EP1813032A2

EP1813032A2 - Antenna architecture and lc coupler

Info

Publication number: EP1813032A2
Application number: EP05807888A
Authority: EP
Inventors: H. Heuermann
Original assignee: Fachhochschule Aachen
Current assignee: Fachhochschule Aachen
Priority date: 2004-11-10
Filing date: 2005-11-08
Publication date: 2007-08-01
Anticipated expiration: 2025-11-08
Also published as: EP1813032B1; DE112005003391A5; US20080030421A1; DE502005006715D1; WO2006050701A3; ATE424062T1; DE102004054442A1; WO2006050701A2; US7812780B2

Abstract

Disclosed is an antenna architecture for the non-reacting connection of an antenna to a power amplifier, the antenna being connected to the power amplifier via a coupler. The inventive architecture is improved by the fact that the coupler is provided with an input gate for feeding the signal that is to be transmitted to the antenna while comprising a first and a second antenna gate for transmitting the signal to the antenna, the input gate and the load gate encompassing a joint gate terminal and the first and the second antenna gate being equipped with a joint gate terminal. Furthermore, the antenna comprises a first and a second, identically designed individual antenna, the first individual antenna being connected to the first antenna gate and the second individual antenna being connected to the second antenna gate. Additionally, an adjusted terminating resistor is connected to the load gate while the coupler transmits the signal to the first antenna gate at a phase angle of 0° and to the second antenna gate at a phase angle of 90°.

Description

Antenna architecture and LC coupler

The invention relates to an antenna architecture for non-reactive connection of an antenna with a power amplifier, wherein the antenna is connected via an LC coupler to the power amplifier, further comprising an LC coupler.

[02] In modern wireless communication systems, such as the UMTS mobile communications standard or in a wirelessly networked computer network, a so-called wireless local area network (WLAN), the digital data to be transmitted is transmitted via a gigahertz radio link. For example, in the UMTS standard frequencies between 1.900 and 2.170 GHz and for a WLAN frequencies around 2.4 GHz are used. For radio signals of these frequencies, the wavelengths are a few centimeters and thus in the microwave range. Radio signals of this wavelength are thus to be disturbed by comparatively small objects, with the interference of an object depending on the distance of the object to the antenna and on the electrical conductivity of the object. The smaller the distance of the object to the antenna and the greater its electrical conductivity, the more the radio signal emitted by the antenna is disturbed. In this case, the disturbance can on the one hand cause the propagation of the radio signal to be impaired, on the other hand, the radio signal can be deflected in its direction, in particular reflected, so that the reflected portion is directed back to the antenna, for example.

[03] If necessary, and in particular in the case that a good electrical conductive object is located in the vicinity of the antenna, not only the emitted signals are disturbed by an object in their propagation, but it comes, for example by the small distance, also to changes in the antenna characteristic, in particular the input resistance of the antenna.

[04] In practice, the antennas of such a UMTS or WLAN device are almost directly connected to a power amplifier, so that for optimum transmission of the transmission power between the power amplifier and the antenna, an adaptation of the resistors must be present. In the ideal state, if no disturbing object in the vicinity of the antenna changes the antenna characteristic, adaptation is present. However, if the input resistance of the antenna changes, this leads to a change in the operating point of the power amplifier and the transmission behavior. In practice, the value of the Error Vector Magnitude (EVM value) increases, which is used as a measure of the linearity deviation of high-frequency power amplifiers.

[05] However, to achieve a high data transmission rate, a linear transmission behavior of the upstream power amplifier must be achieved. A shift of the operating point of the power amplifier, which is accompanied by an increasing EVM value, is disadvantageous. Attempts to design a power amplifier so robust in its behavior that an electrically good conductive, close object does not affect the operating point, have so far been unsuccessful.

[06] It is known in the prior art that in such systems so-called "isolators" are used, which are connected between the antenna and the power amplifier and "isolate" the power amplifier from the antenna, so

To prevent repercussions on the power amplifier. These insulators thus cause the operating point of the power amplifier is not shifted from the ideal point. Furthermore, in addition to these existing passive components insulators to electronic control solutions worked in which electronic controllers are used. Such isolators and electronic control solutions are described for example in Bezooijen A., Chanlo Ch., Roermund, AHM, Adaptively Preserving Power Amplifier Linearity under Antenna Mismatch, IMS2004, Fort Worth.

