AU626210B2 - Radio antennas - Google Patents

Description

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OPI DATE 25/08/89 w AOJP DATE 28/09/89 APPLN. ID 29443 89 PCT NUMBER PCT/GB89/00080 PCr INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT) (51) International Patent Classification 4 (l l) r nal licn Nd ber WO 89/ 07348 HO1Q 21/29, 9/28 Al (43) rn alI lic i Da|: TVAugust 1989 (10.08.89) (21) International Application Number: PCT/GB89/00080 (81) Designated States: AT (European patent), AU, BE (European patent), CH (European patent), DE (Euro- (22) International Filing Date: 27 January 1989 (27.01.89) pean patent), FR (European patent), GB (European patent), IT (European patent), JP, LU (European patent), NL (European patent), SE (European pate'), (31) Priority Application Number: 8802204 SU, US.

(32) Priority Date: 2 February 1988 (02.02.88) Published (33) Priority Country: GB With international search report.

(71X72) Applicants and Inventors: HATELY, Maurice, Clifford [GB/GB]: 1 Kenfield Place, Aberdeen ABI 'IW KABBARY, Fathi, Mohammed [EG/EG]: 2 Okasha Street, Flat 15, Dokki, Cairo (EG).

(74) Agent: KING, James, Bertram; Kings Patent Agency Limited, 73 Farringdon Road, London ECIM 3JB

(GB),

(54) Title: RADIO ANTENNAS (57) Abstract Two synchronised fields, one electric and one magnetic, x are created by two separate stimulating devices each of which is given half the final power of the radio wave synthesised by the geometric cross product of the said fields so as to form an in-/ tense Poynting vector which expands towards infinity, from the original small volume, Two vertical cylindrical electrodes and 31) are fed with about half the transmitter power by feeder (32) through matching and isolating transformer (33) so as to 3 cause a curved electric field as indicated by the E lines. The two horizontal circular plates (35 and 35) are separately fed by an s appropriately phased voltage (causing the displacement current o from feeder (36) via matching and isolating transformer (37) and the said radio frequency displacement current produces a s corresponding magnetic field H by reason of Maxwell's law VXH which field curves around the antenna crossing the said E lines so as to synthesise the said Poynting vector, The twin feeder crossed field antenna is a very compact radio antenna which is efficient, wide-band, low in Q, and will radiate or receive over a frequency band of more than twenty to one.

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Radio Antennas This invention relates to antennas for the transmission and reception of radio waves for telecommunications, broadcasting sound and television, radar, satellite communications and the like.

BO Known antennas usually have a single feeder 000 oa, connected to either a single conductor element of ;approximately half a wavelength, or to a single driven g°o 0 element within a group of parasitic elements as in the Yagi-Uda array. By means of added reactive components such as inductors, end capacitors, resonant traps and 00 such, antennas have been constructed with somewhat 000* smaller dimensions than the basic half wavelength element. Loop antennas are also known and are useful in direction finding. However most antennas of reduced dimensions have disappointing transmission efficiency 0 00 due to the necessarily increased circulation currents which cause large conductor losses and or magnetic core losses.

The Poynting Theorem states that for any superimposed electric and magnetic fields there must be energy flowing in the medium and thus the phenomenon of

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2 radio wave propagation has been explained in the presently accepted theory as the radiation of electromagnetic energy in the form of an electric field E and a magnetic field H in a cross-product Poynting vector E x H S watts per metre squared. The perpendicular geometric relationship and the time synchronism implied by the above formula must be produced by any antenna which is to radiate efficiently.

o o Presently known antennas are probably achieving the 10 requirements in an uncontrolled or accidental manner.

Q00 0 oo Due to extended physical dimensions and high So location above the ground, it is probable that there is o 0 fortuitously provided in the large volume of space a means of setting the necessary perpendicularity and o0 e simultaneity as well as a degree of rotationality for the fields, although the absence of these conjectures from 0 0 the present texts ought not to be used to condemn the validity of the concept. From the large surrounding and lightly stressed volume the comparatively weak Poynting 20 vector progresses outwards to infinity.

