure 4 shows another example of a very compact (volume 1.6 cm 3) * * ·: Modular switching structure inside a 900 MHz GSM mobile phone 6 (dashed lines). The size of the element 9 is 20 mm x 10 mm x 8 mm (length x width x height) and the cell phone body 7 is 110 mm x 40 mm '* ·· * (length x width). The matching circuit 8 is disposed between the body 7 and the capacitive plate 9 35 to minimize the amount of space used. The simulated reflection coefficient (Su) and the radiation efficiency are shown in Figures 5 and 6, respectively. According to the results, the structure is suitable for mobile use. Impedance Bandwidth (Lretn ^ 6 dB)

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is Br = 9.4% (88 MHz) at a center frequency fc = 933 MHz. The structure has a high radiation efficiency (> 90%) in the free range of the GSM900 system. Its radiation pattern is similar to the dipole radiation pattern and is suitable for mobile use.

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The ground plane may include, for example, a cell phone body, a circuit board, or other possible metal structures.

It will be apparent to one skilled in the art that the various embodiments of the invention are not limited to the above examples, but may be modified in many ways according to the inventive concept defined in the appended claims.

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Claims (13)

Modular switching structure for a radio device (6) for transmitting and / or receiving RF signals, characterized in that it consists of at least one 5 non-resonant electromagnetic switching means (2,5,9) for coupling signals to the ground plane (7) waveforms of the device; one matching element (1,4,8) used for impedance matching so that the coupling and matching properties of the structure can be dimensioned separately. Modular switching structure according to Claim 1, characterized in that the matching element (8) forms a substantially one-dimensional (1D) transmission line or centered circuit structure, and the switching element (9) together with the ground plane has a three-dimensional (3D) electromagnetic structure several other waveforms. 15 Modular switching structure according to claim 1, characterized in that the switching element (5,9) consists of at least one capacitive or inductive element whose electric or magnetic field direction is coincident with at least one electric or magnetic field direction of the radiating ground plane waveform. :; The modular switching structure according to claim 3, characterized by: '; that the coupling member on or near the ground plane is in the form of ««: surface-like and plate-like (5.9), a spike or a plurality of parallel spikes. ·, · 25, a loop or a series of connected loops • I, a multi-aperture group, or alternatively ;; the coupling element is implemented by direct galvanic coupling to electrically separated parts of the body '. •: 30 Modular switching structure according to claim 1, characterized in that the matching element consists of (4,8) at least one high frequency circuit which produces low loss inductive or capacitive reactances so that the desired impedance matching of the other RF circuitry of the radio device (6) is achieved. with. * · »* •» 9 11426C Modular switching structure according to Claim 1, characterized in that the matching element is partially or completely contained within the body of the radio device, for example on the main circuit board. 5 7. Modular coupling structure according to claim 1, characterized in that the matching element is partially or completely over the body of the radio device close to the coupling element. Modular coupling structure according to Claim 1, characterized in that the adapter element is partially or completely contained within the coupling element. Modular switching structure according to claim 1, characterized in that the matching circuitry is tunable, for example electrically tunable. 15 Radio device (6), such as a cellular telephone, comprising a modular switching structure for transmitting and / or receiving RF signals, characterized in that it consists of at least one substantially non-resonant electromagnetic switching element (2,5,9) for switching signals to the ground plane of the device. (7) 20 waveforms and at least one matching element (1,4,8) used for impedance matching so that the coupling and matching properties of the structure can be dimensioned separately. • | :. , 11. A radio device (6), such as a cellular telephone, containing one or more antenna structures used for diversity transmission and / or reception or as adaptive antenna structures, at least one of which is implemented in RF -; 'As a modular switching structure for transmission and / or reception of signals, characterized in that it consists of at least one substantially unreasonable electromagnetic switching element (2,5,9) for switching on! ': 30 signals to the ground plane (7) waveforms of the device, and at least one impedance matching means (1,4,8), such that the structure is switched on. ·. field and matching properties can be dimensioned separately. 12. A radio device (6), such as a cellular telephone having specific SAR values (Specific ..!: 35 Absorption Rate) and having a modular switching structure for transmitting and / or receiving RF signals, characterized in that: it consists of at least one substantially non-resonant electromagnetic coupling element (2,5,9) for coupling signals to the ground plane (7) waveforms of the device and at least one impedance matching means (1,4,8) such that the coupling and matching characteristics of the structure may be dimensioned individually and that the location and / or structure of high power switching structures may be designed to minimize SARs. A radio device (6), such as a cellular telephone, held close to the user's body for at least part of the operating time and comprising a modular switching structure for transmitting and / or receiving RF signals, characterized in that it consists of at least one substantially non-resonating electromagnetic switching element 2,5,9) for coupling signals to the ground plane (7) waveforms of the device and at least one impedance matching element (1,4,8) so that the coupling and fitting properties of the structure can be dimensioned separately and the influence of the user's body on the coupling structure -15 and device efficiency can be minimized. t> 1 t 11 11426C