GB2431049A

GB2431049A - Antenna arrangement

Info

Publication number: GB2431049A
Application number: GB0520249A
Authority: GB
Inventors: Patrick Labbe; David G Bateman
Original assignee: Motorola Inc
Current assignee: Motorola Solutions Inc
Priority date: 2005-10-05
Filing date: 2005-10-05
Publication date: 2007-04-11
Anticipated expiration: 2025-10-05
Also published as: GB0520249D0; GB2431049B

Abstract

An antenna arrangement comprising at least a first antenna element 101 having a geometric shape corresponding to a first spiral transformation of a first geometric fractal 107. The antenna arrangement may further comprise a second antenna element 103 having a geometric shape corresponding to a second spiral transformation of a second geometric fractal 109. The first and second geometric fractals 107, 109 may be the same or different fractals. The antenna arrangement may in particular provide improved wideband performance and a compact size and is suitable for Ultra WideBand (UWB) applications.

Description

AN ANTENNA ARRANGEMENT

Field of the invention

The invention relates to an antenna arrangement, a transceiver and a method of manufacturing and in particular, but not exclusively, to an antenna arrangement for Ultra WideBand radio communications.

Background of the Invention

In recent years, wireless data communication in domestic and enterprise environments have become increasingly commonplace. A new wireless transmission technique known as Ultra WideBand (UWB) transmission has been proposed. UWB signals are generated by transmitting information in very short data pulses of typically 10-100 picoseconds duration thereby resulting in a bandwidth of the transmitted signal of several Gigahertz. A high data rate may be achieved by a UWB signal and as the bandwidth is exceedingly large, the spectral power density is relatively low. Accordingly, the interference caused to and the sensitivity to narrowband interference from other signals in the frequency range is relatively low thereby allowing a UWB communication system to co-exist with other communication systems in the same frequency range.

According to a definition of the Federal Communications Commission (FCC), a UWS system can be considered to be any radio system where the bandwidth of the desired signal is , :: * 1:s: :.

* . : : : * * I I S * * q S.. * S ** either larger than 20% of the centre frequency or larger than 500MHz. In the United States of America, the FCC has opened the 3.1 to 10.6GHz radio band to radio communication meeting this definition of UWB, operating in indoor or hand- held peer-to--peer configurations. In Europe, the CEPT (European Conference of Post and Telecommunications Administrations) is currently evolving towards a regulation that is similar to that proposed by the FCC.

The extreme bandwidth requirement of UWB systems places stringent design constraints on the antenna that is used.

The design of a high performance antenna is a key to the performance of UWB transceivers. In particular, in order to preserve the pulse shapes utilized within UWB, the antennae should present a good impedance match and a monotonic phase over the whole frequency range used by the system.

However, the design of antennae which can provide effective performance throughout an extremely large bandwidth is very difficult and tends to lead to comprises which significantly degrade performance.

Antenna design generally comprises trading off between a number of conflicting characteristics including characteristics such as: bandwidth, gain, impedance matching, phase, efficiency, directivity, size and cost.

Three main known antenna families are able to provide ultra- high bandwidth performance, namely: - classical patch antennae; - horn and conical antennae; and *I * ala.sa a.

* I * * * a a * * $ : - log spiral antennae.

However, all of these antenna families have a number of associated disadvantages.

In particular, classical patch antennae tend to exhibit characteristics which correspond more to a multi-band antenna than a genuine wide-band antenna due to the inherent use of successive resonances. Thus, these antennae tend to show relatively large variations in the characteristics over the frequency band.

Horn and conical antennae are well-known broadband antennae.

However, these antennae tend to be very large and bulky and exhibit a directivity characteristic which is unsuitable for many applications. Furthermore, as practical antennae necessarily must be truncated, it is typically difficult to obtain good impedance matching over the entire frequency band.

The log spiral antennae, which are part of the log-periodic family, are also known to be wideband antennae. However, such antennae are usually large and lossy. Furthermore, they tend to exhibit a complex impedance having a real part that remains stable and close to 500hm while the imaginary part is quite different from zero resulting in a poor Sli parameter.

Accordingly, such antennae are impractical for many applications such as for handheld UWS communication units.

