GB2476086A

GB2476086A - Compact photonic circuit arrangement for an ultra-wideband antenna

Info

Publication number: GB2476086A
Application number: GB0921674A
Authority: GB
Inventors: Lye Whatt Chua
Original assignee: Thales Holdings UK PLC
Current assignee: Thales Holdings UK PLC
Priority date: 2009-12-10
Filing date: 2009-12-10
Publication date: 2011-06-15
Also published as: GB0921674D0

Abstract

A ground plane / reflector apparatus 80, suitable for an antenna, or its method of manufacture comprises a laminar dielectric substrate 82 with first and second opposing planar surfaces. A plurality of conductive elements 84 are formed on the first planar surface and a ground element is formed on the second planar surface. A plurality of conductive via paths 88 are formed between the first planar surface and the ground element, for each respective conductive element 84, and a further conductive path 92 electrically connects between each respective conductive path 88 and each respective conductive element 84. The apparatus 80 may be combined in a laminated formation with an ultra-wideband antenna radiating element with a single feed point which is formed on a surface of dielectric substrate. The conductive elements 84 may have regular or irregular shapes or spaced intervals or structures which form an array. The further conductive path 92 may be a straight or spiral strip. The further inductive conductive path 92 enables a compact photonic circuit arrangement to be provided for an ultra-wideband antenna.

Description

I

An Apparatus for Shaping a Radiation Pattern of an Antenna

Field of the Invention

The present invention relates to an apparatus for shaping a radiation pattern of an antenna. In particular, it relates to an apparatus for shaping a radiation pattern of an antenna for radiating ultra wide bandwidth (UWB) pulses.

Background of the Invention

Pulsed electromagnetic (elm) energy transmission and reception systems typically possess wide-band or UWB transmission spectral bandwidths. This UWB characteristic stems from the pulsed nature of the e/m energy transmitted and received by systems. The shape of such energy pulses in the time domain is typically one of any number of approximations to a delta function, and generally has the property that the width of the frequency spectrum of such impulse increases as the time domain "length" or duration of the pulse decreases. Thus, the shorter the pulse of radiation is, the broader is its spectral bandwidth.

UWB was previously defined as an impulse radio technology, but those skilled in the art now view it as an available bandwidth set with an emissions limit that enables coexistence without harmful interference. One of the challenges of the implementation of UWB systems is the development of a suitable antenna that would enhance the advantages promised by a pulsed communication system. UWB systems require antennas that cover up to an octave bandwidth in order to transmit pulses on the order of a sub-nanosecond in duration with minimal distortion.

The UWB performances of antennas result from excitation by impulse or non-sinusoidal signals with rapidly time-varying performances. Thus, when an antenna is used employing such pulses in UWB applications, it is often found that the time-domain behaviour of the antenna is critical to the operation of the antenna. In particular, if an impedance mismatch or discontinuity occurs in such an antenna (such as at the open circuit end of the antenna), the consequence is often the unwanted generation of a standing wave of elm energy within the antenna's radiating element(s) caused by reflections within the antenna of the e/m energy to be transmitted.

This trapped energy not only reduces the efficiency of the transducer of which the antenna forms a part, but also masks, obscures or interferes with signals received by the transceiver while the trapped energy is still present within the antenna.

Thus, in any resonant structure, such as a dipole antenna, an impulse signal injected at the antenna input will typically be partially reflected from the open-circuited end of the dipole causing a residual reflected return signal to appear at the antenna input. This return reflection is often referred to as "ringing" or may be referred to as aperture clutter" since it clutters/obscures the aperture of the antenna.

Pulsed UWB transceivers are often employed in applications such as short-distance positioning, or length measurement and so on, where a pulse e/m signal is transmitted from the transceiver and its reflection is subsequently received after a very brief time period. Such an application requires that the entire e/m signal pulse has exited the antenna of the transceiver before any reflection of that signal is expected to be received. This aims to ensure that the transmitted signal does not interfere with its received reflections and thereby obscure the positioning/measurement process.

