WO2018140843A1

WO2018140843A1 - Electromagnetic transmission line wave amplifier

Info

Publication number: WO2018140843A1
Application number: PCT/US2018/015627
Authority: WO
Inventors: Xiaodong Liu; Yu Liang; Qichang LIANG
Original assignee: Xiaodong Liu; Yu Liang; Liang Qichang
Priority date: 2017-01-29
Filing date: 2018-01-28
Publication date: 2018-08-02

Abstract

An electromagnetic transmission line wave amplifier includes a transmission line and a parasitic dipole. The transmission line carries an electromagnetic transmission having an electric field, a magnetic field, a forward wave at a first wavelength and at a first frequency; and a backward wave. The parasitic dipole includes a pair of equal and oppositely charged or magnetized poles separated by a distance of less than about half of the first wavelength of the electromagnetic transmission. The parasitic dipole is formed with an inductive coil about equidistant from the poles to have a resonant frequency greater than the first frequency of the electromagnetic transmission and optimized for absorption of the forward wave at the first frequency. The parasitic dipole is further configured to emit an amplified electromagnetic wave in the transmission line when placed within the electric field or the magnetic field created by the electromagnetic transmission.

Description

Electromagnetic transmission line wave amplifier

Cross-reference to Related Application

[0001] This application claims the benefit of U.S. Provisional Application No.

62/451 ,754, filed 29-JAN-2017, which is hereby incorporated by reference herein. Technical Field

[0002] In the field of amplifiers, an electromagnetic wave amplifier tuned to a specific frequency of electromagnetic transmission using a parasitic dipole resonantly connected to a transmission line.

Background Art [0003] The most common electromagnetic transmissions involve cell-phone frequencies ranging from about 400 megahertz to 1 ,900 megahertz. While the present application is not limited to any particular frequency, the most prolific application would be for cellular devices, which use sets of frequency ranges within the ultra-high frequency band. [0004] Most mobile networks worldwide use portions of the radio frequency spectrum, allocated to the mobile service, for the transmission and reception of their signals. The particular bands may also be shared with other radio-communication services, e.g. broadcasting service, and fixed service operation.

[0005] There are several types of transmission lines for electromagnetic energy and these include a waveguide, a co-axial cable, a micro-strip and a stripline.

[0006] A waveguide can be a hollow metal tube for directing and containing the transmission of energy in the form of an electromagnetic wave. The hollow metal tube can be any cross sectional shape, such as a rectangular hollow metal tube and a circular hollow metal tube. The waveguide can also be a solid dielectric rod. In electromagnetics and communications engineering, the term waveguide may refer to any linear structure that conveys electromagnetic waves between its endpoints. A dielectric waveguide employs a solid dielectric rod rather than a hollow pipe. For example, an optical fiber is a dielectric guide designed to work at optical frequencies. Transmission lines, such as microstrip, coplanar waveguide, stripline or co-axial cable, may also be considered to be waveguides. [0007] For a waveguide that is a hollow metal tube, the tube wall around the hollow body provides distributed inductance, while the empty space of the hollow body between the tube walls provides distributed capacitance. Thus, waveguides are single- conductor elements. [0008] Typically, the electromagnetic energy is in the form of pulses of high- frequency waves confined within the hollow body of the waveguide. The waves consist of an electric field and a magnetic field, both such fields moving or propagating in a direction of travel through the waveguide. While both such fields are moving in the same direction these fields are perpendicular to each other. [0009] When an electromagnetic wave propagates down a hollow tube, one of two fields present, i.e. either the electric field or the magnetic field, will be transverse to the wave's direction of travel. The other field will travel in a "loop" longitudinally to the direction of travel, and be perpendicular to the other field. Whichever field remains transverse to the direction of travel determines whether the wave propagates in a "TE" (Transverse Electric) mode or "T " (Transverse Magnetic) mode.

[0010] A co-axial cable, also referred to as a coax cable, is a type of transmission line for radio frequency signals. The co-axial cable is used in feedlines connecting radio transmitters and receivers with their antennas, Internet connections, and television signals. The coax cable has a central axial conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield, and having an outer plastic sheath. Typically, the electromagnetic field carrying the signal is confined to the space between the inner and outer conductors.

[0011] In micro-electronics, there are two types of waveguides on a printed circuit board: a microstrip, also known as a microstrip transmission line; and a stripline, also known as a stripline transmission line. Essentially, stripline and microstrip are different methods of routing high speed transmission lines on a printed circuit board.

