ANTENA PIPÓLO DOBLADA
FIELD OF THE INVENTION The present invention relates in general to antennas. More particularly, it refers to a bent dipole antenna for use in wireless telecommunications systems. BACKGROUND OF THE INVENTION Base station antennas used in wireless telecommunications systems have a capability to transmit and receive electromagnetic signals. The received signals are processed by a receiver at the base station and fed into a communications network. The transmitted signals are transmitted at different frequencies than the received signals. Due to the growing number of base station antennas, manufacturers try to minimize the size of each antenna and reduce manufacturing costs. Furthermore, the visual impact of the base station antenna towers in the communities has become a social concern. In this way, it is desirable to reduce the size of these towers and thereby decrease the visual impact of the towers in the community. The size of the towers can be reduced by using smaller base station antennas. There is also a need for an antenna with a width
of wide impedance band that deploys a stable far field pattern across the bandwidth. There is also a need to increase the bandwidth of existing single polarization antennas so that they can operate in cellular frequency bands, the Global Mobile System (GMS), Personal Communication System (PCS), Personal Communication Network (RCP), and Universal Mobile Telecommunications System (SMUT). The present invention attacks the problems associated with the above antennas by providing a novel bent dipole antenna including a conductor forming one or more integral radiation sections. This design has broad impedance bandwidth, is inexpensive to manufacture, and can be incorporated into existing single-polarization antenna designs. SUMMARY OF THE INVENTION A bent dipole antenna is provided for transmitting and receiving electromagnetic signals. The antenna includes a ground plane and a conductor extending adjacent to the ground plane and separated therefrom by a first dielectric. The conductor includes a transmission line cutting adapter with open end, a radiator inlet section, at least one radiation section integrally formed with the radiator inlet section, and a feed section. The radiation section includes
first and second ends, a power dipole and a passive dipole. The power dipole is connected to the radiator inlet section. The passive dipole is arranged in a separate relationship with the feed dipole to form a gap. The passive dipole is shortened to the power dipole at the first and second ends. BRIEF DESCRIPTION OF THE DRAWINGS Other objects and advantages of the invention will become apparent from the reading of the following detailed description and with reference to the accompanying drawings, in which: Figure 1 is an isometric view of a bent dipole antenna according to one embodiment of the present invention. Figure Ib is a side view of a bent dipole antenna of Figure la. Figure 1c is a top view of a conductor before it is bent in the bent dipole antenna of Figure 1. Figure 1d is an isometric view of a dipole antenna bent according to another embodiment of the present invention. The Figure is an isometric view of a dipole antenna bent according to another embodiment of the present invention.
Figure 2 is an isometric view of a dipole antenna bent according to still another embodiment of the present invention. Figure 3 is an isometric view of a dipole antenna bent according to another embodiment of the present invention. The figure 4a is an isometric view of a dipole antenna bent according to yet another embodiment of the present invention. Figure 4b is a top view of the conductor before it is bent in the bent dipole antenna of Figure 4a. Figure 5a is an isometric view of a bent dipole antenna including a shortening adapter according to an embodiment of the present invention. Figure 5b is a side view of the bent dipole antenna of Figure 5a. Figure 6 is an isometric view of the bent dipole antenna including a shortening adapter according to still another embodiment of the present invention, Y
Figure 7 is an isometric view of a bent dipole antenna including a shortening adapter according to another embodiment of the present invention. Although the invention is susceptible to several modifications and alternative forms, the modalities