However, ringing/aperture clutter results in just such obscurement and is highly undesirable.

Prior art pulsed UWB transceiver systems have attempted to overcome this problem by adding e/m signal absorbing material to the ends of the dipole antennas thereof or by loading the antennas with a distributed series of resistors along their length in an attempt to dampen or attenuate the standing waves therein which cause aperture clutter. However, such solutions are generally of little effect or most likely result in undesirably excessive attenuation of received/transmitted signal energy.

A physically small planar UWB antenna with low ringing time is described in UK patent no. GB2453778. Such a UWB antenna demonstrates good impedance match from 3.5 GHz to 18 0Hz which ensures very low ringing from harmonics of the impulse frequency. It also produces a wide elevation beam width of radiated signals and a shallow radiation null along the direction of the geometrical symmetry axis of the radiating element, which one would not expect from a conventional monopole antenna (as one would expect a complete, zero-signal null along the axis of symmetry).

Such a small planar antenna structure, which is also illustrated in figure 1, is suitable for applications which require easy integration of the antenna on a user's clothing or on a PCMCIA PC card for WiFi, Bluetooth and UWB simultaneous applications. The antennas also provide omnidirectional characteristics in their azimuthal direction of radiation and a shallow radiation null along its geometrical symmetry axis of the radiating element.

In some applications, it is desirable to provide an antenna with a unidirectional characteristic. This allows the antenna to radiate greater power in a wanted direction of communication to increase performance, and to reduce interference from unwanted sources.

As shown in figure 2, reflectors 60 are commonly used to modify/shape the radiation pattern of an antenna 62. This is usually achieved by placing a flat sheet reflector 60 of sufficiently large dimension in the plane in the direction of unwanted radiation.

Therefore, the "backward" radiation 64 from the antenna can be significantly reduced (or eliminated) and substantial gain in the "forward" radiation 66 can be increased.

The person skilled in the art would appreciate that the radiation pattern (or the gain in the forward radiation) is determined by the distance, d, between the antenna 62 and the reflector 60. Typically, the reflector 60 is placed one quarter wavelength from the antenna 62. Therefore, the overall size/thickness of the antenna structure 70 could be dependent on the distance, d, and the frequency in which the antenna operates. In some applications, especially for antennas that are integrated on a user's clothing, it is essential to reduce the overall size/thickness of the antenna.

GB2453778 also describes a photonic circuit element coupled to the antenna to form a substantially unidirectional radiation profile, with reduced spacing between the antenna and the photonic circuit element. As shown in figures 3 to 5, the photonic circuit element 50 comprises a plurality of conductive elements 54 printed on one surface of a dielectric substrate 52 and a ground plane 56 printed on an opposing surface of the dielectric substrate. As illustrated in figure 3, the conductive elements 54 are arranged in an array and are spaced from each other at regular intervals. Conductive vias 58 are provided through the dielectric substrate to electrically connect each of the conductive elements 54 to the ground plane 56. Essentially, the operating bandwidth of the photonic circuit element is proportional to the effective inductance of the conductive vias (L), and the capacitance between the conductive elements (C), and is represented as: BWcc-JTii (I) Thus, the bandwidth of the photonic circuit element is dependent upon the value of L and C. In order to achieve a photonic circuit element with a wide operating bandwidth, it is desirable to have a large inductance, L. Consequently, this will lead to long conductive via holes and a thick substrate to support the photonic circuit element.

The present invention provides a photonic circuit element with a reduced thickness and a wide operating bandwidth.

Summary of the Invention

In a first aspect of the invention, there is provided an apparatus for shaping a radiation pattern of an antenna, said apparatus comprising: a laminar dielectric substrate, defining first and second opposing planar surfaces, a plurality of conductive elements formed on said first planar surface of said laminar dielectric substrate and a ground element formed on said second planar surface of said laminar dielectric substrate, said laminar dielectric substrate having a plurality of conductive paths, wherein each of said plurality of said conductive paths corresponds to each of said plurality of conductive elements, said plurality of conductive paths being formed between said first planar surface of said laminar dielectric substrate and said ground plane; wherein each of said plurality of conductive elements comprises a further conductive path for providing electrical connection between each of said corresponding conductive paths and each of said plurality of conductive elements, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element.