[0012] A microstrip consists of a copper trace separated from a ground plate by an insulating substrate. The term "copper trace" is a term of art meaning trace patterning printed on a circuit board typically using photolithography or etching. A copper trace may consist of any electrically conducting material, such as copper or aluminum and is not restricted to being made of just the copper element. Typically, a microstrip is routed on an external layer of the printed circuit board. [0013] A stripline includes a flat strip of metal sandwiched between two metal ground-plates; the flat strip of metal located about equidistant between the two metal ground-plates (See FIG.6) and within a substrate. In a stripline, the parasitic dipole is located alongside of the flat strip of metal within the substrate, i.e., the flat strip of metal and the parasitic dipole are fully contained within the substrate of the printed circuit board, as shown in FIG.6. Thus, a transmission line that is routed on an internal layer (between two metal ground-plates) is referred to as a symmetric stripline and the routing is referred to as "stripline" routing.

Summary of Invention [0014] An electromagnetic transmission line wave amplifier includes a transmission line and a parasitic dipole in a specific structural arrangement. The transmission line carries an electromagnetic transmission having an electric field, a magnetic field, and a forward wave at a first wavelength and at a first frequency. The parasitic dipole includes a pair of equal and oppositely charged or magnetized poles separated by a distance of less than about half of the first wavelength of the electromagnetic transmission. The parasitic dipole is formed with an inductive coil about equidistant from the poles to have a resonant frequency greater than the first frequency of the electromagnetic

transmission and optimized for absorption of the forward wave at the first frequency. The parasitic dipole is further configured to emit an amplified electromagnetic wave in the forward direction in the transmission line when placed within the electric field or the magnetic field created by the electromagnetic transmission.

[0015] Optimal distances separating the poles of the parasitic dipole may also be 1/10 or 1/20 of the first wavelength of the electromagnetic transmission at the first frequency. Other optimal distances less than one-twentieth of the first wavelength may also be applicable.

[0016] Optional components include a phase shifter located in the path of the backward wave, a circulator configured to direct a reflected wave from the parasitic dipole away from the transmitter, a terminal load within the first intersect chamber that absorbs any reflected wave from the circulator. [0017] When the transmission line is a stripline, added components and limitations include a flat strip of metal sandwiched between two metal ground-plates; the flat strip of metal located about equidistant between the two metal ground-plates and within a substrate; and the parasitic dipole is located alongside of the flat strip of metal within the substrate.

[0018] When the transmission line is a microstrip, added components and limitations include a copper trace on a surface of a substrate; and a ground plate below the substrate, and wherein the parasitic dipole is adjacent to the microstrip on the surface of the substrate.

[0019] When the transmission line is a co-axial cable, added components and limitations include a central axial conductor; a tubular insulating layer; and a tubular ground surrounding the central axial conductor; and wherein the parasitic dipole is positioned alongside of the central axial conductor within the tubular insulating layer.

[0020] An alternative embodiment using a co-axial cable includes limitation that the parasitic dipole is tubular and centered on the central axial conductor.

Technical Problem

[0021] The Yagi-Uda antenna of the prior art, has been widely used in radar, broadcasting, and wireless communication only works in open space. In addition, the transmitted wave is attenuated and not amplified because the wave spreads out in the open space.

[0022] Filter technology disclosed in the prior art serves a different purpose even though it utilizes an embedded metal rod or rod array inside a waveguide. Most importantly, a filter is not structurally positioned as disclosed herein and does not amplify an electromagnetic wave.

Solution to Problem

[0023] It is desirable to embed a parasitic dipole inside a transmission line to reduce the wave attenuation and amplify the electromagnetic wave at specific frequency. To enable power amplification of a wave from a transmission line, parasitic dipoles were mounted inside a waveguide cavity. Interaction between the parasitic dipole and the waveguide contributes to power amplification.

[0024] The parasitic dipole is different from prior art filters in two important differences. The first difference is the self-resonant current inside the parasitic dipole, which oscillates within the parasitic dipole itself. This self-resonant current is not present in the prior art filters. Another difference is that prior art filters are intended to be resonance-coupled to waveguide, which current flows from the filter to the walls of waveguide due to capacitive coupling between the filter and waveguide walls. Such resonance-coupling is intended to be minimized or even eliminated in the structural configuration of the parasitic dipole. [0025] The parasitic dipole is essentially a short dipole that stands away from the waveguide walls so that resonance coupling is minimized. A short dipole has a large value of capacity and this is counteracted by adding an inductive coil in the middle of the parasitic dipole to counterpart its capacity.

