JPH03231503A - Curved dipole element antenna - Google Patents

Abstract

PURPOSE: To obtain supersensitivity over a broadband by making a pair of dipole elements have a 1st and a 2nd end parts curved separately on a flat plane that includes a mast. CONSTITUTION: An antenna which is connected to a base plate 20 and has a mast 22 that extends at right angles to the ground plane has a pair of dipole elements 24 and 26 which form a 1st dipole. A pair of dipole elements 24 and 26 separately have 1st end parts 28 and 30 which are connected to the mast 22 and supported at a 1st position that is separated from the ground plane only at a prescribed distance (which is equal to the height of the mast 22) and 2nd end parts 32 and 34 which are arranged near the ground plane. And the dipole elements 24 and 26 are separately curved on the plane which includes the mast 22.

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to antennas, and in particular antennas that are novel, inexpensive, and antennas that span an entire solid-angle hemisphere so that they are essentially omnidirectional even when placed close to the earth's surface. It relates to a very useful antenna with a nearly constant gain.

This antenna has high sensitivity over a wide band and has better impedance matching and standing wave factor (
VSWR) has been improved.

[Conventional technology]

Circular polarization (CP) is desirable for some radio transmissions.

CP is a special case of elliptically polarized waves, where the horizontal and vertical (orthogonal) components are equal in magnitude and exactly 90 degrees out of phase. Most polarized signals are not completely circularly polarized, but have some degree of elliptical polarization. The designation of CP herein includes elliptically polarized waves in all bands.

Relatively inexpensive antennas of the turnstile, batch, and other types are semi-thermally directional (i.e., have approximately uniform gain over a half-sky field as viewed from a point relatively close to the earth's surface); It is known that those antennas have an impedance that can be matched to the impedance of the circuit in which they are used. The turnstile antenna is John D. Kraus.
Book “Antenna” by McGrawHi 11B
ook Company, 2nd edition, 1988, 72
6-731).

A typical conventional turnstile antenna 10 (FIG. 1A) consists of two dipoles 12 and 14 in one plane.
and has. Such an antenna is hereinafter referred to as a "planar turnstile." When the dipoles 12 and 14 are placed in the correct relationship to each other and driven correctly, and the plane defined by the dipoles 12 and 14 is horizontal, this turnstile antenna provides a very good CP in the zenith direction directly above the antenna. Transmission and reception are possible, but as the angle from the zenith increases, the transmission and reception conditions worsen.

Other well-known semi-thermal directional antennas are commonly referred to as "patch" or planar microstrip antennas.

This antenna is also included in the above-mentioned publication of Krauss at 745-749.
It is written on the page. In this type of antenna, the reduction in the vertical electric field E-field component is very significant, resulting in severe losses in the axial ratio of the circularly polarized signal in the horizontal plane. A typical Mythro strip patch antenna is
As shown in FIGS. 1B, 1C, and 1D.

An example of this effect is shown in FIG. In the same figure, the zenith Z
to antenna 10 and from antenna 10 to point 16 (
If the angle is defined by another line to (which is off the zenith), the vertical component of the E vector at point 16 decreases. If this angle (i.e. the angle defined by the line from the zenith Z to the antenna 10 and from the antenna 10 to the horizontal point 18) is 90°, then for batch antennas the vertical component of the E vector is completely eliminated; The case of turnstile antennas is similar; the radiated waves are no longer circularly polarized.

Therefore, conventional batch antennas, and to a lesser extent conventional turnstile antennas mounted horizontally on a tongue base plate that achieve omnidirectionality with respect to a hemisphere,
It is not possible to effectively transmit circularly polarized waves to a region located at 90° from the zenith, or to effectively receive circularly polarized waves from that direction. As shown in FIG. 2, the vertical component of the E vector drops to nearly zero in that region. As the angle with respect to the zenith increases, the axial ratio becomes very poor, and the essential function of conventional batch and turnstile antennas as linearly polarized antennas deteriorates.

In some applications, this reduction in axial ratio (or attenuation from circular to linear polarization) represents a significant loss in system efficiency. For example, in a receiver installed on a ship,
The angle at which the signal from a navigating satellite rises very slightly above the horizon (80 degrees or more from the zenith)
, there will be reflections from the water surface through a large number of paths. In the case of a receiving antenna that can only receive horizontally leaked signals, interference from reflected signals from many paths induces severe fading of the signal, resulting in a loss of information. However, for antennas with good circular polarization (CP), it is unlikely that both the vertical and horizontal components will cancel each other out with exactly 90° phase shift between the two signals, so the degree of fading will be limited. With a very small or good CP, the problem of narrow viewing angle of reception is greatly alleviated.