specific features have been shown by way of example in the drawings and will be described in detail herein. However, it should be understood that the invention is not intended to be limited to the particular forms described. Instead, the invention will cover all modifications, equivalents, and alternatives that fall within the spirit and scope of the invention as defined by the appended claims. DESCRIPTION OF THE ILLUSTRATIVE MODALITIES The present invention is useful in wireless, transmission, military and other communication systems. One embodiment of the present invention operates through several frequency bands, such as the North American Frequency Band of 824-896 Megahertz, the Frequency Band of the North American Trunk System of 806-869 Megahertz, the Frequency Band of the Global System for Mobile (GSM) of 870-960 Megahertz. Another embodiment of the invention operates through different wireless bands, such as the Frequency Band of the Personal Communication System (SCP) of 1850-1990 Megahertz, the Frequency Band of Personal Communication Network (RCP) of 1710-1880 Megahertz. , and the Frequency Band of the Universal Mobile Telecommunications System (SMUT) of 1885-2170 Megahertz. In this embodiment, wireless telephone users transmit electromagnetic signals to the tower of the base station which includes a plurality of antennas which receive the
signals transmitted by wireless phone users. Although useful in base stations, the present invention can also be used in all types of telecommunications systems. The antenna illustrated in Figures la-4b is a bent dipole antenna 10 for transmitting and receiving electromagnetic signals. The antenna 10 includes a ground plane 12 and a conductor 14 formed from a single sheet of conductive material. The conductor 14 consists of three sections, a feed section 20, a radiator inlet section 40, and a radiant portion including the radiating sections 21 and / or 22. The feed section 20 extends adjacent to the ground plane 12. and is separated therefrom by a dielectric, such as air, foam, etc., as shown in Figure Ib. The radiation sections 21 and 22 are spaced apart from the surface or edge of the ground plane 12 in order to provide an antenna capable of operating with wide bandwidth which still has a compact size. A radiator inlet section 40 consists of two conductive sections 41 and 42 separated by a recess 29. The conductor section 41 connects a part of the radiation section 22 to the supply line 20 and the conductor section 42 connects another part of the radiation section 22 with the ground plane 12. The radiator inlet section 40 has an intrinsic impedance which is adjusted to make
the radiation section 22 coincides with the feed section 20. This impedance is adjusted by varying the width of the conductor sections 41, 42 and the hollow 29. In the illustrated embodiments of Figures la-e, the antenna 10 includes two sections of radiation 21 and 22. In the embodiments of Figures la-Ib, the conductor 14 is mechanically and electrically connected to the ground plane 12 in two places 16 and 18. The radiation sections 21, 22 are supported at a distance d by above the ground plane 12. In the wireless frequency band mode (1710-2170 Megahertz), the distance d = 3.09 centimeters. The conductor 14 is bent at the bends 15a and 15b so that the feeding section 20 is supported by and displaced from the ground plane 12, as schematically shown in Figure Ib. As a result, the power section 20 is generally parallel to the ground plane 12. The power section 20 includes a radio frequency input section 38 that is adapted to electrically connect to a transmission line. The transmission line is generally electrically connected to a radiofrequency device such as a transmitter or a receiver. In one embodiment, the radiofrequency input section 38 is directly connected to the radio frequency device. The two illustrated radiation sections 21, 22 are identical in construction, and for this reason only the
Radiation section 22 will be described in detail. The radiation section 22 includes a feed dipole 24 and a passive dipole 26. The feed dipole 24 comprises a first monopole of a quarter of wavelength 28 and a second monopole of a quarter of a wavelength 30. In one embodiment , the first one-quarter wavelength monopole 28 is connected to one end of the conductor section 41. The other end of the conductor section 41 is connected to the supply section 20. The second one-quarter length monopole wave 30 is connected to one end of conductor section 42, and the other end of conductor section 42 is connected to ground plane 12 at location 16. In this embodiment, conductor section 42 can be connected with the ground plane 12 by any convenient fastening device such as a nut and bolt, a screw, a rivet, or any convenient fastening method including welding, soldering, brazing, and forming. n cold. A convenient connection provides both the electrical and mechanical connection between the conductor 14 and the ground plane 12. In this way, the antenna 10 is protected from overvoltage and overcurrent conditions caused by transient phenomena such as lightning. A method for forming a good electrical connection as mechanical is the cold forming process developed by Tox Pressotechni GmbH of Weingarten, Germany (hereinafter