[07] The use of such known from the prior art insulators brings several disadvantages. Insulators are expensive, they require a lot of space and have a high weight compared to other components. Furthermore, they have a high attenuation, so that the output power output by the power amplifier is not optimally transmitted to the antenna and thus emitted. This leads to an increased power consumption by the amplifier and thus in particular in battery-powered mobile devices, such as UMTS mobile phones, so-called handsets, to the fact that the batteries or rechargeable batteries are quickly empty. Furthermore, the electronic control based insulators may tend to be unstable due to the feedback control loop, possibly causing further unwanted noise. The use of such isolators for decoupling the antenna from the power amplifier is thus possible, but associated with great disadvantages and difficulties.

[08] The object of the invention is thus to propose a feedback-free and adapted antenna architecture. In order to achieve this, it is furthermore intended to propose a circuit which can be realized with as few and simple components as possible.

To solve this problem, an antenna architecture according to the preamble of claim 1 is proposed, which is characterized in that the LC coupler for feeding the signal to be transmitted to the antenna is an input port and for transmitting the signal to the antenna a first and a second antenna port, that the antenna has a first and a second, identical single antenna, wherein the first individual antenna is connected to the first antenna port and the second individual antenna to the second antenna port, that the load port is connected with a matching terminating resistor, and that LC coupler the Signal to the first antenna gate with a phase shift of 0 ° and transmits to the second antenna gate with a phase shift of 90 °.

[10] In the present context, the term "LC coupler" encompasses all coupler architectures that use lumped elements, ie concentrated components such as SMD components, thin-film or thick-film elements, semiconductor elements, capacitors or coils and similar assemblies.

Preferably, the LC coupler further comprises a load port on which a signal not emitted and reflected by an antenna can be coupled out, so that it is ensured in a simple and reliable manner that this reflected signal no longer reaches a power amplifier.

The proposed antenna architecture thus preferably consists of a four-door 0790 ° LC coupler and an antenna, which is formed from two identical individual antennas and a termination or load resistor, which is adapted in its resistance value of the system impedance. The input port of the LC coupler is connected to the power amplifier and the load port is terminated with the terminator. Each of the two identical individual antennas is connected to one antenna port each.

[13] The LC coupler causes a wave entering from the output into the LC coupler to be ultimately absorbed in the matched termination resistor. Thus, wave portions reflected on an object close to the antenna and received by one of the individual antennas are absorbed in the terminating resistor of the LC coupler and thus do not revert to the power amplifier. In this respect, the LC coupler acts for these coming from the output into the circuit waves as an insulator with respect to the power amplifier, so that the 0790 ° coupler forms an isolator antenna in conjunction with the two individual antennas. For the simplest possible implementation of such an antenna architecture, alternatively or cumulatively, an O790 ° -Koρpler is proposed which has an input port, a load port and a further first and another second gate, each gate each of a first and a second Torklemme is formed. Between the Torklemmen adjacent gates are not in the working frequency range substantially effective, so ohmic or otherwise influence signals components so that two Torklemmen adjacent gates each coincide to a Torklemme and can form a common Torklemme, of course, negligible and never completely avoidable residual resistances, - inductances and capacities are present or may be present. Such an arrangement is referred to herein as short-circuited, so that the first gate terminal of the input gate and the first gate terminal of the first further gate are short-circuited, the second gate terminal of the input gate and the first gate terminal of the load gate are short-circuited, the second gate terminal of the first further gate and the first gate terminal of the second further gate are short-circuited and the second gate terminal of the second further gate and the second gate terminal of the load gate are short-circuited.

Thus, preferably, the first gate terminal of the entrance gate is the first gate terminal of the first further gate and the second gate terminal of the input gate is the first gate terminal of the load gate. The second gate terminal of the first further gate is the first gate terminal of the second further gate and the second gate terminal is preferably the second gate terminal of the load gate. The 0 ° / 90 ° coupler thus has only four gate terminals.

