EP1511117A1 - Antenna system and transmitting device with such an antenna - Google Patents

Abstract

Antenna system for electromagnetic transmitter and or receiver, especially for a radio unit, such as a mobile phone, has an arrangement of conductor structures, an antenna structure and a coupling structure for measuring characteristic values of the electromagnetic parameters of the antenna system, whereby the coupling structure is not removed after the last measurement, is strongly coupled to the antenna and is dimensioned so that it permits reliable measurements of the characteristic values, while not interrupting the functioning of the antenna in normal use or acting as a part of the antenna in normal use. The invention also relates to a corresponding radio unit, especially a mobile phone.

Description

When adjusting the transmission and reception characteristics of a transmitting / receiving system such as a mobile device, must be a suitable interface for measuring characteristics the electromagnetic properties of the antenna system and other radio frequency parameters of the transceiver system be available. Such an interface must have a suitable impedance level that the connection commercially available measuring devices to this interface. For this purpose, in the usual way so-called 50-Ω interfaces used, which optionally in place of the antenna system a Connection to the transmitting / receiving part of the to be adjusted or make the device to be tested.

Especially in the typical case of mobile applications that during the adjustment, that is, in the measurement of the parameters, already the antenna system with the transmitting / receiving system fixed connected, there is the difficulty that one to Measurement not just an interface parallel to the antenna structure can turn on because this is the burden the circuit parts to be tested / adjusted greatly changed would. In such a case, the actual 50-Q case could not be tested.

Known solutions to this problem are each with different ones Disadvantages:

A coaxial connector with interrupting function to the antenna system It increases costs and requires a lot of space the module of the device. Besides, mistakes are behind the Measuring point not recognizable.

A λ / 4-transformation line in the antenna path to the Measurement is shorted, so that then parallel to her Input can be measured, because doing the short circuit transformed in an idle at the measuring point, works only for a narrow frequency band and requires a more complex Contactor. Again, mistakes would be behind the Measuring point no longer recognizable.

An externally approximated measuring antenna or coupler structure, which is part of the energy radiated by the antenna recording leads to strongly fluctuating measurement results, because normally surrounding parts (equipment and cables, etc.) that Can greatly influence the measurement result. Besides, that's it accompanying mood of the antenna system is not sufficient precisely defined or reproducible.

The present invention sets itself the task, the Overcome disadvantages of the prior art. This task is a product according to one of the independent claims solved.

The solution according to the invention consists essentially of one firmly on the main assembly of the transmitting and / or receiving device fixed coupler structure, the electromagnetically possible is strongly coupled to the existing antenna system. A strong coupling in this sense is a coupling less than 2dB viewed, with only a small part the energy is really radiated, reducing the feedback external effects (such as strong reflections) is avoided. This ultimately means that the coupling structure represents a part of the antenna system itself.

The coupling structure is dimensioned so that they only in the state of the measurement (for example with a 50 Ω measuring device) Can decouple power from the antenna structure. This happens for example by so-called λ / 4 structures, the similar to a λ / 4 antenna. Is the inventive Coupling structure not used for measurement (for example, in the operating state), so there is an idle at the measuring point, which in turn makes this coupling structure no more power the antenna receives. Typical is the distance between the coupling structure and the structures of the actual antenna 2mm or less, but in some cases also clear be more. It is advantageous if the coupling structure arranged so that they are already possible on the feeding element of the antenna works, because so the scattered radiation is reduced.

In this way it is achieved that in the normal operating state (that is, if the coupling structure is not for measurement used) no power lost in the coupling structure goes and all energy is radiated only via the antenna system becomes. Even if a part of the energy to the coupling structure would transmit this, with appropriate sizing in principle also contribute to the radiated power, because there is no loss resistor in this branch. In this case, the coupling structure would be more functional Part of the antenna structure act.