Provision of a further conductive path between each of said plurality of conductive elements and each of said corresponding conducting paths allows the inductance of the photonic circuit to be increased without increasing the thickness of the laminar dielectric substrate.

In an embodiment of the above aspect, the apparatus may further comprise a further conductive element formed on said first surface of said first laminar dielectric substrate and between each of said conductive paths and each of said further conductive paths.

The conductive elements may be arranged in an array on said first surface of said surface of said laminar dielectric substrate.

The conductive elements may be substantially geometrically similar.

Alternatively, the conductive elements may be substantially geometrically non identical.

The conductive elements of said array may be spaced at regular intervals.

Alternatively, the conductive elements of said array may be spaced at irregular intervals.

Each of said conductive elements may be formed of regular or irregular structures.

The further conductive path may be a strip configuration.

The strip may be a substantially spiral-shaped strip configuration. It is noted that the inductance of the spiral-shaped strip can be varied by varying any one of the parameters of the spiral-shaped strip, including: (1) number of turns, (2) pitch angle of the spiral, or (3) width of the strip.

The spiral-shaped strip may emanate from said further conductive element towards said conductive element.

In a second aspect of the invention, there is provided an antenna for use in ultra wideband communications, the antenna comprising: a laminar dielectric substrate layer defining first and second opposing planar surfaces; a radiating element formed on said first planar surface, said radiating element comprising a signal feed point; an apparatus for shaping a radiation pattern of an antenna, said apparatus comprising: a further laminar dielectric substrate, defining first and second opposing planar surfaces, a plurality of conductive elements formed on said first planar surface of said laminar dielectric substrate and a ground element formed on said second planar surface of said further laminar dielectric substrate, said further laminar dielectric substrate having a plurality of conductive paths, wherein each of said plurality of said conductive paths corresponds to each of said plurality of conductive elements, said plurality of conductive paths being formed between said first planar surface of said further laminar dielectric substrate and said ground plane; wherein each of said plurality of conductive elements comprising a further conductive path for providing electrical connection between each of said corresponding conductive paths and each of said plurality of conductive elements, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element; wherein said first planar surface of said further laminar dielectric substrate is substantially coupled with said second planar surface of said laminar dielectric substrate such that said radiating element is operable to form a substantially unidirectional radiation profile.

The radiating element may be substantially tapered towards a narrow end thereof connected with said signal feedpoint, the distal wider end thereof having formed therein a substantially v-shaped notch thereby defining two lobes which diverge with increasing distance from said signal feedpoint, wherein outer edges of said lobes have formed therein a plurality of serrations to inhibit propagation of signal waves at said outer edges.

The v-shaped notch may be extended into said radiating element with an apex angle less than 90 degrees thereby substantially suppressing transverse signal modes of said radiating element.

The serrations are log-periodically distributed such that said radiating element is operable over a wide bandwidth of signal frequencies without increasing size of the radiating element.

The serrations may be formed to enable an enhanced rate of radiative energy loss along said edge thereby reducing reflection signal travelling back along said edge.

The serrations may be formed such that each serration tip is formed by the convergence of two serration edges.

The convergence of said two serration edges may be formed at an angle of between approximately 75° and 105°.

The serrations may be distributed such that corresponding dimensions of successive serrations increase log-periodically whereby the ratio of said corresponding dimensions in respect of successive serrations has constant predetermined ratio value.

The serrations of said opposing edges may be arranged axially symmetrically about an axis extending through the radiating element from said transmission line and between said two edges.

