JP3045767B2 - Curved dipole element antenna - Google Patents

Abstract

An antenna comprises a base plate (20) forming a ground plane, a coaxial feed serving as a mast (22) connected to the base plate (20) and extending along an axis that is normal to the ground plane, and two orthogonal dipoles (24, 26) each formed of two elements. Each dipole element has a first end connected to and supported by the mast at a first location spaced apart from the ground plane by a predetermined distance and a second end closer to the ground plane and exhibits a curvature in a plane containing the mast. <IMAGE>

Description

Description: BACKGROUND OF THE INVENTION The present invention relates to antennas, and more particularly to antennas that are novel and inexpensive, and have a solid angle hemisphere that is essentially omnidirectional even near the surface of the earth. For a very useful antenna with almost constant gain. This antenna is sensitive over a wide band and has improved impedance matching and standing wave factor (VSWR) compared to other inexpensive antennas such as turn-style and patch antennas.

[Conventional technology]

For some radio transmissions, circular polarization (CP) is desirable. CP is a special case of elliptical polarization where the magnitudes of the horizontal and vertical (orthogonal) components are equal and the phases are exactly 90 ° apart. Most polarized signals are not perfectly circularly polarized, but are somewhat elliptically polarized. The indication of CP in this specification includes elliptically polarized waves in all bands.

Turn-style, patch, and other types of relatively inexpensive antennas are semi-omni-directional (i.e., have a nearly uniform gain over a semi-spherical sphere as viewed from a point relatively near the surface of the earth), It is known that those antennas have an impedance that can match the impedance of the circuit used. Turn-style antennas are described in the book "Antenna" by John D. Kraus (McGrawHill Book Company, 2nd ed.
Edition, 1988, pp. 726-731).

Typical conventional turn-style antenna 10 (Figure 1A)
Has two dipoles 12 and 14 in one plane. Such an antenna is hereinafter referred to as "planar turnstile". When the dipoles 12 and 14 are arranged in the correct relationship with each other, are properly driven, and the plane defined by the dipoles 12 and 14 is horizontal, this turn-style antenna has a very good CP in the zenith direction directly above the antenna. Although transmission and reception are possible, the state of transmission and reception deteriorates as the angle from the zenith increases.

Other well-known semi-omni-directional antennas include:
Some are commonly referred to as "patches" or planar microstrip antennas. This antenna is also described in the Klaus publication at pages 745-749. In this type of antenna, the reduction of the vertical electric field E field component is extremely remarkable, and as a result, a severe loss occurs in the axial ratio of the circularly polarized signal in the horizontal plane. Typical mythro strip patch antennas are shown in FIGS. 1B, 1C and 1D.
Shown in the figure.

FIG. 2 shows an example of the effect. In the figure, if the angle is defined by a line from the zenith Z to the antenna 10 and another line from the antenna 10 to the point 16 (off the zenith), the vertical component of the E vector at the point 16 Drops. If this angle (ie, the angle defined by the line from zenith Z to antenna 10 and the line from antenna 10 to point 18 in the horizontal position) is 90 °, the vertical component of the E vector is completely eliminated in the patch antenna, The turn-style antenna is close to that, and the radiation is no longer circularly polarized.

Therefore, conventional patch antennas and, to a lesser extent, conventional turn-style antennas mounted horizontally on the bedplate to achieve omnidirectionality to the hemisphere are in a direction 90 ° from the zenith. It is not possible to effectively transmit circularly polarized waves to the area or to receive circularly polarized waves effectively from that direction. As shown in FIG. 2, the vertical component of the E vector drops to almost zero in that region. As the angle with respect to the zenith increases, the axial ratio becomes very poor, and the conventional patch antenna and turn-style antenna lose their essential function as a linearly polarized antenna.