Furthermore, with conventional batch antennas and turnstile antennas, uniform gain cannot be obtained over the entire solid angle where the arc of the celestial sphere is 180 degrees. 2 placed 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 antennas have greater gain in the direction perpendicular to the ground plane than in the direction parallel to the ground plane. This is particularly true for vehicles (e.g. ships) that yaw, move, or sway back and forth, or from side to side.
This is a disadvantage in applications that require omnidirectional transmission and reception over the entire hemisphere.

For example, consider a conventional batch or turnstile antenna mounted on a ship moored in still water, located in a shipyard, or in dry dock. For best omnidirectional transmission and reception over a hemisphere, the antenna is mounted horizontally to the ground plane and its mast extends perpendicular to the horizontal plane. The gain of the antenna is shown in curve A of FIG. That is, the gain is maximum in the zenith direction (as shown in FIG. 3, +5 isotropic decibels (d B i : decibels relat
ive to is.

tropics ) ), horizontally very low (
(approximately -5 dBi) as shown in FIG.

Also, assume that, for example, it is desired to satisfactorily receive signals from a traveling satellite located anywhere above the horizon. Under this assumption, signals coming from a satellite sailing low above the horizon cannot be satisfactorily received at sea where the ship would be rocking back and forth and side to side. For example, suppose the satellite is 90 degrees from the starboard bow, the ship is rolling 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 causes the direction of the curve in Figure 3 to change in response to the sway, and the antenna gain to be the same as that obtained when the ship is level.
Bi (curve A for a conventional antenna) drops to values less than -5 dBi, where it will not be possible to transmit or receive satisfactorily.

The situation is even worse when two vessels communicate with each other using conventional semi-thermal directional turnstile antennas. Occasionally, a two-stranded ship will sway back and forth, causing the antenna masts to tilt in opposite directions.

In that case, the curve of FIG. 3 for the transmitting antenna is rotated clockwise and the curve for the receiving antenna is rotated counterclockwise. As a result, the signal becomes weaker due to the rocking of one ship, and must be detected by an antenna that is less sensitive to the rocking of the other ship.

Another problem with conventional patch antennas is that the device has a narrow bandwidth and must be carefully tuned to operate satisfactorily at the desired frequency.

This complicates the construction for the impedance matching tuning required to compensate for variations due to materials, etc., and increases cost. The main factor in obtaining a good signal-to-noise ratio is the noise figure of the preamplifier. The antenna is conventionally tuned to obtain the best noise figure for the nominal impedance of the preamplifier. However, if the antenna has narrowband characteristics, it is difficult to ensure that the impedance of the antenna approaches its nominal value at a certain precise frequency.

Another problem with conventional turnstile antennas is that separate mechanical and electrical structures are required, adding complexity and unnecessarily cost. In particular, the mast (mechanical structure) that supports the dipole element and the balanced/unbalanced transformer (electrical structure) that drives it are, for example, Caranselman (
Counselman et al. Patent No. 4,647,942
It is physically separated as stated in the issue.

Various attempts have been made to overcome the problems of conventional turnstile antennas as described above.

The most notable one is Woodward
4,062,019, a drooping dipole structure disclosed in U.S. Pat. This device has a radiating element mounted on the mast at an angle of 45° to the mast.

The dipole element descends in a straight line from its attachment point.

This radiating element therefore makes an angle of 45° to both the horizontal plane and the vertical plane through the mast. This tilting of the radiating element allows the two orthogonal electric field E components to exist over a wider range of solid angles. Planar batch antenna and turnstile antenna (Figures 1A to 1D)
(see figure), the vertical component of the E field in the horizontal plane (ground plane) direction is greatly reduced as described above.

Therefore, Woodward et al.
The need for a CP antenna (onuni) is stated. Its most important feature is that its dipole elements are all straight and 45° to the mast of the turnstile.
This means that it is tilted at an angle of ±5°. Furthermore, the characteristic impedance of the drooping dipole element is a fixed value, which must be provided in the impedance matching circuit. Naturally, the characteristic impedance is variable within a certain range determined by the physical dimensions of the dipole (distance to the ground plane, etc.), but that range is narrow.