[16] The LC coupler is now characterized in that the first gate terminal of the input gate via a first LC element to the second terminal of the second further gate and the second gate terminal of the input gate via a second LC element with the second gate terminal of the first connected to other gates, and that the sizing of the two LC-members in the intended working frequency range causes a phase shift of 90 ° between the two signal transmission paths.

This allows the 0 ° / 90 ° coupler realized in particular with only two passive components, which cause the desired phase shift in the signal transmission paths in the range of the operating frequency of the 0 ° / 90 ° coupler.

On the other hand, couplers are known from the prior art as the possibility of connecting two signal-carrying circuits with one another in such a way that an exchange of the signals can take place. Thus, in the specialist literature, "Measuring systems of high-frequency technology", Burkhard Schiek, Hüthig Verlag 1984, a line coupler mentioned as a possibility for defined signal attenuation or signal attenuation, and it is stated that couplers can be used to divide signals to multiple ports. Finally, it is stated that line couplers can be used to generate two signals with broadband 90 ° phase shift. As an example, an abstract sketched ring coupler is given. Furthermore, a resistive coupler is mentioned, which has only resistances, ie purely ohmic resistors as coupler resistors and for which an example calculation for determining the attenuation is given. A phase shift between the gates is not possible with this resistive coupler due to the use of pure resistors. Finally, for this resistive coupler it is stated that the coupler resistances can also be complex. Thus, for example, one effective resistance can be replaced by an inductance and the other effective resistance can be replaced by a capacitance. Although the coupler would then be lossless and decoupled to a broadband gate, the coupling itself would become frequency-dependent.

[19] The use of "lumped elements" makes it possible to limit the electrical length to 20 ° in the LC couplers according to the invention.

As a result, the corresponding coupler can be built very small and especially in mobile devices are readily used. On the other hand, it is understood that the limitation of the electrical length of the coupler to 20 ° or 18 ° or 15 ° in particular regardless of the use of "lumped elements" is advantageous to structurally small and robust antenna architectures for non-reactive connection of an antenna with a Power amplifier in which the antenna is connected via a coupler to the power amplifier, wherein the coupler for feeding the signal to be transmitted to the antenna has an input port and for transmitting the signal to the antenna, a first and a second antenna port, wherein the antenna a first and a second, identical single antenna, wherein the first individual antenna is connected to the first antenna port and the second individual antenna to the second antenna port, wherein the load port is completed, and wherein the coupler, the signal to the first antenna port with a first phase and the second antenna gate with a second phase shifted by 90 ° from the first phase.

[20] There are now several possibilities for designing the antenna architecture according to the invention and the 0 ° / 90 ° LC coupler in an advantageous manner. in the

Below are now several preferred embodiments of

Antenna architecture and the 0 ° / 90 ° LC coupler described by drawings.

It shows

Figure 1: a schematic circuit diagram of the antenna architecture; FIG. 2 shows a schematic circuit diagram of the antenna architecture with several, in

Series connected 0 ° / 90 ° couplers;

FIG. 3 is a circuit diagram of a 0790 ° coupler; and

Figure 4 is a circuit diagram of a -90 ° / 90 ° dual-band coupler.

FIG. 1 shows a schematic diagram of the antenna architecture 1 with a 0 ° / 90 ° LC coupler, an antenna 3 formed from two identical individual antennas 3a, 3b and a terminating resistor 4. The input port 5 of 0 ° / 90 ° -LC coupler 2 is connected via the non-phase-shifting signal transmission path 6 with the first antenna port 7, to which the individual antenna 3 a is connected. about the 90 ° phase-shifting signal transmission path 8, the input 5 is connected to the second Antennenausgangstor 9, to which the sub-antenna 3b is connected. At the fourth port of the LC coupler, the load port 10, the terminating resistor 4, which is matched in its resistance value to the system impedance of the 0 ° / 90 ° coupler, is connected.