In some applications, this reduction in axial ratio (or attenuation from circular polarization to linear polarization) represents a significant loss in system efficiency. For example, in a receiver mounted on a ship, when the signal from a navigation satellite is incident at an angle slightly rising from the horizon (80 ° or more from the zenith), the very There will be reflections through many paths. In the case of a receiving antenna that can receive only horizontally polarized signals, interference from reflected signals from many paths can cause severe fading of the signal, thereby losing information. However, with an antenna having good circular polarization (CP), it is unlikely that both the vertical and horizontal components with a phase shift of exactly 90 ° between the two signals cancel each other out, so the degree of fading is Very small. That is, in a good CP,
The problem of a narrow viewing angle of reception is greatly reduced.

Furthermore, the conventional patch antenna and the turn-style antenna cannot obtain a uniform gain over the entire solid angle where the celestial sphere has an arc of 180 °. 2 arranged at right angles to each other
By using a pair of dipole elements, a constant gain in the horizontal direction can be easily obtained. However, such an antenna has a greater gain in a direction perpendicular to the ground plane than in a direction parallel to the ground plane. This is especially true for vehicles (eg, ships) that sway, move, or sway back and forth, and which need to transmit and receive omnidirectionally to the entire hemisphere. Disadvantages.

For example, consider a conventional patch or turnstyle antenna mounted on a ship anchored in quiet water, in a shipyard, or in a dry dock.
For best omnidirectional transmission and reception to the hemisphere, the antenna is mounted horizontally on a ground plane and its mast extends perpendicular to its horizontal plane. The gain of the antenna is shown by curve A in FIG. That is, the gain is maximum in the zenith direction (as shown in FIG. 3, +5 decibels relative to isotropics).
Very low in the horizontal direction (about -5dB as shown in Fig. 3)
i).

Also suppose, for example, that one wishes to satisfactorily receive signals from a traveling satellite located anywhere above the horizon.
With this assumption, signals coming from satellites sailing low above the horizon cannot be satisfactorily received over the sea where the ship will sway back and forth. For example, suppose the satellite is 90 ° from the starboard bow, the ship sways to port, and the satellite is low on the horizon. The ground plane of the antenna fixed to the ship also sways to port, which changes the direction of the curve in FIG. 3 in response to the sway, and the antenna gain is obtained when the ship is level at -5 dBi.
From (curve A for a conventional antenna), it falls to a value less than -5 dBi, which would not be able to transmit and receive sufficiently.

The situation is even worse when the two ships communicate with each other using a conventional semi-omni-directional turn-style antenna. Occasionally, the two ships swing back and forth, left and right, and the antenna masts tilt in opposite directions. In that case, the curve in FIG. 3 for the transmitting antenna rotates clockwise and the curve for the receiving antenna rotates counterclockwise. As a result, the signal must be weakened by the sway of one ship and the signal must be detected by an antenna whose sensitivity has been reduced by the sway of the other ship.

Another problem with conventional patch antennas is that the device has a low bandwidth and must be carefully tuned to operate satisfactorily at the desired frequency. This complicates the configuration for impedance matching tuning required to compensate for variations due to materials and the like, and increases costs. The main factor for obtaining a good SNR is the noise figure of the preamplifier. The antenna is usually tuned to get the best noise figure for the nominal impedance of the preamplifier. However, if the antenna has narrow band characteristics, it is difficult to guarantee that the impedance of the antenna approaches its nominal value at some exact frequency.

Another problem with conventional turn-style antennas is that separate mechanical and electrical structures are required, complicating and unnecessarily increasing costs. In particular, the mast supporting the dipole element (mechanical structure) and the driving balun transformer (electrical structure) are physically connected as described, for example, in Counselman et al., US Pat. No. 4,647,942. I know.

Various attempts have been made to overcome the problems of the conventional turn-style antenna as described above. Most notable is the drooping dipole structure disclosed in Patent No. 4,062,019 to Woodward et al. The device has a radiating element mounted on the mast at a 45 ° angle to the mast. The dipole element descends linearly from its point of attachment. Therefore, this radiating element makes an angle of 45 ° with both the horizontal plane and the vertical plane through the mast. Due to the inclination of the radiating element, 2
Two orthogonal electric field E components can be present over a wider range of solid angles. In the case of the planar patch antenna and the turn style antenna (see FIGS. 1A to 1D), the vertical component of the E field in the horizontal plane (ground plane) direction is greatly reduced as described above.