"the cold forming process"). The cold forming process deforms and compresses a metal surface into another metal surface to form a Tox button. The cold forming process uses pressure to block the two metal surfaces together. This process eliminates the need for separate mechanical fasteners to secure the two metal surfaces together. Thus, in the embodiment where the radiation sections 21, 22 are joined to the ground plane 12 by the cold forming process, the resulting Tox buttons at the places 16 and 18 provide structural support to the radiation sections 21. , 22 and provide an electrical connection to the ground plane 12. By joining the conductor 14 to the ground plane 12 by the cold forming process, the intermodulation distortion (DIM) of the antenna 10 is minimized. Certain other types of connections Electricity such as welding will also minimize the intermodulation distortion of the antenna 10. The gap 32 forms a first dipole of half the wavelength (passive dipole 26) on one side of the gap 32 and a second dipole of half the length of the wave (feed dipole 24) on the other side of the gap 32. The centrally located gap 29 separates the feed dipole 24 into the first monopole of a quarter wavelength 28 and the second monopole of a quarter wavelength 30. The portions of the conductor 14 at opposite ends 34 and 36 of the
hollow 32 electrically connect the power dipole 24 with the passive dipole 26. The recess 29 causes the conductor sections 41 and 42 to form a transmission line of the separation line coupled at the edge. Since the transmission line is balanced, it efficiently transfers EM energy from the feed section 20 to the radiation section 22. In the embodiment of Figure la, the ground plane 12 and the feed section 20 are generally orthogonal to the radiation sections 21, 22. Referring to Figure 1c, a top view of the conductor 14 is shown before it is bent into the bent dipole antenna similar to the antenna shown in Figure la. A hole 42 is provided in the radio frequency input section 38 to help connect the radio frequency input section 38 to a conductor of a transmission line of a radiofrequency device. One or more holes 44 are provided to facilitate the joining of one or more dielectric supports between the supply section 20 and the ground plane 12. The dielectric supports may include spacers, nuts and bolts with dielectric washers, screws with dielectric washers, and so on. . In another embodiment shown in Figure 1d, the conductor 14 is bent to form the radiation sections 21 ', 22'. In this embodiment, the conductor 14 is bent so that the passive dipoles 26 and the radiation section 21 'and 22'
they are generally perpendicular to the respective conductor sections 40 and generally parallel to the ground plane 12. In yet another embodiment shown in Figure 1, the radiation sections 21", 22" are bent in opposite directions so that the passive dipoles 26 of each radiation section 21"and 22" are disposed approximately 180 degrees one from the other, they are generally perpendicular to the sections of the respective conductor 40, and each one is generally parallel to the ground plane 12. In the illustrated embodiments, the dipole passive 26 is arranged parallel to and spaced from the feed dipole 24 to form a gap 32. The passive dipole 26 is shortened to the feed dipole 24 at opposite ends 34 and 36 of the gap 32. The gap 32 has a length L and a width W , where the length L is greater than the width. In a modality where the antenna 10 is used in the frequency band of the Universal Mobile Telecommunications System, the length of the gap is L = 5.69 centimeters and the width of the gap is = 0.508 centimeters, while the length of the dipole is 6.7 centimeters and the width of the dipole is 1.52 centimeters. Referring to another embodiment shown in Figure 2, a ground plane 112 is provided which comprises four sections 114, 116, 117, and 118. Sections 114 and 116 are generally coplanar horizontal sections whereas sections 117 and 118 generally they are walls
