A modulator

Abstract

A modulator including an amplitude modulating component for modulating an amplitude of an electromagnetic signal is provided. The amplitude modulating component comprises a first conductor for tunnell

Description

FIELD OF THE INVENTION The invention disclosed herein relates to an apparatus for the modulation of high-frequency electromagnetic signals. It may find particular, although in no way exclusive, applications in telecommunication systems. BACKGROUND TO THE INVENTION Telecommunication technology is continually striving for higher data rates. With speeds of up to 10 gigabits per second (Gbps), fifth-generation (5G) technology theoretically provides as much as a ten-fold increase in speed compared to fourth-generation (4G) technology. The 5G mobile system standard operates in the 30 gigahertz (GHz) to 300 GHz frequency range, and thus in the millimetre (mm) wave part of the frequency spectrum. Working at mm-wave ranges poses multiple challenges and core changes in radio devices and related small-sized components. The designing of small-sized components is but one part of these challenges, with another being its integration with the other components. Present-day microwave components tend to be unsuitable for mm-wave bands (ranging from 28-300 GHz) as they are generally limited to a 6 GHz application. The usage of implementation of such mm-wave systems may further have some economic considerations associated therewith, as the small components that are needed to be used in such systems may have fabrication costs making these components, not only harder to manufacture but also more expensive. As is known, the modulation of signals is universally applied in all forms of telecommunication and electronics. In telecommunication and electronics, modulation is a technique by which a lower-frequency signal (or message signal) is superimposed onto a higher-frequency (carrier) signal. An electronic device that performs this operation is known as a modulator. Modulation schemes can be roughly classified into two major categories: Continuous Modulation and Digital Modulation. Continuous modulation can further be divided into Amplitude Modulation (AM) and Angular Modulation. Similarly, Digital Modulation can be classified into three main categories: Amplitude Shift Keying (ASK), Phase Shift Keying (PSK), and Frequency Shift Keying (FSK). These modulation techniques play a crucial role in multiplexing signals in both frequency and time domains so as to achieve a desired ultra-low latency and myii uuuuyiipui. Due to broader bandwidth, mm-wave systems (such as 5G systems) offer a high data transfer rate but suffer from a weak link budget (meaning that these systems suffer large amounts of losses). Considerable research on the enhancement of signal strength is available in the literature. Multiple-input and multiple-output (MIMO), for example, is a good method that can provide a fast data transfer rate. Considering its small size, a fundamental requirement for communication-based on MIMO methods is that it should allow highly effective transmission in the mm-wave range. This requirement can be met by taking advantage of polar modulators as they amplify a non-constant envelope modulation by utilising highly effective non-linear power amplifiers. A polar modulation technique involves processing a signal in the form of an amplitude component and a phase component. In the prior art of which the Applicant is aware, active components, including high-power, nonlinear and low-power linear power amplifiers are utilised to design most of the polar modulators for mm-wave systems. The drawback of their usage in MIMO systems, integrated chip designs, and phased array radars is linearity and power handling capability. Non-linearity and low power handling capability are among the shortcomings of the active class of demodulators, while the opposite makes it the merits of the passive class of modulators. Due to the capability of polar modulators to perform both magnitude and angular modulations simultaneously, they are widely used and provide a number of advantages and applications in the electronics industry. Active and passive modulators known in the art have a number of limitations. The active modulators are typically developed on the substrate of an integrated circuit (IC), which has high dielectric losses. The passive modulators are typically developed using microstrip structures which inherit the issue of radiation loss. Passive modulators with minimal or no radiation loss are still a research challenge, and much work is still required in this regard. The Applicant considers there to be room for improvement over the prior art. The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was part of the common general knowledge in the art as at the priority date of the application. SUMMARY OF THE INVENTION In accordance with an aspect of the invention there is provided a modulator including an amplitude modulating component for modulating an amplitude of an electromagnetic signal, the amplitude modulating component comprising; a first conductor for tunnelling the electromagnetic signal from an input of the modulator to an output of the modulator; the first conductor being spaced apart from a second conductor electrically connected to a power source, wherein the power source is configured to induce an electrical current in the second conductor thereby creating a magnetic field around the second conductor, and wherein the magnetic field created around the second conductor interacts with the electromagnetic signal of the first conductor, causing electromagnetic interference in the first conductor such that the amplitude of the electromagnetic signal is either increased or decreased by a factor associated with an applied voltage of the power source. Each of the first and second conductors may be conducting wires. The factor with which the amplitude of the electromagnetic signal is increased or decreased