[22] If a wave from a power amplifier, not shown here, now runs via the input port 5 into the 0 ° / 90 ° coupler 2, then this will be transmitted via the non-phase-shifting signal transmission path 6 to the first antenna port 7 and thus to the subantenna 3a transfer. On the other hand, the wave is transmitted via the 90 ° phase-shifting signal transmission path 8 to the second antenna port 9 and thus to the second sub-antenna 3b. The wave signal fed into the 0 ° / 90 ° coupler is thus split between the two signal transmission paths 6, 8 and emitted by the first subantenna 3 a without phase shift and by the second subantenna 3b with a phase shift of 90 °.

Thus, each of the sub-antennas 3a, 3b must emit only half of the energy emitted by the power amplifier, so that thus the sub-antennas 3a, 3b must be designed for only half of the energy emitted by the power amplifier. Thus, the subantenna 3 a, 3 b must be designed compared to the classic solution with an antenna and insulators only for half the current carrying capacity, so that this antenna architecture can also be realized in media that was hardly possible for the classic design with an antenna. The arrangement is also much more robust against interference, since often only one of the two sub-antennas is detected by such a disorder.

[24] Another advantage is that the directional characteristic of the antenna 3 can be optimized, so that, for example, in a mobile phone, the electromagnetic load of a user can be reduced. [25] The arrangement has the particular advantage that a wave reflected by an antenna or a wave traveling from the output into the circuit is absorbed in the terminating resistor 4 and thus is not reflected to the input port.

As LC coupler, for example, a 0 ° / 90 ° hybrid coupler can be used, which is particularly suitable when the subantenna 3 a, 3b and the input port 5 are constructed in unbalanced line technology. It is understood that other 0 ° / 90 ° couplers can be used.

FIG. 2 shows a schematic circuit diagram of the antenna architecture 1 with a plurality of 0 ° / 90 ° couplers connected in series. In this case, the power amplifier is connected to the input port 5 of the uppermost 0 ° / 90 ° coupler 2. To the load port 10 of the first 0 ° / 90 ° coupler 2, the input port 5 of the second 0 ° / 90 ° coupler is connected. A plurality of 0 ° / 90 ° couplers 2 can thus be connected in series one behind the other, wherein an input port 5 of a 0 ° / 90 ° coupler is always connected to the load port 10 of the preceding 0 ° / 90 ° coupler and thus forms the terminating resistor , Only the last 0 ° / 90 ° coupler 2 in the row must then be completed with a matching terminating resistor 4. The 0 ° / 90 ° couplers in this series connection can then be advantageously designed to be dimensioned for different, mutually adjacent operating frequencies, thereby forming an ultra broad band (UWB) antenna and so that the antenna architecture over a wide frequency range can be used. On the other hand, separate frequency bands can be controlled if the operating frequencies do not adjoin one another.

FIG. 3 shows a 0 ° / 90 ° coupler 2, which can be realized in the manner described above only with a capacitance 11 and an inductance 12 and can therefore be referred to as an LC coupler. Each gate of the LC coupler 2 is formed from two gate clamps. Each gate terminal of a gate is connected to a gate terminal of the respective adjacent gate via an ideal line, so that in each case two to one Torklemme coincide. Thus, for example, the gate terminal 5a of the entrance gate 5 is connected via an ideal line to the gate terminal 7a of the first further gate 7, so that these two coincide to form a common gate terminal. Likewise, the Torklemmen 7b and 9a, 9b and 10b and 10a and 5b fall together in each case to a common Torklemme, so that the LC coupler 2 actually has only four gate terminals. The capacitance 11 and the inductance 12 are connected between these four gate terminals so that the capacitance 11, the common gate terminal of the input gate 5 and the first further gate 7 with the common gate terminal of the load gate 10 and the second further gate 9, and the inductor 12th the common gate terminal of the input 5 and the load gate 10 connects to the common gate terminal of the first further gate 7 and the second further gate 9.

The necessary for the function of the 0 ° / 90 ° coupler 2 phase shift is obtained for the intended operating frequency of the LC coupler via a suitable dimensioning of the capacitance 11 and the inductor 12, for the following a short according to the known calculation rules Example is executed.