** * *. 1:. *** Is I I a a * * * * : .* * . a_s:, CMLO1949M A relatively new antenna design technology is the application of fractal designs. Further information of fractal antennae can e.g. be found in D.H. Werner, S. Ganguly, "An overview of fractal antenna engineering research", IEEE Antennae and Propagation magazine, Vol. 45, No. 1, pp. 38-57, February 2003.

The fractal approach of antenna design represents an appealing disruptive technology to address the classical issues of compactness, conformality and multi or wide band response. Breaking with the traditional approaches in analysis and design built upon Euclidean geometry, fractal antenna technologies constitute a new approach to electrodynamics radiation engineering and the consideration of a new class of radiation, propagation and scattering patterns.

Some of the classical 1D-fractals present an infinite length in a finite area. Hilbert, Peano even Von Koch curves fulfil this property. As the length of the antenna is directly linked to the wavelength of the radiated wave, this can allow very compact antennae operating even at very low frequencies. Examples of such antennae can be found in e.g. J. Anguera, C. Puente, J. Soler, "Miniature monopole antenna based on the fractal Hilbert curve", IEEE, pp. 546-549, 2002 and N. Cohen, "Fractal antenna applications in wireless telecommunications", IEEE Electronics Industries Forum of New England, pp. 43-49, May 1997.

As demonstrated in.G. Hohlfeld, N. Cohen, "Self similarity and the geometric requirements for frequency independence in antennae", Fractals, Vol. 7, No. 1, Pp. 79-84, January 1999, : :: ::: * * * . * : . S CMLO1949M the linear property of the Maxwell equations and the intrinsic auto-similar scalability of any fractal lead to an intrinsic auto-similar scalability of the frequency response. Thus, if a fractal design presents a resonance at a given frequency, this resonance will be replicated adinfinitum in the frequency response (which corresponds to the response of each sub-pattern of the initiator of the overall fractal). In this manner, a fractal design generally provides a multiband response. It has also been demonstrated that if the pattern presents a central symmetry, the response becomes a wideband response.

However, although fractal designs are promising for ultra- wideband applications they tend to exhibit a number of disadvantages. Specifically, the infinite replication of a pattern is unachievable both in practical antennae and for simulations. Accordingly, the infinite replication of the initial pattern in the frequency domain is not possible.

Indeed, in practice only two or three iterations tend to be feasible thereby effectively limiting the fractal antennae to a dual or three band antennae. As a consequence, the characteristics of the antenna tend to vary over the desired ultra-wide bandwidth. Specifically, ultra-wide band antennae tend to exhibit large impedance variations.

Hence, an improved antenna arrangement would be advantageous and in particular an antenna arrangement allowing increased flexibility, reduced size, reduced cost, facilitated manufacturability improved wide bandwidth applicability, reduced variation of characteristics over the bandwidth and/or improved performance characteristics would be advantageous.

* * S:. 5.: : * S * S * * * * S * . * * S : : : : : :. * : CMLO1949M *55 * *

Summary of the Invention

Accordingly, the Invention seeks to preferably mitigate, alleviate or eliminate one or more of the above mentioned disadvantages singly or in any combination.

According to a first aspect of the invention there is provided, an antenna arrangement comprising: at least a first antenna element having a geometric shape corresponding to a first spiral transformation of a first geometric fractal.

The invention may allow an improved antenna arrangement. In particular, the invention may allow advantageous cahracteristics with respect to both conventional and fractal antenna arrangements. Specifically, the geometric shape of the first antenna element is not in itself a fractal geometry but can retain some of the advantages of the underlying geometric fractal. In particular, the antenna arrangement can provide an advantageous trade-off between characteristics such as size, cost, complexity, radiation pattern, impedance matching and/or wide band performance.

The invention may in particular provide a highly efficient antenna for extreme wideband applications.

The first spiral transformation can be a two-dimensional or threedimensional transformation. Specifically, the first spiral transformation may result in a geometric shape of the * * S:. .: * S * S * * * * S * S S S * * S S. S * * * S S 55 * . CMLO1949M * I first antenna element corresponding to a conical or cylindrical helix.

According to an optional feature of the invention, the first spiral transformation is a logarithmic spiral transformation.