may be a function of the distance between the first conductor and second conductor, as well as the amplitude of the voltage of the power source. A minimum operating voltage of the modulator may be controlled by the distance between the first conductor and the second conductor. The modulator may include a first waveguide and a second waveguide paced at an 180° bend relative to each other and having a common ground. Each of the waveguides may include boundaries that are configured to only permit a dominant propagating mode to travel through the waveguides. The waveguides may be of a rectangular waveguide geometry and the dominant mode may be the TEw mode. The first conductor and the second conductor may be housed within the waveguide. The first conductor may be a thin metallic wire configured for energy tunnelling. The power source may be an alternating voltage source configured to induce the alternating current to flow in the second conductor. Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS In the drawings: Figure 1A Figure 1B Figure 2 Figure 3 Figure 4A Figure 4B Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 10 Figure 11 is a schematic illustration of an example circuit showing the practical effect of amplitude modulation on an electromagnetic signal; is a graph including waveforms showing the effects of constructive and deconstructive interference; is a schematic illustration showing an example embodiment of a conventional three-port EM modulator; is a graph showing the resultant magnitude of an amplitude modulated signal in different example scenarios; is a schematic illustration of an exemplary embodiment of a modulator including an amplitude modulating component; is a graph showing a normalized frequency and a magnitude of a modulated signal according to aspects of the present disclosure; is a graph showing the relationship between an applied voltage and a distance between a first conductor and a second conductor of the modulator of Figure 4A; is a schematic illustration of an exemplary embodiment of a modulator including a phase modulating component; is a detail view of a switching mechanism of the modulator of Figure 6; is a graph showing the relationship between the length associated with each switch mechanism of Figure 7 and a normalised frequency; is a graph showing a change in phase shift for different switch configurations; is a schematic illustration showing components of a second example embodiment of a modulator including a phase modulation component; is a schematic illustration showing components of an example embodiment of a polar modulator including an amplitude muauictuiiy component and a phase modulating component; and Figure 12 is a graph showing the working of the polar modulator of Figure 12. DETAILED DESCRIPTION WITH REFERENCE TO THE DRAWINGS The disclosure provides a modulator for effecting modulation of an electromagnetic signal. In particular, the disclosure provides multiple embodiments of a modulation device for effecting modulation of an electromagnetic signal. Some of these embodiments are configured to effect amplitude modulation (AM) on an electromagnetic signal. Some of these embodiments are configured to effect phase modulation (PM) on an electromagnetic signal. Some of these embodiments may be configured to effect both amplitude modulation as well as phase modulation on an electromagnetic signal, the collective effect of which provides polar modulation. In a first example embodiment, the modulator device may be a passive class of mm-wave modulator. The modulator may operate based on the phenomenon of interference patterns between two conductors carrying different signals. The phenomenon operates on the principle that, when an electromagnetic (EM) wave / signal is fed into a conducting wire forming part of the modulator and a carrier signal is fed into the other conducting wire of the modulator, where the carrier signal is introduced by an Alternating Current (AC) power source in electrical communication with the other conducting wire, electromagnetic interference is produced. The electromagnetic interference that is introduced may either be constructive electromagnetic interference or destructive electromagnetic interference, depending on the input of the AC power source. In an embodiment, an exemplary three-port EM modulator that generates a modulated signal when an input signal and a carrier signal are fed into a first port and a second port, respectively, is discussed. The EM modulator may include an amplitude-modulating component, including: two ports, a thin metallic wire (also known as the primary sensing element) for supporting energy tunnelling, and a conductor wire powered by an AC power source. The modulator may include a waveguide configured to only permit travelling of the TE10 mode. In other words, the waveguide may be configured such that during the propagation of the electromagnetic signal through the waveguide, the created electric field is perpendicular to the direction of propagation. The EM modulator may further be configured such that, in use, a signal transmitted by a first of the two ports and a carrier signal generated by the AC power source produces AM modulation in the form of a modulated signal being created. Modulating the signal includes creating an interference pattern that is dependent on the change in voltage of the AC source. Two important factors that may affect the interference pattern, and therefore modulation, are the magnitude of the carrier signal provided by the AC power source and the distance between the conductor wire and the energy tunnelling wire. The standardised behaviour reflecting the reciprocating change of one parameter upon the other is a decaying exponential, discussed in more detail below. In some embodiments, the EM modulator may include a phase-modulating component. In addition to two ports, a thin metallic wire for energy tunnelling and a waveguide, the phase modulating component may include an