[30] In this example, let the system impedance of the LC coupler be Z ₀ = 50 ohms and the operating frequency f _o = 2 GHz. The resistance Z _{1 of} a capacitance C and the resistance Z _{2 of} an inductance L can then be determined to Z ₁ = 1 / ω ₀ CZ ₂ = ω ₀ L with ω _o = 2πf _o

With the conditions known for a resonant circuit

1. Z ₁ + Z ₂ = O and

2. Z ₁ H = Z ₂ = Z ₀ ² , the values for the inductance L and the capacitance C can be determined to be L = Z ₀ / 2πf ₀ = 3.97 nH C = I / G) ₀ ² L = 1, 59 pF [31] With this dimensioning of the capacitance and the inductance, a phase shift of 0 ° or 90 ° is achieved for the selected operating frequency of 2 GHz. Thus, the LC coupler is a mono-band 0 ° / 90 ° coupler for a working frequency of 2GHz.

[32] A special feature of this 0 ° / 90 ° coupler is that one point of this circuit may be connected to ground, resulting in two unbalanced gates. If, for example, the common gate terminal of the input door 5 and the load gate 10 is connected to ground, unbalanced components can be connected to these two gates. Thus, it is a 0 ° / 90 ° coupler 2 with integrated balun functionality.

[33] If one interchanges the placement of capacitance 11 and inductance 12, the result is a 07-90 ° coupler, which can be used alternatively.

Furthermore, in this 0 ° / 90 ° coupler, the two individual antennas 3 a, 3 b and the input port 5 can be realized either in symmetrical ladder technology, or all three components must be realized in asymmetrical ladder technology. If, on the other hand, a component to be connected is designed to be asymmetrical with respect to the others, a balun must be connected between the gate and the component in a known manner in order to restore the symmetry. Here, for example, a so-called Balun (balanced - unbalanced) can be used, which can be implemented as a transformer, for example.

[35] Figure 4 shows a circuit diagram in which a mono-band coupler described above is developed into a -90 ° / 90 ° dual-band coupler 13. Like the mono-band 0790 ° coupler 2 described above, the -90790 ° coupler 13 has an input port 5 and a load port 10 as well as a first further port 7 and a second further port 9. The inductance and the capacitance used in the 0790 ° coupler are here by a parallel resonant circuit, which is formed from the inductance 17 and the capacitance 16, and a series resonant circuit consisting of the capacitance 14 and the inductance 15 is formed replaced. The operation for the two operating frequencies of the dual-band coupler 13 is equal to that of the LC and the CL coupler. For the lower of the two operating frequencies of the dual-band coupler 13, the dual-band coupler thus acts as a 90 ° coupler and for the higher operating frequency than -90 ° coupler. If one interchanges the parallel and the series resonant circuit in this variant of the coupler 13, then the dual-band coupler 13 behaves correspondingly at the lower operating frequency as a -90 ° coupler and at the higher operating frequency as a 90 ° coupler. The respective center frequencies of the two operating frequencies of the dual-band coupler must stand in no particular distance from each other.

Claims

claims:

1. Antenna architecture (1) for non-reactive connection of an antenna (3) with a power amplifier, wherein the antenna (3) via an LC coupler (2) is connected to the power amplifier, wherein the LC coupler (2) for feeding the at the antenna (3) to be transmitted signal an input port

(5) and for transmitting the signal to the antenna (3) has a first and a second antenna door (7, 9), wherein the antenna (3) has a first and a second, identical individual antenna (3 a, 3b) the first individual antenna (3 a) is connected to the first antenna port (7) and the second individual antenna (3b) is connected to the second antenna port (9), that the load port (10) is closed, and wherein the LC coupler (2) the Transmits signal to the first antenna port (7) at a first phase and to the second antenna port (9) at a second phase shifted by 90 ° from the first phase.

2. antenna architecture (1) according to claim 1, characterized in that the LC coupler further comprises a load port (10).

3. antenna architecture (1) according to claim 2, characterized in that the load port (10) is completed with a matching terminating resistor (4).

4. antenna architecture (1) according to any one of the preceding claims, characterized in that a Torklemme the load gate (19) is connected to ground.

5. antenna architecture (1) according to any one of the preceding claims, characterized in that the input of the LC coupler (2) in unbalanced conductor technology and the individual antennas (3a, 3b) are each implemented in symmetrical ladder technology.