[0026] Another characteristics is the resonant frequency of the parasitic dipole, which has a narrow bandwidth for optimization a specific frequency for the

electromagnetic transmission. The resonant frequency of the parasitic dipole is preferably higher than the frequency of the electromagnetic transmission. It is preferably higher than the frequency of the electromagnetic transmission so that the parasitic dipole presents capacitive impedance. The capacitive impedance of the dipole is preferably tuned to achieve the best amplification performance at the specific frequency.

Advantageous Effects of Invention

[0027] To minimize the capacitive coupling between the parasitic dipole and the wall of waveguide that might otherwise occur with a filter strongly coupled to the waveguide, the length of parasitic dipole is physically shorter than a filter and is not touching the wall of the waveguide. Preferably, a parasitic dipole is located away from the wall of waveguide so that capacitive coupling is minimized and so that the parasitic dipole works in a self-resonant mode.

[0028] A parasitic dipole as disclosed herein has a larger component of capacitive impedance, an inductive coil is added in the middle of the parasitic dipole to

counterbalance its capacitive impedance. The resonant frequency of the parasitic dipole is preferably tuned to just above the frequency to be amplified.

[0029] The proposed solution employs two significant structural differences between a filter of the prior art and the parasitic dipole disclosed herein. The first is that a filter is connected to the wall of the waveguide directly or by capacitive coupling. The structural positioning of the parasitic dipole disclosed herein does not connect to the wall of waveguide. The second is that the positioning of the parasitic dipole minimizes capacitive coupling. Brief Description of Drawings

[0030] The drawings illustrate preferred embodiments of the electromagnetic transmission line wave amplifier according to the disclosure. The reference numbers in the drawings are used consistently throughout. New reference numbers in FIG.2 are given the 200 series numbers. Similarly, new reference numbers in each succeeding drawing are given a corresponding series number beginning with the figure number.

[0031] FIG. I is a side elevation view of a preferred embodiment of an

electromagnetic transmission line wave amplifier using a waveguide as a transmission line. [0032] FIG.2 is a side elevation view of preferred embodiment of a parasitic dipole.

[0033] FIG.3 is perspective view of two waveguides showing the differing electric and magnetic fields in TE mode and TM mode.

[0034] FIG.4 is a plot of intensity vs the frequency showing the relative intensity of the electromagnetic transmission, the resonant frequency of the parasitic dipole and the amplified wave frequency.

[0035] FIG.5 shows perspective views of 4 different transmission lines including a waveguide with a rectangular cross-section, a waveguide with a circular cross-section, a solid dielectric rod, and a co-axial cable.

[0036] FIG.6 is a perspective view of a stripline. [0037] FIG.7 is a perspective view of a microstrip on a printed circuit board.

[0038] FIG.8 is a cross-sectional view of an electromagnetic transmission line wave amplifier using a co-axial cable and a tubular parasitic dipole.

[0039] FIG.9 is a cross-sectional view of an electromagnetic transmission line wave amplifier using a co-axial cable and the parasitic dipole shown in FIG.2. [0040] FIG.10 is a length-wise sectional elevation view of a waveguide with a transmitter at one end, parasitic dipole in the middle and a receiver at the other end.

[0041] FIG.1 1 is a length-wise sectional elevation view of a waveguide showing 3 intersect chambers, a circulator at each intersection, and a terminal load in each intersect chamber to absorb a reflected wave from the parasitic dipole. [0042] FIG.12 is a length-wise sectional elevation view of a waveguide with two parasitic dipoles. [0043] FIG.13 is a length-wise sectional top view of a waveguide showing 3 upper intersect chambers and 3 lower intersect chambers with a parasitic dipole in each of the upper intersect chambers, a circulator at each intersection, and a terminal load to absorb a reflected wave from the parasitic dipole in each lower intersect chamber. [0044] FIG.14 is a perspective of a parasitic dipole that is tubular.