This may provide an antenna arrangement having particularly advantageous performance and/or which exhibits an advantageous trade-off between performance characteristics over a wide bandwidth.

According to an optional feature of the invention, the spiral transformation is in polar coordinates substantially given by: r'=r t '= O+1!1og(r) where r is a length and B is an angle of a vector to a point in a two dimensional plane and a is a selectable parameter value.

The selectable parameter value a may be selected as a specific constant for a given embodiment and can typically be in the range from 0.6 to 1.2.

* * * *.* .: :.

* * S * * * * S S * S S * * I *. * * : ** * * ** * * * * * * 1 CMLO1949M eSS S According to an optional feature of the invention, the spiral transformation is a non-logarithmic spiral transformation.

According to an optional feature of the invention, the geometric fractal is a fractal from the group consisting of: a. a Sierpinsky Gasket; b. a Sierpinsky Carpet; C. a Koch Island; and d. a Pythagorean Tree.

These basic fractals have been found to result in particularly advantageous performance and/or result in an advantageous trade-off between performance characteristics over a wide bandwidth.

According to an optional feature of the invention, the antenna arrangement further comprises a second antenna element having a geometric shape corresponding to a second spiral transformation of a second geometric fractal.

This may allow an improved antenna. In particular, an improved radiation pattern and/or impedance matching can be achieved over a wide bandwidth.

* S I:. S.: : * . * S S * * S * S S * * * S S S S S S S * * ** ** . : * CMLO1949M According to an optional feature of the invention, the first geometric fractal is the same as the second geometric fractal.

This may allow high performance and a suitable trade-off between performance characteristics for many embodiments. In addition, it may facilitate design and modelling of the antenna arrangement.

According to an optional feature of the invention, the first geometric fractal is different from the second geometric fractal.

This may allow high performance and a suitable trade-off between performance characteristics for many embodiments. In particular, the feature may allow an improved cancellation of resonances in the wideband characteristics of the antenna arrangement.

According to an optional feature of the invention, a number of fractal iterations of the first geometric fractal is different from a number of fractal iterations of the second geometric fractal.

This may allow high performance and a suitable trade-off between performance characteristics for many embodiments. In particular, the feature may allow an improved cancellation of resonances in the wideband characteristics of the antenna arrangement. The feature may in particular facilitate design, modelling and/or manufacturing of the antenna arrangement.

* . * *s* .: :.

* S * S * * * S S * S * * * * S *. * * : . * * ** . * * CMLO1949M According to an optional feature of the invention, the first spiral transform is the same as the second spiral transform.

According to an optional feature of the invention, the first spiral transformation is different from the second spiral transformation.

This may allow high performance and a suitable trade-off between performance characteristics for many embodiments. In particular, the feature may allow an improved cancellation of resonances in the wideband performance of the antenna arrangement.

According to an optional feature of the invention, the first antenna element is a planar antenna element.

This may provide improved performance and/or characteristics for some embodiments. In particular, it may allow a reduced size, reduced cost, improved integration with other functionality and/or facilitated manufacturing. For example, the antenna arrangement may be implemented as a conductive pattern on a printed circuit board.

In embodiments where a plurality of antenna elements is used, some or all of the antenna elements may be planar antenna elements. In particular, for a dipole comprising two antenna elements both the first and second element may be a : : :: ::: S * * * 05 CMLO1949M . S planar element, resulting in a fully planar antenna arrangement.

According to an optional feature of the invention, the antenna arrangement further comprises a substrate and wherein the first antenna element is disposed on the substrate.

This may allow facilitated manufacturing and/or a practical and advantageous implementation of the antenna arrangement.

The first antenna element may be implemented as a conductive pattern adhered to the substrate.

In embodiments where a plurality of antenna elements is used, some or all of the antenna elements may be disposed on the substrate.

According to an optional feature of the invention, the geometric fractal is a fractal of iteration N where N is an integer larger than one.

This may result in a high-performance wideband antenna arrangement which is practical to design, model and/or implement.

According to an optional feature of the invention, an Ultra WideBand (UWB) antenna comprising an antenna arrangement as described above.

The invention may provide a particularly advantageous antenna for UWB applications.

