Patent Application
20120293067
1. Field of the Invention
The present invention relates to a lamp to be driven from a source of microwave energy and having an electrodeless plasma discharge.
In the Parent application Ser. No. 12/227,750, the plasma discharge is in a bulb in a ceramic receptacle. In this Continuation in Part, the bulb and the ceramic receptacle are replaced by a two-region/two-volume arrangement.
Efficient coupling of microwave energy into the bulb is crucial to strongly exciting the contents of the bulb, to cause it to incandesce. For this reason, air wave guides have not been successful for this purpose.
2. Description of the Related Art
In U.S. Pat. No. 6,737,809, in the name of F M Espiau et al., there is described:
A dielectric waveguide integrated plasma lamp with a body consisting essentially of at least one dielectric material having a dielectric constant greater than approximately 2, and having a shape and dimensions such that the body resonates in at least one resonant mode when microwave energy of an appropriate frequency is coupled into the body. A bulb positioned in a cavity within the body contains a gas-fill which when receiving energy from the resonating body forms a light-emitting plasma. (Despite reference to a “bulb”, this specification does not describe a discrete bulb, separable from the lamp body.)
In our European Patent No. EP2188829—Our '829 patent, there is described and claimed (as granted):
A light source to be powered by microwave energy, the source having:
As used in Our '829 patent:
“lucent” means that the material, of the item which is described as lucent, is transparent or translucent—this meaning is also used in the present specification in respect of its invention;
“plasma crucible” means a closed body enclosing a plasma, the latter being in the void when the void's fill is excited by microwave energy from the antenna.
We describe the technology protected by Our '829 patent as our “LER” technology.
We have filed a series of patent applications on improvements in the LER technology.
There are certain alternatives to the LER technology, the principal one of which is known as the Clam Shell and is the subject of our International Patent Application No PCT/GB08/003,811. This describes and claims (as published):
A lamp comprising:
The LER patent, the Clam Shell application and the LER improvement applications have in common that they are in respect of:
A microwave plasma light source having:
In this specification, we refer to such a light source as a Lucent Waveguide Electromagnetic Wave Plasma Light Source, with the express proviso that this term is not necessarily intended to infer that the fabrication of solid-dielectric, lucent material fills the Faraday cage. Having rejected LUWAG EMPLIS as an acronym we use the abbreviated acronym LUWPL to refer to the light source of the previous paragraph. We pronounce this “loople”.
For the purposes of this specification, we define “microwave” to mean the three order of magnitude range from around 300 MHz to around 300 GHz. We anticipate that the 300 MHz lower end of the microwave range is above that at which a LUWPL of the present invention could be designed to operate, i.e. operation below 300 MHz is envisaged. Nevertheless we anticipate based on our experience of reasonable dimensions that normal operation will be in the microwave range. We believe that it is unnecessary to specify a feasible operating range for the present invention.
In our existing LUWPLs, the fabrication can be of continuous solid-dielectric material between opposite sides of the Faraday cage (with the exception of the excitable-material, closed void) as in a lucent crucible of our LER technology. Alternatively it can be effectively continuous as in a bulb in a bulb cavity of the “lucent waveguide” of our Clam Shell. Alternatively again fabrications of as yet unpublished applications on improvements in our technology include insulating spaces distinct from the excitable-material, closed void.
Accordingly it should be noted that whereas terminology in this art prior to our LER technology includes reference to an electroplated ceramic block as a waveguide and indeed the lucent crucible of our LER technology has been referred to as a waveguide; in the this specification, we use “waveguide” to indicate jointly:
Insofar as the lucent material may be of quartz and/or may contain glass, which materials have certain properties typical of solids and certain properties typical of liquids and as such are referred to as super-cooled liquids, super-cooled liquids are regarded as solids for the purposes of this specification.
Also for the avoidance of doubt “solid” is used in the context of the physical properties of the material concerned and not to infer that the component concerned is continuous as opposed to having voids therein.
