EP4674075A1 - Method of radio telecommunication jamming and related radio telecommunication jamming system - Google Patents

Abstract

The present invention relates to a method of active radio telecommunication j amming comprising the steps of : setting up at least one transmitting station and one receiving station; providing at least one communication channel and one j amming channel between the two stations in the same carrier frequency; transmitting a j amming signal on the j amming channel; transmitting a communication signal on the communication channel during the transmission of the j amming signal; where at least the communication channel is set to a carrier wave characteri zed by an orbital angular momentum ( OAM). The invention also concerns a related telecommunications apparatus.

Description

Method of radio telecommunication jamming and related radio telecommunication jamming system

The present invention relates to a method of radio telecommunication interference (in jargon: jamming) and related radio telecommunication jamming system (in jargon: jammer) .

In the field of radio telecommunications, "jamming" generally refers to a desired condition of "interference", therefore deliberately created, so that it can also be defined as "actively" disturbed telecommunication. In the following, "interference" and "jamming" will be used synonymously.

The invention was made with reference to both analog and digital telecommunications.

Said telecommunication is at least of transmission and reception, but two-way communication is not excluded.

The invention was made in reference to both a single-user and multi-user transmission.

STATE OF THE ART

RECTIFIED SHEET (RULE 91) ISA/EP Jamming is the act of deliberately disturbing radio (wireless ) communications by decreasing the signal- to-noise ratio, an index of signal clarity ( in j argon SNR) , typically by transmitting on the same frequency and with the same modulation of the signal we want to disturb (Wikipedia ) .

Jamming is known for various uses , e . g . , to censor a data transmission, to confuse warning systems , and even for defensive military purposes to prevent the detonation command of improvised mines placed on the path of patrols . More generally, radio j ammers limit the management of the adversary ' s force by disrupting the communications of enemy command and control . A communication deliberately covered by a disturbance could also be desirable in many other civilian sectors .

Jamming has however the side ef fect of inhibiting the ability to communicate securely with a target , e . g . , with other patrol vehicles or drones used for exploration .

Therefore, it is of paramount importance to develop new technological solutions that allow users to be securely connected by distributing with transmitters on board mobile units , or in base stations the information in an ef ficient manner, previously obtained through satellite communications or reached by other methods of point-to-point data distribution between base stations , by associating multiple data transmission channels independent from each other in a frequency band for a given geographic area .

RECTIFIED SHEET (RULE 91 ) ISA/EP Some examples of j ammers available on the market come from ECS Ltd (UK) , such as Grif fin, with frequency coverage 20MHz-2500MHz in 11 independent bands and Falcon Plus , a Radio Controlled Improvised Explosive Devices (RCIEDs ) j ammer, which is a vehicle-mounted programmable broadband radio frequency inhibitor with a total output power of 140 Watts .

There are other units of greater power made to create a cell- free zone up to 1 . 5 km away from the j ammer . To inhibit channel access to external users , the j ammer must at all times occupy a large part of the frequency spectrum with noise or with an encrypted/dummy communication channel that can also be used to share information between vehicles or patrols .

Even i f the communication channel is outside the j ammed bands , in any case, due to the presence of spurious harmonics and of power that is inevitably intercepted by the receiving antennas , interference with the receiving devices becomes unavoidable . The use of band filters for adj acent frequencies also limits any possible communication between vehicles in any case . A lot of power is needed to overcome the background noise and the ef fect of filters . There is still noise due to the effect of ultra-wideband emitters on the receiving antennas . The intermodulation devices generated by the ultra-wideband spectra also increase noise in the receiving band of the receiver .

In conclusion : the state of the art available today is that the only way to communicate between vehicles during a patrol , or in any case between two

RECTIFIED SHEET (RULE 91 ) ISA/EP af fected users , covered by electronic j amming is to occupy a frequency and use it alternately for disturbance and communication .

Instead, it would be desirable to communicate in the same frequency band of the interference transmission simultaneously with the interference transmission, thus sharing the same band .

The purpose of the present invention is therefore to overcome all or part of the problems of the known technique .

In particular, a preferred purpose of the present invention is to allow the simultaneous transmission of interference and communication in the same frequency with a high quality of the communication signal on the receiving side .

A preferred purpose of the present invention is to allow said simultaneous transmission between mobile transmitters and receivers .

Another further preferred purpose is to provide an easy and practical method to perform said transmission .

Another preferred purpose of the present invention is to provide a system for making said transmission easy and inexpensive to build .

GENERAL INTRODUCTION

The purposes are achieved by the invention as defined in the attached claims , which are incorporated as an integral part of the present description .

RECTIFIED SHEET (RULE 91 ) ISA/EP In general , the present invention solves at least in part the problems of the known technique by adopting " radio vortices" to set up the communication channels .

"Radio vortices" are " radio waves" with a spatial memory, also called " twisted waves" , which carry finite amounts of orbital angular momentum - referred to by the acronym OAM . In the following, radio vortices are therefore also referred to as "OAM waves" . The phase model of OAM waves , to use a practical and non- restrictive figurative example , is similar to fusilli ( a famous Italian spiral-shaped pasta) .

In particular, according to its first general aspect , the present invention concerns a method of j ammed radio telecommunication comprising the following phases : setting up at least one transmitting station and one receiving station ; setting up at least one communication channel and one j amming channel between the two stations in the same carrier frequency; transmitting a j amming signal on the j amming channel ; transmitting a communication signal on the communication channel during the transmission of the interference signal ; where at least the communication channel is set to a carrier wave characteri zed by an orbital angular momentum ( OAM) .

RECTIFIED SHEET (RULE 91 ) ISA/EP According to a second general aspect , the invention concerns a radio communication j amming system comprising : at least one transmitting station ( Tx ) and one receiving station (Rx) ;

- at least one communication channel ( Chx, x ) and one interference channel ( Chx, x ) between the two stations in the same carrier frequency; at least one interference signal transmitted on the j amming channel ; at least one communication signal transmitted on the communication channel during the transmission of the j amming signal ; where at least the communication channel is set to a carrier wave with an orbital angular momentum

( OAM) .

