Abstract: A wideband antenna with backlobe elimination in a confined space is disclosed. Backlobe elimination is by an array of electromagnetically conductive members disposed between the spiral element and the ground plane and almost contacting the ground plane so as to bleed a backlobe away from the spiral antenna to the ground plane. In one embodiment, the members are conical elements disposed between the spiral element and the ground plane of a spiral antenna such that the apexes of the conical elements almost contact the spiral element and the bases of the conical elements contact the ground plane. In some embodiments, other means may be employed to perform this function. In operation, conical elements bleed the backlobe of the signal away from the spiral element to the ground plane.

Abstract: A collapsible antenna (10) comprises an elongate boom (12) having a main axis (14) and a plurality of elongate radiating elements (16) having respective first ends (18.1) and respective second ends (18.2). At least some of the elongate radiating elements are flexible and are mounted at the respective first ends to the boom in longitudinally spaced relation. Regions towards the respective second ends of the at least some of the elongate radiating elements engage a flexible rope (20). The flexible rope forms part of a frame (22) which is manipulatable relative to the boom between a first collapsed configuration and a second operative configuration wherein the at least some radiating elements are in an operative configuration relative to the boom.

Abstract: A non-planar, ultra-wide band, quasi-self-complementary feed antenna is disclosed. The antenna provides an invariant phase center location over its entire frequency band, is compact and includes a low profile, and includes input matching better than is currently available over a decade of frequency bandwidth. The very compact feed couples dual polarization electromagnetic energy to a transmitter from free space or air with minimum losses and mismatches over a very wide frequency band.

Abstract: A printed dual-band Yagi-Uda antenna is disclosed, which includes a substrate, a first driver, a first director, a second driver and a reflector. The first driver is formed on the substrate, and is utilized for generating a radiation pattern of a first frequency band. The first director is formed at a side of the first driver on the substrate, and is utilized for directing the radiation pattern of the first frequency band toward a first direction. The second driver is formed between the first driver and the first director on the substrate, and is utilized for generating a radiation pattern of a second frequency band. The reflector is formed at another side of the first driver on the substrate, and is utilized for reflecting both the radiation patterns of the first frequency band and the second frequency band toward the first direction.

Abstract: In the field of wideband directional antennas employing linear polarization, and in particular in the context of amplitude goniometry systems, polarization purity defects lead to deformation of the radiation diagrams that increases with the elevation, inducing degraded detection system location performance. An antenna is provided operating with linear polarization and having radiating elements of “sinuous” shape inscribed within a circle, and includes radiating elements printed on the two faces of a support, the elements of the first face being deduced from those of the other face by a rotation.

Abstract: The invention relates to an antenna structure for coupling electromagnetic energy between a chip and an off-chip element, including a first resonant structure disposed on or in a chip. The first resonant structure is configured to have a first resonant frequency. The antenna structure also includes a second resonant structure disposed on or in an off-chip element. The second resonant structure is configured to have a second resonant frequency substantially the same as the first resonant frequency. The first resonant structure and the second resonant structure are mutually disposed within a near field distance of each other to form a coupled antenna structure that is configured to couple electromagnetic energy between the chip and the off-chip element. The electromagnetic energy has a selected wavelength in a wavelength range from microwave to sub-millimeter wave. The invention also relates to a method of calculating dimensions for a highly coupled antenna structure.

Abstract: A planar broadband beam-steering phased array antenna with approximately 10:1 bandwidth is comprised of planar broadband traveling wave antenna elements positioned parallel to a conducting ground plane and spaced less than 0.5 wavelength at the highest operating frequency and more than 0.01 wavelengths at the lowest operating frequency. Each planar traveling wave antenna element is a planar frequency-independent antenna or planar self-complementary antenna, and is truncated to fit a unit cell of the phased array. Adjacent antenna elements are arranged to be tightly coupled together or connected with each other and spaced less than 0.5 wavelength apart between their centers throughout its operating frequency range. One or more layers of dielectric or magneto-dielectric substrates/superstrates can be added to enhance specific performances.