According to this invention there is provided a radio antenna in which electromagnetic waves are radiated from a small volume using two separate element systems, one of which produces a high frequency electric field, and the other of which produces a high frequency

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magnetic field, separate feeder means driving,- each said element system, each said element system bh-izi_ positioned in adjacent interactive -relationship cross stressing a common interaction zone of both said fields to create a source from which electromagnetic waves radiate.

In a preferred arrangement the said electric field is originated by establishing a radio frequency alternating potential difference across an interaction 0zone between two conducting surfaces or mater ials and across which zone a magnetic field of the same frequency is originated by an alternating current flowing in a 0 coil.

In an alternative preferred arrangement the said electric field is originated by establishing a radio 0:00 frequency potential difference across an interaction zone 0 :u between two conducting- surfaces or materials and in whichi zone a magnetic field of the same frequency is originated by applying a radio frequency potential difference between two other second conducting surfaces or materialsso that an intense radio frequency displacement current flowing between the second said surfaces will establish an intense circulating magnetic field and cause a significant portion to cross the said interaction zone.

In the present invention the objective adopted in the design is to synthesise and launch an intense r- I 4 Poynting vector from a very small volume which may be less than 1/100th of a wavelength in height or width or depth. Two separately controlled fields stimulated as radio frequency electric field E and an independent magnetic field H, driven by power from the same source but time phased so that across the interaction zone around the antenna there is E X H synchronism and Poynting vector synthesis occurs. Since it can be shown that the components of a radiated Poynting vector must have rotational E and H fields, then there is no absolute limit of reduction of size of antenna which will o° efficiently radiate a radio wave since very small but very intense Poynting vectors can once synthesised, expand to infinity just like radio wa.es initiated by conventional antennas.

This invention also relates to the said rac.io antenna in combination with a phasing unit in which the output of a radio transmitter is split into two parts having separate fixed or variable delay. arrangements to produce synchronised electric and magnetic fields at the interaction zone. Preferably, the phasing unit has fixed and variable phase delay circuits and one or more tapped transformers and switches by which each said part of the output of the said radio transmitter may be adjusted. The phasing unit may have a wideband constant I u V:i* 5 phase difference circuit for low power operation and driving two separate power amplifiers for developing sufficient power to provide separate feeds to the two electrode systems of the antenna so that within the interaction zone radio wave power is synthesised.

A preferred embodiment may include a single feeder to one electrode system and connected thereto a second feeder, or a phasing circuit, for driving the se3ond 0 electrode system in the correct phase and magnitude to synthesise electromagnetic waves at a predetermined o0 frequency. Alternatively the arrangement may be 00 o modified so that the two electrode systems are constructed as half structures with a conducting surface of sufficient area whereby the other half structure is o° o defined by a vertical image thereof.

o The radio antenna may be used to radiate or receive electromagnetic waves when mounted within or along with other conductors, or conducting surfaces forming an array in order to reflect, direct, focus or enhance the said- 0 °"o0o0 radiation or fed with either constant phase related power in parts, or varying phase power in parts so that a shaped radiation pattern is produced by said the array and directed in a desired direction or directions.

This invention also provides an antenna having a first set of bwo or more spaced elements defining 4 ^.4 9* T

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6 surfaces lying in end to end relationship with means to feed radio frequency power to produce an E-field between the set of elements, and a second set of two or more spaced elements defining surfaces in face to face parallel planes with means to feed radio frequency power to produce a displacement current therebetween to produce an H field therearound, the arrangement being such that interactive coupling between said E-field and said H- Sfield produces a propagating electromagnetic radio wave system.

0.0 Preferably the surfaces of said second set of Selements are positioned between the surfaces of said first set of elements and perpendicular thereto. The first set of elements may comprise coaxial cylinders, the So second set of elements comprising parallel circular plates, or the first set of elements may comprise plates, the second set of elements comprising parallel plates.

In a construction according to this invention there is provided an antenna for.an electromagnetic field '20 polarised in a predetermined direction at right angles to the field propagation direction, the field having a wide bandwidth range, the antenna comprising plural metal first elements that are not resonant in said bandwidth range excited to transduce an electric field in said polarisation direction over said oandwidth range, said 7 plural elements having an extent in the polarisation direction no greater than an order of magnitude less than *the shortest wavelength in the wide bandwidth range, means between said elements excited to transduce a magnetic field having lines of flux at right angles to the polarisation and propagation directions, said elements and means being arranged and said electric and magnetic fields being excited by power from the same source with phases so that there is an interaction region 0 10 of said fields between a pair of said metal elements to oo00o provide ExH synchronism and a radiation Poynting vector having rotational E and H fields to transduce said electromagnetic field.