DETAILED DESCRIPTION

Further features and advantages of the present invention will be best seen in the following detailed description of its preferred applications , made with reference to the attached drawings , and given as an indication and not as a limitation . In such drawings :

Figure 1 schematically shows a telecommunication system according to the present invention, and the first telecommunication channels defined by it ;

Figure 2 shows a telecommunication system according to the present invention with a di fferent

RECTIFIED SHEET (RULE 91 ) ISA/EP arrangement of the antennas compared to the system in Figure 1 , seen in a plane orthogonal to the direction of propagation, where said first channels are highlighted;

Figure 3 schematically shows the system of Figure 2 in perspective view where the division into sections of the radio transmission device is highlighted;

- Figure 4 shows the sectors of the cylindrical wavefront of the twisted electromagnetic wave of Figures 2 and 3 , subdivided by the sections of the radio transmission device ;

- Figure 5 shows the first and second channels according to the present invention generated through the same system as in Figure 1 ;

- Figure 6 shows the first and second channels according to the present invention generated through the same system as in Figures 2 to 4 ;

- Figure 7 shows the sectors of the cylindrical wavefronts of the twisted electromagnetic waves , generated by the system in Figure 6 ;

- Figures 8 and 9 show an example of a practical application of a communication system mounted on a pair of vehicles .

With reference to Figure 1 , a first radio telecommunication system is represented according to the present invention, indicated as a whole by reference number 1 .

Said system comprises at least one radio transmitting device 2 , hereinafter referred to for brevity as Tx or transmitting receiving station, and one

RECTIFIED SHEET (RULE 91 ) ISA/EP radio receiving device 3 , hereinafter referred to for brevity as Rx or receiving station .

System 1 defines between Rx and Tx a set of telecommunication channels having in common the same frequency and the fact that they are defined by an electromagnetic wave in a carrier frequency with the phase twisted around a predetermined direction in space , hereinafter referred to as twisted wave or carrier wave for brevity .

Figure 1 in particular shows a plurality of first telecommunication channels Chl , l and Chi , 2 , which have in common :

- the same carrier electromagnetic wave Wl ;

- the same angular momentum 0AM1 of said wave Wl .

Said channels are dif ferent from each other in that each of them corresponds to a respective S l-Sp sector of the wavefront of said twisted carrier electromagnetic wave Wl .

In each sector, wave Wl is modulated di f ferently than in the other sectors . Said modulation is preferably in at least one of the following : phase, amplitude, polari zation, frequency, path diversity, and other methods of known art .

Frequency modulation is intended as a modulation of the carrier frequency within a predetermined bandwidth, in which case for the purposes of the present invention the corresponding channels are considered carrier frequency channels . In general , the carrier frequency is preferably in the order of Mhz , while the

RECTIFIED SHEET (RULE 91 ) ISA/EP modulation bandwidth is in the order of magnitude of KHz. For example, for a carrier frequency of 88.8 MHz the modulation bandwidth can be +/- 100 KHz.

In general, the bandwidth is therefore preferably a fraction of the frequency of the carrier wave (or, in jargon, of the "carrier") .

The channels are centered on the carrier wave frequency, where an FM radio "tunes in" for example; the frequency modulation does not appreciably change the 0AM, and phase modulations such as those of digital multiplexing (MUX) like PSK, QPSK, QAM and so on, such as digital TV MUXes for example, are a small perturbation in phase (a controlled ripple) on the fusillo azimuthal phase typical of each of the 0AM states. Each channel in that chosen 0AM state acts as a "phase carrier" on a channel characterized by a carrier frequency.

To sum up, we therefore have the possibility to make a frequency modulation on the carrier frequency and a phase modulation on the carrier phase shape characteristic of each 0AM state. Each 0AM state obviously has its own phase imprint which is like a 1- layer spiral, with 0AM 1=+1 if levorotatory or 1=-1 if dextrorotatory or with 2 or more layers, ideally up to spirals with infinite layers. A non-limiting figurative example is fusilli, i.e., the well-known pasta shape.

The Tx transmission device in general includes: a plurality of Tl-Tn transmitting antennas;

RECTIFIED SHEET (RULE 91) ISA/EP a plurality of Sl-Sp modulation sections, each defined by a group of said antennas operationally associated with each other; piloting means 10, configured to drive said Tl-Tn antennas to generate at least one electromagnetic wave, preferably a plurality of them (Wl-Wk) , with respective desired and distinct angular orbital momenta (0AM) for each wave;

- modulation means 11, operationally associated with said sections (Sl-Sp) to modulate corresponding sectors of the fronts of said electromagnetic waves with orbital angular momentum (0AM) , where the modulations of the sectors of each wave are independent of each other.

In this way, every single electromagnetic wave with 0AM is used as the main signal carrier and each sector of each of these waves corresponds to a channel.

Preferably, the piloting means 10 modulate in at least one of the following: amplitude, frequency, path diversity and phase.

Preferably, the modulation means 11 modulate in at least one of the following: amplitude, frequency, path diversity and phase.

As a practical figurative example, we can imagine a parallel with a well-known pasta shape. Let's imagine, for example, the spatial structure of the 0AM "carrier" as a fusillo (the screw shape of a well-known pasta) ; we can imagine each fusillo associated with 0AM as having lines or small undulations that do not significantly alter its main flap structure, i.e., they always remain fusilli. To have an 0AM channel, we need a fusillo with a

RECTIFIED SHEET (RULE 91) ISA/EP number of flaps equal to the OAM 1 value, therefore the structure must be maintained, and the various modulations do nothing but add a small structure on top of the main fusillo structure . The modulation in phase can be thought of as a groove in the fusillo , and in amplitude as a variation in the si ze of the fusillo , but in any case they preserve the average topology of the phase structure of the OAM .

Figure 1 shows the example of a single twisted electromagnetic wave W1 where the S l-Sp sectors of the corresponding wavefront define as many channels Chi , 1 (W1/0AM1 , S I ) and Ohl , 2 (W1 /0AM1 , S2 ) . Wave W1 has orbital angular momentum 0AM1 .

Figure 5 shows the general example of two twisted electromagnetic waves Wl , W2 generated by the same Tx of Figure 1 with respective orbital angular momenta 0AM1 and 0AM2 , where the wavefronts are divided into the same sectors Sl-Sp . The second wave W2 therefore doubles the number of channels , as it associates the same number of channels of wave Wl to its 0AM2 . Additional channels are indicated with Ch2 , 1 (W2/OAM2 , S I ) and Ch2 , 2 (W2/OAM2 , S2 ) .