Abstract: Methods for assembling an active array system are described. In one exemplary embodiment, an active subarray panel assembly having a first surface with a first array of electrical contacts and a radiator aperture with an array of radiator structures and an aperture mounting surface with a second array of electrical contacts are assembled together. The first surface of the panel assembly and the aperture mounting surface of the radiator aperture are brought into contact with an adhesive layer including microwave interconnects in a pattern corresponding to the first array of electrical contacts and the second array of electrical contacts so that the adhesive layer is between the first surface of the panel assembly and the aperture mounting surface of the radiator aperture. Pressure, heat and vacuum are applied to cure the adhesive and complete engagement of the microwave interconnects.

Abstract: Directional wide band antenna that may be utilized to enhance cell phone coverage within a building, or for signals intelligence collection (SIGINT). Includes a log-spiral slot antenna with feed-point configured to transfer energy to/from the antenna. Includes an energy absorbent backing and an energy absorbent siding coupled with the log-spiral slot antenna. Includes a cavity behind the log-spiral slot antenna and in front of the energy absorbent backing. Includes a cable connector coupled to a tapered microstrip line coupled to the feed-point wherein the tapered microstrip line is configured to transform the input impedance to the antenna impedance. Housed in a container configured to hold the above listed components. Energy absorbent siding, cavity and energy absorbent backing greatly reduces back lobes. Another embodiment has log-spiral shaped slots at an outer portion of the log-spiral slot antenna overlap with the energy absorbent siding and wherein the feed-point overlaps the cavity.

Abstract: A foldable log-periodic antenna includes a feed line, one or more transmitting elements for transmitting and/or receiving electromagnetic signals, one or more supporting elements for holding the transmitting elements, and one or more elements for producing a tensile stress on the transmitting elements. One of the a transmitting elements is connected to one of the supporting elements and to the feed line, and with one supporting element is connected to the feed line via an articulated joint apparatus, such that the antenna can be moved from a transport position to an operating position and vice versa. The one or more elements for producing a tensile stress on the transmitting elements is a flexible tube, and can have an internal pressure applied to them and are connected to the supporting elements for holding the transmitting elements.

Abstract: A CPW fed planar log-periodic antenna is provided. The antenna includes: an upper substrate; a planar log-periodic antenna structure formed beneath the upper substrate; a CPW-fed structure formed on the upper substrate for feeding energy into the planar log-periodic antenna structure; a lower substrate disposed beneath the upper substrate; and a wire structure formed beneath the lower substrate. The antenna of the present invention features efficient reduction of cross polarized radiation and thereby enhancing the performance.

Abstract: The invention describes a broadband multi-dipole antenna that has low input reflection coefficient, low cross polarization, rotationally symmetric beam and constant beam width and phase center location over several octaves bandwidth. The dipoles are fed from one or a few feed points, and they may with advantage have log-periodic dimensions. The antenna is more compact, has lighter weight and is cheaper to manufacture than other solutions. It is very well suited for feeding single, dual or multi-reflector antennas.

Abstract: A concentric ring, log-periodic slot antenna used for direction finding is disclosed. There are a number of continuous, circular slots nested inside of each other. A cover over the slots cavities has excitation plates and conductors thereon. There are four excitation plates spaced ninety degrees apart over each circular slot, and the excitation plates of all slots in each ninety degree sector are electrically interconnected. A conductor from the interconnected excitation plates in each of the four sectors conducts received signals to a Butler matrix which processes the signals and provides Mode 0, Mode +1, Mode ?1, and Mode ? outputs. These Mode outputs are used to provide direction finding information for DF signal sorting, and they may be used to provide radio frequency voltages to other equipment to provide accurate DF (CIDF) and CIGL transmitter geo-location information.

Abstract: Disclosed is a log periodic antenna and a manufacturing method thereof. In the log periodic antenna, antenna elements are attached to an antenna body to thereby simplify a structure of the antenna, the antenna can be manufactured in various designs without restriction to the configuration of the antenna, and the number of contacting points between the antenna element and a feeder is minimized to thereby simplify the manufacturing process. By the antenna, it is possible to produce the log periodic antenna of the simple structure and of various designs without the restriction to the antenna configuration by attaching the signal pattern and ground pattern to the pattern receiving surface.

Abstract: A collapsible antenna (10) comprises an elongate boom (12) having a main axis (14) and a plurality of elongate radiating elements (16) having respective first ends (18.1) and respective second ends (18.2). At least some of the elongate radiating elements are flexible and are mounted at the respective first ends to the boom in longitudinally spaced relation. Regions towards the respective second ends of the at least some of the elongate radiating elements engage a flexible rope (20). The flexible rope forms part of a frame (22) which is manipulatable relative to the boom between a first collapsed configuration and a second operative configuration wherein the at least some radiating elements are in an operative configuration relative to the boom.