In a further independent aspect of the invention, there is provided a method of manufacturing an apparatus for shaping a radiation pattern of an antenna, the method comprising: providing a laminar dielectric substrate, defining first and second opposing planar surfaces; forming a plurality of conductive elements on said first planar surface of said laminar dielectric substrate and a ground element on said second planar surface of said laminar dielectric substrate; forming a plurality of conductive paths between said first planar surface of said laminar dielectric substrate and said ground plane, wherein each of said plurality of said conductive paths corresponds to each of said plurality of conductive elements; forming a further conductive path between each of said plurality of conductive elements and each of said corresponding conductive paths for providing electrical connection therebetweefl, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element.

In another further independent aspect of the invention, there is provided a method of manufacturing an antenna for use in ultra wideband communications, the method comprising: providing a laminar dielectric substrate layer defining first and second opposing planar surfaces; forming a radiating element on said first planar surface, said radiating element comprising a signal feed point; providing a further laminar dielectric substrate, defining first and second opposing planar surfaces; forming a plurality of conductive elements on said first planar surface of said further laminar dielectric substrate and a ground element on said second planar surface of said further laminar dielectric substrate; forming a plurality of conductive paths between said first planar surface of said further laminar dielectric substrate and said ground element, wherein each of said plurality of said conductive paths corresponds to each of said plurality of conductive elements; and forming a further conductive path between each of said plurality of conductive elements and each of said corresponding conductive paths for providing electrical connection therebetween, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element; coupling said first planar surface of said further laminar dielectric substrate with said second planar surface of said laminar dielectric substrate such that said radiating element is operable to form a substantially unidirectional radiation profile.

Brief description of the Drawinc

Embodiments of the present invention will now be described with reference to the accompanying drawings, wherein: Figure 1 shows a plan view of a front surface of an antenna; Figure 2 shows a side view of an antenna structure having an antenna element and a reflector; Figure 3 shows a plan view of a front surface of a photonic circuit element; Figure 4 shows a plan view of a back surface of the photonic circuit element illustrated in figure 3; Figure 5 shows a side view of the photonic circuit element illustrated in figure 3; Figure 6 shows a plan view of a front surface of a photonic circuit element according to an embodiment of the invention; Figure 7 shows a plan view of a back surface of the photonic circuit element illustrated infigure6; Figure 8 shows a side view of the photonic circuit element illustrated in figure 6; Figures 9 to 12 show alternative configurations of the conductive elements according to embodiments of the invention; and Figure 13 shows a side view of the antenna element illustrated in figure 1 coupled with the photonic circuit element illustrated in figure 6.

Detailed Description

Specific embodiments of the present invention will be described in further detail on the basis of the attached diagrams.

In the following description, a number of specific details are presented in order to provide a thorough understanding of embodiments of the present invention. It will be apparent, however, to a person skilled in the art that these specific details need not be employed to practice the present invention.

Figures 6 to 8 show various views of a photonic circuit element 80.

Figure 6 illustrates a front surface of the photonic circuit element 80 comprising a plurality of conductive elements 84 printed on one surface of a dielectric substrate 82.

Figure 7 illustrates a ground plane 86 printed on an opposing surface of the dielectric substrate 82. As illustrated in figure 6, the conductive elements 84 are geometrically similar and have square structures. The conductive elements 84 are arranged in an array and are spaced from each other at regular intervals. It is noted that the conductive elements 84 can be of different geometries and structures, and can be arranged in a different array pattern with elements spaced at irregular intervals. In fact, it is noted that such an arrangement would also substantially increase the operating bandwidth of the photonic circuit element.

As shown in figures 6 and 8, conductive vias 88 are provided through the dielectric substrate 82 and approximately in the middle of the conductive elements 84. In this example, the conductive elements.84 have a non-conductive etched out region 90 substantially surrounding the conductive vias 88. The conductive vias 88 are connected to the conductive elements 84 by conductive strips 92 provided therebetween. In this arrangement, each of the conductive elements 84 can be electrically connected to the ground plane 86. Essentially, the conductive strip 92 increases the inductance between the conductive elements 84 and the ground plane, thereby increasing the inductance of the photonic circuit structure without the thickness of the substrate being increased.