There is a further clarification of terminology required. Historically a “Faraday cage” was an electrically conductive screen to protect occupants, animate or otherwise, from external electrical fields. With scientific advance, the term has come to mean a screen for blocking electromagnetic fields of a wide range of frequencies. A Faraday cage will not necessarily block electromagnetic radiation in the form of visible and invisible light. Insofar as a Faraday cage can screen an interior from external electromagnetic radiation, it can also retain electromagnetic radiation within itself. Its properties enabling it to do the one enable it to do the other. Whilst it is recognised that the term “Faraday cage” originates in respect of screening interiors, we have used the term in our earlier LUWPL patents and applications to refer to an electrical screen, in particular a lucent one, enclosing electromagnetic waves within a waveguide delimited by the cage. We continue with this use in this present specification.
The object of the present invention is to provide improved coupling of microwave energy to an electrodeless bulb in a lamp.
According to the invention there is provided a lamp to be driven from a source of microwave energy, the lamp comprising:
Whilst the preferred embodiment below the matching circuit is an air wave guide bandpass filter, it is specifically envisaged that a wave guide based on other dielectric materials may be used, for instance ceramic material. Such wave guide is described in U.S. Pat. No. 4,607,242.
Conveniently the circuit is arranged to be tunable, not only to take account of small production variations between the bulbs and the filters themselves, but also to give the filter bandwidth to include the resonant frequency of the wave guide and bulb.
An additional tuning element can be provided in the iris between the PECs.
We determine whether the coupling means is or is not “at least partially inductive” in accordance with whether or not the impedance of the light source, assessed at an input to the coupling means has an inductive component.
We can envisage certain arrangements in which the coupling means may not be totally surrounded by solid dielectric material. For instance, the coupling means may extend from solid dielectric material in the waveguide space and traverse an air gap therein. However we would not normally expect such air gap to exist.
The excitable plasma material containing void can be arranged wholly within the second, relatively low average dielectric constant region. Alternatively, it can extend through the Faraday cage and be partially without the cage and the second region.
In certain embodiments, the second region extends beyond the void in a direction from the inductive coupling means past the void. This is not the case in the first preferred embodiment described below.
Normally, the fabrication will have at least one cavity distinct from the plasma material void. In such case, the cavity can extend between an enclosure of the void and at least one peripheral wall in the fabrication, the peripheral wall having a thickness less than the extent of the cavity from the enclosure to the peripheral wall.
In a possible, but not preferred embodiment, the fabrication has at least one external dimension which is smaller than the respective dimension of the Faraday cage, the extent of the portion of the waveguide space between the fabrication and the Faraday cage being empty of solid dielectric material.
In another possible, but not preferred embodiment, the fabrication is arranged in the Faraday cage spaced from an end of the waveguide space opposite from its end at which the inductive coupler is arranged.
In another embodiment, the solid dielectric material surrounding the inductive coupling means is the same material as that of the fabrication.
In the first, preferred embodiment described below, the solid dielectric material surrounding the inductive coupling means is a material of a higher dielectric constant than that of the fabrication's material, the higher dielectric constant material being in a body surrounding the inductive coupling means and arranged adjacent to the fabrication.
Normally, the Faraday cage will be lucent for light radiation radially thereof. Also the Faraday cage is preferably lucent for light radiation forwardly thereof, that is away from the first, relatively high dielectric constant region of the waveguide space.
Again, normally the inductive coupling means will be or include an elongate antenna, which can be a plain wire extending in a bore in the body of relatively high dielectric constant material. Normally the bore will be a through bore in the said body with the antenna abutting the fabrication. A counterbore can be provided in the front face of the separate body abutting the rear face of the fabrication and the antenna is T-shaped (in profile) with its T head occupying the counterbore and abutting the fabrication.
In accordance with another aspect of the invention, there is provided a lamp to be driven from a source of microwave energy, the lamp comprising:
The difference in front and rear semi-volume volume average of dielectric constant can be caused by the said fabrication having end-to-end asymmetry and/or being asymmetrically positioned in the Faraday cage.