impedance-matched switch for varying the length of the tunnelling wire. By varying the length of the tunnelling wire, phase modulation may be achieved, as described in more detail below. In some embodiments, the phase modulating component may include multiple impedance-matched switches. Each of the multiple switches may be configured to control the respective dimension of the energy tunnelling wire, thereby changing the device's operating frequency. The length of the tunnelling wire and the operating frequency of the device may exist in an inverse relationship with each other. In an example embodiment, three switches are provided and placed on the outer surface of the modulator device. It should, however, be appreciated that the exact location of the switches may be a choice of one skilled in the art. In some embodiments, the phase-modulating component may include a cylinder placed proximate the tunnelling wire. The cylinder may be made from an electronically tunable dielectric material such that changing of the dielectric constant of the cylinder placed close to the tunnelling wire can produce the required phase modulation. The dielectric constant (relative permittivity) of the cylinder may be changed / tuned by changing the voltage supplied by the AC power source. Finally, the disclosure provides for a modulator including both of a phase-modulating component and an amplitude-modulating component, as described above. Figure 1A is a schematic illustration of an example circuit (100) showing the practical effect of amplitude modulation on an electromagnetic signal. The circuit (100) includes a first conductor (102) through which an incident electromagnetic wave (108) may flow. The conductor (102) may be configured such that the flow of the electromagnetic wave through the conductor (102) produces an electric field within the conductor (102). The circuit (100) further includes a second conductor (104) and a power source (106), such as an alternating current (AC) power source. The second conductor (104) is in electrical communication with the power source (106) such that the power source (106) may transmit an alternating current through the second conductor (104). oy uai iai।mm iy a current through the second conductor, a magnetic field is produced around the wire. The magnetic field is caused by the current, representing an electromagnetic wave / signal, induced in the conductor by the power source. The electromagnetic wave / signal may be referred to as the carrier signal. Each of the first conductor and the second conductor may be a conducting metallic wire. The second conductor (104) is placed at a predetermined distance (112) from the first conductor (102) such that the electric field of the first conductor (102) may interact with the magnetic field of the second conductor (104). The interaction between the fields (114) of each conductor (102, 104) produces an interference effect that may be either a constructive or a destructive interference effect. A resulting interference pattern (110), associated with the interference effect, may depend on the profile of an alternating voltage applied by the power source (106). This is illustrated in the waveforms shown in Figure 1B, in which the electromagnetic (EM) signals generated across the conductors (102, 104) are illustrated by the traces (103) and (105), respectively. The electromagnetic fields produced across the conductors (102, 104) may either add up to give constructive interference, illustrated by trace (107), or nullify the effect of each other resulting in destructive interference, illustrated by trace (109). This principle of interference and superposition will be utilized in the embodiments of modulators described below. Figure 2 is a schematic illustration showing an example embodiment (200) of a conventional three-port EM modulator (202). The EM modulator (202) consists of two input ports (204, 208) and an output port (212). One of the input ports (204) may receive an input signal (206) and the other input port (208) may receive a carrier signal (210). When the input signal (206) and the carrier signal (210) are fed into the modulator via the respective input ports (204, 208), the modulator (202) generates an amplitude modulated (AM) signal (214) at the output port (212). The AM signal (214) is a composite of the signals received at the respective inputs. Figure 2 is therefore a simplified graphical representation of amplitude modulation in practice and is included to facilitate the discussion of the modulators of the present disclosure. The so-called mechanism or effect of AM modulation is illustrated in the graph (300) shown in Figure 3. In particular, Figure 3 shows the resultant magnitude response of an (AM) modulated signal in different example scenarios. As can be seen from Figure 3, the normalized frequency is taken along the x-axis (304), while the magnitude is taken along the y-axis (302). The purpose of the normalised value is to show the behaviour of the moduiaiui. m pei »ui । ui skill in the art would appreciate that passive modulators exhibit the property of scalability along the frequency scale. Figure 3 depicts the (AM) modulated signals' normalized behaviours (306, 308, 310, 312). In some embodiments, a modulator may be configured such that constructive or destructive interference occurs depending on the direction of the current in the interfering wire (i.e. the second conductor (104) with reference to Figure 1A). For example, the modulator may be tuned such that constructive interference takes place for the positive values of the current, and destructive interference takes place for the negative values of the current passing through the interfering wire. It should be appreciated that there is a frequency up to which the magnitude of the modulated signal would increase. During the phase when the magnitude of the signal is increasing, constructive interference takes place. In other words, during constructive inference, the