Abstract: A log periodic antenna includes first and second transmission lines parallel with each other; and a plurality of broadband radiation elements having first sides electrically connected to the first and second transmission lines, a predetermined angle being defined between the first sides of the broadband radiation elements and the first and second transmission lines, and second sides not electrically connected with the first and second transmission lines, the second sides having radiation surfaces larger than radiation surfaces of the first sides. A plurality of broadband radiation elements electrically connected with the first transmission line and a plurality of broadband radiation elements electrically connected with the second transmission line are positioned to face each other with reference to the first and second transmission lines.

Abstract: A cladding (2) for a microwave antenna comprises at least one plate (3a, 3b, 3c, 3d) which has, in a first section plane (x=0; y=0), a cross section in the shape of a logarithmic spiral, characterized in that the plate (3a, 3b, 3c, 3d) has a cross section in the shape of a logarithmic spiral also in at least one second section plane perpendicular to the first one.

Abstract: A log periodic antenna comprises a plurality of radiating elements in an end fire configuration, each radiating element in the plurality of radiating elements comprises a conductor, and at least two shunt inductances connected to the conductor; a substrate connecting the plurality of radiating elements; and a log periodic stripline feed pathway superimposed on the substrate. The height of each radiating element of the plurality of radiating elements is about one hundredth the size of the wavelength and the length is about 0.14 the size of the wavelength at the lowest operating frequency of the log periodic antenna. The plurality of radiating elements is configured to produce impedance and radiation characteristics that are regularly repetitive as a logarithmic function of an excitation of frequency without performance degradation.

Abstract: There is provided a broadband antenna including: an insulating block having opposing first and second main surfaces and a side surface between the first and second main surfaces; a first radiator pattern formed on the first main surface and having a tapered slot with an open end; and a second radiator pattern including two patterns connected to opposing ends of the first radiator pattern, respectively, and extending to the second main surface.

Abstract: A non-planar, ultra-wide hand, quasi-self-complementary feed antenna is disclosed. The antenna provides an invariant phase center location over its entire frequency band, is compact and includes a low profile, and includes input matching better than is currently available over a decade of frequency bandwidth. The very compact feed couples dual polarization electromagnetic energy to a transmitter from free space or air with minimum losses and mismatches over a very wide frequency band.

Abstract: A CPW fed planar log-periodic antenna is provided. The antenna includes: an upper substrate; a planar log-periodic antenna structure formed beneath the upper substrate; a CPW-fed structure formed on the upper substrate for feeding energy into the planar log-periodic antenna structure; a lower substrate disposed beneath the upper substrate; and a wire structure formed beneath the lower substrate. The antenna of the present invention features efficient reduction of cross polarized radiation and thereby enhancing the performance.

Abstract: A helmet substrate is covered with a highly absorptive layer and an antenna layer. The antenna layer includes a conformal log periodic dipole array wherein adjacent antenna elements connect through switches. By driving appropriate ones of the switches, the log periodic dipole array tunes to a desired frequency band.

Abstract: An antenna includes at least one element whose physical shape is at least partially defined as a second or higher iteration deterministic fractal. The resultant fractal antenna does not rely upon an opening angle for performance, and may be fabricated as a dipole, a vertical, or a quad, among other configurations. The number of resonant frequencies for the fractal antenna increases with iteration number N and more such frequencies are present than in a prior art Euclidean antenna. Further, the resonant frequencies can include non-harmonically related frequencies. At the high frequencies associated with wireless and cellular telephone communications, a second or third iteration, preferably Minkowski fractal antenna is implemented on a printed circuit board that is small enough to fit within the telephone housing.

Abstract: An on-vehicle antenna system which offers a superior receiving performance, by suppressing reception of reflected/scattered waves coming from inside of the vehicle's cabin; these reflected/scattered waves being an adverse factor which deteriorates signal receiving performance of an antenna. The antenna system is installed at glass pane portion of a vehicle with direction (12) of the greatest radiation pattern (11) directed towards ahead (14) of the vehicle from boundary plane (10) containing power supply portion (9), while direction (13) of the smallest radiation pattern (11) towards behind (15) of the vehicle. The above-configured antenna system can suppress those waves reflected/scattered in the vehicle cabin from being received; as the result, it demonstrates improved characteristics.