6. antenna architecture (1) according to any one of the preceding claims, characterized in that the terminating resistor (4) is an effective resistance.

7. antenna architecture (1) according to one of claims 3 or 6, characterized in that the terminating resistor (4) at least one further

^• 5 coupler, preferably a further LC coupler, having an antenna.

8. Antenna architecture (1) according to claim 7, characterized in that the further coupler for feeding the signal to be transmitted to its antenna has an input port and for transmitting the signal to its antenna a first and a second antenna port and further comprises a load port that its

10 antenna has a first and a second, identical individual antenna, wherein its first individual antenna is connected to its first antenna port and its second individual antenna to its second antenna port, that its load port is completed, and that the coupler, the signal to its first antenna port with a first antenna Phase and on its second antenna door with a second, um

15 90 ° relative to the first phase shifted phase transfers.

9. LC coupler (2), in particular high-frequency coupler, with an input port (5), a load port (10) and a further first and a second gate (7, 9), each gate of a first and a second Torklemme is formed, between the entrance gate and each of the other gates associated

20 signal transmission paths (6, 7) exist and

the first gate terminal (5a) of the input gate (5) and the first gate terminal (7a) of the first further gate (7) are short-circuited,

the second gate terminal (5b) of the input gate (5) and the first gate terminal (10a) of the load gate (10) are short-circuited,

25 - the second gate clamp (7b) of the first further gate (7) and the first

Gate terminal (9a) of the second further gate (9) are short-circuited as well - The second Torklemme (9b) of the second further gate (9) and the second

Gate terminal (10b) of the load gate (10) are short-circuited, characterized in that the first gate terminal (5a) of the input gate (5) via a first LC element with the second terminal (9b) of the second further gate (9) and the second Gate terminal (5b) of the entrance gate (5) via a second

LC-member with the second gate terminal (7b) of the first further gate (7) is connected, and that the dimensioning of the two LC elements in the intended working frequency range between the two Signalübertragungs¬ paths (6, 7) causes a phase shift of 90 °.

10. LC coupler (2) according to claim 9, characterized in that the first LC element is a capacitor (11).

11. LC coupler (2) according to claim 9 or 10, characterized in that the second LC element is an inductor (12).

12. LC coupler (2) according to claim 9, characterized in that the first LC element is an inductor.

13. LC coupler (2) according to claim 9 or 12, characterized in that the second LC element is a capacitor.

14. LC coupler (13) according to claim 9, characterized in that the LC coupler has two operating frequency ranges and the two LC elements both capacitors (14, 16) and inductances (15, 17) include, wherein the capacity of a the two LC elements and the inductance of the other of the two LC elements are dimensioned such that the dimensioning in a first of the two operating frequency ranges between the two signal transmission paths (6, 7) causes a phase shift of 90 °, while the inductance of the one both LC-links and the capacitance of the other of the two LC-links is dimensioned so that the sizing in the second of the two working frequency ranges between the two signal transmission paths (6, 7) causes a phase shift of 90 °.

15. LC coupler (2, 13) according to claim 9 or 14, characterized in that at least one of the two LC-members has a capacitance and a parallel thereto

~ 5 arranged inductance.

16. LC coupler (2, 13) according to claim 9, 14 or 15, characterized in that at least one of the two LC elements has a capacitance and an inductance arranged in series therewith.

17. LC coupler (2, 13) according to one of claims 9 to 16, characterized in that the load gate is provided with a preferably ohmic load resistor.

18. LC coupler (2, 13) according to claim 17, characterized in that the load resistance between the first Torklemme (10a) and the second Torklemme (10b) of the load gate (10) is arranged.

19 19. LC coupler (2, 13) comprising at least two couplers according to one of claims 9 to 18, wherein one of the two couplers is connected via its input port with the load port of the other of the two couplers.

20. LC coupler (2, 13) according to claim 19, characterized in that the first gate terminal of the input port of the first of the two couplers with the second

20 Torklemme the Lasttores the second coupler is shorted.

21. LC coupler (2, 13) according to claim 20, characterized in that a load resistor is provided in the load port of the first coupler.