Therefore, a small, simple and semi-omnidirectional (semi-om)
The need for uni) CP antennas is stated. The most important feature is that the dipole elements are all straight and inclined at an angle of 45 ° ± 5 ° with respect to the turn-style mast. In addition, the characteristic impedance of the hanging dipole element is a fixed value, which must be provided in an impedance matching circuit. Naturally, the characteristic impedance is the physical dimension of the dipole (distance to ground plane, etc.)
Is variable within a certain range, but the range is narrow.

Other important prior art includes U.S. Patent No. 1,988,434.
No. 2,110,159, No. 2,976,534, No. 3,919,710, and No. 3,922,683.

[Problems to be solved by the invention]

However, the prior art described above is semi-omnidirectional with essentially constant gain over the solid angle hemisphere, has excellent CP near the horizon, and is highly sensitive over a wide band. Does not disclose an inexpensive antenna with even better VSWR.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to solve the above problems, and in particular to provide a new, inexpensive, and very useful antenna that is semi-omnidirectional with a constant gain over a solid angle hemisphere. is there.

Another object of the present invention is to provide an antenna having an excellent CP over a wide range of viewing angles, especially near the horizon.

It is another object of the present invention to provide an antenna which can have high sensitivity over a wide band and has excellent impedance matching and VSWR.

Another object of the invention is that no tuning is required, or
An object of the present invention is to provide an antenna which can be easily tuned without using a special circuit such as an impedance matching transformer having an unavoidable loss.

[Summary of the Invention]

The above problems can be solved by the present invention described below, and the above object can be achieved. That is,
A curved dipole element antenna according to the present invention includes a base plate forming a ground plane, a mast connected to the base plate and extending in a direction perpendicular to the ground plane, each of which is separated from the ground plane by a predetermined distance. A dipole element having a first end connected and supported to the mast in a first position and a second end provided near the ground plane; Each of the elements is curved on a plane containing the mast.

Further, according to another aspect of the present invention, a base plate that forms a ground plane XY defined by an X axis and a Y axis that intersect at right angles with each other at the origin, and is connected to the base plate, and the ground plane at the origin. And a pair of dipole elements extending on an XZ plane defined by the X axis and the Z axis, each of the dipole elements being a predetermined distance from the ground plane. A first end connected and supported to the mast at a first location separated by a distance, and a second end provided near the ground plane, wherein each of the dipole elements is It is curved on the XZ plane, the curvature having the first derivative of a continuous and constant sign.

Further, according to another aspect of the present invention, a base plate forming a ground plane, a mast connected to the base plate and extending in a direction of an axis perpendicular to the ground plane, and connected to and supported by the mast And two pairs of dipole elements in an orthogonal relationship, wherein the mast is a coaxial cable feeder.

〔Example〕

FIG. 8 shows a preferred embodiment of an antenna constructed in accordance with the present invention. The antenna of the present embodiment has a base plate 20 forming a ground plane, and a mast 22 connected to the base plate 20 and extending in a direction perpendicular to the ground plane. Further, the antenna of this embodiment has a pair of dipole elements 24 and 26 forming the first dipole (the latter is hidden in FIG. 8,
For example, see FIG. 6). A pair of dipole elements 24,26 are connected to and supported by a mast 22 at a first location, each at a first location remote from the ground plane by a predetermined distance (equal to the height of the mast 22). 28 or 3
0, and a second end provided near the ground plane (ie, in contact with the ground plane as in FIG. 10 or closer to the ground plane than the predetermined distance as in FIG. 8) 32 or 34
Having.

According to the invention, each of the dipole elements 24, 26 is curved in the plane containing the mast 22.

In order to obtain circularly polarized waves and to obtain a constant antenna gain in the direction in which the ground plane spreads, a pair of dipole elements 2
4 'and 26' are added. The added pair of dipole elements 24 'and 26' are also curved as described above. That is, the mast 22 is a pair of curved dipole elements.
It lies at the intersection of the plane defined by 24, 26 and the plane defined by another pair of curved dipole elements 24 ', 26'.

