1. Field of the Invention
The present invention enables combining broadband GW peak power to achieve MV/m and GV/m radiated electromagnetic fields of air or vacuum breakdown across the entire electromagnetic spectrum, including optical frequencies. The invention applies to broadband electromagnetic radiating systems, operating in transmitting and/or receiving modes.
More particularly, the invention relates to radiating systems generating the MV/m E-field that can be used as an ultimate microwave weapon facilitating the destruction of electronic systems at distances that at 1 GHz correspond to 10's of kilometres. Furthermore, the broadband character of this invention provides the maximum coupling of electromagnetic power and energy to target and the ultimate power density assures the highest probability of target destruction. The GV/m radiating systems operating in the 300 GHz frequency range, by reaching power density exceeding breakdown i.e. ionization, allow broadband excitation at resonance plasma frequencies permitting molecular, atomic and fusion research. In the receiving mode, the radiated power from single or multiple points/transmitters is received in a collimated beam/beams and is directed simultaneously to multiple spatially-dispersed broadband antennas and receivers allowing multichannel independent time and frequency data processing.
2. Description of the Related Art
Use of narrowband coherent (i.e. identical frequency and phase) power combined at specific frequencies (U.S. Pat. No. 7,800,538 B2 to Crouch et al.) intended to destroy distant targets vulnerable at unknown frequencies resulted in unspecified coupling of the electromagnetic energy to the target undermining the effectiveness and usefulness of the electromagnetic weapons. These designs use multiple, narrowband, relatively low power (MW instead of GW) generators operating simultaneously at different frequencies, and low gain antennas that suffer significant beam dispersion (U.S. Pat. No. 7,126,530 B2 to Brown). These factors limit the power density and E-field that can be delivered to distant targets resulting in a low probability of target destruction.
As per Reference 1, a broadband radiating system that uses a single GW generator and low-gain TEM-mode antenna illuminating a reflector has a limited weapons range since there is no possibility of adding more generators and antennas to increase the radiated E-field.
An effort (U.S. Pat. No. 8,576,109 B2 to Stark et al.) to create higher E-fields, by adding to the surface of the reflector of Reference 1, non-linear semiconductor switches to increase power allows generation of E-fields limited by low withstand voltage tolerance of the semiconductor devices. Since the E-field at the antenna reflector is limited to prevent damage to the semiconductor switches, the radiated E-field intensity precludes destruction of the semiconductor devices of a distant target.
Reference 1. Carl E. Baum et al., “JOLT: A Highly Directive, Very Intensive Impulse-Like Radiator”, Report of ITT Industries for US Air Force Research Lab., AFRL-DE-PS-TR-2006-1073, 2006.
This invention, by using many separate and independently triggered generators and spatially and angularly positioned high power antennas that allow adding individual pulses and beams to deliver to the target the maximum power density limited only by the E-field of air or vacuum breakdown. Operation very close to the E-field breakdown level, optimization of each generator triggering time and selection of pulse frequency spectral content, allow achieving ultimate peak power and energy transfer to the target. Delivery of broadband frequency spectral content that induces an oscillating response at specific resonance frequencies in the target further improves the energy transfer. In response to a short pulse, with duration defined by the minimum frequency of the bandwidth, the induced resonances will prolong the effects of excitation for a period proportional to the oscillation quality factor. Since the oscillation quality factor, for example for cable coupling in electronic equipment is in the range 5 to 10, the effect of single pulse excitation can be prolonged up to 10 times, reducing the number of required excitation pulses, therefore reducing the energy requirements from generators. This invention addresses only a few applications in 1 to 500 GHz frequency range, but the power addition applies to the entire electromagnetic spectrum from GHz, including optical frequencies as it assures that the power density and therefore the E-field on target does not decrease with frequency. The power density remains almost constant, as it is proportional to the radiated power that is decreasing with frequency divided by the illumination area on target that as well is decreasing with frequency. This invention allows selecting the frequency range of operation and by means of geometrical scaling assembling systems that could be used for a variety of purposes: plasma physics leading to fusion, fusion propulsion, particle accelerators, material deposition, medical interventions at molecular and atomic levels, quantum computing, nonlinear electromagnetics, electromagnetic and particle missiles, electromagnetic weapons and in other areas relaying on high power electromagnetic interactions.