Description of Embodiments

[0045] In the following description, reference is made to the accompanying drawings, which form a part hereof and which illustrate several embodiments of the present invention. The drawings and the preferred embodiments of the invention are presented with the understanding that the present invention is susceptible of

embodiments in many different forms and, therefore, other embodiments may be utilized and structural, and operational changes may be made, without departing from the scope of the present invention.

[0046] FIG.1 shows a lengthwise cross-section of a transmission line (105) in the form of a rectangular waveguide. A parasitic dipole (1 10), sometimes referred to as a parasitic resonator, is mounted in the center of the waveguide. The resonant frequency (410) of the parasitic dipole (1 10) is preferably tunable by adjusting the inductivity or capacitance of the parasitic dipole (1 10). Typically, the width of the rectangular waveguide roughly corresponds to the lowest frequency that can propagate inside the waveguide. The height of the rectangular waveguide can be made so as to achieve an optimized output. When an electromagnetic transmission (1 18) or wave propagates inside the waveguide, there is usually a simultaneous current

propagated the wall and a charge usually accumulates on the top and bottom surfaces of the waveguide. Both the charge on the surface and the current along the wall often induce an electric current in the parasitic dipole. The reflected impedance from the parasitic dipole (1 10) to the waveguide is negative so that the wave amplitude of the electromagnetic transmission (1 18) is amplified.

[0047] In a first preferred embodiment an electromagnetic transmission line wave amplifier (100), includes a transmission line (105) and a parasitic dipole (1 10) sized and placed in a defined structural arrangement.

[0048] The transmission line (105) is configured to carry or conduct an

electromagnetic transmission (1 18), also known as a wave or a signal. The wave inside the waveguide may be standing wave or travelling wave. The electromagnetic transmission (1 18) includes an electric field (315); a magnetic field (320); a forward wave (1 16) at a first wavelength and at a first frequency.

[0049] The parasitic dipole (1 10) is a charged electrical conductor or magnetized element. The parasitic dipole (1 10) is either magnetized or is electrically charged so that it includes opposite poles (a positive pole and a negative pole) at either end. Thus, the parasitic dipole (1 10) includes a pair (130) of equal and oppositely charged or magnetized poles.

[0050] To be maximally effective, the length of the parasitic dipole (1 10) is less than half of the first wavelength of the electromagnetic transmission sought to be amplified. The optimized size will depend on the specific frequency of the electromagnetic transmission (1 18), the placement of the parasitic dipole (1 10) and the resulting impedance of the transmission line. Variations in size for many applications range from one-tenth of the first wavelength of the electromagnetic transmission (1 18) at the first frequency to one-twentieth of the first wavelength of the electromagnetic transmission (1 18) at the first frequency. However, a shorter distance of less than one-twentieth of the first wavelength is also practical.

[0051] A table of approximate "less than lengths" of the parasitic dipole (1 10) using common electromagnetic frequencies and wavelengths is as follows.

12.0 GHz 15 cm 7.5 cm 1 .5 cm 7.5 mm

12.5 GHz 12 cm 6 cm 1 .2 cm 6.0 mm

13.0 GHz 10 cm 5 cm 11 .0 cm 5.0 mm

14.0 GHz 7.5 cm 3.25 cm 7.5 mm 3.75 mm

Ϊ 5.0 GHz 6.0 cm 3 cm 6.0 mm 3.0 mm

M O GHz 3.0 cm 1 .5 cm 3.0 mm 1.5 mm

[0052] The parasitic dipole (1 10) is formed with an inductive coil (210) about equidistant from the pair (130) of equal and oppositely charged or magnetized poles. Preferably, this means that if the parasitic dipole (1 10) were a wire, then the wire would be shaped with one or two loops near the midpoint of the wire. Alternatively, a separate coil could be added around the mid-point of the parasitic dipole (1 10).

[0053] The parasitic dipole (1 10) is configured to have a resonant frequency (410) greater than the first frequency, that is greater than the frequency of the

electromagnetic transmission (1 18). Preferably, the resonant frequency (410) of the parasitic dipole (1 10) is optimized for absorption of the forward wave (1 16) at the first frequency. This optimization effectively means that there is an impedance match between the parasitic dipole (1 10) and transmitter (1 15).

[0054] The parasitic dipole (1 10) is configured to emit an amplified electromagnetic wave (120) in the transmission line (105) when the parasitic dipole (1 10) is placed within the electric field (315) or within the magnetic field (320) created by the

electromagnetic transmission (1 18). The location of the parasitic dipole (1 10) is similar to its position in an alternative embodiment where the transmission line is a solid dielectric rod (515).