For applications with radios operating in multiple frequency bands should work, as for example in so-called Multiband cell phones are the case, for example, in the Range of GSM900, PCN, PCS1900 or UMTS, a coupling structure can be advantageous, which consists of more than consists of a coupling element. In these cases it can be beneficial be, in each case a coupling structure in a frequency band to use for measurement.

In carrying out measurements of characteristics of electromagnetic Systems of radios is often in the industrial Production of the case before that housing parts of this Devices are mounted only after the measurement. These Housing parts often have an influence on the electromagnetic Behavior of the system, in particular on the E-nergieabstrahlung. Thus, in the case of operation, the antenna system usually by the surrounding housing in his Fre quenching behavior compared to the state in the measurement in which The surrounding housing is partly missing, noticeably changed. This results in a shift of certain characteristics in Frequency range determined by a suitable design and Dimensioning of the coupling structure according to the invention easily can be compensated. That means the coupling structure while measuring in the same or similar Way acts like the missing housing parts. In this context it is advantageous to carry out the coupling structure so that the loaded structure is elongating for the antenna element acts, so the resonance frequency decreases.

The present invention is not only suitable for applications in cellular mobile communications, but in principle for broadcasters and / or receiver systems of all kinds, especially in the field Medical technology or in the ISM band (Bluetooth) or in other applications. The skilled person is based on in this Description given notes easily capable of that Invention to transfer to these respective applications. A particular advantage of the present invention is in that when measuring the actual of the antenna radiated power is measured, so that functional tests can be omitted with respect to the radio behavior in the series.

It is possible, the coupling structure according to the invention on the the same assembly as the antenna itself; in In some cases, however, it may also be advantageous for the Coupling structure and the antenna structure on different Assemblies are housed. In the last case, of course to make sure that a well-defined and exactly reproducible Relative position of the coupling structure to the antenna structure is complied with. As building technologies are suitable basically u.a. etched or printed structures, the so-called Punching and bending technology, the so-called MID technique (MID = "molded interconnect devices", direct connection of mechanical and electronic functions on injection molded Parts or foils) or combinations of the above Techniques.

Coupling structures according to the invention are provided with one or more Contact elements for connection of 50 Ω measuring instruments executable. Contact points for a coupler port may possibly be embedded in a ground plane. The inventive Coupling structure can one or more ground contacts exhibit.

Figure 1 shows an inventive device in the state of measurement. On the assembly of the device (FG) here is an antenna structure (AS) and a coupling structure (KS) provided. The antenna structure (AS) radiates an electromagnetic Radiation (RAD) off. The coupling between the antenna structure (AS) and the coupling structure (KS) is strong, that is, the coupling loss (CD) is small, typically smaller as 2dB. In the feed point (SP) is the high frequency power (PHF) is fed. At the measuring point (MP), also contact point called, a meter is connected, typically a so-called 50 Ω meter.

FIG. 2 shows the same system in the operating state. In the Infeed point (SP) of the antenna system (AS) is the high frequency power (PHF) fed. As a result, beams the antenna system emits the radiation RAD. In operating condition is the coupling loss (CD) large, that is the coupling between Antenna structure (AS) and coupling structure (KS) is small. In this state, the measuring point (MP) is not contacted, as a result, the impedance here approaches infinity goes.

FIG. 3 shows an embodiment of the invention in the case a planar so-called inverted-F antenna. In this example is the coupling structure as a substantially linear λ / 4 structure executed, whose main legs close and parallel is aligned with the antenna structure (AS). In this case The coupling structure can essentially as one in the extreme Proximity to the main antenna structure, housed on the same carrier Auxiliary antenna structure are understood. The high frequency power is at the feed point (SP) in the antenna structure fed. The measuring point (MP) is used for the measurement End of the coupling structure (KS).

FIG. 4 shows the course of the most important measured variables as Function of the frequency in MHz in the measurement mode of an arrangement according to FIG. 3. The adaptations (AS22 and AS11) measured at the measuring point (MP) or at the feed point (SP). The course of the coupling damping (CD) makes it easy to see that their maximum (approximately at 2000 MHz) below 2.7db lies.