Other important prior art includes U.S. Pat. No. 1.988.
No. 434, No. 2.110.159, No. 2.976.5
No. 34, No. 3,919,710 and No. 3,922,6
There are issues such as No. 83.

[Problem to be solved by the invention]

However, the prior art described above has semi-thermal directivity with essentially constant gain over the entire solid-angle hemisphere, excellent CP near the horizon, and high sensitivity over a wide band. , does not disclose an inexpensive antenna with even better VSWR.

It is therefore an object of the present invention to solve the above-mentioned problems, and in particular to provide a novel, inexpensive and highly useful semi-thermal directional antenna with constant gain over the solid angular hemisphere. be.

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

Another object of the present invention is to provide high sensitivity over a wide band and excellent impedance matching and VSWR.
An object of the present invention is to provide an antenna having the following characteristics.

Another object of the invention is to provide an antenna that does not require tuning or is easily tuned without the use of special circuits such as impedance matching transformers with unavoidable losses.

[Summary of the invention]

The above-mentioned problems can be solved by the present invention described below, and the above-mentioned objects can be achieved.

That is, the curved dipole element antenna according to the present invention includes a base plate forming a ground plane, connected to the base plate,
a mast extending in a direction perpendicular to the ground plane; first ends each connected to and supported by the mast at a first location a predetermined distance from the ground plane; a pair of dipole elements having adjacent second ends, each dipole element being curved in a plane containing the mast.

Further, according to another aspect of the invention, a base plate forming a ground plane XY defined by an X axis and a Y axis intersecting each other at right angles at an origin; a mast extending in the Z-axis direction perpendicular to the
a pair of dipole elements extending on a plane, each of the dipole elements being connected to and supported by the mast at a first position separated from the ground plane by a predetermined distance; and a second end disposed near the ground plane, each of the dipole elements being curved on the XZ plane, the curvature being continuous and having a first derivative of constant sign. have

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

〔Example〕

FIG. 8 shows a preferred embodiment of an antenna constructed in accordance with the present invention. The antenna of this 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. Also,
The antenna of this embodiment has one antenna that forms the first dipole.
It has a pair of dipole elements 24, 26 (the latter is hidden in FIG. 8, but can be seen, for example, in FIG. 6). A pair of dipole elements 24, 26 each have first ends connected to and supported by the mast 22 at a first location a predetermined distance (equal to the height of the mast 22) from the ground plane. 28 or 30, and be provided near the ground plane, i.e. contact the ground plane as shown in FIG.
Alternatively, as shown in FIG. 8, it has a second end 32 or 34 (which is closer to the ground plane than the predetermined distance).

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

A pair of die ball elements 24 are used to obtain circularly polarized waves and to obtain a constant antenna gain in the spreading direction of the ground plane.
', 26'' are added. The added pair of dipole elements 24', 26' are also curved as described above. In other words, the mast 22 has a curved pair of dipole elements 24', 26'. 26 and the plane defined by another pair of curved dipole elements 24'', 26'.

The curvature of the dipole element is determined by the example in FIG. 8 and n=in FIG.
It may be convex as shown by the curves n=0.5 and n=0.7 in FIG. 4, or concave as shown by the curves n=0.5 and n=0.7 in FIG. The convexity and concaveness are made clear, for example, in an external view, such as that shown in FIG. 8, which shows the antenna as it would appear when held in the hand.

As shown in FIG. 9, the invention preferably includes a pair of elongated parasitic elements (1) cooperating with each of the dipole elements 24, 26 and 24', 26'.
c element ) 36 , 38 ,
Each of them is preferably curved in a plane containing the mast 22. Each of the parasitic elements 36.38 may be provided on a plane containing the dipole elements 24.26 and 24", 26', or on a plane different from the plane containing the dipole elements 24.26 and 24", 26'. It may be provided at a position rotated about the axis of the mast 22 such that it is provided above. Each of the parasitic elements 36, 38 need not be parallel to the 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 that intersect at right angles to each other at the origin 0. The mast 22 is connected to the base plate 20 at origin 0,
It extends in the direction of the Z-axis (FIG. 7) perpendicular to the ground plane XY at the origin 0. The dipole elements 24,26 extend on the XZ plane defined by the X and Z axes. The dipole elements 24', 26' extend on 72 planes defined by the Y and Z axes. Dipole element 24゜2
6, 24', and 26' are each curved on the XZ plane or the 72 plane. This curvature (curve) is continuous and has a first derivative with a constant sign. dipole pair 24.26
In this case, the curve is given by the following formula:

(x /a) + (z /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, a and b are arbitrary constants, n
is a parameter in which 0×n×■ and n≠1.