Figure 9 illustrates an alternative configuration of the conductive element 84. As shown in figure 9, a circular conductive element 94 is provided around the circumference of the conductive vias 88, between the stripline 92 and the conductive vias 88.

The etched out region 90 illustrated in figures 6 and 9 is substantially circular in shape and the strip 92 is provided directly across the radius of the circular etched out region 90. However, it is noted that the etched out region can be of different geometries.

Furthermore, different configurations of the strip 92 can also be used to increase the inductance between the conductive elements 84 and the ground plane 86.

Figures 10 to 12 show alternative configurations of the conductive element 84 according to the present invention.

As shown in figures 10 and 11, the strip 92 is replaced by a spiral shape strip 96 in order to further increase the inductance of the conductive element 84. It is also noted that the inductance can be varied by varying the parameters of the spiral shape strip 96, including the number of turns, the pitch angle of the spiral, and the width of the strip.

Figure 12 illustrates a conductive element having a square shape etched out region 98 and a square shape conductive element 100 around the conductive vias 88.

The photonic circuit element described above can be coupled to an antenna to form a substantially unidirectional radiation profile, with reduced spacing between the antenna and the photonic circuit element. The person skilled in the art would appreciate that any form of antenna structure can be employed with the photonic circuit element. One such antenna will now be described in detail with respect to figure 1 to aid in the understanding of the photonic circuit element described above.

Figure 1 shows a front surface of the planar antenna element 10 comprising a radiating element 12, a transmission line 19 and a ground plane element 27 printed on the dielectric substrate 14. The transmission line 19 has a signal feedpoint 15 to provide (and to receive) signal to and from the radiating element. The planar antenna is capable of being utilised in transmission and reception.

The opposing end of the signal feedpoint 1.5 of the transmission line 19 is connected to the radiating element 12. The radiating element 12 is shaped as a segment having two opposed slant edges 21, which diverge outwardly from an apex 16 of the segment.

The two opposed slant edges 21 diverge with increasing distance from the microstrip feed line 19 such that the radiating element 12 tapers outwardly from the transmission line 19. The radiating element 12 possesses two distal peripheral edges (11 and 13) which are arcuate and which respectively bridge the terminal outermost ends of the two opposed slant edges 21 and form curved outermost peripheries of the radiating element 12.

The radiating element 12 has two corresponding series of serrations 17 each formed within a respective one of the two opposed slant edges 21. Each serration of a given series of serrations is formed by a pair of successive angular (tapering) notches 18 which extend into the radiating element 12 from the respective slant edge 21. Each tapering notch has notch edges which converge to terminate within the radiating element 12 at a right-angled apex 18.

Each such serration, and the series of serrations 17 collectively, present a slow-wave structure to a signal propagating along the slant edge 21. Essentially, the slow-wave structure formed along the slant edge 21 of the radiating element 12 is provided with a meander which slows down the progress of a signal wave travelling along the slant edge 21. This is achieved by constraining the signal wave to progress along the longer meandering slant edge rather than to progress directly along a shorter linear slant edge. As a result, the radiating element is operable over a wide bandwidth of signal frequencies without increasing the physical size of the radiating element 12.

The meanders of the slant edge 21 are shaped such that the Q-factor of the antenna is minimised thereby reducing aperture clutter by reducing the relative magnitude of a signal reaching the terminal (open circuit) end of the slant edge 21 where signal reflection tends to occur, this being the source aperture clutter. The Q-factor of the radiating element 12 is given as: stored energy Q factor rate of energy loss Thus, the relative magnitude of a signal reaching the terminal outer edge of the slant edge (i.e. relative to the magnitude of that signal at the beginning of the slant edge) is sensitively dependent upon the rate of loss of energy from the signal during propagation along the slant edge. By suitably shaping the meanders of the slow-wave structure may enhance the rate of radiative energy loss of the propagating signal as it progresses along the slant edge thereby reducing aperture clutter.