FIG. 5 shows, for comparison, an arrangement in which the coupling structure (KS) at a greater distance from the actual Antenna structure (AS) is arranged. This will be a significant weaker coupling of the coupling structure to the antenna structure causes. The coupling structure was in this example meander-shaped.

FIG. 6 shows the corresponding curves as in FIG 4, only here for the arrangement in Figure 5. It can be seen that the Coupling loss in the relevant range is about 12 dB.

FIG. 7 shows an embodiment of the present invention, in which the antenna structure and the coupling structure on a common carrier are arranged. This carrier (TAS) is in turn on an assembly of the transmitting and / or receiving device attached so that the contact elements for the Antenna (SP) extend in this case at least partially vertically, to contact the antenna with the rest To enable assembly. The measuring point (MP) of the coupling structure (KS) is located in the immediate vicinity of the coupling structure on the carrier (TAS).

Figure 8 shows another embodiment of the present invention Invention, in which the coupling structure (KS) on the module is arranged, on the one hand the ground plane of the antenna system, but also the carrier (TAS) for the antenna structure AS is arranged. In the area of the coupling structure (KS) is the ground plane (MF) recessed (AM). The actual antenna structure (AS) is located on the carrier (TAS), so that despite the separation of coupling structure (KS) and antenna structure (AS) a defined relative positioning of coupling structure and antenna structure is ensured. By the closely adjacent spatial arrangement of the coupling structure to Antenna structure can also be an electromagnetic in this case strong coupling of both structures are ensured.

FIG. 9 shows an embodiment of the invention in which the Coupling structure (KS) only in the state of measurement on the module is fixed, on which the antenna structure (AS) housed is. In this case, the coupling structure is located (KS) on a separate carrier (TKS), which is a body for Connection of a measuring cable (K) includes. The carrier (TKS) comprises also positioning pins (PS), which its exactly defined and exactly reproducible positioning relative to Antenna structure (AS) allow. For measurement, the carrier (TKS) of the coupling structure (KS) using the positioning pins (PS) in a defined manner relative and closely adjacent positioned to the antenna structure (AS). The antenna structure (AS) is here in a recess (AM) of the mass surface (MF), where the mass surface (MF) in turn housed on the assembly of the device.

FIG. 10 shows a basic form of a coupling structure according to the invention (KS). Where (MP) denotes the measuring point, (SP) the feeding point and (MF) a ground plane. A typical thickness this structure is about 0.5 mm. The distance (d) to Antenna structure is typically about 1 mm. The length of the coupling structure (KS) typically corresponds to a λ / 4 structure, ie about 31 mm at a frequency of 2.45 GHz (ISM band). The Coupling becomes similar to a stripline coupler (Backward coupler) via magnetic (H) and electrical (E) causes fields. Although this structure for operation is optimized in a frequency band, its use is also possible for several tapes.

FIG. 11 shows a coupling structure with predominantly inductive Coupling. This principle corresponds to a loop structure for decoupling. The length of the coupling structure can also be here be significantly smaller than λ / 4. The coupling structure shown is unilaterally connected to mass (MF). The coupling occurs mainly via magnetic (H) fields. The others Dimensions are similar to Figure 10. Again, this is a Multi-frequency operation possible.

FIG. 12 shows a feedforward coupling structure (KS), whose length is again about λ / 4 of the operating frequency should. The width is preferably between about 0.5 mm and 2 mm, the distance to the antenna structure is typical about 0, 5 mm to 1.0 mm. The coupling takes place here via magnetic and electric fields but predominantly inductive. The measuring point (MP) is embedded in the ground plane (MF).

FIG. 13 shows a coupling structure with predominantly capacitive Verkoppelung. The length of the coupling structure (KS) is here rather small against λ / 4; For this, the width of the coupling structure with typical values between about 1 and 5 mm rather large. The distance the coupling structure (KS) to the antenna element (AntE) will typically be between 0.5 and 2 mm. The coupling structure (KS) should if possible be arranged so that they are in as close as possible to the location of greatest electric field strength is located along the antenna element (AntE). Form The coupling surface (width and length) can in individual cases by Experiments are optimized. There are also several such capacitive Coupling structures next to each other conceivable. Especially this is advantageous in connection with multiband antennas.