opposite verticals. In this embodiment, the feeding section 120 is disposed between the two generally vertical walls 117, 118. The walls 117, 118 of the ground plane 112 are generally parallel to the feed section 120. The feed section 120 and the walls 117 , 118 form a triplet microtira transmission line. The feed section 120 is separated from the walls 117, 118 by a dielectric such as air, foam, and the like. The two sections 114 and 116 are generally orthogonal to the radiation sections 121, 122. Parts of the antenna of Figure 2 that are identical to the corresponding parts in the antenna of Figure la have been identified with the same reference numbers in both figures. In another embodiment shown in Figure 3, a single ground plane 212 is provided which is generally vertical. A single feed section 20 and the radiation sections 121, 122 are then all generally parallel to the ground plane 212. In this embodiment, the feed dipole 24 should be at a distance d from the upper edge of the ground plane 212 to ensure proper transmission and reception. In one modality, the distance d = 3.09 centimeters. If the ground plane 212 extends beyond the point where the radiator inlet section 40 begins, transmission and reception can be prevented. Parts of the antenna of Figure 3 that are identical
the corresponding parts in the antenna of Figure 1 have been identified with the same reference numbers in both figures. In the embodiments of Figures 2 and 3, conductor 114 or 214 is generally vertical and planar (i.e. does not bend over most of its length), although conductor 114 or 214 shown in Figures 2 and 3 it is bent slightly for its connection with the places 116, 118 on the ground planes 112, or the places 216, 218 on the ground plane 212. Alternatively, the conductor 114 or 214 could be flat along its entire length, thereby allowing the conductor to be made of a microtira of non-bend dielectric substrate which is directly connected to the ground planes 112, 212, respectively, by means of, for example, gluing. In another embodiment shown in Figure 4a, radiation sections 321a, 322a are supported on ground plane 312 and are generally orthogonal thereto. A conductor 314a is bent at the bends 315a and 315b so that the feed section 320a is supported by and displaced from the ground plane 312. The ends 334a, 336a of the radiation sections 321a, 322a are bent downwardly to the plane 312. This configuration minimizes the size of the resulting antenna 10. In addition, bending the radiation sections 321a, 322a increases the beamwidth
Half Power of the E plane (AHMP) of the field pattern away from the resulting antenna. This modality is particularly attractive to produce near-identical co-polarization patterns of the E plane and H plane in the far field. In addition, one or more of these radiation sections can be used for 45 degree tilt variation, in which the radiation sections are arranged in a vertically arranged row, with each section of radiation rotated so as to have its polarization at a antenna of 45 degrees with respect to the central axis of the vertical row. In the modality of the bent radiation section, when the patterns are shortened in the horizontal plane for the horizontal and vertical polarizations, the patterns will be very similar over a wide range of viewing angles. Figure 4b illustrates a top view of the driver
14a before it is bent in the bent dipole antenna 10 of Figure 4a. In the embodiment of Figures 4a and 4b, a passive dipole 326a is arranged in separate relation with a feed dipole 324a to form a recess 332a. The passive dipole 326a is shortened to the feed dipole 324a at the ends 334a and 336a. The recess 332a forms a first dipole of the wavelength half (passive dipole 326a) on the side of the recess 332a and a second dipole of the wavelength half (feed dipole 324a) on the other side of the recess 332a. The 24a power dipole includes a hole centrally
located 329a which forms the first monopole of a quarter of wavelength 328a and the second monopole of a quarter of wavelength 330a. In a modality where the antenna is used in the 824-896 Megahertz cellular band and the GSM band of 870-960 Megahertz, the length of the Dipole L is approximately 16.61 centimeters, and the width of the dipole is approximately 1.22 centimeters. In this embodiment, the innermost section of the power dipole 24a is a distance d from the upper part of the ground plane 12, where the distance d is approximately 7.34 centimeters. In another embodiment illustrated in Figures 5a and 5b, the conductor section 42 terminates in an open-end transmission line shortening adapter 50 that is not electrically connected to the ground plane 12. Instead the adapter 50 is supported above the ground plane 12 by a dielectric separator 52 which is, for example, glued to both the adapter 50 and the ground plane 12. Figure 5b schematically illustrates a side view of a portion of the antenna 10, including one of the dielectric separators 52. Alternatively, the adapter 50 can be secured to the ground plane 12 by a dielectric holder extending through the adapter 50 and the ground plane 12 at the locations 16, as shown in Figures 5a and 5b. The length of the adapter 50 is a quarter of a wavelength in the operating frequency of the antenna.