In the case of the dipole pair 24', 26', the curve is given by:

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

Furthermore, according to the invention, the mast 22 is formed by a coaxial cable feeder. As shown in FIG. 8, the center conductor (e.g., conductor 40) of the coaxial cable feed is connected to two perpendicularly intersecting elements, such as dipole elements 24 and 24 (24' is hidden in FIG. 8). Connected to a dipole element.

Other conductors of the coaxial cable feed (e.g., outer conductor 42
) are connected to other dipole elements, such as dipole elements 26 (hidden in FIG. 2) and 26'. The dipole length ratio D1/D2 is approximately 1.17. The dipole is made of a suitable length to provide circularly polarized waves to the feeder.

The dipole elements 24, 26 and 24", 26' are preferably formed as part of a printed circuit board. The dipole elements 24, 26 and 24", 26' are preferably formed as part of a printed circuit board. 24.26 and 24',
26" is formed. Adjacent orthogonal dipole elements are printed on both sides of a thin cross-shaped fiberglass substrate. Doing so facilitates connection to a coaxial feeder, i.e., a mast. However, at the outer end, the dipole elements do not have to extend as far as the conductive tabs 46.48, 50.52, which are the same width as the cross arms of the fiberglass substrate 44. As shown in FIG. 5, each through hole 62.6 formed in the base plate 20
4.Protrusions 54, 56.5 that can be inserted into 66.68
8.60 is formed. Through holes 62, 64, 66.6
8 is spaced from the central hole 70 for the mast 22 by a distance determined depending on the arm length of the fiberglass substrate 44 and the height of the mast 22. Therefore, the protrusion 54°56.5
8.60 are inserted into the through holes 62, 64, 66. 68 and the mast 22 is correctly positioned, the arms of the fiberglass substrate 44 and the dipole elements 24, 26 and 24', 26' will automatically move to the desired position. It becomes curvature.

FIG. 7 is an exploded view showing the mast 22, fiberglass substrate 44, and baseplate 20 in assembled position, FIG. 8 shows the final assembly, and FIG. 9 shows the parasitic resonator. 3
6.38 is additionally shown and this parasitic resonator 3
6.38 is an improvement, which makes curve B in FIG. 3 larger overall. As curve B shows, the antenna gain is about +3 dBi in the zenith direction and about -2 dBi in the horizontal direction. Compared to curve A of the conventional antenna, the gain is somewhat lower in the zenith direction, but this is because experience shows that from the zenith direction, for example, the attenuation and distortion of the received signal from a navigating satellite is minimal. What is known and not critical is that near the horizon the antenna gain is considerably improved over the gain of conventional turnstiles. Moreover, according to the invention, the signal gain remains approximately the same even at somewhat subhorizontal angles. Therefore, even if a ship, an aircraft, etc. equipped with the antenna of the present invention swings back and forth and left and right at a considerable angle, transmission and reception will not be disturbed.

The direction of the dipole element's curve (inward toward the mast and ground plane, or outward away from the mast and ground plane) determines the impedance and radiation pattern (ra
Change diation pattern>.

The best configuration to obtain good impedance matching, good gain) (turns, and good circular polarization (axial ratio) is one in which the dipole element is curved like an umbrella. A preferred embodiment of the invention is an “umbrella”
It can also be called an antenna. Since the curve of each dipole element lies in the plane containing the coaxial mast, there is no helical component that would make the shape of the dipole element three-dimensional.

In the above equation and FIG. 3, when n=1, the linear dipole element described in the aforementioned Woodward et al. patent is an inferior case. As the value of n increases, the curvature becomes convex (outward toward the viewer).

If n is 2 and a and b are equal, it will be a circle, which is the preferred umbrella dipole strand. As n increases,
The curve approaches a rectangle. When n is less than 1, the dipole element begins to fall down and become concave (inward away from the viewer) as shown in the examples for n=0.7 and n=0.5. n can be any value greater than 0 (except n = 1, in which case it is a linear dipole element), but the preferred range of n is narrow, and the best known implementation of the invention According to the mode, it is n=2.