FIG. 14 shows a coupling structure that fulfills the principles of the Structures of Figures 10 and 13 combined. The coupling thus happens both inductively (via magnetic (H) fields along the rather thin strip conductor elements) as well as capacitive (via electrical (E) fields the places where the rather planar structural elements are located. The total length of the coupling structure (KS) is thereby typically about λ / 4 or smaller; the width of the structures is - depending on the location along the structure - typically between about 0.5 and 5 mm vary. The distance between the coupling structure and the antenna element (AntE) becomes typical between about 0.2 and 0.5 mm. The planar structural elements Be useful in the places of maximum electrical Field strength placed.

FIG. 15 shows another variant of the invention Coupling structures, in which the principles of structures Figures 10, 11 and 14 combined in some ways with each other become. The coupling is also here through a combination of inductive and capacitive couplings causes, with the respective proportions for different frequency ranges can be different. Furthermore this structure has an extension structure area (VSB) on which two inductive coupling structure sections with each other combines. The measuring point (MP) is between two Substructures arranged, each according to the principles designed the structures shown in Figures 11 and 14, respectively are. Hints for advantageous dimensioning arise for the expert from the references to the previous embodiments.

FIG. 16 shows a coupling structure with two coupling elements (KS1 or KS2), each acting as forward couplers. each Coupling element has its own measuring point (MP1 or MP2). The Coupling is both capacitive and inductive. The Lengths of the coupling elements can be two different Frequencies f1 and f2 are adjusted so that they are typical be approximately (λ1) / 4 or (λ2) / 4.

FIG. 17 shows a coupling structure with two contact points (MP1 or MP2). The total length of this structure is chosen with Advantage as λ / 4 corresponding to the smallest frequency used. Determines the most suitable location for the second contact point one by optimizing the coupling for the second Frequency range.

As shown schematically in Figure 18, the inventive is Coupling structure basically also for antenna elements (AntE), which are called helical or as a deformed Ladder arrangements are formed. The coupling structure can it also coiled itself, so integrated into the antenna element be. Also the others shown in this description Coupling structures are basically suitable for one Use in connection with such antenna elements.

Claims (8)

Antenna system for electromagnetic transmitters and / or receivers, in particular for radios,
comprising an arrangement of electrical conductor structures, namely at least one antenna structure and at least one coupling structure for the measurement of characteristics of the electromagnetic properties of the antenna system and other radio frequency parameters of the radio, said coupling structure a) remains in the same after the last measurement before delivery of the radio and b) is designed such that it is electromagnetically coupled as strongly as possible to the antenna structure and dimensioned that it allows a reliable measurement of the parameters in the state of the measurement and at the same time does not disturb the function of the antenna structure in the operating state or acts as a functional component of the antenna structure. Antenna system according to claim 1,
in which the coupling structure is not connected serially in the high-frequency path between transmitter and / or receiver on the one hand and antenna structure on the other hand. Antenna system according to one of the preceding claims, in which, provided the coupling structure with the antenna structure is galvanically connected, such compounds regardless of whether the system is in the operating state or in the state the measurement remains. Antenna system according to one of the preceding claims, in which the coupling of the coupling structure to the antenna structure is effected by at least one λ / 4 structure. Antenna system according to claim 4,
in which the λ / 4 structure is arranged parallel to the antenna structure. Antenna system according to one of the preceding claims, in which the coupling structure designed and dimensioned in this way is that they lack the effects in the state of measurement Housing parts compensates, the only after completion of the measurement to be assembled. Antenna system according to one of the preceding claims, in which the coupling structure consists of several separate substructures exists or in which several independent Coupling structures are provided. Radio, in particular mobile telephone, with an antenna system according to one of the preceding claims.

Images