The curvature of the dipole element is equal to that of the example of FIG.
= 2 and n = 10 may be convex or concave as shown by the curves n = 0.5 and n = 0.7 in FIG. The convex and concave shapes are, for example,
Eighth showing antennas that will be visible when held in hand
It is made clear in the external view as shown in the figure.

As shown in FIG. 9, the present invention preferably has one cooperating with each of the dipole elements 24, 26 and 24 ', 26'.
It may further comprise a pair of elongated parasitic elements 36, 38, each of which may be curved in the plane containing the mast 22. Each of the parasitic elements 36, 38 may be provided on a plane including the dipole elements 24, 26 and 24 ', 26', or a plane different from the plane including the dipole elements 24, 26 and 24 ', 26'. It may be provided at a position rotated about the mast 22 so as to be provided above. Parasitic element 36,3
Each of 8 need not be parallel to dipole elements 24, 26 and 24 ', 26'.

The base plate 20 forms a ground plane XY (FIG. 5) defined by an X axis and a Y axis which intersect at right angles at the origin 0. The mast 22 is connected to the base plate 20 at the origin 0,
Extends in the Z-axis (FIG. 7) direction perpendicular to the ground plane XY. The dipole elements 24 and 26 extend on an XZ plane defined by the X axis and the Z axis. Dipole element 24 ', 2
6 'extends on the YZ plane defined by the Y and Z axes. Each of the dipole elements 24, 26 and 24 ', 26'
It curves on the XZ plane or the YZ plane. This curvature (curve) has a first derivative with a continuous and constant sign. In the case of the dipole pair 24, 26, the curve is given by the following equation.

(X ⁿ / a) + (z ⁿ / b) = 1 where x is the distance from the origin 0 along the X axis, z is the distance from the origin 0 along the Z axis, and a and b are arbitrary Definition, n
Is a parameter where 0 <n <∞ and n ≠ 1.

For a dipole pair 24 ', 26', the curve is given by:

(Y ⁿ / a) + (z ⁿ / b) = 1 where y is the distance from the origin 0 along the Y axis, and other symbols are the same as those described above.

Furthermore, according to the invention, the mast 22 is formed by a coaxial cable feed. As shown in FIG. 8, the center conductor (eg, conductor 40) of the coaxial cable feeder intersects at right angles, such as dipole elements 24 and 24 '(24' is hidden in FIG. 8). Connected to one dipole element. Other conductors of the coaxial cable feed (eg, outer conductor 42) are connected to other dipole elements, such as dipole elements 26 (hidden in FIG. 2) and 26 '. The ratio D ₁ / D ₂ of the length of the dipole is about 1.17. The dipoles are of different lengths to provide circular polarization to the feed.

The dipole elements 24, 26 and 24 ', 26' are preferably formed as part of a printed circuit board. Dipole elements 24, 26 and 24 ', 26' are formed on a fiberglass substrate 44 (FIG. 6) having a thickness of 0.01 inch and having a cross shape. Adjacent orthogonal dipole elements are printed on both sides of a thin cross-shaped fiberglass substrate. This facilitates the connection to the coaxial feed, i.e. the mast. However, at the outer end, the dipole element need not reach the conductive tabs 46, 48, 50, 52 of the same width as the cross arms of the fiberglass substrate 44. As shown in FIG. 5, the tabs 46, 48, 50, and 52 have respective through holes 62, 64, 66, and 6 formed in the base plate 20, respectively.
Protrusions 54, 56, 58, 60 that can be inserted into 8 are formed. The through holes 62, 64, 66, 68 are separated from the center hole 70 for the mast 22 by a distance determined according to the length of the arm of the fiberglass substrate 44 and the height of the mast 22. Therefore, protrusions 54,5
6,58,60 are inserted into the through holes 62,64,66,68, and when the mast 22 is properly positioned, the arm of the fiberglass substrate 44 and the dipole elements 24,26 and 24 ', 26' automatically The desired curvature is obtained.