input signals, when superimposed, tend to accumulate and have a reinforcing behaviour. This reinforcing behaviour may be controlled by the power source (106) powering the second conductor (104), as briefly discussed above. Once a specific frequency value is surpassed, the input signals, when superimposed, tend to mitigate the effect of each other, which results in a decrease in the magnitude of the modulated output signal. This is referred to as destructive inference. The destructive inference phase culminates at a certain frequency on the spectrum where the magnitude of the output signal decreases to zero. This phenomenon of constructive and destructive inference may be exploited to produce polar modulation, as discussed in more detail with reference to example embodiments below. A schematic illustration of an exemplary embodiment of a modulator (400) including an amplitude modulating component is shown with reference to Figure 4. The modulator (400) includes at least two ports - a first input port (402) and a second receiving port (404), a first conductor (406), a second conductor (408) and a power source (410). The input port (402) may be configured to generate and / or receive an electromagnetic signal (412), such as a message or information signal, to be modulated. The receiving port, on the other hand, may be configured to receive the modulated signal (414). In addition to the above components, the modulator may include a plurality of waveguides for guiding the waves / signals generated by and introduced into the modulator. In the present embodiments two waveguides (416, 418) are shown ata 180° bend and having a common ground (420). It should be appreciated that even though the above rectangular waveguide configuration is shown, alternative configurations, or so-called waveguide geometries, may be implemented for the same purpose. For example, in some embodiment a auuauctie-miegrated waveguide structure may be implemented. Similarly, coplanar waveguide environment can also be exploited to achieve a similar arrangement. An advantage of a substrate-integrated waveguide structure is that these structures are generally planar and compact making them flexible and easy to configure. The two waveguides (416, 418) may include boundaries (420, 422, 424, 426) which are configured such that only the dominant mode of the waveguides may travel therethrough. The dominant mode is the propagation mode of the waveguide having the lowest cut-off frequency. As one skilled in the art would appreciate, for a rectangular waveguide structure, as is the case, the dominant mode is the TE10 mode. Accordingly, the waveguide boundaries (420, 422, 424, 426) of the present embodiment may be selected / configured such that only the TEw mode travels through the waveguides. The electromagnetic signal (412) generated and / or received by the input port (402) may be an information signal or message signal. The signal (412) may travel to a top end of the first conductor (406) of the modulator and through the conductor. The first conductor (406) may be a thin metallic wire that is resonant on a particular frequency, referred to as a tunnelling frequency. The thin metallic wire may act as a microwave sensing element. In order to modulate the electromagnetic signal, power source (410), being an alternating current (AC) power source, may be configured to generate an electromagnetic signal that flows through the second conductor (408). This electromagnetic signal flowing through the second conductor (408) may be referred to as the carrier signal. The properties of the carrier signal are dependent on the input received from the power source (410). As can be seen in Figure 4, the current carrying conductor, being the second conductor (408) is placed in close proximity to the first conductor (406). When a current is induced in the second conductor (408) such that a carrier signal travels through the conductor, the magnetic field created by the carrier signal may influence the electromagnetic signal carried by the first conductor (406) and electromagnetic interference takes place, as discussed in more detail, below. This interference may either be constructive or destructive interference. It should be appreciated that, in order for the desired interference to take place, the first conductor (406), which extends in both the first and the second waveguides, must be an impedance matched wire configured to facilitate the smooth flow of the electromagnetic signal therethrough. An advantage of the construction of the waveguides in the present embodiment is that, as one skilled in the art would appreciate, impedance matching may be achieved naturally as a result of the symmetrical geometry of the waveguides. It should further be appreciated that, as the waveguide boundaries are configured to only permit the dominant modes to travel through the waveguides, energy tunnelling may be achieved by the modulator. The modulator of the present embodiment is specifically designed such that full energy coupling takes place at the resonance frequency, which highly depends on the length of the first conductor (406) and the permittivity of the area close to the conductor. Figure 4B is a graph (401) showing the normalized frequency and the magnitude of the modulated signal (409). As discussed above, the modulation of the EM signal (412) depends on the carrier signal and therefore the magnitude of the change in the voltage of the second conductor (408). Track (411) of the graph represents the constructive interference for the positive values of the AC power source (410), while track (407) represents the destructive interference for the negative values of the AC power source. Both of these tracks may be compared to the original state of the modulated signal. This interference phenomenon may be exploited to produce a highly scalable amplitude modulator. The operating frequency range is highly dependent on the length of the first conductor (406), and may