The Rx receiving device is placed at a distance from Tx and includes : a plurality of Rl -Rm receiving antennas ; discrimination means 20 , operationally associated with said receiving antennas and configured to carry out amplitude and phase measurements of the electromagnetic field at di f ferent reception points (R) in order to acquire first data (DATA1 ) indicative of the

RECTIFIED SHEET (RULE 91 ) ISA/EP individual discrimination of said electromagnetic waves Wl-Wk and to process them into second data (DATA2 ) indicative of the discrimination in sectors S I . . . , Sp of each wavefront .

Finally, the discrimination means 20 are configured to process said second DATA2 data in order to obtain third DATA3 data that allow to discriminate in di f ferent Sl-Sp sectors of the various wavefronts the Chx, x data transmission channels , i f present .

Figure 1 shows an example of transmitting device 2 where the Tl-Tn antennas are arranged to define an ( ideal ) transmitting surface T and a transmitting direction D orthogonal to it . Such an ideal transmission surface is , for example , a transmission plane . Preferably, the antennas are arranged in a radial pattern around a D axis orthogonal to the transmitting surface . Overall , the wavefront is omnidirectional and is modulated sector by sector . I f we need to communicate with an Rx target moving with respect to Tx or in any case towards a predetermined direction, it is the modulation that points or follows the receiver, while the carrier wave remains omnidirectional .

More generally, there can be two cases : in the first case , the wave is omnidirectional and therefore the D axis is orthogonal to the propagation plane and the modulation of the omnidirectional carrier wave towards a predetermined Rx receiver is done using part of the antennas . In the second case, the wave is not omnidirectional and propagates from a point A to a point

RECTIFIED SHEET (RULE 91 ) ISA/EP B. Also in this case various sectors can be modulated independently, for instance like a satellite transmission to different users, which broadcasts to Earth but transmits different channels in different directions always using different modulations along different directions; in this case the D axis coincides with the propagation axis.

In the example in Figure 1, the receiving antennas Rl-Rm are arranged as to define an (ideal) receiving surface R intersecting the wavefront and orthogonal to the transmission direction D - this ideal receiving surface is e.g. a receiving plane.

In the following, alternative forms of implementation of the invention will be described, where elements that are the same or similar to the previous ones will be indicated with the same reference numbers, or with the same numbers increased by 100 or multiples thereof .

Figures 2-4 and 6-7 show an alternative form of implementation of a radio telecommunication system denoted as a whole by reference number 101, which differs from system 1 described above substantially by a different reciprocal arrangement of the transmitting and receiving antennas.

In particular, the Tx 102 transmitting device has the Tl-Tn antennas arranged as to define a transmitting surface T and a transmission direction parallel to said surface, e.g., with a cylindrical or conical wavefront.

RECTIFIED SHEET (RULE 91) ISA/EP The Rx 103 receiving device has the Rl -Rm receiving antennas arranged as to envelop the propagation wavefront transmitted by Tx .

For example , when said wavefront is cylindrical or conical around said D axis , the receiving antennas Rl - Rn are arranged in a radial pattern around said axis .

For example , the Rl-Rm receiving antennas can be arranged as to define a plurality of receiving surfaces concentric to the D axis .

For example , the discrimination means 20 of the Rx 103 device can be configured to perform an anamorphic trans formation of af fine homology of the wavefront propagating with conic or cylindrical symmetry centered on the D axis .

The two devices 1 and 101 are able to generate the same channels .

For the sake of completeness , we note that Figure 7 shows the general example of two twisted electromagnetic waves Wl , W2 generated by the same Tx of Figures 2 , 3 and 4 with their respective orbital angular momenta 0AM1 and 0AM2 where the wavefronts are divided into the same S l-Sp sectors . The second wave W2 therefore doubles the number of channels , as it associates the same number of channels of wave Wl to its 0AM2 . Additional channels are indicated with Ch2 , 1 (W2/OAM2 , SI ) and Ch2 , 2 (W2/OAM2 , S2 ) .

In general , in practice multiple channels can be advantageously associated with each 0AM wave by

RECTIFIED SHEET (RULE 91 ) ISA/EP independently modulating non-overlapping sectors of the wavefront .

In other words , the modulation in the S l -Sp sectors of the wavefronts of each OAM wave can be considered as a real novelty, which identi fies at least one of the Chx, x data channels that are transmitted simultaneously, on the same carrier frequency, in the same OAM mode either in an omnidirectional direction or along one direction, fixed or selectable .

This represents a maj or element of di f ferentiation with respect to the apparatuses of known art .

In the present invention, in general , each twisted OAM electromagnetic wave , received in correspondence with a generic reception plane , is associated with a data channel ChX, X for which the identi fying quantity is constituted by the orbital angular momentum OAM of the Wl-Wk wave itsel f .

In order to detect the identi fying quantity, i . e . the OAM, of a given data channel Chx, x, it is therefore necessary to know the exact rotation value of the wavefront phase of the electromagnetic wave received in correspondence with the reception plane R, and then to perform phase measurements of the electromagnetic field in correspondence with the chosen wavefront sector and on the corresponding receiving surface R .

RECTIFIED SHEET (RULE 91 ) ISA/EP In practice , only one or more angular sectors of the chosen OAM wave are modulated to communicate with a desired receiver Rx by means of the appropriate selection of some of the antennas that make up the Tx array . Those that are used to communicate toward a chosen Rx receiving user will transmit codes , symbols , or other types of signals modulated on the wave with OAM, while the rest of the antennas can, for example, contribute to j amming by sending random symbols or signals , or communicate with other Rx users . The j amming transmission can be simultaneous with the data communication transmission, for example , the j amming transmission can be continuous . The resulting channels used for said communication transmission are herein referred to as communication channels , and those used for j amming are called j amming channels .

The OAM transmission of the present invention is called " selective" because it preferably activates one or more Tl-Tn antennas oriented towards one or more Rx receiving devices by means of an electronic feedback ( not excluding the mechanical one ) which appropriately activates one or more antennas that transmit OAM and directs the desired transmission within certain angular sectors of the omnidirectional beam that identi fy the directions of the receiving stations (which can in turn be other j amming sources ) . Thi s system also makes it possible to direct and tighten at will each angular sector (or cone ) of communication where the communication modulation takes place . The rest of the wavefront can be

RECTIFIED SHEET (RULE 91 ) ISA/EP a source of j amming, which takes place by means of a modulation to be chosen appropriately .