Freferably, said elements include first and second ooo metal plates having spaced planar faces substantially at o°o right angles to the electric field, means for exciting the plates with voltages displaced in phase by 1800 so the electric field is established between said planar faces, a coil disposed between said plates and having '0 windings positioned to excite said lines of flux, and means for exciting said coil with current from the same source which excites the plates with a current displaced in phase by 90o relative to the voltages which excite the plates.

The faces of the plates may diverge from a central

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oI Y~I I ir-u V 8 region where the coil is located so that curved electric field lines extend between the plates. The said elements may further include first, second, third and fourth metal plates having spaced planar faces substantially at right angles to the electric field, means for exciting tht first and second. plates with a first voltage having the same phase and for exciting the third and fourth pla'es with a second voltage having the same phase, the first and second voltages being from the 10 same source and displaced in phase from each other by 1800, a coil disposed between said plates and having windings positioned to excite said lines of flux, and means for exciting said coil with current from the same source which excites the plates with a current displaced in phase by 90o relative to the voltages which excite the plates, The radio antenna described may be used for receiving electromagnetic waves by induction of a high frequency electric field (E-field) s-ignal in one said ,O (first) set or system of elements and induction of a high frequency magnetic field (H-field) signal in the other said (second) set or system of elements, said signals being combined to produce a radio frequency power output signal.

This invention and further preferred features are

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9 described and illustrated with reference to the accompanying drawings, showing embodiments by way of examples.

In the drawings: Figure 1 shows schematically a plan view of an embodiment with a horizontal coil, Figure 2 shows the embodiment of Figure 1 in elevation, Figure 3 shows a phasing unit for feeding an antenna according to the invention, Figure 4 shows a further feeder unit, Figure 5 shows an embodiment for radiation of vertically polarised waves, Figure 6 shows a further embodiment using capacitive effect to produce the magnetic field, Figure 7 shows an embodiment similar to Figure 6 using cylindrical elements.

Figure. 8 shows an embodciment forming a ground plane construction, and Figure 9 shows the feed arrangement for an antenna similar that shown in Figure 8.

Figure 1 shows a plan view of an elementary form of twin feeder crossed field antenna according to this invention. The horizontal coil 1 is fed by feeder 2 via 2 matching arid isolating transformer 3 and carries a radio frequency current shown by arrows indicating an anticlockwise maximum in the cycle time. Thus upwardly directed in the centre of the coil there is high magnetic field density H from J D' VXH which returns downwards all around the periphery of the coil. There are two pairs of conducting plates 4 and 5, 6 and 7, with planes standing vertically which are insulated from everythinig else but are fed with antiphase, voltage of the same frequency in pairs as shown, by power in feeder 8 via matching and isolating transformer 9. At the same instant in the cycle the plate pair 4 and 5 are electrically positive relative to the plate pair 6 and 7. Thus due to the very small dimension of the whole antenna, the Propagation delay across the interaction zones marked X and Y is negligible antd so the correct simultaneity, orthogonality and rotationality exists and Poynting vector synthesis occurs and radio power radiates away with thp, velocity of light in the g0 directions marked S.

Figure 2 shows the same antenna in elevation.

Detailed consideration of the phase requirement may be deduced as follows. Sinusoidal carrier waves are being applied and electric field E is in phase with the voltage across the plate pairs. The retardation due to tJ 4I 11 size is negligible as is the magnetic field retardation around the coil. Thus the field "T is in synchronism with the current causing it, that is the magnetic field is in phase with the current. Current in a coil is however always lagging by about 900 relative to the 0 0 voltage across the coil due to self inductance. So, in order to obtain phase synchronism of the fields o interacting in the crossed field antenna, the feed voltage to the coil needs to be approximately advanced on the feed voltage between the electrical plates. Assuming both transformers have identical phase characteristics, then the signal to feeder 2 requires to be phase advanced by 900 compared with the power in feeder 8. Cable lengths are only significant if different, so for a single frequency application an electrical quarter wavelength extra in feeder 8 would fulfil the phase requirement. If there were a power divider so that a single transmitter could supply approximately half the power to each .of the tLin feeders, the interaction zone will send out the eal power in the synthesised Poynting vector. An antenna for general radio communications requiring many operational frequency changes will require to have a phase adjusting unit.