This invention relates to broadband electromagnetic radiating systems, operating in a transmitting and/or receiving mode in the entire electromagnetic spectrum, including optical frequencies, at power levels up to or exceeding ionization. In the transmitting mode, the present invention allows combining broadband GW peak power to achieve MV/m and GV/m radiated E-fields of air or vacuum breakdown. In the receiving mode, the radiated power from a single or multiple points/transmitters is received in a collimated beam/beams and it is directed simultaneously through multiple spatially dispersed broadband antennas and receivers allowing multichannel independent time and frequency data processing at large distances. Considering the reciprocity principle in electromagnetics, only the transmitting mode operation is described in this submission. However, it should be understood that reversing the direction of signal propagation and replacing generators with receivers allows changing between transmitting and receiving mode of operation. The overall view of
The Cassegrain antenna 40 is converting diverging conical beams 14 and 15 coming from a focal point from each illuminating TEM-horn, after being reflected from the secondary reflector 11 and primary reflector 10, to non-diverging beams 16 and 17 that illuminate the entire target. Considering that, the radiated power from a single illuminating antenna 30 is limited to GW range, to achieve the MV/m E-field multiple illuminating antennas need to be used. This results in beam 15 originating from antennas furthest from the reflector axis being skewed 17, i.e. the beam 17 diverges from the main beam 16. Therefore, to prevent beam skewing it is desired to use a reflector antenna with the largest angular amplification, i.e. largest ratio of the angle between beams 14 and 15 versus angle between beams 16 and 17. Currently the only antenna with the largest angular amplification and no focal point in the radiating path is a Cassegrain antenna and such antenna is used in this invention. To show the effect of beam skewing,
In spite of diminishing power in function of frequency, the invention assures constant power density and therefore constant E-field on target in the entire electromagnetic spectrum including optics. The method of this invention is applicable in the frequency range above 500 GHz even if the broadband TEM-horns are replaced using different antenna concepts. Moreover, progress in high power generation and antenna technology can only improve the peak-power density delivered to targets. One skilled in the art will understand that all broadband radiating systems and antennas of this invention can also operate in the narrowband mode. Furthermore, the invention could be used as broadband and narrowband multi-beam receivers and for wireless combining and dispersing information and control without switching.
In broadband high power radiating systems the power density along the path from the generator to the target that may result in breakdown of the E-field, is a restraining factor in achieving the maximum radiated E-field. In this invention, to assure uniform power density along the path from individual generators to the target the power is added in stages. The first stage consists of multiple individual antennas 30 that can either be powered by one or multiple generators. In the second stage, the conical beams from each antenna in the array 13 are added by directing them into a centre point of the secondary reflector 11. The secondary reflector directs the diverging beams from all antennas into the primary reflector 10. The primary reflector converts all diverging beams into a non-diverging beam directed to the target. In this submission, the simpler-to-visualize and to design on-the-axis Cassegrain antenna is used. However, one skilled in the art will understand that all embodiments of this submission include off-the-axis Cassegrain type antenna arrays. When implementing this embodiment, the effects of beam dispersion and beam skew on power density at the target are to be considered. Since only beams from antennas located on the axis of the array are not skewed, for balanced design of the Cassegrain antenna the number of antennas in the array has to be limited and/or the angular amplification of the Cassegrain antenna has to be increased.
For the best performance of the Cassegrain-antenna that has angular amplification of approximately 10, the power density and the distance from the antenna to the target have to be optimized. At the maximum distance, i.e. at the end of the non-diverging beam region, the target and antenna diameter are equal Dt=Da=D, and the maximum number of antennas Nopt is defined by the diameter of the primary reflector
expressed in wavelength A corresponding to the “central” frequency of the band.
The maximum target distance R is a function of antenna diameter Dλ expressed in wavelength λ.
In the narrowband systems operating in the 1 to 5 GHz, the maximum power is lower than 1 GW and the E-field is approximately 75 kV/m for 9 m diameter reflector antenna. For identical frequency range and reflector size, the optimally designed broadband system of this invention, consisting of Cassegrain antenna using 32-antenna array delivers at a distance of Ropt=500 m, 2.5 TW power, and E-field of 3 MV/m. Therefore, in comparison to the narrowband system this invention allows reaching the 75 kV/m at a distance up to 30 times greater, while illuminating a target having diameter 30 times larger.
The 9 m reflector diameter expressed in the wavelength as Dλ=60 allows, when scaled in the frequency, to cover the entire microwave band up to 500 GHz and as such:
GW peak power, and max. E-field of 5 MV/m, 30 J/cm2 at 20 kHz pulse repetition frequency,
For all frequency bands, from 1 to 500 GHz the E-field is close to air breakdown limit and it is approximately 30 times greater than fields currently accepted as electromagnetic threats levels required for the destruction of electronic equipment.