Preferably:
Possibly:
Further, preferably:
Where a separate body is used of the same or different dielectric material to that of the fabrication, the inductive coupling means can extend beyond the rear semi-volume into the front semi-volume as far as the fabrication.
Again, preferably:
Whilst, the or each cavity can be evacuated and/or gettered, normally the or each cavity will be occupied be a gas, in particular nitrogen, at low pressure of the order of one half to one tenth of an atmosphere. Possibly the or each cavity can be open to the ambient atmosphere.
It is possible for the enclosure void to extend laterally of the cavity, crossing a central axis of the fabrication. However, normally the enclosure of the void will extend on the central longitudinal, i.e. front to rear, axis of the fabrication.
The enclosure of the void can be connected to both a rear wall and a front wall of the fabrication. However, preferably the enclosure of the void is connected to the front wall only of the fabrication.
Preferably, the enclosure of the void extends through the front wall and partially through the Faraday cage.
Possibly the front wall can be domed. However, normally the front wall will be flat and parallel to a rear wall of the fabrication.
Normally, the enclosure of the void and the rest of the fabrication will be of the same lucent material. Nevertheless, the enclosure of the void and at least outer walls of the fabrication can be of the differing lucent material. For instance, the outer walls can be of cheaper glass for instance borosilicate glass or aluminosilicate glass. Further, the outer wall(s) can be of ultraviolet opaque material.
In the preferred embodiment, the part of the waveguide space occupied by the fabrication substantially equates to the front semi-volume.
Where provided, the separate body could be spaced from the fabrication, but preferably it abuts against a rear face of the fabrication and is located laterally by the Faraday cage. The fabrication can have a skirt with the separate body both abutting a rear face of the fabrication and being located laterally within the skirt.
Preferably the void enclosure is tubular.
Preferably the fabrication and the separate body of solid dielectric material, where provided, are bodies of rotation about a central longitudinal axis.
Alternatively, the fabrication and solid body can be of other shapes for instance of rectangular cross-section.
Conveniently the LUWPL is provided in combination with
Preferably the electromagnetic wave circuit is a tunable comb line filter; and.
The electromagnetic wave circuit can comprise:
A further tuning element can be provided in the iris between the PECs.
In accordance with a third aspect of the invention, there is provided a lamp to be driven from a source of microwave energy, the lamp comprising:
Conveniently, the fabrication and the alumina body together fill the waveguide space.
In accordance with a fourth aspect of the invention, there is a lamp to be driven from a source of microwave energy, the lamp comprising:
According to a fifth embodiment of the invention there is provided a lamp to be driven from a source of microwave energy, the lamp comprising:
Conveniently:
Alternatively:
The separate bodies where provided can be abutted against a rear face of the fabrication and be located laterally by the Faraday cage. However, preferably, the fabrication has a skirt with the separate body both abutting the rear face of the fabrication and being located laterally within the skirt.
To help understanding of the invention, a various embodiments thereof will now be described by way of example and with reference to the accompanying drawings, in which:
Referring to
Threaded tuning projections 14, 15 opposite the PECs and 16 in the iris are provided, whereby the pass band and the transmission characteristics of the filter in the pass band can be tuned to match the input impedance of the band pass filter and the wave guide to the output impedance of a microwave drive circuit (not shown). Typically the impedance will be 50Ω.
The wave guide 12 is of ceramic and metallised on its outer surfaces. It is mounted on one end of the filter chamber, with an electrodeless bulb 21 in a central cavity 22 directed axially away from the chamber and the radiator in a further cavity 23 set to one side of the central cavity. This arrangement is a lamp. The arrangement is such that the filter has a pass band including the resonant frequency of the wave guide, conveniently when resonant in the half wave mode. When the filter is driven, the wave guide resonates driving the bulb.
In use, the input impedance, of the combined matching circuit and ceramic wave guide with its bulb, is such that the microwaves at the design frequency are transmitted inwards of the input with negligible reflection. Waves reflected from the ceramic wave guide are reflected back into the wave guide from the output of the matching circuit and are not transmitted through the matching circuit for propagation back towards the drive circuit.