[0055] The electromagnetic transmission line wave amplifier (100) may additionally include a phase shifter (135) located in the path of the backward wave (1 17). A distance adapter may also be utilized to adjust the distance between the transmitter and the parasitic dipole.

[0056] For most embodiments that utilize a transmission line (105) that is a hollow metal tube forming a waveguide (1 1 10), then in those embodiments, the

electromagnetic transmission line wave amplifier (100) preferably includes a transmitter (1 15) that is configured to input the electromagnetic transmission (1 18) into the waveguide (1 1 10); a circulator (1 105) configured to direct the reflected wave (1 125) from the parasitic dipole (1 10) away from the transmitter (1 15); the parasitic dipole (1 10) being located or positioned about mid-way (1015) within a cross section of the hollow metal tube (1010) that forms the waveguide (1 1 10); and a receiver (121 ) to collect the amplified electromagnetic wave (120). Optionally, there may also be a plurality of parasitic dipoles (See FIG.1 1 ), and a circulator (1 105) between any two adjacent parasitic dipoles (See FIG.1 1 ).

[0057] When the parasitic dipole (1 10) is embedded inside a waveguide (1 1 10), there is preferably a transmitter (1 15) at one end to input the electromagnetic

transmission (1 18) into the waveguide (1 1 10) and a receiver at other end to receive and re-transmit the amplified electromagnetic wave (120) from the waveguide (1 1 10). The waveguide (1 1 10) can be rectangular in cross-section, i.e., a rectangular hollow metal tube (505), or cylindrical, i.e., a circular hollow metal tube (510), and work in the TE mode (305) or the TM mode (310) as well.

[0058] For most embodiments that utilize a transmission line (105) that is a hollow metal tube forming a waveguide (1 1 10), then in those embodiments, the

electromagnetic transmission line wave amplifier (100) may further include a first intersect chamber (1 1 15) extending radially from the hollow metal tube that forms the waveguide (1 1 10), the intersect chamber located longitudinally where each circulator (1 105) is positioned; and a terminal load (1 120) within the first intersect chamber (1 1 15) that absorbs any reflected wave (1 125) from the circulator (1 105). [0059] The first preferred embodiment may include additional components in an alternative embodiment when the transmission line (105) is a hollow metal tube forming a waveguide (1 1 10), as shown in FIG.1 1 . The black spots represent the parasitic dipole (1 10). The wave amplitude is amplified by the parasitic dipoles, sequentially. The symbol "T" represents the terminal load that consumes the reflected wave. [0060] These additional components include a transmitter (1 15) configured to input the electromagnetic transmission (1 18) into the waveguide (1 1 10); a circulator (1 105) configured to direct the reflected wave (1 125) from the parasitic dipole (1 10) away from the transmitter (1 15); the parasitic dipole (1 10) is located in a second intersect chamber (1305) extending radially from the hollow metal tube that forms the waveguide (1 1 10); a circulator (1 105) is located at a junction (1 130) of the second intersect chamber and the hollow metal tube that forms the waveguide (1 1 10); and a receiver (121 ) is configured to collect the amplified electromagnetic wave (120). [0061] The emitted wave from the parasitic dipole (1 10) also has a backward flow, also referred to as a backward wave (1 17), and also considered a reflected wave (1 125). The backward wave (1 17) from the parasitic dipole (1 10) could break the impedance match with the transmitter (1 15) so that an issue could be raised as how to maintain the impedance match with the transmitter (1 15).

[0062] The impedance match includes two parts. One is phase match and the other one is amplitude match. The phase match can be achieved by adding a phase shifter (135) located in the path of the backward wave (1 17) or by adjusting the distance (1015) between them. A phase shifter (135) is a module that provides a controllable phase shift in the electromagnetic wave. The amplitude match is that the sum of transmitter (1 15) impedance and the reflected impedance from the backward wave (1 17) from the parasitic dipole (1 10) should be equal to the standard input impedance like 50 ohm or 75 ohm depending on the device specification. For example, if the standard input impedance is 50 ohm and the reflected impedance from the backward wave (1 17) is -20 ohm, then the transmitter (1 15) impedance would be adjusted to 70 ohm to meet the amplitude match. When the impedance match is achieved, the backward wave (1 17) from the parasitic dipole (1 10) will merge with the input wave harmonically.