Successive serrations of each series of serrations are shaped to increase in size relative to the preceding serrations in a log-period manner. Thus, the serrations in a given series have a common shape. In this example the common shape is a straight-edged serration with two tapering edges extending from the body of the radiating element 12 at predetermined angles and converging at increasing distance from the body of the radiating element 12 to a terminal right-angular serration tip or apex 18.

Each serration in a given series of serrations 17 possess two tapering edges which each extend from the body of the radiating element 12 at the same predetermined angles as occurs in respect of the edges of an adjacent serration of the series, and also converge at a right angular serration apex 18. The ratio of the lengths of the two tapering edges of any given serration is shared by all serrations in the same series since all serrations in a given series share the same general shape. However, due to log-periodic scaling, the lengths themselves increase by a predetermined scaling value such that the ratio of a serration edge length of a given serration and the corresponding edge length of the succeeding serration has a constant predetermining ratio value shared by all such neighbouring serrations.

Furthermore, each series of serrations 17 is arranged such that the distance between the location of the apex 18 of the segment of the radiating element 12 and the location of the serration increase log-periodically as one encounters successive serrations of a given series. The result is that the ratio of the aforesaid distance, as between two neighbouring (successive) serrations, is equal to a constant predetermined ratio value shared by all such neighbouring serrations. The location of the serration may be considered to be the location of the apex 18 of the tip of the serration in question, for

example.

The planar antenna element 10 also includes a ground plane 27 formed on the same surface as the radiating element 12. The ground plane 27 is separated from the transmission line 19 and the feed point 15 by the substrate 14 around the perimeter 25 of said transmission line 19 and feed point 15 thereby forming a coplanar waveguide structure.

In order to design an antenna which is capable of operating over a wide bandwidth, biasing and impedance effects of the associated DC networks must be considered from an RF or microwave perspective. DC biasing achieved from the use of RF chokes and resistors is effective only if the chokes are effectively an open circuit with no resonances, and if the combinations of inductance, resistance and capacitance do not limit the ability of the circuit to respond broad band.

The ground plane 27 comprises a plurality of slots 26 along its two longitudinal edges 28. The slots 26 along the longitudinal edges 28 have different lengths 29 and are spaced from each other at irregular intervals. In this configuration, the slots are essentially series inductance that functions as RF choke to attenuate any unwanted signals.

This configuration has an advantage in that all of the metallisation is formed on one surface of the dielectric substrate. This allows surface mount components for the associated circuitry to be mounted on the opposing surface, which is particularly useful for PCMCIA PC card applications.

Figure 13 illustrates a side view of the antenna of the present invention including the photonic element being positioned under the antenna element. This configuration provides an antenna that produces a unidirectional radiation characteristic. This antenna is unidirectional, having a substantially linearly polarised radiation.

It will be appreciated by those of ordinary skill in the art that the invention can be embodied in other specific forms without departing from the spirit or essential character thereof. The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than the foregoing description, and all changes which come within the meaning and range of equivalents thereof are intended to be embraced therein.