therefore be changed and / or altered, by changing the length of the first conductor. As alluded to above, the interference between the conductors (406, 408) may be controlled, i.e. increased or decreased, by controlling the magnitude of the signal fed into the modulator by the AC power source (410) and / or by reducing the distance (428) (D) between the conductors. The distance (428) (D) should be selected so that the interference may be achieved with the minimum input voltage of the AC power source. The minimum voltage required to operate the modulator may be referred to as the critical voltage. In light of the above, it is clear that the distance between the first conductor (406) and the second conductor (408) plays a crucial role in the interference between the carrier signal and the information signal. When the first conductor and the second conductor are placed at a large distance (428) (D) from each other, the interference between the signals becomes minimum or even zero. This behaviour is shown in the graph (500) of Figure 5. The distance (428) (D) between the conductors (406, 408) is taken along the x-axis (504) , and the change in voltage is taken along the y-axis (502). The standardized behaviour reflecting the reciprocating change of one parameter upon the other is a decaying exponential, shown by track (506). Figure 6 therefore illustrates that the change in voltage is inversely proportional to the distance (D) between the conductors (406, 408); hence, the voltage change exponentially decays with an increase in distance. A schematic illustration of a first example embodiment of a modulator (600) including a phase modulating component is shown with reference to Figures 6to 12. The modulator may have a similar design to the modulator discussed above with reference to Figures 4 to 6. However, instead of having two conductors and a power source, included in the amplitude modulating component, the embodiment shown in Figure 6 includes one conductor (602), including conducting elements (discussed in more detail below), and a switch mechanism. In the present embodiment, the switch mechanism is an impedance-matched switch (604). Exemplary push button switches which connect different wire lengths. The exact type of the switch is left to the choice of skilled in the art person. In a closed condition, the pin (606) creates a short between the conducting elements, thereby increasing the effective length of the conductor. In effect, the switch can be said to join two smaller antennas to create one larger antenna. On the other hand, in an open condition, when the pin (606) is removed between the conducting elements, the elements become disjoint (disconnected), shortening the effective length of the conductor, and enabling operation in high-frequency ranges. The conductor (602) may be similar to the first conductor (406) discussed with reference to Figure 4 above, and be configured to carry an electromagnetic signal, such as a messaging signal, to travel therethrough. The conductor (602) and the impedance-matched switch (604) may be housed within the waveguides (608, 610). The impedance-matched switch (604) may be configured such that an operator may change the effective length of the conductor (602), by turning the switch on or off. By changing the effective length of the conductor, the phase of the electromagnetic signal changes at the tunnelling frequency (being the frequency at which energy tunnelling is achieved), which depends on the length of the conductor (602). The phase change may be achieved in a pre-tunned radio by changing the phase response left or right along the frequency scale. Wavelength and frequency are inversely related. In other words, as the wavelength increases, frequency decreases and vice versa. In the present embodiment, the length of the conductor (602) is directly proportional to the wavelength and, accordingly, an increase in the length of the conductor (602) results in a lower frequency, while the opposite is true when the length of the conductor (602) decreases. Figure 7 is a detailed view showing a switch mechanism, being an impedance matching switch (604), provided between conducting elements of the conductor (602) of the modulator. As discussed above, the impedance matching switch may be configured to permit a change in the effective length of the conductor (602) so as to enable frequency shifting. It should be appreciated that a plurality of switches (604) may be provided, where each switch is associated with a discrete frequency point and configured to perform phase modulation, as discussed above. These multiple switches are shown in Figure 7. Figure 8, is a graph showing the relationship between the length associated with each switch and the normalised frequency. The graph shows that as the number of closed switches (and therefore the length of the conductor) increases, the frequency decreases, and vice versa. It should also be appreciated that each switch may be associated with a different conductor element. Even though only two conducting elements are shown, a person skilled in the art would appreciate that any number of conducting elements may be used. The change in the phase shift is shown in the graph of Figure 9. The curve (902) represents when all the switches are opened, the curve (904) represents when only one switch is closed and whereas the curve (906) is shows when two switches are closed, respectively. In the present embodiment, only three switches are provided. It should be appreciated that the exact location of the switches is merely a design choice and should not be limited to the locations shown. The switches (604) may be placed on an outer surface of the modulator and may either be switched on to increase the effective length of the conductor, or switched off to decrease the length of the conductor. Figure 10 shows a second example embodiment of a modulator including a phase modulation component (1000). This embodiment provides for phase