Figure 3 shows a simple phasing unit with which the 12 said phase adjustment could be provided. The transmitter power is split partly into the upper capacitive path and partly into the lower inductive path.

Setting the capacitor 10 to some value will give advance; setting the inductor to another value will o 0 result in a corresponding 450 delay which will ensure that after stimulating the two fields the radio wave will be correctly synthesised in the interaction zones.

o Figure 4 shows a more sophisticated form of phasing unit which will provide phasing for any kind of twin feeder crossed field antenna under almost any Scircumstances over a wide frequency range. A switched a" o auto transformer 12 is connected to feeder output 88 and S is preceded by phase adjustment arrangements switchable into either sense by switch 14, of which coarse settings are provided by the dual gang switch 13A, 13B and a selection of cable lengths and a fine adjustment by the variable capacitor 16.

A more complex phase adjustment system,., (not shown) would have a series of two-pole change-over switches able to connect any total combination of delay cables selected from a sequence of lengths incremented in a 1/8 1/4 1/2 1 2 4 8 16 32 metre system. Such a scheme would allow a user to correct the phase of the feed to a crossed field antenna so well that a single device could be radiating -13successfully at any frequency in the whole HF spectrum.

In a further preferred arrangement the phasing unit has a wideband constant phase difference circuit for low power operation and followed, either inside the unit or outside as two separate units, by two separate power e0 amplifiers which develop sufficient power to provide S separate feeds to the two electrode systems of the antenna so that within the interaction zone sufficient 0 4 radio wave power is synthesised.

An alternative twin feeder crossed field antenna which will radiate vertically polarised waves instead of horizontal, is shown in Figure 5. The antenna consists o of a narrow vertical coil 17 fed from cable 2C via matching transformer 18, and two conducting plates 19 and fed by feeder 8C via matching and isolating transformer 21. A widespread electric field E is created in arcs from the top plate to the lower plate and produces a cross-product with the magnetic field H rotating in the directions indicated and thus synthesises intense Poynting vectors S which radiate outwards in broad azimuthal angles to space. The said antenna having several advantageous features namely a reduced number of components and also a larger interaction volume than has the first type according t "igures 1 and 2. The first feature reduces costs and simplifies the structure. The 26 14 second advantage gives enhanced signal voltages when used in the receive mode. Furthermore, since any one of the four input terminals (two plates and two coil terminals) may be connected to earth it will be optimal to have the lower plate earthed for safety as well as providing an Sopportunity to bond the screens of the coaxial feeders S thereto.

o It is possible for transformer 21 to be dispensed o* with, and direct feed from the inner of feeder 8C to be connected to the upper plate 19 with the screen remaining connected to plate As a further development of the twii .i.eeder crossed "o "field antenna types which use a coil to generate the magnetic field, a further arrangement is proposed called o the Maxwell type, in which the magnetic field is produce from an electric field displacement current located within Sa capacitor. It is an arrangement which has many advantages theoretically and practically, and allows the construction of a truly omni.directional vertically polarised antenna. Examination of the Maxwell law D' VXH where D' D/ t shows that a changing displacement field causes a rotational magnetic field. As the displacement current density is simply related in space (or in air) by the formula D' E' where E is the electric field intensity and is the dielectric l ml I I 15 constant,it is easy to calculate that this will be a very useful technique for HF crossed field antennas of small size. Also it can be seen that-as before, the S E X H relationship of the Poynting vector demands geometric perpenCicularity synchronism and rotational S form to both fields. The differentiation with respect to time within the Maxwell law again inserts a 900 phase r o change but in this type it is of the opposite sign.

There is a 90o advance of magnetic field relative to the voltage gradient and so there must be a 900 delay in the voltage fed to the plates of the said capacitor. The Maxwell type of crossed field antenna requires two oO separate electric field stimulator plates; one pair as in the first type to initiate the E field, and the other pair to initiate the magnetic field by the Maxwell law.

The second pair are called therefore, the D plates. I, total there are four phases of electric potential within the antenna structure: 0 and 180o of the E plates; and 2700 of the D plates.