FIG. 7 is an exploded view showing the mast 22, the fiber glass substrate 44, and the base plate 20 in the assembled position, and FIG. 8 shows the final assembled product. FIG. 9 additionally shows the non-excited resonators 36 and 38, which are improvements and generally increase the curve B in FIG. Curve B
The antenna gain is about +3 dBi in the zenith direction and about −2 dBi in the horizontal direction, as shown by. Although the gain is somewhat reduced in the zenith direction as compared with the curve A of the conventional antenna, it is empirically found that the attenuation and distortion of the received signal from the zenith direction, for example, from a traveling satellite are minimal. Not important because it is known. Importantly, near the horizon, the antenna gain is significantly improved over conventional turnstyle gain. Moreover, according to the present invention, the gain of the signal remains substantially the same even at angles somewhat below the horizon. Therefore, even if the ship or aircraft or the like equipped with the antenna of the present invention swings back and forth by a considerable angle,
The transmission and reception are not disturbed.

The direction of the curve of the dipole element (inward toward the mast and ground plane or outward toward the mast and ground plane) depends on the impedance and radiation pattern (ra
diation pattern). The best configuration for obtaining good impedance matching, good gain pattern, and good circular polarization (axial ratio) is one in which the dipole element is curved like an umbrella bone. Hence, the preferred embodiment of the present invention may be referred to as an "umbrella" antenna. Since the curve of each dipole element is in a plane including the coaxial mast, there is no spiral component that makes the shape of the dipole element three-dimensional.

In the above equation and FIG. 3, the case where n = 1 is the case where the linear dipole element described in the aforementioned Woodward et al. Patent is inferior. As the value of n increases, the curvature becomes convex (outwards towards the viewer). When n is 2 and a and b are equal, a circle is obtained,
It is a preferable umbrella dipole element. As n increases, the curve approaches a rectangle. When n is less than one, the dipole element begins to fall and becomes concave (inward away from the viewer) as shown in the example of n = 0.7 and n = 0.5. n may be any value larger than 0 (however, except for n = 1. When n = 1, the element becomes a linear dipole element). The preferred range of n is narrow, according to the best known mode of implementation of the invention, where n = 2.

When a and b are equal and n = 2, the curve of the dipole element is circular as described above, and when a and b are not equal, and when n = 2, the curve is elliptical.

The dipole element does not need to contact the base plate 20 forming the ground plane (FIG. 10), and may be formed as close as possible to the ground plane (for example, FIG. 8). In order to provide the necessary support and to connect the mast or coaxial cable to the transmitter or receiver (not shown), the mast to which the dipole elements are connected contacts and penetrates the base plate. ing.

The curvature of a dipole element with a constant sign and a continuous first derivative offers two advantages not previously available to designers. The first is that the characteristic impedance of the dipole, and therefore of the entire assembly, can cover a very wide range. Second, by changing the position of the dipole relative to the ground plane when used as an array to form a practical antenna, the radiation pattern of the dipole, and thus of the entire assembly, is significantly altered.

The antenna can be connected to a transmitter, a receiver, or both. When connecting to both, combiner (combinin
g junction). In the case of a receiver, it is usually important to be able to achieve the exact impedance matching necessary to obtain the best receiver performance, determined by the system goodness index given by the ratio G / T of the antenna gain G to the system noise temperature T. It is. The detected signal-to-noise ratio is proportional to this commonly used figure of merit. It is difficult to obtain the desired impedance level directly from the components of the antenna. Instead, various impedance matching techniques using various types of transmitters or transformers are used. These impedance matching circuits often cause resistive losses and reduce the effective gain G of the antenna. Therefore, it is important that the impedance level of the antenna of the present invention can be varied over a wide range. The preferred embodiment of the present invention achieves the desired impedance level and maintains it over a wide frequency range.

Similarly, when using an antenna as a transmitter,
For maximum power transmission, it is important to match the antenna impedance to the source impedance. Therefore,
The ability to change the impedance level is not easily obtainable with a turn style structure and is a major advantage of the present invention, regardless of the application.