modulation by changing the dielectric constant of a hosting material placed in close proximity to the conductor (1014), instead of changing the length of the conductor using switches to influence the frequency. The dielectric constant of the hosting material may be varied by introducing a rod (1002) near the conductor (1014), a discussed above. The rod (1002) may be configured to exhibit a different permittivity at different portions thereof. For example, as shown in the detailed view of Figure 12, the rod may have a round cross-sectional profile and may be comprise of different sections (1008, 1010, 1012) which extend radially along the length of the rod. Each of the different sections may have a different permittivity. Each section may be of equal proportion such that, for example, if there are three sections each section constitutes one-third of the rod. The section of the rod nearest to the conductor will be the dominant section. Accordingly, phase modulation may be achieved by rotating the rod, and thereby changing the dominant section associated with a preselected permittivity. In some embodiments, the rod may be rotated mechanically by means of an actuator (1004), such as a microelectromechanical system-based actuator. As discussed above, the top view of the rod (1002) shows the three sections of the discord (1008, 1010, 1012). Even though three sections are shown, it should be appreciated that the rod may be divided into any desired number of sections. Each section (1008, 1010, 1012) of the rod comprises a different material having a different dielectric constant. The dielectric constant of each region in the disc is indicated with a value (1008), e2 (1010), and e3 (1012). The change in field interaction is achieved by changing the section of the rod that faces the conductor (1014). For example, the field interaction that is achieved when the conductor (1014) is nearest to and facing the section of the rod (1008) with a dielectric constant will be different when compared to when the conductor is facing the section with a dielectric constant of e2 or e3, respectively. Therefore, in this way, a variable field interaction may be achieved. Electrical tunability may be performed using a material whose permittivity may be controlled via voltage. The disclosure extends to a polar modulator (1100) including both an amplitude-modulating component and a phase-modulating component, as shown in Figure 11. The polar modulator (1100) may be made by combining the modulator discussed with reference to Figure 4 with the modulator discussed with reference to Figure 10. Even though it is not shown, the polar modulator may include a waveguide geometry / configuration similar to that described with reference to Figure 4. In other words, the components shown in Figure 11 may all be housed in the waveguides. The polar modulator may further include two conductors - a first conductor (1108) and a second conductor (1110), a rod (1106), a first AC power source (1102) in electrical communication with the second conductor (1110), and a second AC power source (1104) in electrical communication with the rod (1106). Amplitude modulation may be achieved in a manner similar to the manner described with reference to Figure 4. In other words, amplitude modulation of the electromagnetic signal fed into the modulator may be achieved by varying the voltage of the power supply (1102) feeding the second conductor (1110). The change in the voltage of the signal in the second conductor results in a change in the magnetic interference between the second conductor (1110) and the first conductor (1108), carrying the messaging / information signal. Phase modulation, on the other hand, may be achieved in a manner similar to the manner described with reference to Figure 11. In other words, phase modulation may be achieved by varying the voltage of the power source (1104) in electric communication with the rod (1106). In the present embodiment, the rod may be made from a predetermined, highly polarisable material, such as barium titanate, so that the permittivity of the rod may be changed, by changing the voltage. Accordingly, phase modulation is achieved by applying a varying voltage to the rod (1106) thereby changing the permittivity of the rod. In some embodiments the rod may be a tuneable dielectric. The working of the polar modulator is shown in the graph of Figure 12. Tracks (1202, 1208 and 1214) show the phase variation and (1204, 1206, 1210, 1212, 1216, 1218) represent the amplitude variation of a signal. It should be appreciated that various different combinations of a modulator include an amplitude modulating component and a phase modulating component may be envisaged. For example, even though only one combination of a polar modulation is shown, it should be appreciated that the amplitude modulating component may be combined with any phase modulating component in order to achieve polar modulation. The amplitude modulator and phase modulator may each provide for continuous and discrete amplitude and phase modulation to be achieved, respectively. The foregoing description has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure. The language used in the specification has been principally selected for readability and instructional purposes, and it may not have been selected to delineate or circumscribe the inventive subject matter. It is therefore intended that the scope of the invention be limited not by this detailed description, but rather by any claims that issue on an application based hereon. Accordingly, the disclosure of the embodiments of the invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims. Finally, throughout the specification and accompanying claims, unless the context requires otherwise, the word ‘comprise’ or variations such as ‘comprises’ or ‘comprising’ will be understood to imply the inclusion of a stated integer or group of integers but not the exclusion of any other integer or group of integers.