Claims

CLAIMS: 1. An apparatus for shaping a radiation pattern of an antenna, said apparatus comprising: a laminar dielectric substrate, defining first and second opposing planar surfaces, a plurality of conductive elements formed on said first planar surface of said laminar dielectric substrate and a ground element formed on said second planar surface of said laminar dielectric substrate, said laminar dielectric substrate having a plurality of conductive paths, wherein each of said plurality of said conductive paths corresponds to each of said plurality of io conductive elements, said plurality of conductive paths being formed between said first planar surface of said laminar dielectric substrate and said ground element; wherein each of said plurality of conductive elements comprises a further conductive path for providing electrical connection between each of said is corresponding conductive paths and each of said plurality of conductive elements, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element.
2. An apparatus according to claim 1 further comprising a further conductive element formed on said first surface of said first laminar dielectric substrate and between each of said conductive paths and each of said further conductive paths.
3. An apparatus according to claim 1 or claim 2, wherein said conductive elements are arranged in an array on said first surface of said surface of said laminar dielectric substrate.
4. An apparatus according to any one of the preceding claims, wherein said conductive elements are substantially geometrically similar.
5. An apparatus according to any one of the preceding claims, wherein said conductive elements are substantially geometrically non identical
6. An apparatus according to any one of the preceding claims, wherein said conductive elements of said array are spaced at regular intervals.
7. An apparatus according to any one of the preceding claims, wherein said conductive elements of said array are spaced at irregular intervals.
8. An apparatus according to any one of the preceding claims, wherein each of said conductive elements are formed of regular or irregular structures.
9. An apparatus according to any one of the preceding claims, wherein said further conductive path is a strip configuration.
10. An apparatus according to claim 9, wherein said strip is a substantially spiral-shaped strip configuration.
11. An apparatus according to claim 10, wherein said spiral-shaped strip is emanated from said further conductive element towards said conductive element.
12. An antenna for use in ultra wideband communications, the antenna comprising: a laminar dielectric substrate layer defining first and second opposing planar surfaces; a radiating element formed on said first planar surface, said radiating element comprising a signal feed point; an apparatus for shaping a radiation pattern of an antenna, said apparatus comprising: a further laminar dielectric substrate, defining flrst and second opposing planar surfaces, a plurality of conductive elements formed on said first planar surface of said laminar dielectric substrate and a ground element formed on said second planar surface of said further laminar dielectric substrate, said further laminar dielectric substrate having a plurality of conductive paths, wherein each of said plurality of said conductive paths corresponds to each of said plurality of conductive elements, said plura'ity of conductive paths being formed between said first planar surface of said further laminar dielectric substrate and said ground element; wherein each of said plurality of conductive elements comprising a further conductive path for providing electrical connection between each of said corresponding conductive paths and each of said plurality of conductive elements, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element; wherein said first planar surface of said further laminar dielectric substrate is substantially coupled with said second planar surface of said laminar dielectric substrate such that said radiating element is operable to form a substantially unidirectional radiation profile.
13. An antenna according to claim 12, wherein said radiating element is substantially tapered towards a narrow end thereof connected with said signal feedpoint, the distal wider end thereof having formed therein a substantially v-shaped notch thereby defining two lobes which diverge with increasing distance from said signal feedpoint, wherein outer edges of said lobes have formed therein a plurality of serrations to inhibit propagation of signal waves at said outer edges.
14. An antenna according to claim 13, wherein said v-shaped notch is extended into said radiating element with an apex angle less than 90 degrees thereby substantially suppressing transverse signal modes of said radiating element.
15, An antenna according to claim 13 or claim 14, wherein said serrations are log-periodically distributed such that said radiating element is operable over a wide bandwidth of signal frequencies without increasing size of the radiating element.
16. An antenna according to any one of claims 13 to 15, where said serrations is formed to enable an enhanced rate of radiative energy loss along said edge thereby reducing reflection signal travelling back along said edge.
17. An antenna according to any one of claims 13 to 16, wherein said serrations are formed such that each serration tip is formed by the convergence of two serration edges.
18. An antenna according to claim 17, wherein said convergence of said two serration edges is formed at an angle of between approximately 75° and 105°.
19. An antenna according to any one of claims 13 to 18, wherein said serrations are distributed such that corresponding dimensions of successive serrations increase log-periodically whereby the ratio of said corresponding dimensions in respect of successive serrations has constant predetermined ratio value.
20. An antenna according to any one of claims 13 to 19, wherein said serrations of said opposing edges are arranged axially symmetrically about an axis extending through the radiating element from said transmission line and between said two edges.