Abstract: A broadband antenna may include a conductive antenna surface for radiating signals, a conductive backplane for reflecting signals radiated by the conductive antenna surface, and a dielectric layer disposed between the conductive antenna surface and the conductive backplane. The dielectric layer may include a plurality of dielectric substrates having differing dielectric constants.

Abstract: A tapered meander line antenna is formed by having a conductive material disposed on or in a non-conductive material, in which a length of the conductive material traversing from a proximal end to a distal end meanders in an approximately perpendicular direction from an axis of traversal from the proximal end to the distal end. The spacing between conductive lines that meander are made non-uniform and tapered to have less spacing between the conductors toward the distal end. In one instance the spacing is tapered to have a logarithmic pattern.

Abstract: An antenna including an electrically conductive portion defined substantially by a self-similar geometry present at multiple resolutions. The electrically conductive portion includes two or more angular bends and is configured to radiate broadband electromagnetic energy. The antenna further includes an electrically non-conductive portion that structurally supports the electrically conductive portion.

Abstract: A log-periodic dipole array system employs a structure for the transmitter and the receiver designed in a way such that they compensate for the non-linear characteristics of each other to realize linear phase characteristics as a pair. Radiation elements on the receiver are positioned with respect to its corresponding transmission line in an order opposite to the positioning of the radiation elements on the transmitter. Although neither the transmitter dipole array nor the receiver dipole array itself has linear phase characteristics, the overall dipole array antenna system can realize linear phase characteristic. The log-periodic dipole array system has the advantages that linear phase characteristics can be obtained without sacrificing high radiation efficiency and gain.

Abstract: Methods for assembling an active array system are described. In one exemplary embodiment, an active subarray panel assembly having a first surface with a first array of electrical contacts and a radiator aperture with an array of radiator structure and an aperture mounting surface with a second array of electrical contacts are assembled together. The first surface of the panel assembly and the aperture mounting surface of the radiator aperture are brought into contact with an adhesive layer including microwave interconnects in a pattern corresponding to the first array of electrical contacts and the second array of electrical contacts so that the adhesive layer is between the first surface of the panel assembly and the aperture mounting surface of the radiator aperture. Pressure, heat and vacuum are applied to cure the adhesive and complete engagement of the microwave interconnects.

Abstract: An electronic apparatus having an upper housing, a lower housing to which the upper housing is connected so as to be openable and closable, where the lower housing is formed with a signal line path running near a connecting portion with the upper housing and the signal line path has a signal line disposed therein. A receiving member having a base portion accommodated in the lower housing, a receiving portion provided upright on the base portion and protruding above an upper surface of the lower housing to receive the upper housing from below, and a first fin portion protruding frontward from the base portion to extend over the signal line path.

Abstract: The invention relates to an antenna structure for coupling electromagnetic energy between a chip and an off-chip element, including a first resonant structure disposed on or in a chip. The first resonant structure is configured to have a first resonant frequency. The antenna structure also includes a second resonant structure disposed on or in an off-chip element. The second resonant structure is configured to have a second resonant frequency substantially the same as the first resonant frequency. The first resonant structure and the second resonant structure are mutually disposed within a near field distance of each other to form a coupled antenna structure that is configured to couple electromagnetic energy between the chip and the off-chip element. The electromagnetic energy has a selected wavelength in a wavelength range from microwave to sub-millimeter wave. The invention also relates to a method of calculating dimensions for a highly coupled antenna structure.

Abstract: A log-periodic antenna coupled to a channelizer is described in which matched scale constants for the antenna and the channelizer are used to achieve substantially identical coupling over each fractional bandwidth channel. Embodiments for simultaneous dual polarization operation are described as well as embodiments suited for planar lithographic fabrication.

Abstract: A log-periodic antenna having a layer of dielectric media interposed between a microstrip log-periodic portion and a slot log-periodic portion where an array of two or more log-periodic antennas that may be placed about vehicles, such as air vehicles, or mounted on stationary structures, such as communication towers.