GENERAL DEFINITIONS

As is known from the literature, the OAM of an electromagnetic wave is a guantity that uniguely characteri zes an azimuthal phase distribution in the wavefront on a plane orthogonal to the propagation of the wave itsel f and around the propagation axis D of the wave itsel f .

More precisely, the OAM associated with an electromagnetic wave is characteri zed by an integer quantity, positive or negative , which expresses the number of complete rotations ( i . e . 360 degrees ) made in the wavefront within a distance equal to the wavelength in a left- or right-handed sense .

An electromagnetic wave with non- zero OAM value has a region in which the electromagnetic field, in a neighborhood of the line coincident with the direction of propagation, also known as the electromagnetic vortex, has intensity and amplitude that tend to zero . This phenomenon is due to di f fraction ef fects in the remote transmission of the electromagnetic wave .

Electromagnetic waves with an integer value of OAM have a characteristic intensity structure with an axial symmetry in the form of concentric rings characteri zed by dif ferent values of electromagnetic field intensity on a plane orthogonal ( in j argon "doughnut" ) to the propagation axis , and a phase

RECTIFIED SHEET (RULE 91 ) ISA/EP structure characteri zed by a finite number of spirals wrapped along the direction of propagation D and formed by the phase of the wavefront , properties independent , in the far field, from the polari zation state of the wave itsel f ( in j argon " fusilli" ) . In this case , it is said that the electromagnetic wave has a well-defined spatial structure of phase and amplitude that is preserved during propagation in a preferably homogeneous medium .

The present invention associates at least two independent data transmission channels with an electromagnetic wave having a certain carrier frequency and a certain OAM . The channels can be used both to carry a communication signal and to transport a disturbing signal ( amming) , a distinction is therefore made between communication channels and interference channels .

The definition o f "data transmis sion channel" (or "data channel" ) is used here to indicate a signal that carries information, without any limitation regarding the type of such signal ( audio , video, multimedia, digital data exchange, etc . ) or the technological method used for its generation and transmission, including for example both analog and digital .

Multi-user omnidirectional distribution using OAM states benefits from the multiplication of the data transmission channels , preferably after a topological trans formation of the wavefront that sees as a singularity of coordinates the intersection of the measurement plane (or surface ) with the D axis of propagation of the OAM wave transformed into an axis of symmetry coincident with D in a propagation orthogonal to

RECTIFIED SHEET (RULE 91 ) ISA/EP it following the rules of geometric anamorphic trans formations of af fine homology, as in the case of a directional OAM beam characteri zed by a doughnut-shaped wavefront with the vortex at the center (which i s always characteri zed by having zero field intensity and is the center of symmetry for every integer value of OAM) when it reflects on the surface of a cone whose axis coincides with the propagation axis of the electromagnetic waves beam ( D axis ) and is thus reflected omnidirectionally on a plane perpendicular to the D propagation axis .

In the case of a single OAM mode with known symmetry of the field intensity with respect to the D axis on the plane orthogonal to it , the anamorphic trans formation of af fine homology trans forms this figure into a wavefront with conical or preferably cylindrical symmetry, preserving the intensity symmetry of the electromagnetic field and trans forming the original " fusilli" spatial phase structure into a spiral centered on D, whose pitch is determined by the phase shift imposed by the value of the OAM itsel f .

As indicated above , the present invention provides a system and a method for the creation of a radio link that allow each individual OAM channel to be multiplied by dividing the wavefront of each OAM electromagnetic wave into di f ferent sectors that share the same carrier, which is modulated independently in amplitude, frequency, polarization or phase in each of these sectors .

In this way we preserve the physical and

RECTIFIED SHEET (RULE 91 ) ISA/EP structural properties of the original carrier wave , guaranteed by the well-known topological stability of 0AM waves during propagation, thus increasing the data transmission capacity of each wave and its stability after propagation by dividing the wavefront into sectors .

The definition of "carrier" or "carrier wave" is used here to indicate a generic electromagnetic wave or electrical signal with known freguency, amplitude, polari zation and phase characteristics , which is modi fied by a modulating signal , usually containing information, and then transmitted over the air or in other ways used by current art such as for instance fiber, waveguide , or cable .

The definition of " sector" is used here to indicate a portion of the wavefront of the 0AM electromagnetic wave that preserves its structure during its propagation toward at least one receiving Rx user .

PRACTICAL EXAMPLES

As mentioned, in general the present invention refers to a system 1 for creating a radio link with waves propagating along the propagation axis D and to an alternative configuration of such system where , following an anamorphic trans formation of af fine homology, the wavefront of these electromagnetic waves propagates with cylindrical or conical symmetry in directions orthogonal to the axis itsel f . In each of the configurations , the wavefront of the sample electromagnetic wave W is divided in a plurality of example S l-Sp in which the wavefront is

RECTIFIED SHEET (RULE 91 ) ISA/EP modulated independently.

System 1 comprises a plurality of transmission antennas Tl, T2, TN capable of transmitting an electromagnetic wave, Wl, in OAM mode and characterized by a precise and integer value 0AM1 = 11, and at least one other wave W2 with a different value 0AM2 = 12, which in this case form a pair of electromagnetic waves.

The OAM value of at least one wave is mandatorily different from 0, but it is not excluded that the antennas can simultaneously generate also "standard" waves with OAM=0 that will be used, for example, as a jamming channel in the same freguency of the other waves.

As mentioned, the plurality of antennas Tl, T2, . . . , TN is preferably suited to transmit a set of electromagnetic waves Wl, W2, ..., Wk with different OAM values and to independently modulate each of the OAM carriers in selected sectors SI, S2, ..., Sp of each wavefront .

The electromagnetic waves Wl, W2, ..., Wk have the same carrier frequency, preferably in the range between 30KHz and 300GHz, and propagate uniformly so that the wavefront propagates along directions orthogonal to a given axis having direction D, or alternatively along the axis itself.

Preferably, system 1 comprises a plurality of transmission antennas Tl, T2, ..., TN arranged on a transmission plane T orthogonal to direction D and suited to transmit the pair of electromagnetic waves Wl, W2 along the propagation directions orthogonal to D.