If the curvature of the dipole element is approximately circular (n = 2), the resulting characteristic impedance will optimize the noise figure of the amplifier of the receiver and therefore the figure of merit G / T of the receiver
Is in the most suitable area to optimize. Tuning and impedance matching can be achieved without the use of lossy transformers or additional circuitry. Moreover, the shape of the dipole element makes the manufacture of the antenna used relatively easy.

In the preferred embodiment, the support structure for the mast or dipole element typically comprises a coaxial feeder used in the telecommunications industry and a standard 0.141 inch diameter semi-rigid shell. The mast is actually the balun needed to properly transfer energy to and from the dipole element,
Functions as a balun. The height of the mast above the ground plane is about a quarter wavelength (for an open circuit) or half a wavelength (for a short circuit), thereby performing the balun conversion process.

According to the method described in Woodward et al. Using an umbrella antenna, circularly polarized waves can be obtained. Dipole elements on the XZ plane (or YZ plane) are made slightly shorter (D ₂ ) than those that actually resonate at the desired operating frequency. The dipole element in the YZ plane (or the XZ plane) is made slightly longer (D ₁ ). This difference in resonance frequency provides a mechanism for obtaining the 90 ° phase shift required to form a circularly polarized signal. At the operating frequency, the phase of the longer dipole precedes the phase of the shorter dipole. By adjusting the length you can get the desired 90 ° shift. This method is well known and widely used in the design of patch antennas and other antennas.

At the feed point, i.e. at the top of the mast, the four dipole conductive elements form two orthogonal dipole pairs. One adjacent pair is a cross-shaped dielectric support 44
Is printed on the upper side, and the other is printed on the lower side (FIG. 6). The inner end of the dipole element of the dipole pair (ie, the end near the mast 22) is connected to the inner end of the dipole element of the other dipole pair above the dielectric support 44. The two dipole elements so connected are connected to the center conductor of the coaxial cable forming the support mast 22.

Similarly, the inner ends of the remaining two dipole elements under the supporting dielectric 44 are connected to each other and to the other (outer) conductor of the coaxial cable forming the mast 22. Then, adjacent pairs of orthogonal dipole elements are balanced by a balancing method (ba
driven in a lanced manner). The drawing shows a structure for generating left-handed circularly polarized waves. By reversing the connection between adjacent orthogonal dipole elements, the direction of polarization can be reversed (from left to right).

The type of dipole used for radiating elements is
As a preferred embodiment, either an open circuit type as shown in FIGS. 6 to 9 or a short circuit type as shown in FIG. 10 may be used. In the short circuit embodiment of the present invention, the end not connected to the mast or balun is connected so as to be electrically grounded. In this case, the mast is
Preferably, it is a half wavelength long, rather than a quarter wavelength for an open circuit.

In order to change the radiation pattern of the basic dipole, an unexcited resonator is used in an antenna for receiving a television signal (for example, a so-called Yagi antenna). These non-excited resonators have substantially the same shape and dimensions as the operating dipole. In a similar manner, by providing a set of parasitic resonators whose overall shape resembles the shape of a working dipole element, the far-field pattern (far) of a basic antenna according to the invention with two pairs of dipoles
field pattern). These non-excited resonators can increase the on-axis gain near the zenith or reduce the zenith gain and increase the horizontal gain by squashing the radiation pattern. Moreover, these parasitic elements can be arranged in any direction in the XY plane.

The above equations do not show the curves used to define the shape of the dipole element. This equation shows that as n approaches infinity, the dipole element has a near right-angle bend.

Half the length of each dipole need not be the same length. Each dipole element should have its left half shorter or longer than its right half, or in other words, not plane symmetric.

Further, the above equation defines the shape of only half of a complete dipole pair, ie, the shape of only one resonant element. If the same equation applies to both dipole elements of a dipole pair, the sign of the derivative changes at x = 0 or y = 0.