Turning now to
Whilst
The PECs 108,109 are 5.04 mm thick in the direction of the 16.04 mm height and 4.28 mm thick in the direction of the 6.60 mm thickness of the side walls 105,107. The PEC's are positioned at mid-height of the block in the direction of the height of the side walls. Also they are equally spaced from at 3.15 mm and parallel to the side walls. Thus they have an iris gap between them of 11.84 mm. Extending into the central cavity from the opposite direction, i.e. from the tuning side wall 105 is a full height iris ear 112 centrally placed and 5.70 mm thick. It extends 5.28 mm into the cavity. From the opposite side wall, the PECs extend 26.54 mm. The block, the PECs and the iris ear are all machined from solid. All internal corners are radiused 1.5 mm.
The tuning screws are received in finely tapped bore inserts 113 aligned with the central axes of the PECs. The thread is ¼ inch by 64 threads per inch UNS, which is a very fine thread and allows fine adjustment of the characteristics of the circuit.
The end walls are tapped to receive screws 115 for input and output connectors 116. These have central wires 117 which pass direct to the PECs 3.26 mm from the inside face of the opposite side walls. The PECs are drilled 1.3 mm to receive wires 117. These are soldered in position.
The invention of the Parent is not intended to be restricted to the details of the above described embodiment. For instance, the skin inside of the aluminium block and the side plates can be plated with very high conductivity metal such as silver or gold. A 2.4 GHz, the skin depth is 2 microns. Plating to 6 or 10 microns provides amply sufficient plating for the currents induced to be in the high conductivity plating.
Referring to
The end plate 5 is circular and has the enclosure 2 sealed in a central bore in it, the bore not being numbered as such. The plate is 2 mm thick. A similar plate 6 is positioned to leave a 10 mm separation between them with a small approximately 2 mm gap between the inner end of the enclosure and the inner plate 6. The plates are 34 mm in diameter and sealed in a drawn quartz tube 7, the tube having a 38 mm outside diameter and 2 mm wall thickness. The arrangement places the two tubes concentric with the two plates extending at right angles to their central axis. The concentric axis A and is the central axis of the waveguide as defined below.
The outer end 10 of the outer tube 7 is flush with the outside surface of the outer plate 5 and the inner end of the tube extends 17.5 mm back from the back surface of the inner plate 6 as a skirt 9. This structure provides:
Accommodated in the skirted recess is a right-circular-cylindrical block 14 of alumina dimensioned to fit the recess with a sliding fit. Its outside diameter is 33.9 mm and it is 17.7 mm thick. It has a central bore 15 of 2 mm diameter and a counter-bore 16 of 6 mm diameter and 0.5 mm depth in its outer face 17 abutting the back face of the inner plate 6. The rim of the outer face is chamfered against sealing splatter preventing the abuttal being close. An antenna 18 with a Tee/button head 19 is housed in the bore 15 and counter-bore 16.
The quartz fabrication 1 is accommodated in hexagonal perforated Faraday cage 20. This extends across the fabrication at the end plate 5 and back along the outer tube for the extent of the cavity 10. The cage has a central aperture 21 for the outer end of the void enclosure and an imperforate skirt 22 extending 8 mm further back than the quartz skirt 9, which accommodates the alumina block 14. An aluminium chassis block 23 carries the fabrication and the alumina body, with the imperforate cage skirt partially overlapping the aluminium block. Thus, the Faraday cage holds these two components together and against the block 23. Not only does the block provide mechanical support, but also electro-magnetic closure of the Faraday cage.
The above dimensions provide for the Faraday cage to be resonant at 2.45 GHz.
The waveguide space being the volume within the Faraday cage is notionally divided into two regions divided by the plane P at which the alumina block 14 abuts the inner plate 6 of the fabrication. The first inner region 24 contains the antenna, but this has negligible effect on the volume average of the dielectric constant of the material in the region. Within the region are the alumina block and the quartz skirt. These contribute to the volume averages as follows:
Alumina block 14: Volume=π×( 33.9/2)2×17.7=15967.7,
Dielectric constant=9.6,
Volume×Dielectric constant=153289.9.