Abstract: A log periodic dipole array (LPDA) antenna including a first antenna element, a second antenna element and a pair of transmission line structures is provided herein. The first antenna element is fabricated as a continuous piece of conductive material to include a plurality of dipole elements extending outward from a center conductor. The second antenna element is fabricated in the same manner, albeit a mirror image, of the first antenna element. In one embodiment, the antenna elements are fabricated by cutting a contour of the plurality of dipole elements and the center conductor from a sheet of metal (e.g., aluminum or one of its alloys). The antenna elements and transmission line structures are preferably coupled, such that no electrical discontinuities exist between the antenna elements and a respective transmission line structure.

Abstract: This invention relates to improved ultra-wideband synthetic aperture radar and inverse synthetic aperture radar, capable of simultaneously and independently imaging a plurality of spectral and polarimetric channels covering multiple radio frequency octaves. Advances in technologies relating to signal processing, graphical user interfaces, color representations of multi-spectral radar images, low aerodynamic drag polarimetric SAR antenna systems, and synthetic aperture radar aircraft platforms are some of the advancements disclosed herein.

Abstract: The present invention relates to an active photonic band gap antenna. In this case, the photonic band gap structure is constituted by metal rods, some of which are discontinuous, namely composed of sections of rods connected by a switching element such as a PIN diode. According to the invention, only one rod in a row of rods seen from the radiating source is discontinuous. The antenna pattern can be controlled at a low cost.

Abstract: A log-periodic dipole array system employs a structure for the transmitter and the receiver designed in a way such that they compensate for the non-linear characteristics of each other to realize linear phase characteristics as a pair. Radiation elements on the receiver are positioned with respect to its corresponding transmission line in an order opposite to the positioning of the radiation elements on the transmitter. Although neither the transmitter dipole array nor the receiver dipole array itself has linear phase characteristics, the overall dipole array antenna system can realize linear phase characteristic. The log-periodic dipole array system has the advantages that linear phase characteristics can be obtained without sacrificing high radiation efficiency and gain.

Abstract: A broadband dipole antenna includes a dielectric substrate, a first radiating portion, a second radiating portion, a substantially U-shaped or V-shaped feed gap, and two feed points. The feed gap is located in-between the first radiating portion and the second radiating portion. The two feed points are located in the first radiating portion and the second radiating portion, respectively, and separated by the feed gap.

Abstract: An antenna device includes a power supply, a first antenna element, a second antenna element, and a film. The first antenna element includes a first feed line connected with the power supply, and first radiators connected with the first feed line and arranged along the drawing direction of the first feed line. The second antenna element includes a second feed line connected with the power supply, and second radiators connected with the second feed line and arranged along the drawing direction of the second feed line. The second antenna element is linearly symmetric with the first antenna element. The film holds at least the first and second antenna elements.

Abstract: A dual-port corporate-feed broadband antenna uses two pairs of crossed dipoles in each bay, fed by a single hybrid coupler in each bay, to support hybrid-mode IBOC® VHF-band broadcasting. Each 3 dB quarter-wave coupler receives a share of an analog FM broadcast signal on a first input and a digital OFDM broadcast signal, 20 dB down, on a second input. The respective coupler output ports drive coaxial lines to tees feeding respective quarter-wave-separated crossed dipoles. The dipoles in each bay are arranged in a square to one side of their coupler, making side mounting practical. The resultant omnidirectional analog and digital radiation patterns have the same circular polarization and opposite phase rotation. Bay spacing for vertical null is a function ((n?1)/n) of the number of bays in the antenna.

Abstract: A vertical complementary fractal antenna is provided, which includes a first fractal structure and a second fractal structure. The first fractal structure is defined as a superposition over at least one iteration of a motif, while the second fractal structure has a pattern complementary to that of the first fractal structure. Thus, the antenna may effectively increase bandwidth.

Abstract: A reduced height log periodic antenna that may safely be positioned under the rotating blades of a helicopter sitting on the ground and still resonate in the frequency range at which the antenna was originally designed to resonate. The antenna comprises a pair of antenna booms, a first plurality of vertical antenna radiating elements connected to the booms, and a second plurality of vertical antenna radiating elements connected to the booms. In addition, the antenna includes a plurality of tuned horizontal antenna radiating elements, each tuned horizontal radiating element being connected to the top of one of the second plurality of vertical antenna radiating elements, and a plurality of tuned upwardly bent horizontal antenna radiating elements, each tuned upwardly bent horizontal antenna radiating element being connected to the bottom of one of the second plurality of vertical antenna radiating elements.