Claims

1. A modulator including an amplitude modulating component for modulating an amplitude of an electromagnetic signal, the amplitude modulating component comprising; a first conductor for tunnelling the electromagnetic signal from an input of the modulator to an output of the modulator; the first conductor being spaced apart from a second conductor electrically connected to a power source, wherein the power source is configured to induce an alternating electrical current in the second conductor thereby creating a magnetic field around the second conductor, and wherein the magnetic field created around the second conductor interacts with the electromagnetic signal of the first conductor, causing electromagnetic interference in the first conductor such that the amplitude of the electromagnetic signal is either increased or decreased by a factor associated with an applied voltage of the power source.

2. The modulator as claimed in claim 1, wherein the factor with which the amplitude of the electromagnetic signal is increased or decreased is a function of the distance between the first conductor and second conductor, as well as the amplitude of the voltage of the power source.

3. The modulator as claimed in claim 1 or claim 2, wherein the minimum operating voltage of the modulator is controlled by the distance between the first conductor and the second conductor.

4. The modulator as claimed in any one of claims 1 to 3, including a first waveguide and a second waveguide paced at an 180° bend relative to each other and having a common ground, wherein each of the waveguides include boundaries that are configured to only permit a dominant propagating mode to travel through the waveguides.

5. The modulator as claimed in claim 4, wherein the waveguides are of a rectangular waveguide geometry and the dominant mode is the TE10 mode.

6. The modulator as claimed in claim 4 or claim 5, wherein the first conductor and the second conductor are housed within the waveguide.

7. The modulator as claimed in any one of the preceding claims, wherein the first conductor is a thin metallic wire configured for energy tunnelling.

8. The modulator as claimed in any one of the previous claims, wherein the power source is an alternating voltage source configured to induce the alternating current to flow in the secondconductor.

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