[0063] In order to achieve the impedance match, an alternative embodiment adds a circulator (1 105) between the transmitter (1 15) and parasitic dipole (1 10) to direct the backward wave (1 17) from the parasitic dipole (1 10) in a direction away from the transmitter (1 15). If multi parasitic dipoles are used in sequence, the circulator (1 105) is preferably placed in between each adjacent dipoles to bypass the backward wave (1 17) from the parasitic dipole (1 10). [0064] A circulator (1 105) is a passive device, in which a microwave, radio

frequency or optical signal is received in a first port of the circulator (1 105) and rotated within the circulator (1 105) to a second port for transmission. A signal received in the second port will be routed to a third port instead of being sent to the first port. Thus, the backward wave (1 17) will propagate in a different direction within the transmission line. [0065] FIG.13 is a length-wise sectional top view of a waveguide showing 3 upper intersect chambers and 3 lower intersect chambers with a parasitic dipole in each of the upper intersect chambers, a circulator at each intersection, and a terminal load to absorb a reflected wave from the parasitic dipole in each lower intersect chamber. [0066] The FIG.13 embodiment may be referred to as a traveling wave power amplifier. The FIG.13 optional structure includes the first intersect chamber (1 1 15) that extends opposite to a second intersect chamber (1305). This first intersect chamber (1 1 15) includes the terminal load (1 120) that absorbs any reflected wave (1 125) from the parasitic dipole (1 10). There is a circulator (1 105) in the center of each intersect. The input wave come from the left side and the output power go to the right side. The black spots represent the parasitic dipole (1 10) in each resonating cavity. The wave amplitude is amplified by the parasitic dipoles, sequentially. The symbol "T" represents the terminal load that consumes the reflected wave. [0067] The first preferred embodiment may be configured with a transmission line (105) that is a microstrip (705) or stripline (605).

[0068] When the first preferred embodiment is configured with a transmission line (105) that is a stripline (605), then the stripline (605), as shown in FIG.6, preferably includes a flat strip of metal (606) sandwiched between two metal ground-plates (615) and (616). The flat strip of metal (606) is located about equidistant between the two metal ground-plates (615) and (616) and within a substrate (610). The parasitic dipole is (1 10) located alongside of the flat strip of metal (606) within the substrate (610).

[0069] When the first preferred embodiment is configured with a transmission line (105) that is a microstrip (705), then the microstrip (705), as shown in FIG.7, preferably includes a copper trace on a surface (710) of the substrate (610). In this configuration, the ground plate (615) is below the substrate (610) and the parasitic dipole (1 10) is adjacent to the microstrip (705) on the surface (710) of the substrate (610).

[0070] When the first preferred embodiment is configured with a transmission line (105) that is a co-axial cable (520), then the co-axial cable includes a central axial conductor (521 ); a tubular insulating layer (522); and a tubular ground (523)

surrounding the central axial conductor (521 ). In this configuration, the parasitic dipole (1 10) is positioned alongside of the central axial conductor (521 ) within the tubular insulating layer (522). In an alternative embodiment, the parasitic dipole (1 10) is tubular (810) and centered on the central axial conductor, as shown in FIG.8 and FIG.14. Example 1

[0071] In this example, an electromagnetic transmission line wave amplifier (100), includes a transmission line (105) and a parasitic dipole (1 10) sized and placed in a defined structural arrangement according to the disclosure herein. A transmitter (1 15) introduces an electromagnetic transmission (1 18) into the electromagnetic transmission line wave amplifier (100). The forward wave (1 16) component of the electromagnetic transmission (1 18) passes through a parasitic dipole (1 10), the parasitic dipole (1 10) is excited at its resonant frequency (410). Assuming that the parasitic dipole (1 10) has a quality factor, this excitation also occurs at a higher adjacent frequency (415) and a lower adjacent frequency (405). Referring to FIG.4, an absorption peak (420) is narrowly distributed around the resonant frequency (410). The parasitic dipole (1 10) once excited, then emits an electromagnetic wave in both forward and backward directions. This process is called stimulated-emission. The emitted wave is at a lower adjacent frequency (405) and it overlaps positively with the forward wave (1 16) so that the forward wave (1 16) at lower adjacent frequency (405) is amplified. The emitted wave at higher adjacent frequency (415) overlaps negatively with the forward wave (1 16) so that the forward wave (1 16) at higher adjacent frequency (415) is reduced. FIG.4 shows that the absorption peak (420) at frequency of f1 is the resonant frequency (410) of the parasitic dipole (1 10). The wave at lower adjacent frequency (405), fO, is amplified, while the wave at higher adjacent frequency (415), f2, is reduced.