Abstract: The subject invention provides a log-periodic antenna and method for controlling multiple polarizations of the antenna per a given frequency or frequencies The antenna includes a boom and a plurality of pairs of elements where each element of each pair of elements extends laterally from the boom in opposite directions. The plurality of pairs of elements includes a first pair of elements disposed in a first plane with the boom and a second pair of elements disposed in a second plane with the boom. The first plane extends radially from the boom at a first radial angle and the second plane extends radially from the boom at a second radial angle. The first radial angle is offset to the second radial angle. The antenna may include at least one adjustment mechanism. Each adjustment mechanism allows angular adjustment of at least one of the elements for controlling the multiple polarizations of the antenna.

Abstract: A center fed half-wave dipole antenna system includes first and second end brackets that are separated by a center bracket. The center bracket and each of the end brackets include a plurality of electrically isolated terminals allowing the center bracket to be coupled to each of the end brackets via a pair of dipole lines that may contain multiple dipole wires. As such, the antenna system is able to increase the effective length of the dipole antenna in a reduced amount of space, thus reducing the mounting area requirements of the antenna system.

Abstract: The invention describes a broadband multi-dipole antenna that has low input reflection coefficient, low cross polarization, rotationally symmetric beam and constant beam width and phase centre location over several octaves bandwidth. The dipoles are fed from one or a few feed points, and they may with advantage have log-periodic dimensions. The antenna is more compact, has lighter weight and is cheaper to manufacture than other solutions. It is very well suited for feeding single, dual or multi-reflector antennas.

Abstract: An antenna includes at least one element whose physical shape is at least partially defined as a second or higher iteration deterministic fractal. The resultant fractal antenna does not rely upon an opening angle for performance, and may be fabricated as a dipole, a vertical, or a quad, among other configurations. The number of resonant frequencies for the fractal antenna increases with iteration number N and more such frequencies are present than in a prior art Euclidean antenna. Further, the resonant frequencies can include non-harmonically related frequencies. At the high frequencies associated with wireless and cellular telephone communications, a second or third iteration, preferably Minkowski fractal antenna is implemented on a printed circuit board that is small enough to fit within the telephone housing.

Abstract: A printed antenna includes a smaller antenna member attached onto the circuit board, one or more greater antenna members attached onto the circuit board and electrically coupled to the smaller antenna member with conductive coupling members and coupled in series with each other, a feed-in terminal electrically coupled to the smaller antenna member, and a ground member attached onto the circuit board and spaced away from the feed-in terminal for a spaced distance for increasing the gain value and the frequency bandwidth of the printed antenna. The ground member may include one or more extensions located beside the feed-in terminal and the smaller antenna member.

Abstract: A panel antenna is provided having one or more radiating elements and a series of directors associated with each radiating element. Each series of directors is angled with respect to a direction of maximum radiation of the associated radiating element, in order to tilt the panel antenna beam. The directors may be dimensioned and/or arranged such that they couple weakly to radiation of a wavelength emitted by the associated radiating element. The directors may be dimensioned and/or arranged such that they are non-resonant at the wavelength emitted by the associated radiating element. The directors may be smaller than the length of an associated dipole radiating element.

Abstract: A log periodic dipole array (LPDA) antenna including a first antenna element, a second antenna element and a pair of transmission line structures is provided herein. The first antenna element is fabricated as a continuous piece of conductive material to include a plurality of dipole elements extending outward from a center conductor. The second antenna element is fabricated in the same manner, albeit a mirror image, of the first antenna element. In one embodiment, the antenna elements are fabricated by cutting a contour of the plurality of dipole elements and the center conductor from a sheet of metal (e.g., aluminum or one of its alloys). The antenna elements and transmission line structures are preferably coupled, such that no electrical discontinuities exist between the antenna elements and a respective transmission line structure.

Abstract: An antenna assembly having an operating frequency and a vertical radiation pattern with a main lobe axis defining a downtilt angle with respect to the earth's surface. The antenna assembly comprises a plurality of antennas in first, second, and third antenna groups physically disposed along a backplane, the backplane having a longitudinal axis along which the antennas are disposed, and a phase adjustment mechanism disposed electrically connected between the second first and third antenna groups, such that adjustment of the phase adjustment mechanism results in variation of the vertical radiation pattern downtilt angle.