* * * *: .: * * * * : : * * * * * * S S. * * * * S. S S * . S CMLO1949M According to another aspect of the invention, there is provided a transceiver arrangement comprising an antenna arrangement including at least a first antenna element having a geometric shape corresponding to a first spiral transformation of a first geometric fractal.

The invention may provide for a transceiver arrangement with improved performance and/or reduced complexity, size and/or cost.

According to an optional feature of the invention, the transceiver arrangement further comprises means for generating an Ultra WideBand (UWB) signal and means for feeding the UWB signal to the antenna arrangement.

The invention may provide a particularly advantageous UWB transceiver.

According to an optional feature of the invention, the transceiver arrangement comprises a plurality of transceiving means arranged to operate in different frequency bands and wherein all of the plurality of transceiving means are arranged to use the antenna arrangement simultaneously.

The invention may provide a transceiver arrangement which is suited for operation on different frequency bands without requiring individual antennae optimised for the individual bands to be used. This may substantially reduce cost and/or size of the transceiver arrangement.

*. : .: I * I e * I * * * I I I * * * S :: , : . CMLO1949M The different transceiving means may not only be arranged to operate on different frequency bands but may also be arranged to operate in accordance with different communication standards and/or in different communication systems. For example, one antenna arrangement may be used for a transceiver arrangement supporting both 2 Generation and 3rd Generation cellular communication systems.

According to another aspect that of the invention, there is provided a method of manufacturing an antenna arrangement comprising: providing a substrate; and disposing on the substrate at least a first antenna element having a geometric shape corresponding to a first spiral transformation of a first geometric fractal.

The invention may allow a low complexity, low-cost and/or facilitated manufacturing of the antenna arrangement.

These and other aspects, features and advantages of the invention will be apparent from and elucidated with reference to the embodiment(s) described hereinafter.

Brief Description of the Drawings

Embodiments of the invention will be described, by way of example only, with reference to the drawings, in which FIG. 1 illustrates an antenna arrangement in accordance with some embodiments of the invention; I. 4. 4 * : * * * * : . * *1 CMLO1949M FIG. 2 illustrates an antenna arrangement in accordance with some embodiments of the invention; FIG. 3 illustrates an antenna arrangement in accordance with some embodiments of the invention; FIG. 4 illustrates an example of a transceiver arrangement in accordance with some embodiments of the invention; FIG. 5 illustrates an example of an impedance for a fractal

antenna in accordance with prior art;

FIG. 6 illustrates an example of an impedance for a spiral

antenna in accordance with prior art;

FIG. 7 illustrates an example of an impedance for an antenna in accordance with some embodiments of the prior art; FIG. B illustrates an example of the efficiency of an antenna in accordance with some embodiments of the invention in comparison to a bow tie antenna; FIG. 9 illustrates an antenna arrangement in accordance with some embodiments of the invention; and FIG. 10 illustrates an example of a bow tie antenna in

accordance with prior art.

Detailed Description of Some Embodiments of the Invention S * * S P * * * * a : * CMLO1949M Fig. 1 illustrates an antenna arrangement in accordance with some embodiments of the invention.

In the example, the antenna arrangement comprises a first antenna element 101 and a second antenna element 103. It will be appreciated that in other embodiments, an antenna arrangement may comprise only one antenna element or may comprise more than two antenna elements. The first and second antenna elements 101, 103 adjoins each other at a feed point 105 to which a transceiver may be connected for example by a transmission line.

In the example, the first and second antenna elements 101, 103 are planar antenna elements. The elements 101, 103 do not themselves have a fractal shape. Specifically they do not correspond to patterns arising from self replicating iterations of a basic shape. However, the geometric shape of the antenna elements 101, 103 are obtained by applying a spiral transformation to an underlying fractal shape. In the example of FIG. 1, the first antenna element 101 is obtained by a spiral transformation of the underlying fractal shape 107 and the geometric shape of the second antenna element 103 is obtained by a spiral transformation of the underlying fractal shape 109.

Depending on the preferences and requirements of the individual embodiment, the spiral transformation can be a log spiral transformation or a non-log spiral transformation.