RECTIFIED SHEET (RULE 91) ISA/EP Preferably, the transmitting antennas Tl, T2, . . . , TN are arranged in correspondence with a set of transmission points tl, t2, ..., tN belonging to the transmission surface T.

Preferably, the transmitting antennas Tl, T2, . . . , TN are positioned along at least one circumference or ellipse lying on said transmitting surface T.

The transmission antennas Tl, T2, ..., TN are preferably arranged on a single circumference or ellipse lying on the transmission plane T and centered on axis D.

Certain forms of implementation (not illustrated) of the present invention may, however, envisage that the transmitting antennas Tl, T2, ..., TN be arranged on several concentric (or confocal) circumferences or ellipses on the same plane orthogonal to D or on planes parallel to or sharing a single attachment point on the A axis and open in a radial pattern.

Preferably, second piloting means 10 can be electronic means operationally associated with the transmission antennas Tl, T2, TN to regulate the transmission of electromagnetic waves Wl, W2.

The piloting means 10 can include any type of analog or digital circuit, depending on needs.

The transmission of the electromagnetic waves Wl and W2 can be done with known multiplexing techniques. For example, the piloting means 10 can drive the transmission antennas Tl, T2, . .., TN through their corresponding transmission signals, each of which is characterized by a different phase.

RECTIFIED SHEET (RULE 91) ISA/EP In this way, the array of transmission antennas Tl, T2, TN can easily generate electromagnetic waves Wl, W2, Wk superimposed on each other but characterized by a different orbital angular momentum.

Preferably, in the configuration of Figure 1, the axes of the transmission antennas Tl, T2, ..., TN are oriented in such a way that they converge at a midpoint between the transmission plane T and the receiving plane R, along the propagation direction D.

Alternatively, in the configuration of Figures 2, 3 and 4 obtained with the anamorphic transformation of affine homology, the axes of the transmitting antennas Tl, T2, ..., TN are oriented so as to converge at a midpoint of common junction between the transmission plane T and the concentric surface of reception R, in directions orthogonal to the propagation direction D.

In some forms of implementation of the present invention, the transmission antennas Tl, T2, ..., TN may consist of very simple structures, e.g. Yagi-Uda antennas, rotation paraboloids, holes in metallic screens or "backfire antennas", thereby reducing the costs of building the transmission system of apparatuses 1,101.

Preferably, to further improve their directivity, transmitting antennas Tl, T2, ..., TN can be realized using dielectrics, complex optical schemes, metamaterials and/or plasmonic materials.

Preferably, the piloting means 10 are able to associate at least one transmission channel Chx,x to the electromagnetic wave Wl superimposed on waves W2, . ..,

Wk.

RECTIFIED SHEET (RULE 91) ISA/EP To this end, means of encoding, including those of a known type, may be operationally associated or integrated to/in the piloting means 10 to transmit data along the transmission channel Chx,x.

Preferably, the modulation means 11 independently modulate the wavefronts in the wavefront sectors (SI, S2, ..., Sp) using as carrier waves each of the electromagnetic waves with OA /0 (i.e., both 0> and 0< are possible) .

Preferably, the regulation means (not illustrated) of the polarization state of electromagnetic waves W1 - Wk are operationally associated or integrated to/in the modulation means 11. In this way, the data transmission channels can be doubled using the degree of freedom offered by polarization . Preferably, the transmitting antennas Tl, T2, . . . , TN are able to transmit multiple electromagnetic waves Wl-Wk and to associate each electromagnetic wave to at least one different transmission channel Chx,x for each Sl-Sp sector of the wavefront. The receiving device 3,103 in general includes a plurality of receiving antennas Rl, R2, ..., RM capable of simultaneously receiving a Wl, W2, ..., Wk set of these electromagnetic waves superimposed on each other.

The set Wl, W2, ..., Wk set of electromagnetic waves is preferably used for the transport at a distance of k*P different signals of data channels (where k is the number of waves and P is the number of sectors of each

RECTIFIED SHEET (RULE 91) ISA/EP wavefront) with carriers Pl, P2, Pk respectively associated with them.

The electromagnetic waves Wl, W2, Wk are characterized, respectively, by different orbital angular momenta, e.g., a first and second orbital angular momentum ml, m2, ..., mk, where ml, m2, ..., mk are different integers, positive or negative. Possibly, one of the electromagnetic waves Wl, W2, ..., Wk can have zero orbital angular momentum (in this case it is not a twisted wave but it can still be used for example for jamming modulation) .

The carriers Pl, P2, ..., Pk of each of the electromagnetic waves Wl, W2, ..., Wk can be modulated separately and independently in different sectors SI, S2, . . . , Sp, to increase the capacity of each wave by at least p times the capacity compared to a channel exploiting the entire wavefront. Each of the Sj sectors, l<j<p, can be advantageously used as an independent data channel to distribute information along a given direction toward different users.

As schematically illustrated in Figure 1, on the path to the receiving antennas Rl, R2, . .., RM the wavefront of each of the electromagnetic waves Wl, W2, . . . , Wk rotates around the propagation axis D, on the generic plane orthogonal to this direction of propagation. The electric field of each of the electromagnetic waves thus draws a set of helical trajectories in space that extends along the direction of propagation D (helical axis) .

RECTIFIED SHEET (RULE 91) ISA/EP As mentioned above, angular momenta express the number of complete rotations made by the wavefront of the electromagnetic waves respectively, by wavelength, while the rotation direction of the wavefront of each of the electromagnetic waves is expressed by the modulus and sign of its orbital angular momentum.

The receiving antennas Rl, R2 , . .., RM are arranged on a receiving surface R, which in Figure 1 we identify with a plane intersecting the propagation direction D of the electromagnetic waves, positioned at a distance Z with respect to a transmission source T of the electromagnetic waves themselves.

Preferably, the receiving antennas Rl, R2, ..., RM are arranged in correspondence with a plurality of points rl, r2, ..., rM belonging to the receiving plane R and suitably positioned to use each of the observation sectors Sri, Sr2, ..., Srp corresponding, at least in pairs, to the wavefront sectors SI, S2, ..., Sp composing the electromagnetic waves Wl, W2, ..., Wk.

Preferably, the receiving antennas Rl, R2, ..., RM are positioned along at least one circumference or closed curve lying on R and centered on the propagation direction D of electromagnetic waves Wl, W2, ..., Wk.