An embodiment of “on-the-axis” Cassegrain antenna focused at infinity with a Barlow lens system is shown in
In the Cassegrain antenna with a Barlow lens system, the on-the-axis beam 14 and the most distant from the axis 15 coming from the antenna array 13 are directed towards the target after passing through the beam collimating Barlow lens system 18, 19 and 20. After being reflected from the secondary reflector 11 and primary 10, the beams are converted to non-diverging beams 16 and 17 that illuminate the entire target. The angle between beams 14 and 15 divided by the angle between beams 16 and 17 that represents the beam skew, defines the angular amplification of the Cassegrain antenna with Barlow lens system mB while m0 is the angular amplification of the antenna without Barlow lens systems. Since at the maximum distance, i.e. at the end of the non-diverging beam region, the target and antenna diameter are equal Dt=Da=DB, the diameter of the Cassegrain antenna primary reflector 10, when expressed in wavelength λ corresponding to the “central” frequency of the band is equal:
The maximum number of antennas NBopt is defined by the diameter DBλ of the primary reflector 10 and so is the distance RBA opt between the antenna and target:
The Cassegrain antenna with Barlow lens system focuses the beam at the third lens 20 into an area inversely proportional to the angular amplification, resulting in an increase of the E-field at that lens. To operate below the breakdown E-field at lens 20, the maximum angular amplification has to be limited.
An example of the effect of using the Barlow lens system follows. The Cassegrain antenna with the angular amplification increased from m0=10 to mb=15, increases the diameter of the main reflector 10 from Dλ=60 λ to DBλ=97 λ, and increases number of antennas from Nopt=32 to NBopt=85, resulting in an optimum target distance increase from Rλopt=3333 λ to RBλopt=8338 λ. Although the peak E-field at the target remains the same, the addition of the Barlow lens system increases significantly the range and the target illumination area therefore it improves the weapons “kill capability”. Consequently in the entire 1 to 500 GHz frequency range the Cassegrain antenna with Barlow lens system having the main reflector diameter of DBλ=97 λ, number of antennas of NBopt=85, and the optimum target distance of RBA opt=8338 λ assures the following:
In the above example, use of the Barlow lens system changed the angular amplification from 10 to 15, increasing the distance to target proportionally to the square of the change in the antenna amplification factor, i.e. increasing the distance
times while the maximum E-field remains unchanged. In summary, the E-field is approximately 30 times higher than fields currently accepted as electromagnetic threats causing destruction of electronic equipment. Considering the E-field obtained using this invention and currently accepted threat level in the 1 to 5 GHz band, the electronic systems located as far as 40 km away could be destroyed. Such destruction distance is approximately 100 times greater than distance achieved using current narrowband or broadband systems.
An embodiment of “on-the-axis” Cassegrain antenna focused at infinity, collimating beams at a single point 22 using focusing lens 21 is shown in
Collimating parallel beams radiated by many focusing Cassegrain antennas, into a single point 22 located few beam diameters from the focusing lens 21 allows achieving GV/m E-field that constitutes an enhancement in power addition. Currently, to achieve 0.5 PW peak power required for plasma studies the US National Ignition Facility (NIF) combines 192 laser beams. In this embodiment, after collimating beams coming from 192 Cassegrain antennas having diameter of Dλ=60, into a single point the following is achieved.
This invention instead of using plasma heating at optical frequencies excites and supports oscillation of fusion plasma in the 300 GHz range therefore assuring more efficient coupling of electromagnetic energy into the plasma. Since the E-field achieved in this embodiment exceeds 100 times the breakdown E-field in vacuum, operation in the 100 to 500 GHz band allows excitation of resonances not only at the fusion plasma frequency of 300 GHz, but also at the 280 GHz fusion plasma cyclotron frequency. Additionally, the broadband excitation that covers numerous frequencies simultaneously allows tracking the change in the resonance frequencies resulting from the changes in plasma density and temperature. Furthermore, increasing frequency of excitation by shortening the pulse duration increases the E-field resulting in larger energy deposition into plasma. Operation in the 100 to 500 GHz band, assures that the diameter of focal point is in the range of 1 to 10 mm and that the 192 Cassegrain antennas occupy volume having small 35 cm radius. Considering that, standard MRI magnets already produce 10 T magnetic fields required for fusion confinement, the entire 192 Cassegrain antenna could be placed within it. Although not shown in
The embodiment of broadband concave, convex and flat face antenna arrays as presented in FIG. 2 of the U.S. Pat. No. 6,295,032 B1 which was issued Sep. 25, 2001 under the title “Broadband horn antennas and electromagnetic field test facility”, and is assigned to the applicant of the present invention is shown in
Each array of
Alternatively, the four generators output power could be decreased four times to maintain the same output power as in the single septum antenna while the high voltage durability of this invention apparatus will be increased.
The embodiment of broadband, conical, double-polarization, multi-septum TEM-horn, bisected to form two enclosures is shown in