Quartz Skirt 9 Volume=π×(( 38/2)2−( 34/2)2)×18=4069.4,
Dielectric constant=3.75,
Volume×D. constant=15260.3.
First Region 24 Volume=π×(( 38/2)2)×18=20403.7
Volume average dielectric constant=(153289.9+15260.3)/20403.7=8.26.
The second region 25 comprises the fabrication less the skirt. Its part contribute to the volume averages as follows:
Void Enclosure Volume=π×(( 8/2)2−( 4/2)2)×8=301.4,
Dielectric constant=3.75,
Volume×D. constant=1130.3.
Cavity Enclosure Volume=π×(( 38/2)2−( 34/2)2)×10=2260.8,
Dielectric constant=3.75,
Volume×D. constant=8478.1.
Outer Plate Volume=π×(( 38/2)2)×2=2267.1,
Dielectric constant=3.75,
Volume×D. constant=8501.6.
Inner Plate Volume=π×(( 38/2)2)×2=2267.1,
Dielectric constant=3.75,
Volume×D. constant=8501.6.
Cavity Volume=Entire volume less sum of quartz parts=15869.5−301.4−2260.8−2267.1−2267.1=8773.1,
Dielectric constant=1.00,
Volume×D. constant=8773.1.
Second Region 25 Volume=π×(( 38/2)2)×14=15869.5
Volume average dielectric constant=(1130.3+8478.1+8501.6+8501.6+8773.1)/15869.5=2.23.
It can thus be seen the volume averaged dielectric constant of the first region is markedly higher than that of the second region. This is due to the high dielectric constant of the alumina block. In turn the result of this is that the first region has a predominant effect on the resonant frequency of combination of parts contained within the wave guide.
The contrasting average values for the two regions, 8.26 and 2.23, can be usefully contrasted with the average for the entire waveguide space of (20403.7×8.26)+(15869.5×2.23)/(20403.7+15869.5)=5.62.
If the comparison of regions is not done of the basis of the first and second regions being divided by the abuttal plane between the fabrication and the alumina block, but between the two equal semi-volumes the comparison has an essentially similar result. The division plane V, parallel to the abutment plane, falls 1.85 mm into the alumina block. The latter is uniform in the direction of the axis A. Therefore the volume average of the first, rear semi-volume 26 remains 8.26. The second, other, front semi-volume 27 has a contribution from the slice of alumina and quartz skirt. This contribution can be calculated from its volume average dielectric constant:
1.85 mm slice Volume=π×( 38/2)2×1.85=301.4,
Dielectric constant=8.26,
Volume×D. constant=2097.0.
Front Semi-Volume Volume=π×(( 38/2)2)×14π+π×( 38/2)2×1.85=15869.5+301.4=16170.9
Volume average dielectric constant=(15869.5×2.23+2097.0)/16170.9=2.32.
Thus for this particular embodiment, using quartz, alumina, 2 mm wall thickness and an operating frequency of 2.45 GHz, the difference in ratio between:
Thus it can be said that the two ratios are alternative comparisons which are both determinative of the same inventive concept.
It will be noted that this LUWPL is appreciably smaller than an LER quartz crucible operating at 2.45 GHz, eg 49 mm in diameter by 19.7 mm long.
Turning now to
It should be noted that the arrangement described may not start spontaneously. In prototype operation, the plasma can be initiated by excitation with a Tesla coil device. Alternatively, the noble gas in the void can be radio-active such as Krypton 85. Again, it is anticipated that the plasma discharge can be initiated by apply a discharge of the automotive ignition type to an electrode positioned close to the end 4 of the void enclosure.