The receiving antennas Rl, R2, ..., RM are preferably arranged on one or more circumferences or closed curves on the receiving plane R.

The number M of receiving antennas may vary, depending on needs.

RECTIFIED SHEET (RULE 91) ISA/EP The number p of the sectors of each of the electromagnetic waves Wl, W2, Wk can advantageously vary according to each emitted wave.

Preferably, M is an even number greater than or equal to two.

The reception plane R is preferably arranged in such a way as to be substantially orthogonal to the propagation direction D of the electromagnetic waves Wl, W2, . . . , Wk.

The receiving device Rx 3,103 includes the discrimination means 20, e.g. electronic means, operationally associated with the receiving antennas Rl, R2, . . . , RM.

The discrimination means 20 may include any type of analog or digital circuit, as required.

The discrimination means 20 are suited to carry out, in correspondence with the observation sectors Sri, Sr2, ..., Srp, amplitude and phase measurements of the electromagnetic field on the receiving plane R, in order to acquire the first DATA1 data.

The discrimination means 20 are also suited to process the DATA1 data obtained from the above-mentioned amplitude and phase measurements of the electromagnetic field ER, to separate the 0AM channels associated with waves Wl, W2, . . ., Wk, and to derive the DATA2 data, to subdivide and identify each 0AM carrier in each of the sectors Sri, Sr2, ..., Srp.

The discrimination means 20 are also suited to further process the DATA2 data thus obtained, in order to obtain the third DATA3 data by decoding each generic

RECTIFIED SHEET (RULE 91) ISA/EP channel Chx, x, obtained by multiplying with analog or digital techniques the OAM data channel in the corresponding sector Sj of the generic OAM electromagnetic wave Wq, l<q<k, for example in such a way that the final output signal from the Rx receiving device of system 1 , 101 contains one and only one of said data channels .

Preferably, the discrimination means 20 receive from each of the receiving antennas Rl , R2 , . . . , RM a receiving signal detected at one of the observation points rl , r2 , . . . , rM .

By processing the DATA1 measurement data, indicative of the amplitude of the resulting electromagnetic field ER, on the receiving plane R, it is therefore possible to recogni ze the function that expresses the amplitude distribution of the electromagnetic field, on the receiving plane R, and thus obtain the DATA2 data, indicative of the di f ference between the angular momenta of the electromagnetic waves Wl , W2 . , . . . , Wk and their separation in reception .

As explained above , the discrimination means 20 are able to acquire the DATA2 data, indicative of the di f ference between the various OAM waves .

Preferably, as above mentioned, multiple channels can be associated with each OAM wave by independently modulating non-overlapping sectors of the wavefront .

In the receiving device Rx 3 , 103 the acquisition of data transmitted through data channel C can be advantageously carried out thanks to appropriate decoding

RECTIFIED SHEET (RULE 91 ) ISA/EP means (not illustrated) , including known ones, operationally associated with or integrated to/in the discrimination means 20.

Preferably, the receiving antennas Rl, R2, ..., RM are able to receive multiple electromagnetic waves Wl, W2, W3, W4 (Figure 1) in the wavefront sectors taken as example , SI, S2.

Preferably, the receiving antennas Rl, R2, ..., RM are movable on the receiving surface R as reguired.

The position of the observation points rl, r2, . . . , rM on the receiving surface R can thus vary as needed, in order to optimize the reception of the superimposed electromagnetic waves Wl, W2, ..., Wk.

Preferably, the observation points rl, r2, ..., rM are placed in a neighborhood of the points of maximum of the modulus of the electromagnetic field ER.

The receiving antennas Rl, R2 , ..., RM can be made up of dipoles, paraboloids or other structures of known type. Metamaterials and/or plasmonic materials can be advantageously used for their realization.

The number N of receiving antennas can vary, depending on needs. Preferably, that number N is an even number greater than or equal to two.

In general, in the use of the remote radio link made by the present invention, the following steps can be performed :

Activating sections of the transmitting antenna in order to transmit an analog or digital communication

RECTIFIED SHEET (RULE 91) ISA/EP channel in a well-established direction obtained by appropriate analog or digital modulation .

Activating said sections of the transmitting antenna so that only the receiving station is illuminated and preferably transmitting a j amming modulation in the remaining directions .

Directing the transmission with an active feedback method in order to optimi ze the transmission of information to the recipient .

Receiving at least one of the electromagnetic waves Wl , with orbital angular momentum OAM = 11 , at a receiving surface R, intersecting the propagation direction D, or alternatively, in the directions orthogonal to D, following an anamorphic trans formation of affine homology of the wavefront , and positioned at a distance with respect to at least one source T of the electromagnetic waves Wl , W2 , . . . , Wk .

Carrying out amplitude and phase measurements of the electromagnetic field in order to acquire the first DATA1 data indicative of the amplitude and phase distributions of the electromagnetic field ER resulting from the superimposition of electromagnetic waves Wl , W2 , . . . , Wk, in correspondence with said observation points rl , r2 , . . . , rM .

Processing the first DATA1 data to obtain the second DATA2 data that allow the separation of the electromagnetic waves Wl , W2 , . . . , Wk into carrier signals for each chosen wavefront sector S .

Preferably, it is also possible to process the

RECTIFIED SHEET (RULE 91 ) ISA/EP second DATA2 data in order to obtain third DATA3 data that allow to discriminate , i f present , multiplexed data transmission channels in the various sectors , S .

Preferably, the method, according to the invention, also includes the steps of : identi fying, on the reception surfaces R, the points of maximum and minimum of the electromagnetic field ER resulting from the superimposition of the electromagnetic waves Wl , W2 , . . . , Wk; identi fying the observation points rl , r2 , . . . , rM according to the number and position of said points of minimum in the various wavefront sectors S ; merging the channels of each wavefront sector to increase the data trans fer capacity of a single OAM wave ; associating one or more di f ferent users to each of the wavefront sectors S for single or broadcast data transmission .

It has been seen in practice that the system and the method, according to the invention, allow to solve the drawbacks described in the known art , achieving the set goals by associating multiple channels and multiple users to the same single OAM value .

The system and the method, according to the invention, provide for simple amplitude and phase measurements of the electromagnetic field to detect this identi fying characteristic quantity in the chosen sectors of the wavefront .