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

The dipole element does not need to be in contact with the base plate 20 forming the ground plane (FIG. 10), but may be formed close to the ground plane (for example, FIG. 8). To provide the necessary support and for the connection from the mast or coaxial cable to the transmitter or receiver (not shown), the mast to which the dipole element is connected contacts and passes through the base plate. ing.

The curvature of a dipole element with a constant sign and continuous first derivative gives designers a previously unobtainable 2
provides two advantages. The first is that the characteristic impedance of the dipole, and therefore of the entire assembly, can cover a very wide range. Second, when used as an array to form a practical antenna, changing the position of the dipole relative to the ground plane significantly changes the radiation pattern of the dipole, and therefore of the entire assembly.

An antenna can be connected to a transmitter, a receiver, or both. When connecting to both, use a combiner (combi
ning junction). In the case of a receiver, it is usually possible to achieve the precise impedance matching required to obtain the best receiver performance, which is determined by the system figure of merit given by the ratio G/T of the antenna gain G to the system noise temperature T. is important. 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 antenna components. Instead, various impedance matching techniques using various types of transmission lines or transformers are used. These impedance matching circuits often generate resistive losses that reduce the effective gain G of the antenna. It is therefore important that the impedance level of the antenna of this invention can be varied over a wide range. Preferred embodiments of the invention achieve the desired impedance level and maintain it over a wide frequency range.

Similarly, when using an antenna as a transmitter, it is important to match the antenna impedance to the power supply impedance for maximum power transmission. Therefore, the ability to vary impedance levels, which is not readily available with turnstile structures, 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 receiver amplifier and hence the receiver figure of merit G/T.
It is in the most suitable area to make the best of it. Tuning and impedance matching can be accomplished without the use of lossy transformers or added circuitry. Moreover, the shape of the dipole element makes it relatively easy to manufacture the antenna used.

In a preferred embodiment, the support structure for the mast or dipole element is a coaxial feed thI commonly used in the telecommunications industry.
I and a semi-rigid outer tube with a standard diameter of 0.141 inches. The mast is actually a balun, which is necessary to properly transfer energy to and from the dipole element.
That is, it functions as a balanced unbalanced transformer. The height of the mast above the ground plane is approximately a quarter wavelength (open circuit) or
or half wavelength (in the case of a short circuit), thereby performing a balanced-unbalanced conversion process.

Using an umbrella antenna, circular polarization can be obtained using the method described in the Woodward et al. patent. The dipole element on the XZ plane (or YZ plane) is made slightly shorter (D2) than it would be if it were actually resonant at the desired operating frequency.

The dipole element in the YZ plane (or XZ plane) is slightly longer than
(Dl) made. This difference in resonant frequencies provides a mechanism for obtaining the 90° phase shift necessary to form a circularly polarized signal. At the operating frequency, the phase of the longer dipole leads the phase of the shorter dipole. The desired 90'' shift can be obtained by adjusting the length.

This method is well known and widely used in patch and other antenna designs.

At the feed point, ie at the apex of the mast, four dipole conductive elements form two orthogonal dipole pairs. One adjacent pair is a cross-shaped dielectric support 44
is printed on the top side, and the other is printed on the bottom side (
Figure 6). The inner ends of the dipole elements of the dipole pair (ie, the ends closer to the mast 22) are connected to the inner ends of the dipole elements of the other dipole pair on the upper side of the dielectric support 44. 2 connected in that way
The two dipole elements are connected to the center conductor of the coaxial gable forming the support mast 22.

Similarly, the inner ends of the two remaining dipole elements on the underside of support dielectric 44 are connected to each other and to the other (outer) conductor of the coaxial cable forming mast 22. Then, adjacent orthogonal pairs of dipole elements are arranged using a balancing method (
The polarization direction can be reversed by reversing the connections between adjacent orthogonal dipole elements (left to the right).

The type of dipole used for the radiating element may be of the open circuit type as shown in FIGS. 6 to 9 as a preferred embodiment or of the short circuit type as shown in FIG. 10, according to the present invention. In a short circuit embodiment, the end not connected to the mast or balloon is connected to electrical ground. In this case, the mast is
Preferably, the length is half a wavelength rather than a quarter wavelength for open circuits.

In order to change the radiation pattern of the basic dipole, parasitic resonators are used in antennas for receiving television signals (eg so-called Yagi antennas). These parasitic resonators have approximately the same shape and approximately the same dimensions as the working dipole.