The resonant frequency of the fabrication and alumina block system changes marginally between start up when the plasma is only just establishing and full power when the plasma is full established and acts as a conductor within the plasma void. It is to accommodate this that a bandpass filter, such as described, is used between the microwave generator and the LUWPL.
Turning now to
Turning to another modified LUWPL as shown in
In the modified LUWPL of
In another modification, as shown in
In yet another modification, shown in
Turning to
Normally the components that are sealed to form the fabrications will be of quartz which is transparent to a wide spectrum of light. However, where it is desired to restrict the emission of certain coloured light and/or certain invisible light such as ultra-violet light, quartz which is opaque to such light can be used for the outer components of the fabrication or indeed for the whole fabrication. Again, other parts of the fabrication, apart from the void enclosure can be made of less expensive glass material.
The embodiment described above with reference to
Referring first to
The emitter as such has a central cavity 1011 in which is arranged a bulb 1012 having a void 1013 containing a microwave excitable material 1014. Typically the bulb is of transparent quartz. The cavity is surrounded by plane back and front walls 1015, 1016 and a circular cylindrical side wall 1017. The walls are sealed together, whereby the central cavity is sealed—typically with a vacuum maintained in it. In the embodiment shown, the bulb is integral with the front wall 1016 and extends towards the back wall with an insulating gap 1018 established at the distal/back end 1019 of the bulb.
The back, front and side walls define an enclosure 1020 for the cavity and are also formed of transparent quartz, whereby not only do they maintain the sealed nature of the cavity 1011, but they allow emission of light from the bulb, as explained in more detail below.
The cylindrical side wall extends back from the rear wall as a skirt 1021, defining with the back wall a recess 1022. In the recess is received—with a conventional engineering sliding as opposed to interference fit—a circular cylindrical, opaque body 1023 of alumina, which is a material of higher dielectric constant than quartz, typically 9.6 to 3.75. Centrally this has an antenna bore 10231 in which the antenna 1006 extends. The latter has a button head 1024, accommodated in a complementary recess 1025 in a front face 1026 of the body, the face being in abutment with the back wall 1015 of the enclosure. This arrangement places the high electric field present at the button in close proximity with the bulb and the excitable material in it.
A Faraday cage 1027 surrounds the enclosure, including the skirt 1021, extending back as far as a grounded, aluminium boss 1028 on which the light emitter is mounted, being held onto the boss by means of the cage and screws 1029 holding the cage to the boss. Thus the cage is grounded. The cage is reticular, that is netlike with apertures, in region of the cavity 1011 and plain further back to the boss 1028.
In use, microwaves are applied to the antenna and radiated into the enclosure from the antenna's button head 1024. Not only do they propagate to the bulb, but the enclosure together with the body, taking account of the dielectric constants of their materials, form a resonant system within the Faraday cage, as a result of which the microwaves propagated from the antenna build up a resonant electric field in the light emitter. The resultant electric field at the void in the bulb is much greater than it would be in the absence of the components being dimensioned for resonance. The field establishes a plasma in the excitable material in the void and light emitted therefrom radiates through the front and side walls. Nothing, except the bulb, extends into the cavity whereby no shadow is cast—as might be if the antenna extended into the cavity—except for any shadow from the Faraday cage. However its mesh is so small as not to cast a perceptible shadow.
Turning now to
For operation at 2.45 GHz, the tube 1101 is 28.7 mm long and has a 38 mm outside diameter and 2 mm wall thickness. The discs are of 2 mm plate, the disc 1102 being a sliding fit in the tube 1101 and the disc 1104 being of 38 mm diameter. The disc 1102 is fused 9 mm from the open end of the tube 1101. The bulb forming tube is set to extend 8 mm from the disc 1104, giving an assembled clearance of 1 mm from the plate 1102. This tube is 6 mm in diameter with a 1.5 mm wall thickness.
Thus are formed the:
With the resultant dimensions and the alumina body 1023 completely filling the recess 1022 within the skirt 1021 and the Faraday cage 1027 closely surrounding the emitter, resonance at 2.45 GHz is possible.