Figure 6 shows a basic form of the Maxwell type of twin feeder crossed field antenna. Two flat plates 22 and 23, standing vertically are insulated from other electrodes and ground and are fed by coaxial cable 26 via matching and isolating transformer 27, thereby producing the electric field E shown in the downwards phase. Two i C U 16 insulated flat elliptical plates 24 and 25, disposed horizontally are also insulated from earth and other electrodes and constitute the capacitor within which a large displacement current density D' is produced by radio frequency power arriving from feeder 28 via pg pg matching and isolating transformer 29. The rapidly el aao changing displacement current is then the origin of the considerably curved H around the whole antenna in the So direction shown. In the wide interaction zones at mid height, in front of and behind the structure, copious field crossing is present and so considerable Poynting t vector power density is generated and radio waves 4 o4 o propagate away at the velocity of light in the directions shown S. The waves are vertically polarised; the horizontal polar diagram is a figure of eight. The lower plate may be earthed and the screens of the coaxial feeders bonded to it. The transformer 27 may be dispensed with and a direct connection made between the inner of the feeder 26 and the plate 23.

Many variants of the Maxwell type are conceivable and they constitute a generic family of twin feeder crossed field antennas disclosed herein. For instance the form described in Figure 6 could be turned through 900 and it will then generate horizontally polarised waves and have a radiation polar diagram which is a A T __li 17 figure of eight in the horizontal plane.

Two further antennas of this family will be described as they are important in having a robust structural shape as well as a vertically polarised omnidirectional radiation which is often required in 0 *0 0 o0 broadcasting and communicating to mobiles.

op V Figure 7 shows the cylindrical form of Maxwell type o0 crossed field antenna. The downwards electric field E o, is initiated by voltage between the hollow cylindrical conducting electrodes 30 and 31 which are fed from feeder 32 via matching transformer 33. The lower cylinder may °o stand safely on the ground or could be formed as a flat plate on site. The displacement current D is stimulated upwards at the same time in the cycle by 0004 feeding the appropriate phase voltage between the two horizontal disc conductors 34 and 35 (having their central °0 area removed for space to mount transformers, feeders etc.

using feeder 36 via matching and isolating transformer 37.

Should there be a requirement to reduce weight or wind.

2C resistance, the said electrodes and conductors may be made with alternative materials such as conducting wire mesh, or a conducting surface applied to a plastics or other nonconducting structural component.

Figure 8 shows a ground plane (or half symmetry) form of the cylindrical twin feeder crossed field antenna of the i S- 18 Maxwell type. The downwards electric field E is produced by applying a voltage between the hollow conducting cylinder 37 and the large conducting earth plane 38 with the upwards displacement current D' from the said earth plane to the circular conducting plate 39 with a central missing area marked 39a in order to create the required 9660 0 rotational magnetic field H to interact with the said E 6 field and synthesise the Poynting vector S radiating all round to space.

6 *o In a practical construction for the frequency range 3.6to30 MHz, the cylinder 37 has a height of 25 cm o6 6 and a diameter of 20 cm with the base spaced 10 cm from the 0 3 plate 39. Plate 39 has a diameter of 40 cm and is positioned coplanar to and 5 cm distance 66Q6 from plane 38. The parts may be mechanically connected by insulating pillars or foamed plastics blocks.

The feed arrangement is shown in Figure 9 and this has the E-field feeder 90 connected between ground plane 38 and Scylinder 37 and the H-field feeder 91 terminating in toroidal ferrite coupling transformer 92 feeding between ground plane 38 and plate 39. It is important that the outer conductor of feeder 91 is not electrically connected with any part of the structure.

For weatherproofing the structure may be encased for protection but in a preferred embodiment a louvred or 19 apertured screen is used in conjunction with a top cover to provide air through flow.

Twin feeder crossed field antennas of the above forms or other forms may be made almost as small as desired. With correct time phasing, the power radiated from the interaction zones can be made as large as o desired and is limited only by the necessary voltages at the electrodes and the ultimate possibility of corona x« o discharge. However since the plates are large in area 0 9 compared with the surface areas for wire antennas the problem is of comparative insignificance. Antennas of o^ o these types only 1/200 th of a wavelength in length (and less in diameter) have been able to radiate 400 watts on HF with no perceptible problems of electrode distress.