As an example, the following non-log spiral transformation can be applied to a fractal shape to generate a **. S.: * . . S * * * S :: ** : CMLO1949M corresponding geometric shape of an antenna element that may provide suitable performance in many embodiments: r=h0 or r=-- where r is a length and e is an angle of a vector to a point in a two dimensional plane and a is a selectable parameter value.

In the example of FIG. 1, the spiral transformation is a log spiral transformation given by the equation: I r'=r 0=0 + -log(r) I. a where r is a length and e is an angle of a vector to a point in a two dimensional plane and a is a selectable parameter value.

Thus in the example, a point in the two dimensional plane having the polar coordinates (r1, e1) is transformed to the point: 011= ±log(r1) a a is a design parameter that can be selected for the specific requirements and preferences of the individual embodiment.

*S *SS S'

S S S

* * S S * * S * * : : . *s: CMLO1949M In the example of FIG. 1, the underlying fractals 107, 109 used for both antenna elements are the same basic fractal.

Specifically, in the example, a Sierpinsky Carpet with an iteration of three is used. Thus, for the specific underlying fractal, the basic Sierpinsky carpet pattern is iterated three times within each other.

It will be appreciated that any suitable underlying fractal and/or iteration number can be used without detracting from the invention. In particular, it has been found that an iteration value of around 2-4 tends to provide suitable performance while being practical to implement.

Furthermore it has been found that in addition to the Sierpinsky carpet pattern, particularly good performance can be achieved by using the following basic tractals: a. the Sierpinsky Gasket; b. a Koch Island; and c. a Pythagorean Tree.

In the example of FIG. 1, the antenna arrangement comprised two antenna elements 101, 103 which were based on identical spiral transformations of identical underlying fractals.

This may provide suitable performance for many embodiments and tends to lead to a facilitated design, implementation and manufacturing process.

In other embodiments, different antenna elements of the antenna arrangement may not be identical or symmetrically equivalent. * ..*

S **. S S * S * * S * S * * * * S * S * * * 1 * * CMLO1949M *5 * * S *. * S * S Fig. 2 illustrates an antenna arrangement in accordance with some embodiments of the invention. In this example, the same spiral transformation is applied and the same basic fractal pattern, specifically the Sierpinsky carpet, is used but the iteration number for the fractals is different. Hence, a first antenna element 201 is obtained by a spiral transformation of a Sierpinsky carpet 203 with an iteration of three whereas the second antenna element 205 is obtained by applying the same spiral transformation to a Sierpinsky carpet with an iteration of two 207.

The use of different iterations for the fractals is advantageous in many embodiments as it tends to provide cancellation or smoothing of the individual resonances in the bandwidth supported by the antenna arrangement.

In some embodiments, it may further be advantagous to use different underlying fractal patterns.

Fig. 3 illustrates an antenna arrangement in accordance with some embodiments of the invention. In the example, a first antenna element 301 has a geometric shape which corresponds to a spiral transformation of a Sierpinsky Carpet fractal 303 while a second antenna element 305 has a geometric shape which corresponds to a spiral transformation of a Sierpinsky Gasket fractal 307.

In this example, a further improvement in the smoothness and attenuation of individual resonances is achieved leading to more consistent characteristics across the frequency band.

* ** : ::: :: . . : CMLO1949M In the example of FIG. 3, the two fractals 303, 307 have the same number of iterations but it will be appreciated that in other embodiments the different fractals may further have a different number of iterations.

The described antenna arrangements tend to exhibit excellent wideband performance and are highly suitable for wideband communication systems and in particular to UWB communication systems.

FIG. 4 illustrates an example of a UWB transceiver arrangement 400 in accordance with some embodiments of the invention.

The transceiver arrangement 400 comprises the antenna arrangement 401 described in connection with FIG. 3. The antenna arrangement 401 is coupled to a combiner 403 through a transmission line 405. The combiner 403 is furthermore coupled to a transmitter 407 and a receiver 409. The transmitter 407 and the receiver 409 are coupled to a data interface 411.

When the transceiver arrangement 400 is used for the transmitting a UWB signal, the data to be transmitted is received by the data interface 411 from a suitable source (not shown). The data is then fed to the transmitter 407 which generates the transmission signal in accordance with the requirements and preferences for a UWE communication system. The generated signal is then fed to the antenna arrangement 401 through the combiner 403 and the transmission line 405. The signal is then radiated from the antenna arrangement 401.