The dimensions of the antenna and its button head 1024 are important for maximum energy transfer into the resonant system. The aerial is of brass and 2 mm in diameter, with the button being 6 mm in diameter and 0.5 mm in thickness. The aerial extends into the boss 1028, where within an insulating sleeve 1030 of alumina, it is threaded into a connection 1031 from the matching circuit 1005,
Surrounding the enclosure 1020 and the skirt 1021, outside the Faraday cage 1027 extends a borosilicate glass cover 1032. This provides physical protection for the cage and the quartz enclosure and skirt. Also it filters and protects against any small amount of UV emission from the plasma—the Faraday cage protecting against microwave emission. A final detail of note is a bore 1033 through the alumina body 1023 for an optic fibre 1034 for detecting establishment of the plasma, where the microwave power for continued light emission can be controlled.
As can be appreciated from
The invention is not intended to be restricted to the details of the above described embodiments. For instance, the Faraday cage has been described as being reticular where lucent and imperforate around the alumina block and aluminium chassis block. It is formed from 0.12 mm sheet metal. Alternatively, it could be formed of wire mesh. Again the cage can be formed of an indium tin oxide deposit on the fabrication, suitably with a sheet metal cylinder surrounding the alumina and aluminium cylinders. Again where the fabrication and the alumina block are mounted on an aluminium chassis block, no light can leave via the alumina block. Where the alumina block is replaced with quartz, light can pass through this but not through the aluminium block. The block electrically closes the Faraday cage. The imperforate part of the cage can extend back as far as the aluminium block.
Indeed the cage can extend onto the back of the quartz with the aluminium block being of reduced diameter.
Another possibility is that there might be an air gap between the fabrication and the alumina block, with the antenna crossing the air gap to abut the fabrication.
Whereas above, the fabrication is said to be of quartz and the higher dielectric constant body is said to be of alumina; the fabrication could be of other lucent material such as polycrystalline alumina and the higher dielectric material body could also be of other ceramic material.
As regards frequency of operation, all the dimensional details above are for an operating frequency of 2.45 GHz. It is anticipated that since this LUWPL of the invention can be more compact at any specific operating frequency than an equivalent LER LUWPL, the LUWPLs of this invention will find application at lower frequencies such as 434 MHz (still within the generally accepted definition of the microwave range), due balance between greater size due to the longer wavelength of electromagnetic waves and reduced LUWPL size resulting from the invention. For 434 MHz frequency, a solid-state oscillator is expected to be feasible in place of a magnetron, such as is used in productions LUWPLs operating at 2.45 GHz. Such oscillators are expected to be more economic to produce and/or operate.
In all the above embodiments, the fabrication is asymmetric with respect to its central longitudinal axis, particularly due to its normally provided skirt. Nevertheless, it can be anticipated the fabrication could have such symmetry. For instance, the embodiment
Further, the above fabrications are positioned asymmetrically in the waveguide space. Not only is this because the fabrications are not arranged with the inter-region abutment plane P coincident with the semi-volume plane V, but also because the fabrication is towards one end of the waveguide space; whereas the separate solid dielectric material body is towards the other end. Nevertheless, it can be envisaged that the separate body could be united into the fabrication where it is of the same material. In this arrangement, the fabrication is not positioned asymmetrically in the waveguide space. Nevertheless it is asymmetric in itself, with a cavity at one end and being substantially voidless at the other to provided different end to end volume average of its dielectric constant.
Another possible variant is the provision of a forwards extending skirt on the aluminium carrier block. This can be provided with a skirt on the fabrication or not. With it, the Faraday cage can extend back outside the carrier block skirt and be secured to it. Alternatively, where the cage is a deposit on the fabrication, the carrier block skirted can be urged radially inwards onto the deposited cage material for contact with it.
This application is a Continuation-in-part application, which takes the benefit of and claims priority from U.S. application Ser. No. 12/227,752 filed on Apr. 7, 2009, the contents of which are hereby incorporated by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 12227752 | Apr 2009 | US |
| Child | 13453185 | US |