Calculations show that for the magnitudes of voltage used in wire antennas, teraWatt capabilities will be possible with crossed field antennas. There are no large circulating currents in any conductor since nothing is in resonance. It is a major advantage of the twin feeder crossed field antenna system that it is broadband, and low Q. For any given antenna radiating efficiently because it is correctly phased, the bandwidth is very broad, firstly because of the phase-sense of frequency change acting by the Maxwell Law is the same sense as change due to a wave on the delay cable, secondly because t P 's> *P 20 the two fields are both originated from capacitor stimulus and also change in the same phase sense, thirdly .the two fields interact in such a way as to pruvide a lower input impedance in each capacitor and therefore self-optimise the synthesis. Thus an antenna which is Sr say 1/400 th of a wavelength height may be expected to 0.0 e have a small depreciation of efficiency by a frequency change of about plus and minus SoMany of the electrical properties of the system described are uncritical. For instance the adjustments need in the phasing unit to produce a low VSWR in the common feeder leading will be found in practice to be selfo^"n optimising. The magnetic field generated around the displacement current capacitor is in the direction of curvature to reduce the impedance experienced by the electric field generator since the synthesised Poynting 9 I vector takes away power from the radio wave continuously, and at no part of the cycle do s the E field find its path as impedant as normal space; it is always presented to the field lines as a power sink as long as the magnetic field H is synchronous. For the same reasons, the H field lines find that they are flowing into a low reluctance interaction zone of a similar power sinking nature due to the cross-curved E field in phase at all times. Only in the unproductive zones around the antenna do the fields

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&3j -21 experience the normal path impedance and reluctances. The crossed field antenna system is almost an efficient 'open frequency" antenna. It will also receive radio signals and so may be used in two way radio systems.

In fact th~i device is such a small sized source that I4 o many techniques not before possible are now within easy achievement. When used in a reflecting or phasing arrangement, the crossed field antenna allows perceptible 4, 4 directivity to be attained in either transmit or receive modes even when the waves concerned are much larger v..han the reflector or array diameter.

The radio antenna may be used to radiate or receive 4 electromagnetic waves when mounted within or along with other conductors, or conducting surfaces in order to 0 to4 reflect, direct, focus or enhance the said radiation or fed with either constant phase related power in parts, or varying phase power in parts so that a shaped radiation pattern is produced by the array and may be directed in any desired direction or directions.

The invention also relates to the use of the antenna for radio communication through a medium comprising ground, water, air or space.

Claims (31)