*S **.

* *SS * S * 5 S S * S * * S * * S * S : * * * S *_* * S When the transceiver arrangement 400 is used for a receiving a UWB signal, this is fed from the antenna arrangement 401 to the receiver 409 through the combiner 403 and the transmission line 405. The receiver 409 proceeds to decode and demodulate the received signal in accordance with the specifications and requirements for a UWB communication system. The received data is then fed to the data interface 411 and then on to a suitable destination (not shown).

A transceiver arrangement may in some embodiments comprise a plurality of transceiving means similar to the one described with reference to FIG. 4 but with each of the transceiving means being arranged to communicate on a different frequency band within the bandwidth of the antenna arrangement. For example, both a GSM (Global System for Mobile communications) and a UMTS (Universal Mobile Telecommunication System) remote station can be connected to a single antenna arrangement. Thus, a substantially reduced size, complexity and/or cost can be achieved since a single antenna can be used for multiple purposes. Furthermore as the antenna can be small for the given bandwidth and wavelength, this may be particularly suitable for handheld communication units such as mobile phones.

The described embodiments may provide advantageous characteristics suitable for an ultra-wideband application.

An important performance characteristic for a high performance antenna ía the impedance matching. The described embodiments can provide improved impedance matching over a wide bandwidth.

*.s **t S * * S S * S : . :.

For a fractal antenna, the real part of the impedance tends have a high mean value and to ripple significantly over a large bandwidth while the imaginary part tends to remain relatively constant and close to zero.

For a conventional spiral antenna, simulations indicate that the real part of the impedance is relatively stable and close to 50 Ohm while the imaginary part has a very high absolute resulting in a poor Sli parameter value.

The described embodiments tend to eliminate these disadvantages and to lead to a real part of the impedance which is more stable and lower than for a fractal antenna corresponding to the underlying fractal, while the imaginary part of the impedance tends to be as low as for a fractal antenna corresponding to the underlying fractal.

This is further illustrated in FIG. 5 to 7 where FIG. 5 shows the impedance for a fractal antenna corresponding to the original fractal, FIG. 6 shows the impedance for a corresponding spiral antenna and FIG. 7 shows the impedance for an antenna corresponding to a log spiral transformed Sierpinsky Carpet fractal. Furthermore, simulations have shown that the global efficiency of this

antenna remains above 80% over the whole UWB range as presented in FIG. 8 for the antenna having dimensions as indicated in FIG. 9 with reference to a bow tie antenna with dimensions as indicated in FIG. 10. * ..* S.. S

S * * * . . . * S * * * * * . * **, : : . *. CMLO1949M As illustrated, the two antennae exhibit approximately the same performance while the antenna arrangement in accordance with the described embodiments use only around half the area of the bow tie antenna. Thus, a substantial reduction in size can be achieved.

For pulse based UWB systems, the phase distortion of the radiated signal is critical. The Sli parameters provide a good indication that the phase centre of the antenna is stationary with frequency.

It will be appreciated that any suitable process for manufacturing the antenna arrangement can be used.

Specifically, an advantage of the described embodiments is that they can be implemented as planar patterns. For example, the antenna element may be manufactured as conductive patterns on a flat substrate and specifically can be manufactured as a conductor pattern on a printed circuit board.

As a specific example, a conductive plane can be adhered to a flat substrate of a material having suitable dielectric properties. E.g. a cobber plane may be adhered to a pertinax or glass fibre substrate. An etch resistant film can be placed on the conductive plane and the desired pattern for the antenna can be transferred to this film by a suitable photo-lithographic process as will be known to the person skilled in the art. A suitable etching process can then be applied resulting in the desired conductive pattern remaining. S..

* *S' * * S * * S * * S * S * * * S * * S : : : . * : Such an approach can be particularly advantageous as it can be combined with the creation of a printed circuit board for suitable transceiver functionality. Thus, a highly compact and integrated transceiver implementation can be achieved.

It will be appreciated that the above description for clarity has described embodiments of the invention with reference to different functional units and that references to specific functional units are only to be seen as references to suitable means for providing the described functionality rather than indicative of a strict logical or physical structure or organization.