Since the end of the adapter 50 forms an open circuit, it will appear that there is an electrical short to ground at the end of the conductor section 42 when the antenna is excited at its operating frequency. This causes the antenna 10 to operate in the same manner as if the connector section were electrically connected to the ground plane 12. With this arrangement, there are no electrical connections to ground in the structure of the radiation element. The direct current ground connection for the complete array of the antenna is provided by electrically connecting one end of a shortened transmission line with a quarter wavelength 54
(Figure 6) to the supply network 20 and to the ground plane 12. The advantage provided by this open end adapter mode is that the number of connections between the antenna and the ground plane is reduced from one connection per section of radiation to a connection by antenna arrangement. This embodiment substantially reduces manufacturing time, reduces the number of parts required for assembly and reduces the cost of the resulting antenna. These advantages are considerable when the antenna 10 contains a large number of radiation sections. The open end adapter described above can be used in any of the embodiments illustrated in Figures la-4b. Figure 6 shows still another embodiment similar to Figure 2 but with the end of a conductor section 142
which includes an open-ended split-line adapter 150. The adapter 150 is separated from the ground plane 112 by dielectric spacers similar to the spacers 52 described above in relation to Figure 5a. As in the case of Figures 5a and 5b, the direct current ground connection for the complete antenna array can be provided by electrically connecting a quarter wavelength transmission line 54 between the power section 120 and the plane Fig. 7 shows another embodiment where the antenna 10 is supported by the dielectric spacers 252. The end of the conductor section 242 includes a separation line adapter 250 separated from the ground plane 212 by the spacers 252, similar to the spacers 52 described above in relation to Figure 5a. Here also the direct current connection to ground for the complete antenna array can be provided by electrically connecting a quarter-wavelength transmission line between the supply section and the ground plane. Although the illustrated embodiments show the conductor 14 forming two radiation sections 21 and 22, the antenna 10 would operate with as few as a radiation section or with multiple radiation sections. The bent dipole antenna 10 of the present invention provides one or more sections of radiation that are
they form integrally from the conductor 14. Each radiation section is an integrated part of the conductor 14. In this way, there is no need to separate radiation elements (i.e. radiation elements that are not an integral part of the conductor 14) or fasteners for connecting the radiation elements separated from the conductor 14 and / or from the ground plane 12. The entire conductor 14 of the antenna 10 can be manufactured from a single piece of conductive material such as, for example, a metal sheet composed of aluminum, copper, brass or alloys thereof. This improves the reliability of the antenna 10, reduces the manufacturing cost of the antenna 10 and increases the speed at which the antenna 10 can be manufactured. The construction of a piece of the doubling conductor mode is superior to previous antennas using microtiras of dielectric substrate because these microstrips can not be bent to create the radiation sections shown, for example, in Figures la-e and 4a -b. Each radiation section, such as the radiation sections 21, 22 in the antenna of Figure 1, is fed by a pair of conductive sections, such as the conductive sections 41 and 42 in the antenna of Figure 1, which form a Line of transmission of lines of strips coupled by the edge balanced. Since the transmission line is balanced, it is not necessary to provide a balum. The result is an antenna with a very high impedance bandwidth
broad (for example, 24 percent). The impedance bandwidth is calculated by subtracting the highest frequency from the lowest frequency that the antenna can accommodate and dividing the center frequency of the antenna. In one modality, the antenna operates in the frequency bands Personal Communication System, Personal Communication Network and Universal Mobile Telecommunications System. Thus, the impedance bandwidth of this mode of antenna 10 is: (2170 MHz - 1710 MHz) / l940 MHz = 24% In addition to having wide impedance bandwidth, antenna 10 displays a field pattern Stable remote through the impedance bandwidth. In the wireless frequency band mode (1710-2170 Megahertz), antenna 10 is a half-beam, 90-degree azimuth beam antenna, that is, the antenna achieves a width of more than 3 decibels of 90 degrees . To produce an antenna with this half-power beam width, a ground plane with side walls is required. The height of the side walls is 1.27 centimeters and the width between the side walls is 15.5 centimeters. The ground plane in this mode is made of aluminum having a thickness of 0.152 centimeters. In another wireless frequency band modality (1710-2170 Megahertz), the antenna 10 is an antenna of half power width 65 degrees azimuth, that is, the antenna achieves a beam width of three decibels of 65
degrees. To produce an antenna with this half-power beam width, a ground plane with side walls is also required. The height of the side walls is 3.5 centimeters and the width between the side walls is 15.5 centimeters. The ground plane in this mode is also aluminum having a thickness of 0.152 centimeters. The antenna 10 can be integrated into existing single polarization antennas in order to reduce costs and increase the impedance bandwidth of these existing antennas to cover the cellular frequency bands, Global Mobile System, Personal Communication System, Network of Personal Communication and Universal Mobile Telecommunications System. Although the present invention has been described with reference to one or more preferred embodiments, those skilled in the art will recognize that many changes can be made thereto without departing from the spirit and scope of the present invention which is presented in the following claims.