1. 3. A radio antenna according to Claim 1 in which the said electric field is originated by establishing a radio frequency potential difference across an interaction zone between two conducting surfaces or materials and in which zone a magnetic field of the same frequency is originated II II 23 by applying a radio frequency potential difference between two other second conducting surfaces or materials so that an intense radio frequency displacement current flowing between the second said surfaces will establish an intense circulating magnetic field and cause a S significant portion to cross the said interaction zone.
2. 4. A radio antenna according to any one of Claims 1 to 3, in combination with a phasing unit in which the output of a radio transmitter is split into two parts having separate fixed or variable delay arrangements to produce synchronised electric and magnetic fields at o the interaction zone. A radio antenna according to Claim 4, wherein the phasing unit has fixed and variable phase delay circuits and one or more tapped transformers and switches by which each said part of the output of the said radio transmitter may be adjusted.-
3. 6. A radio antenna according to Claim 4 or 5, wherein the phasing unit has a wideband constant phase difference circuit for low power operation and driving two separate power amplifiers for developing sufficient power to provide separate feeds to the two electrode systems of I r i~c*rrp~- L"' 24 the antenna so that within the interaction zone radio wave power is synthesised.
4. 7. A radio antenna according to Claim 1 or 2 or 3, including a single feeder to one electrode system and connected thereto a second feeder, or a phasing circuit, for driving the second electrode system in the correct phase and magnitude to synthesise electromagnetic waves at a predetermined frequency. 0 n
5. 8. A radio antenna according to Claims 1 and 2, or 1 and 3, modified so that the two electrode systems are constructed as half structures with a conducting surface 0 of sufficient area whereby the other half structure is 0 o0. 0 defined by a vertical image thereof. 0 9, A radio antenna according to Claim 1 or 2 or 3, used to radiate or receive electromagnetic waves when mounted within or along with othex conductors, or conducting surfaces forming an array in order to reflect, direct, focus or enhance the said radiation or fed with either constant phase related power in parts, or varying phase power in parts so that a shaped radiation pattern is produced by said the array and directed in a desired direction or directions. An antenna having a firsb set of two or more spaced elements defining surfaces lying in end to end relationship with means to feed radio frequency power to produce an E-field between the set of elements, and a second set o_ two or more spaced elements defining surfaces in face to face parallel planes with means to feed radio frequency power to produce a displacement current therebetween to produce an H field therearound, I the arrangement being such that interactive coupling -40 between said E-field and said H-field produces a f- 0 0 Spropagating electromagnetic radio wave system. o e
6. 11. An antenna according to Claim 10, wherein the surfaces of said second set of elements are positioned between the surfaces of said first set of elements and 0i2 perpendicular thereto.
7. 12. An antenna according to Claim 10 or 11, wherein the oa fe first set of elements compris.e coaxial cylinders, the becond set of elements comprising parallel circular I plates.
8. 13. An antenna according to Claim 10 or 11 therein the first sat of elements comprise plates, the second set of elements comprising parallel plates. i r 2 r 26
9. 14. An antenna according to any one of Claims 10 to 13 wher in -the means for feeding radio frequency power comprises a coaxial feeder cable coupled through a transformer preferably embodying a ferrite toroidal core. An antenna according to any preceding Claim 10 to 14, wherein said first and second sets of elements are o °secured and spaced by electrically insulating support o000 members.
10. 16. An antenna according to any preceding claim 10 to forming a ground-plane structure wherein one of each of the spaced set of elements is constituted by a virtual «o o image of the other said element to the other side of a o 0 9 o ground plane element electrically bisecting the antenna.
11. 17. An antenna for an electromagnetic field polarised in a predetermined direction at right angles to the field propagation direction, the field having a wide bandwidth range, the antenna comprising plural metal first elements that are not eesonant in said bandwidth range excited to transduce an electric field in said polarisation direction over said bandwidth range, said plural elements having an extent in the polarisation direction no greater than an order of magnitude less than 0 r 27 the shortest wavelength in the wide bandwidth range, means between said elements excited to transduce a magnetic field having lines of flux at right-angles to the polarisation and propagation directions, said elements and means being arranged and said electric and magnetic fields being excited by power from the same source with phases so that there is an interaction region of said fields between a, pair of said metal elements to S provide ExH synchronism and a radiation Poynting vector S;a having rotational E and H fields to transduce said oa electromagnetic field.
12. 18. The antenna of Claim 17 wherein said elements include first and second metal plates having spaced o planar faces substantially at right angles to the electric field, means for exciting the plates with voltages displaced in phase by 1800 so the electric field is established between said planar faces, a coil disposed between said-plates and having windings positioned to excite said lines of flux, and means for exciting said coil with current from the same source which excites the plates with a current displaced in phase by 900 relative to the voltages which excite the plates. :1k, -28