Although the present invention has been described in connection with some embodiments, it is not intended to be limited to the specific form set forth herein. Rather, the scope of the present invention is limited only by the accompanying claims. Additionally, although a feature may appear to be described in connection with particular embodiments, one skilled in the art would recognize that various features of the described embodiments may be combined in accordance with the invention. In the claims, the term comprising does not exclude the presence of other elements or steps.

Furthermore, although individually listed, a plurality of means, elements or method steps may be implemented by e.g. a single unit or processor. Additionally, although individual features may be included in different claims, these may possibly be advantageously combined, and the inclusion in different claims does not imply that a combination of features is not feasible and/or advantageous. Also the *SS * *.S * S : : : * :: *. : CMLO1949M inclusion of a feature in one category of claims does not imply a limitation to this category but rather indicates that the feature is equally applicable to other claim categories as appropriate. Furthermore, the order of features in the claims does not imply any specific order in which the features must be worked and in particular the order of individual steps in a method claim does not imply that the steps must be performed in this order. Rather, the steps may be performed in any suitable order.

SS * . S * S * I * S * * * S * * I :: . ** : CMLO1949M

Claims

1. An antenna arrangement comprising: at least a first antenna element having a geometric shape corresponding to a first spiral transformation of a first geometric fractal.

2. The antenna arrangement of claim 1 wherein the first spiral transformation is a logarithmic spiral transformation.

3. The antenna arrangement of claim 2 wherein the first spiral transformation is in polar coordinates substantially given by: r=r 9 + --1og(r) where r is a length and e is an angle of a vector to a point in a two dimensional plane and a is a selectable parameter value.

4. The antenna arrangement of claim 1 wherein the spiral transformation is a non-logarithmic spiral transformation.

5. The antenna arrangement of any previous claim wherein the geometric fractal is a fractal from the group consisting of: a. a Sierpinsky Gasket; b. a Sierpinsky Carpet; c. a Koch Island; and S.. **.

* iSI * S * S I * * S * S * * * S S * S * * * * . * CMLO1949M *: : * ** d. a Pythagorean Tree.

6. The antenna arrangement of any previous claim further comprising a second antenna element having a geometric shape corresponding to a second spiral transformation of a second geometric fractal.

7. The antenna arrangement of claim 6 wherein the first geometric fractal is the same as the second geometric fractal.

8. The antenna arrangement of claim 6 wherein the first geometric fractal is different from the second geometric fractal.

9. The antenna arrangement of claim 8 wherein a number of fractal iterations of the first geometric fractal is different from a number of fractal iterations of the second geometric fractal.

10. The antenna arrangement of any of the claims 6 to 9 wherein the first spiral transform is the same as the second spiral transform.

11. The antenna arrangement of any of the claims 6 to 9 wherein the first spiral transform is different from the second spiral transformation.

12. The antenna arrangement of any previous claim wherein the first antenna element is a planar antenna element.

*s *** * *** * * S * * S S * * : : : : * : *_: *

13. The antenna arrangement of any previous claim further comprising a substrate and wherein the first antenna element is disposed on the substrate.

14. The antenna arrangement of any previous claim wherein the first geometric fractal is a fractal of iteration N where N is an integer larger than one.

15. An Ultra WideBand (UWB) antenna comprising an antenna arrangement as claimed in any previous claim.

16. A transceiver arrangement comprising an antenna arrangement including at least a first antenna element having a geometric shape corresponding to a first spiral transformation of a first geometric fractal.

17. The transceiver arrangement of claim 16 further comprising means for generating an Ultra WideBand (UWB) signal and means for feeding the UWB signal to the antenna arrangement.

18. The transceiver arrangement of claim 16 or 17 wherein the transceiver arrangement comprises a plurality of transceiving means arranged to operate in different frequency bands and wherein all of the plurality of transceiving means are arranged to use the antenna arrangement simultaneously.

19. A method of manufacturing an antenna arrangement comprising: providing a substrate; and

I

S * * * . S * S S * * . * * CMLO1949M _5: * disposing on the substrate at least a first antenna element having a geometric shape corresponding to a first spiral transformation of a first geometric fractal.

*g *.* * *SS * S * CMLO1949M