One of the most important advantages of this new antenna when compared to a planar patch antenna is that the frequency band over which very good impedance matching can be obtained is very wide. For example, since a typical planar patch antenna operates at a frequency of 1575 MHz, it shows a standing wave ratio (VSWR) versus frequency characteristic as shown in FIG. 11 (in the figure, the horizontal axis represents frequency (MHz)). Shown, one scale is 50MHz,
The entire range (10 scales) is 500 MHz, and the center line of the scale (5 scales from the left) is 1575 MHz. The same applies in FIG. ). On the other hand, the umbrella antenna has a VSWR versus frequency characteristic as shown in FIG. The limit of acceptable VSWR is arbitrarily chosen to be 1.92 or 10 dB return loss.

Points 1 and 2 in each graph (Figs. 11 and 12)
The bandwidth delimited by is improved by more than 400%. This is representative of what can be expected from this new dipole element. With this degree of freedom provided by the curved dipole element, satisfactory performance can be more easily obtained.

Improving VSWR versus bandwidth characteristics is very important from a manufacturability perspective. This means that less tuning effort is required to obtain a satisfactory level of performance, and therefore, lower manufacturing costs compared to planar patch antennas. This is beneficial for manufacturers and consumers.

Thus, according to the present invention, since the solid-state hemisphere has a substantially constant gain over the entire hemisphere, it is essentially omnidirectional and circularly polarized, has high sensitivity over a wide band, and has been improved. A new and highly beneficial antenna with impedance matching and VSWR is provided.

In the above disclosure and claims, regarding one structure and another structure, or one structure and surroundings,
Words such as "vertical", "orthogonal", "right angle" and "parallel" are used, but these words use words such as "about", "approximately" or "almost" for orthogonal and vertical etc. It is intended to also include an allowable range that does not presuppose substantial achievement of the objects and advantages of the present invention. In addition, the present invention is not limited to the above-described embodiments, but includes many modifications of the preferred embodiments disclosed herein, which will be readily apparent to those skilled in the art.

[Brief description of the drawings]

FIG. 1A shows a perspective view of a conventional planar turn-style antenna, and FIG. 1B shows a substantially square (L1> L2) shape and a coaxial input located off the center of the patch on a diagonal line of the patch. 1C is a side view of the structure of FIG. 1B, FIG. 1D is a plan view showing the connection of the patches of FIGS. 1B and 1C to the hybrid branch line in the microstrip, FIG. The figure illustrates the ability to transmit and receive circularly polarized electromagnetic waves as a function of the angle formed by a first line from the zenith to the antenna and a second line extending through the antenna parallel to the propagation direction of the electromagnetic wave. FIG. 3 shows a perspective view of a turn-style antenna in a typical conventional turn-style antenna (curve A) and an antenna constructed according to the invention (curve B). There are a graph representing the antenna gain as a function of the propagation direction relative to the horizontal direction (or zenith) in dBi, Fig. 4, the formula ^{(x n / a) + (} z n / b) = 1 ( this formula the (Representing a subset of all possible curves according to the invention), a graph representing the different curves of a dipole element according to the invention having n as parameter, FIG. 5 defining the ground plane of an antenna constructed according to the invention. FIG. 6 is a plan view of a printed circuit board which supports two pairs of dipole elements and is used to construct an antenna according to the present invention. FIG. 7 is a plan view of a printed circuit board for forming an antenna according to the present invention. FIG. 8 is an exploded perspective view showing a coaxial cable to be a mast, and an assembled part having the configuration shown in FIGS. 5 and 6, FIG. 8 is a perspective view of the antenna after assembly according to the present invention, and FIG. 8 is a perspective view in which a passive dipole element forming a parasitic coupling resonator according to the present invention is added to the antenna of FIG. 8; FIG. 10 is a quarter of FIG. 8 in place of a half-wave dipole element connected to a ground plane; FIG. 11 is a perspective view showing a case where a wavelength dipole element is placed, FIG. 11 is a graph of return loss in VSWR as a function of frequency in a conventional patch antenna, and FIG. 12 is a function of frequency of an antenna configured according to the present invention. 6 is a graph of return loss in VSWR of FIG. 20 ... Base plate 22 ... Mast or balun 24,26,24 ', 26' ... Dipole elements 24 and 26 ... One pair of dipoles 24 'and 26' ... One pair of dipoles 36,38 ... Non Exciting element or non-exciting resonator 40 Central conductor 42 External conductor 44 Fiber glass substrate or dielectric support 46, 48, 50, 52 Conductive tab