21. A method of manufacturing an apparatus for shaping a radiation pattern of an antenna, the method comprising: providing a laminar dielectric substrate, defining first and second opposing planar surfaces; forming a plurality of conductive elements on said first planar surface of said laminar dielectric substrate and a ground element on said second planar surface of said laminar dielectric substrate; forming a plurality of conductive paths between said first planar surface of said laminar dielectric substrate and said ground element, wherein each of said plurality of said conductive paths corresponds to each of said plurality of conductive elements; forming a further conductive path between each of said plurality of conductive elements and each of said corresponding conductive paths for providing electrical connection therebetween, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element when said photonic circuit structure.
22. A method according to claim 21 further comprising forming a further conductive element on said first surface of said first laminar dielectric substrate and between each of said conductive paths and each of said further conductive paths.
23. A method according to claim 21 or claim 22, wherein said conductive elements are arranged in an array on said first surface of said surface of said laminar dielectric substrate.
24. A method according to any one of claims 21 to 23, wherein said conductive elements are substantially geometrically similar.
25. A method according to any one of claims 21 to 23, wherein said conductive elements are substantially geometrically non identical
26. A method according to any one of claims 21 to 25, wherein said conductive elements of said array are spaced at regular intervals.
27. A method according to any one of claims 21 to 25, wherein said conductive elements of said array are spaced at irregular intervals.
28. A method according to any one of claims 21 to 27, wherein each of said conductive elements is formed of regular or irregular structures.
29. A method according to any one of claims 21 to 28, wherein said further conductive path is a strip configuration.
30. A method according to claim 29, wherein said strip is a substantially spiral-shaped strip configuration.
31. A method according to claim 30, wherein said spiral-shaped strip is emanated from said further conductive element towards said conductive element.
32. A method of manufacturing an antenna for use in ultra wideband communications, the method comprising: providing a laminar dielectric substrate layer defining first and second opposing planar surfaces; forming a radiating element on said first planar surface, said radiating element comprising a signal feed point; providing a further laminar dielectric substrate, defining first and second opposing planar surfaces; forming a plurality of conductive elements on said first planar surface of said further laminar dielectric substrate and a ground element on said second planar surface of said further laminar dielectric substrate; forming a plurality of conductive paths between said first planar surface of said further laminar dielectric substrate and said ground plane, wherein each of said plurality of said conductive paths corresponds to each of said plurality of conductive elements; forming a further conductive path between each of said plurality of conductive elements and each of said corresponding conductive paths for providing electrical connection therebetween, thereby allowing electrical connection to be established between said plurality of conductive elements and said ground element when said photonic circuit structure; and coupling said first planar surface of said further laminar dielectric substrate with said second planar surface of said laminar dielectric substrate such that said radiating element is operable to form a substantially unidirectional radiation profile.
33. A method according to claim 32, wherein said radiating element is substantially tapered towards a narrow end thereof connected with said signal feedpoint, the distal wider end thereof having formed therein a substantially v-shaped notch thereby defining two lobes which diverge with increasing distance from said signal feedpoint, wherein outer edges of said lobes have formed therein a plurality of serrations to inhibit propagation of signal waves at said outer edges.
34. A method according to claim 33, wherein said v-shaped notch is extended into said radiating element with an apex angle less than 90 degrees thereby substantially suppressing transverse signal modes of said radiating element.
35. A method according to claim 33 or claim 34, wherein said serrations are log-periodically distributed such that said radiating element is operable over a wide bandwidth of signal frequencies without increasing size of the radiating element.
36. A method according to any one of claims 33 to 35, where said serrations is formed to enable an enhanced rate of radiative energy loss along said edge thereby reducing reflection signal travelling back along said edge.
37. A method according to any one of claims 33 to 36, wherein said serrations are formed such that each serration tip is formed by the convergence of two serration edges.
38. A method according to claim 37, wherein said convergence of said two serration edges is formed at an angle of between approximately 750 and 105°.
39. A method according to any one of claims 33 to 38, wherein said serrations are distributed such that corresponding dimensions of successive serrations increase log-periodically whereby the ratio of said corresponding dimensions in respect of successive serrations has constant predetermined ratio value.
40. A method according to any one of claims 33 to 39, wherein said serrations of said opposing edges are arranged axially symmetrically about an axis extending through the radiating element from said transmission line and between said two edges.
41. An apparatus substantially as herein described with reference to figures 1 to 13.