The system and the method, according to the invention, are thus relatively simple and inexpensive to

RECTIFIED SHEET (RULE 91 ) ISA/EP implement in practice , compared to the telecommunication systems and methods of the known art .

The system and the method, according to the invention, involve the use of receiving/transmitting antennas with very simple geometries and easy to use in practice .

So far, we have focused mainly on practical examples of the invention where the j amming channel , or j amming channels , used for j amming are sectors of the same wave with OAM .

However, it is possible to achieve very good results also by defining communication channels and interference channels on distinct waves .

For example , the waves can be distinguished by di f ferent orbital angular momenta .

Electromagnetic waves emitted independently from each other, with the same frequency but di fferent 0AM, do not interact with each other during propagation and are always physically distinguishable thanks to their spatial phase distribution, of fering additional physical support to increase the ef ficiency of the data transmission .

Another possibil ity is that the j amming channel is defined by a wave with zero orbital angular momentum ( OAM=0 ) .

In this case , for example , the communication between a transmitting station and one or more receiving stations takes place through a modulation of the 0AM wave within one or more angular sectors which define

RECTIFIED SHEET (RULE 91 ) ISA/EP respective communication channels , where the OAM wave is superimposed on the non-OAM wave that is used for j amming .

The decoding of the transmitting signal from the j amming signal can simply be done by discriminating the OAM channel used to transmit either data or communications in general , from a non-OAM channel that is used as j amming even with the same frequency band and even with greater or equal intensity .

To separate the various OAM channels there are known techniques , such as antenna spatial divers ity ( two or more antennas suitably arranged and combined together to read the amplitude, intensity and phase of the various electromagnetic waves ) or known feedback techniques , or other alternative methods that use the properties of OAM beams .

In the event that both the OAM transmission and the j amming transmission are omnidirectional ( even i f non-OAM or with dif ferent OAM) they generally have axial symmetry centered on the transmitter and preferably share the axis of symmetry .

OTHER APPLICATION EXAMPLES

Thanks to the present invention, instead of using only frequency filtering as in the known technique , it is possible to adopt an active phase filtering method in predetermined directions in adaptive mode .

In the same frequency band we have in fact set up a j amming channel which can have continuous transmission,

RECTIFIED SHEET (RULE 91 ) ISA/EP and an overlapping communication channel which can be discriminated through phase/spatial diversity .

A MIMO system or, in a more robust way, the use of the spatial phase distribution properties of beams due to the orbital angular momentum, allow the creation of fixed or mobile phase-encoded radio links that improve the SNR of the j amming communication channels , allowing communication between di f ferent users .

Consider the simplest case where the communication channel between two vehicles is outside of the blocked bands , protected by standard encryption techniques .

With reference to Figures 8 and 9 let ' s consider two vehicles VI and V2 where vehicle VI is fitted with at least one Tx transmitting station and vehicle V2 with at least one Rx receiving station .

We assume the geometry for a two-dimensional analysis , on a plane parallel to that of the battlefield, with the propagation of radio waves in the transverse direction with respect to the convoy direction .

On this plane let ' s consider two receiving antennas A and B of the Rx receiving station, placed at a distance A-B called the "baseline" and indicated by " 1" in Figure 8 .

The transmitting station Tx corresponds to point

C of Figure 7 and transmits a communication signal on an OAM wave , and through a single antenna a signal of co-

RECTIFIED SHEET (RULE 91 ) ISA/EP polar disturbance, which propagates with spherical geometry .

Depending on the phase separation and on the number of transmitting/receiving antennas , one of the two signals , either the j amming or the communication signal , can be selected using interferometric techniques with an SNR that can be determined through standard MIMO schemes . When one signal is selected, the other will be canceled due to destructive interference occurring at the receiver end, behaving as uncorrelated background noise .

In the simplest case , e . g . in the static case, this dephasing tuning technique can be obtained by simulating the OAM with a 2X2 MIMO in the line of sight ( LoS ) .

An interesting advantage is that an enemy receiver equipped with a single antenna and/or unaware of the phase selection channel protocol or very far from the vehicles cannot discriminate this signal from a standard j amming unless it is equipped with the same technology, but being necessarily placed at greater distances from vehicle VI , this would require baselines 1 (distance between receiving antennas A and B ) much larger in the desired direction in that speci fic transmission cone .

In the past the case of mounting the setup on widespread vehicles has been studied and hypothesi zed, assuming that on average they have the following overall dimensions :

RECTIFIED SHEET (RULE 91 ) ISA/EP Length 5, 504 mm

Width 2,050 mm

Height 1,950 mm

The antennas array can be placed at the rear of the vehicle .

In reception, vehicle V2 captures a fraction of the beam with a baseline of antenna AB, the phase difference experienced by the receiver is

APH - 1 * (6(p/2u)

At the frequency of 2.4 GHz, for vehicles 50 to 100 meters away, with distance AB 1=1.5m, the phase difference detected in reception is about 3.49°.

It is clear that in this case the AB antennas have a distance compatible with the size of the vehicle and with patrol distances between vehicles. At a greater distance from the transmitting vehicle VI, the AB antennas must be at greater distances.

If we deal with moving objects, however, the scheme is much more complicated. Firstly, the sender/receiver must inevitably phase out the transmitting elements and align the beam through the beam steering to point in the direction of vehicle V2 and preserve the phase difference in reception. Then the receiver must track and extract from the noise the

RECTIFIED SHEET (RULE 91) ISA/EP channel characteri zed by a di f ferent spatial phase distribution . In any case , the receiver must adapt the interferometric setup to optimi ze the reception of the data transmission channel and to increase/preserve the SNR .

Our — proposal — ±-e — a A possible solution to improve a LoS MIMO configuration with vehicles in motion is the use of an omnidirectional antenna for communication within j ammed bands emitting s OAM ( in the Tx figures ) by transforming a doughnut-shaped OAM beam into a circular strip, for example with the use of a conical/cylindrical reflector .

Its emission pattern may be a practical solution to the problem of pointing at another vehicle the radio wavefront marked in the transmitting phase . In this way we distribute a circular beam centered on vehicle VI and parallel to the battlefield with phase properties equivalent to those of the standard MIMO link when received by vehicle V2 .