13. 19. The antenna of Claim 18 wherein the faczes of the plates diverge from a central region where the coil is located so that curved electric field lines extend between the plates. The antenna of Claim 18 or 19 wherein said elements include first, second, third and fourth metal plates having spaced planar faces substantially at right angles to the electric field, means for exciting the first and second plates with a f irst voltage having the same phase and for exciting the third and fourth plates with a second voltage having the same phase, the first and second voltages being from the same source and displaced in phase from each other by 1800, a coil disposed between said plates and having windings positioned to excite said lines of flux, and means for exciting said coil with current from the same source which excites the plates with a current displaced in phase by 900 relative to the voltages which excite the plates.
14. 21. The antenna of Claim 18 or 19 or 20 wherein the faces of the plates diverge from a central region where the coil is located so that curved electric field lines extend between the first and third plates and between the second and fourth plates. 29
15. 22. The antenna of Claim 17 wherein at least one of the metal elements has a first surface extending in substantially the same direction as the electric field, at substantially right angles to the magnetic lines of flux and at substantially right angles to the propagation direction so that the electric field is curved as it propagates from said first surface to a second surface of another of the metal elements, and .0o4 means for exciting the elements including said first and second surfaces with voltages from the same source that oo Q are displaced 1800 from each other.
16. 23. The antenna of Claim 22 wherein the element including the second surface is configured so that the first and second surfaces extend in substantially the same direction. Ift
17. 24. The antenna of Claim 23 wherein the first and second surfaces are .s-ubstantially planar and substantially aligned. The antenna of Claim 23 wherein the first and second surfaces are cylindrical, the cylindrical surfaces having substantially the same radii and substantially common axes. ri 30
18. 26. The antenna of Claim 22 wherein the second element has a planar surface that extends in a plane substantially parallel to the propagation direction.
19. 27. The antenna of Claim 26 wherein the first surface is cylindrical, the cylindrical surface having an axis substantially at right angles to the plane of the second 00 eo 0 0 element.
20. 28. The antenna of Claim 22 wherein the means to 00 0D 00 0 transduce the magnetic field includes a coil disposed between said elements and having windings positioned to excite said lines of flux, and means for exciting said oo o coil with current from the same source which excites the o 0go elements with a current displaced in phase by 900 relative to the voltages which excite the elements. 4
21. 29. The antenna of Claim 28 wherein the element including the second surface is configured so that the first and second surfaces extend in substantially the same direction. The antenna ol Claim 29 wherein the fir3t and second surfaces are substantially planar and substantially aligned. J': 31
22. 31. The antenna of Claim 21 wherein the means to transduce the magnetic field comprises a capacitor having first and second substantially parallel planar electrodes extending substantially in the direction of propagation and substantially at right angles to the electric field lines, and means for exciting the electrodes so that voltages phase displaced from each other by 1800 are Se eo applied to the first and second electrodes so that a 800n displacement current correlated with the magnetic field subsists between the electrodes. 0
23. 32. The antenna of Claim 31 wherein at least one of the metal elements has a first surface extending in 9oD.: substantially the same direction as the electric field, o""So substantially at right angles to the magnetic lines of flux and substantially at right angles to the propagation direction so that the electric field is curved as it propagates from said first surface to a seco-nd surface of another of the metal elements, and means for exciting the elements including said first and second surfaces with voltages from the same source that are displaced 1800 from each other.
24. 33. The antenna of Claim 32 wherein the element including the second surface is configured so that the r fo 32 first and second surfaces extend in substantially the same direction.
25. 34. The antenna of Claim 33 wherein the first and second surfaces are substantially planar and substantially aligned. s o e The antenna of Claim 32 wherein the first and second ar surfaces are cylindrical, the cylindrical surfaces having substantially the same radii and substantially common axes.
26. 36. The antenna of Claim 32 wherein the second element o has a planar surface that extends in a plane substantially parallel to the propagation direction.
27. 37. The antenna of Claim 36 wherein the second element includes the second electrode.
28. 38. The antenna of Claim 37 wherein the first electrode includes a central aperture, a first cable including a first feed line extending through the aperture and connected to said first element and a second line connected to said second element, a second cable including a third and fourth lines connected to terminals 1 k y r 33 of a primary winding of a transformer having a secondary winding having opposite terminals respectively connected to the firjt electrode and the second element.
29. 39. The antenna of Claim 38 wherein said cables are coaxial, the first and third lines being centre conductors of the first and second cables, respectively, the second and fourth lines being shields of the first and second cables, respectively. S• 40. The antenna of Claim 37 wherein the first surface is cylindrical, the cylindrical surface having an axis at right angles to the plane of the second element. '2 41. A radio antenna or feeder system constructed and arranged to function as described herein and exemplified' with reference to the drawings.
30. 42. The use of a radio antenna according to any one of the preceding Claims for radio communication through a medium comprising ground, water, air or space.
31. 43. A radio antenna according to any one of the preceding claims used for receiving electromagnetic waves by induction of a high frequency electric field (E-field) p 0a aI~ 34 signal in one said (first) set or system of elements and induction of a high frequency magnetic field (H-field) signal in the other said *(second) set or system of elements, said signals being combined to produce a radio frequency power output signal. Dated this 31st day of March 1992 0 n 8-P o M.C. HATELY and F.M. KABBARY By their Patent Attorneys II LLIDAYS a 0 88s