[0072] The above-described embodiments including the drawings are examples of the invention and merely provide illustrations of the invention. Other embodiments will be obvious to those skilled in the art. Thus, the scope of the invention is determined by the appended claims and their legal equivalents rather than by the examples given.

Industrial Applicability [0073] The invention has application to the telecommunications industry.

Claims

What is claimed is:

1. An electromagnetic transmission line wave amplifier, comprising: a transmission line configured to carry an electromagnetic transmission, the electromagnetic transmission comprising an electric field; a magnetic field; and a forward wave at a first wavelength and at a first frequency;; and a parasitic dipole, the parasitic dipole: comprising a pair of equal and oppositely charged or magnetized poles separated by a distance of less than half of the first wavelength; formed with an inductive coil about equidistant from the pair of equal and oppositely charged or magnetized poles; having a resonant frequency greater than the first frequency, said resonant frequency optimized for absorption of the forward wave at the first frequency; and configured to emit an amplified electromagnetic wave in the transmission line when placed within the electric field or the magnetic field created by the electromagnetic transmission.

2. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

distance separating the equal and oppositely charged or magnetized poles is selected from the group consisting of one-tenth of the first wavelength of the electromagnetic transmission at the first frequency, and one-twentieth of the first wavelength of the electromagnetic transmission at the first frequency.

3. The electromagnetic transmission line wave amplifier of claim 1 , further comprising a phase shifter located in the path of a backward wave.

4. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

transmission line is a hollow metal tube forming a waveguide, the electromagnetic transmission line wave amplifier further comprising: a transmitter configured to input the electromagnetic transmission into the waveguide; a circulator configured to direct a reflected wave from the parasitic dipole away from the transmitter; the parasitic dipole located about mid-way within a cross section of the hollow metal tube that forms the waveguide; and a receiver to collect the amplified electromagnetic wave.

5. The electromagnetic transmission line wave amplifier of claim 4, wherein there is a plurality of parasitic dipoles and there is a circulator between any two adjacent parasitic dipoles.

6. The electromagnetic transmission line wave amplifier of claim 5, further comprising a first intersect chamber extending radially from the hollow metal tube that forms the waveguide, the first intersect chamber located longitudinally where a circulator is positioned; and a terminal load within the first intersect chamber that absorbs any reflected wave from the circulator.

7. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

transmission line is a hollow metal tube forming a waveguide, the electromagnetic transmission line wave amplifier further comprising: a transmitter configured to input the electromagnetic transmission into the waveguide; a circulator configured to direct a reflected wave from the parasitic dipole away from the transmitter; the parasitic dipole located in a second intersect chamber extending radially from the hollow metal tube that forms the waveguide; a circulator at a junction of the second intersect chamber and the hollow metal tube that forms the waveguide; and a receiver to collect the amplified electromagnetic wave.

8. The electromagnetic transmission line wave amplifier of claim 7, wherein a first intersect chamber extends opposite to the second intersect chamber; the first intersect chamber comprising a terminal load that absorbs any reflected wave from the parasitic dipole.

9. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

transmission line is a microstrip or stripline.

10. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

transmission line is a stripline comprising a flat strip of metal sandwiched between two metal ground-plates; the flat strip of metal located about equidistant between the two metal ground-plates and within a substrate; and the parasitic dipole is located alongside of the flat strip of metal within the substrate.

11. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

transmission line is a microstrip comprising a copper trace on a surface of a substrate; and a ground plate below the substrate, and wherein the parasitic dipole is adjacent to the microstrip on the surface of the substrate.

12. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

transmission line is a co-axial cable comprising a central axial conductor; a tubular insulating layer; and a tubular ground surrounding the central axial conductor; and wherein the parasitic dipole is positioned alongside of the central axial conductor within the tubular insulating layer.

13. The electromagnetic transmission line wave amplifier of claim 1 , wherein the

transmission line is a co-axial cable comprising a central axial conductor; a tubular insulating layer; and a tubular conducting shield surrounding the central axial conductor; and wherein the parasitic dipole is tubular and centered on the central axial conductor.