Continued on the front page (72) Inventor David, Earl, Gildea United States, 94025 California Menlo Park Harmosa Way 435 (72) Inventor James, M., Janky United States, 94087 California Sunnyvale Lewiston Court 793 (56) References JP 55-91208 (JP, A) JP-A-1-117504 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01Q 21/26 H01Q 9/44 H01Q 21/20

Claims (14)

(57) [Claims] 1. A base plate forming a ground plane, a mast connected to the base plate and extending in a direction perpendicular to the ground plane, a first position each being separated from the ground plane by a predetermined distance. And a pair of dipole elements having a first end connected to and supported by the mast and a second end provided near the ground plane, wherein each of the dipole elements is A curved dipole element antenna that is curved on a plane including the mast. 2. A second end, each having a first end connected to and supported by the mast near the first location and a second end provided near the ground plane. And wherein each of the second pair of dipole elements is curved on a plane perpendicular to the plane including the mast and including the first named dipole element. Item 1
The described antenna. 3. The antenna according to claim 1, wherein said curve is convex. 4. The antenna according to claim 1, wherein said curvature is concave. 5. The antenna of claim 1, further comprising a pair of elongated parasitic elements, each cooperating with said pair of dipole elements, each curved in a plane containing said mast. 6. The antenna of claim 5, wherein each of said parasitic elements is substantially parallel to each of said dipole elements. 7. An antenna according to claim 1, wherein said second end contacts said ground plane. 8. The antenna of claim 1, wherein said second end is remote from said ground plane. 9. A base plate forming a ground plane XY defined by an X axis and a Y axis intersecting at right angles to each other at the origin, and a Z axis connected to the base plate and perpendicular to the ground plane at the origin. A mast extending in a direction, and a pair of dipole elements extending on an XZ plane defined by the X axis and the Z axis, wherein each of the dipole elements is separated by a predetermined distance from the ground plane. A first end connected to and supported by the mast at a position, and a second end provided near the ground plane, wherein each of the dipole elements is curved on the XZ plane. A curved dipole element antenna, wherein the curvature is continuous and has a first derivative of a constant sign. 10. The YZ defined by said Y axis and Z axis
A second end of a dipole element extending over the surface, each of the second pair of dipole elements being connected to and supported by the mast near the first position; And a second end provided near the ground plane, wherein each of the second pair of dipole elements is curved on the YZ plane, and wherein the curvature of the second pair of dipole elements is 10. The antenna according to claim 9, wherein? Has the first derivative of a continuous and constant sign. 11. Let x be a distance from the origin along the X axis,
If z is the distance from the origin along the Z-axis, a and b are arbitrary constants, and n is a parameter of 0 <n <∞ and n ≠ 1, the first named curvature is 11. The antenna according to claim 10, which is given by the following equation: (x ⁿ / a) + (z ⁿ / b) = 1 12. If y is the distance from the origin along the Y axis, the second named curvature is given by: (y ⁿ / a) + (z ⁿ / b) = 1 The antenna according to claim 11, wherein 13. A base plate forming a ground plane, a mast connected to the base plate and extending in a direction perpendicular to the ground plane, and two pairs of orthogonally connected dipoles connected to and supported by the mast. A mast is a coaxial cable feeder, and each of the dipole elements is connected to and supported by the mast at a first position separated by a predetermined distance from the ground plane. A curved dipole element antenna having an end and a second end provided near the ground plane, wherein each of the dipole elements is curved on a plane including the mast. 14. The first pair of first dipole elements are connected to the two pairs of first dipole elements and the inner conductor of the coaxial cable feeder, and the first pair of second dipole elements are connected to each other. 14. The antenna according to claim 13, wherein the dipole element is connected to the second dipole element of the second pair and an outer conductor of the coaxial cable feeder.