In this case , because of the omnidirectional properties of the antenna, the symmetry of the beam proj ected onto the battlefield i s circular, with an axis of symmetry orthogonal to it ; noteworthy, the distribution of the azimuthal spatial phase of the OAM beam is preserved across the strip .

Nothing changes in reception, as we have to correct the phase di f ference crossed by the interferometric setup and then select one of the two channels .

RECTIFIED SHEET (RULE 91 ) ISA/EP The advantages are the stability of the beam due to the geometry and the possibility of frequency j ump pattern for the dominance of battlefield communications within a given broadband .

With a system such as that shown in the previous figures , the signal used for communications is based on a modulation made by modulation means 11 , digital or analog, of the carrier in a direction chosen in such a way as to transmit the given signal to a precise receiver and to maintain its orientation by activating one or more S I , Sp sectors of the transmitting antenna, the remaining of which will continue to transmit the analog or digital signal used for j amming .

At the reception stage , the transmission signal is decoded using OAM techniques and the receiving station is appropriately identified to activate the appropriate sections of the transmitting antenna so as to make the communication cone as narrow as possible and pointed towards the receiver .

GENERAL INTERPRETATION OF TERMS

In understanding the purpose of the present invention, the term " comprehending" and its derivatives , as used herein, are understood to be open-ended terms that speci fy the presence of the stated features , elements , components , groups , integers , and/or phases , but do not exclude the presence of other undeclared features , elements , components , groups , integers , and/or

RECTIFIED SHEET (RULE 91 ) ISA/EP phases. The above also applies to words that have similar meanings such as the terms "including", "having" and their derivatives. In addition, the terms "part", "section", "portion", "member" or "element" when used in the singular may have the double meaning of a single part or a plurality of parts. As used here to describe the form(s) of actuation above, the following directional terms "forward", "backward", "above", "down", "vertical", "horizontal", "below" and "transverse", as well as any other similar directional term, refer to the actuation form described in operative position.

Finally, grade terms such as "substantially, " "about, " and "approximately" as used here mean a reasonable amount of deviation of the modified term such that the final result is not significantly changed.

While only selected embodiments have been chosen to illustrate the present invention, it will be clear to experts in the field from this description that various modifications and variations may be made without straying from the scope of the invention as defined in the attached claims. For example, the size, shape, position, or orientation of the various components can be changed as needed and/or desired. The components that are shown directly connected or in contact with each other may have intermediate structures arranged between them. The functions of one element can be performed by two and vice versa. The structures and functions of one form of realization can be adopted into another form of realization. It is not necessary for all the benefits to be present in a particular form of realization at the

RECTIFIED SHEET (RULE 91) ISA/EP same time . Any feature that is original compared to the known technique , alone or in combination with other features , should also be considered a separate description of further inventions by the applicant , including the structural and/or functional concepts incorporated by such features . Therefore , the above descriptions of the forms of implementation in accordance with this invention are provided for illustrative purposes only and not for the purpose of limiting the invention as defined by the attached claims and their equivalents .

RECTIFIED SHEET (RULE 91 ) ISA/EP

Claims

1. Method of radio telecommunication jamming comprising the steps of:

- setting up at least one transmitting station and one receiving station;

- setting up at least one communication channel and one jamming channel between the two stations in the same carrier frequency;

- transmitting a jamming signal on the jamming channel ; transmitting a communication signal on the communication channel during the transmission of the jamming signal;

- where at least the communication channel is set to a carrier wave characterized by an orbital angular momentum (OAM) .

2. Method according to claim 1, characterized by the fact that the communication channels and interference channels are both defined on carrier waves characterized by an orbital angular momentum (OAM) .

3. Method according to claim 2, characterized by the fact that the communication channels and interference channels are set on different angular sectors of the same carrier wave characterized by an orbital angular momentum (OAM) .

4. Method according to claim 3, characterized by the fact of modulating at least one angular sector corresponding to a communication channel by pointing it towards the receiving station.

5. Method according to claim 4, characterized by the fact that: the transmitting station and the receiving station are in relative motion to each other; said sector is modulated to follow the motion of the receiving station.

6. Method according to claim 4 or 5, characterized by the fact of modulating the at least one sector corresponding to the jamming channel to point in different directions from that of the communication channel .

7. Method according to claim 3 or dependent on it, characterized by the fact that a plurality of communication channels are set on different angular sectors .

8. Method according to claim 7, characterized by the fact of modulating at least two sectors (SI, Sp) corresponding to the respective channels of communication to point to two separate and respective receiving stations (Rx) .

9. Method according to claim 1, characterized by the fact that the disturbing channel is set to a carrier wave carrying zero orbital angular momentum ( OAM) .

10. Method according to any of the above claims , characteri zed by the fact that the communication signal and the interference signal are discriminated at least in phase at reception .

11. Method according to any of the above claims , characteri zed by the fact that the interference signal is transmitted continuously .

12. Jamming radio telecommunication system comprising :

- at least one transmitting station ( Tx) and one receiving station (Rx ) ;

- at least one communication channel ( Chx, x ) and one interference channel ( Chx, x ) between the two stations in the same carrier frequency;

- at least one interference signal transmitted on the j amming channel ;

- at least one communication signal transmitted on the communication channel during the transmission of the interference signal ;

- where at least the communication channel is set to a carrier wave characteri zed by an orbital angular momentum ( OAM) .

13. System according to claim 12 characteri zed by the fact that both the transmitting station (Tx) and the receiving station (Rx) comprise respective arrays of antennas, where the transmitting station includes the piloting means (10) of the antennas to generate at least said carrier wave characterized by an orbital angular momentum (0AM) , and the receiving station includes the discrimination means (20) to discriminate said channel of communication .

14. System according to claim 13, characterized by the fact that the transmitting station (Tx) comprises:

- a plurality of modulation sections (Sl-Sp) each defined by a group of said antennas (Tl, Tn) and by modulation means (11) configured to modulate independent non-overlapping sectors (SI, Sp) of said carrier wave.

15. System according to claim 14, characterized by the fact that those modulation means (11) are configured to modulate at least one sector (SI- Sp) to define said communication channel (Chx,x) , and at least one other sector to define said jamming channel (Chx,x) .

16. System according to any of claims 12 to 15, characterized by the fact that the transmitting station (Tx) and the receiving station (Rx) have relative motion to each other, where the modulation means are configured to modulate said sector to follow the motion of the receiving station (Rx) .