In a similar manner, the far field pattern of a basic antenna according to the invention with two pairs of dipoles is achieved by providing a set of parasitic resonators whose overall shape resembles that of the operating dipole elements.
rn) can be changed. These parasitic resonators can increase the gain on the axis pointing near the zenith direction, or can squash the radiation pattern to reduce the gain in the zenith direction and increase the gain in the horizontal direction.

Moreover, these parasitic elements can be arranged in any direction in the XY plane.

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

The lengths of each dipole half need not be the same length. The left half of each dipole element should be shorter or longer than the right half; in other words, it should not be plane symmetrical.

Furthermore, 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 formula is applied to both dipole elements of a dipole pair, the sign of the derivative changes at X=0 or y=o.

One of the most important advantages of this new antenna when contrasted with planar batch antennas is that the frequency band in which very good impedance matching can be obtained is very wide. The antenna operates at a frequency of 1575MH2.
Figure 1 shows the standing wave rate (VSWR) vs. frequency characteristics (in the figure, the horizontal axis shows the frequency (MHz),
Scale is 50MHz, full range (10 scales) is 500MHz
, the center line of the scale (5th scale from the left) indicates 1575 MHz. The same applies to FIG. 12.

). On the other hand, an umbrella antenna exhibits a VSWR vs. frequency characteristic as shown in FIG. Acceptable VS
Set the WR limit to be 1°92 or 10d
The return loss of B can be arbitrarily selected.

The bandwidth delimited by points 1 and 2 in each graph (Figures 11 and 12) is improved by more than 400%. This is representative of what can be expected from this new dipole element. This degree of freedom afforded by curved dipole elements makes it easier to obtain satisfactory performance.

VSWR vs. Bandwidth characteristics are very important from the viewpoint of manufacturability. This means that less effort is required in the tuning operation to obtain a satisfactory level of performance, and therefore manufacturing costs are lower than in the case of planar batch antennas. This is beneficial to manufacturers and consumers.

Thus, according to the present invention, the gain is substantially constant over the entire solid-angle hemisphere, making it essentially omnidirectional and circularly polarized, resulting in high sensitivity in a wide band, and improved A novel and highly beneficial antenna with impedance matching and VSWR is provided.

In the above disclosure and claims, words such as "perpendicular,""orthogonal,""rightangle," and "parallel" are used with respect to the structure of - and other structures, or with respect to the structure of - and its surroundings. However, these words are intended to be used in conjunction with words such as "approximately,""approximately," or "habo," and are intended to be used in conjunction with orthogonal, perpendicular, etc., and do not substantially achieve the purpose and benefits of this invention. This invention also includes a permissible range that is not a prerequisite for the above-described embodiments.
It is intended to include many modifications of the preferred embodiments disclosed herein that will readily occur to those skilled in the art.

[Brief explanation of drawings]

FIG. 1A is a perspective view of a conventional planar turnstyle antenna, and FIG. 1B is a diagram showing the shape of a square (Ll > L2),
1C is a side view of the structure of FIG. 1B; FIG. 1D is a hybrid in microstrip. 1B and 1C to branch lines; FIG. 2 shows a first line from the zenith to the antenna and a second line extending through the antenna parallel to the direction of propagation of the electromagnetic waves; FIG. 3 is a perspective view of a turnstile antenna illustrating its ability to transmit and receive circularly polarized electromagnetic waves as a function of the angle formed by, in the case of a typical conventional turnstile antenna (curve A), In the case of the antenna constructed according to the present invention (curve B), a graph representing the antenna gain as a number in dBi in the propagation direction with respect to the horizontal direction or the zenith direction), FIG. 4 shows the equation (x /a) Graph representing different curves of a dipole element according to the invention with n as parameter, with + (z0/b)=1 (this equation represents a subset of all possible curves according to the invention), FIG. is a plan view of a base plate defining the ground plane of an antenna constructed according to the present invention; FIG. 6 is a plan view of a printed circuit board supporting two pairs of dipole elements and used to construct the antenna according to the present invention; FIG. 7 is an exploded perspective view showing an assembled part consisting of a coaxial cable serving as a mast and the configuration of FIGS. 5 and 6 to form an antenna according to the present invention, and FIG. 9 is a perspective view of the antenna of FIG. 8 with the addition of a passive dipole element forming a parasitic coupled resonator according to the present invention, and FIG. 10 is a half-wavelength dipole element connected to the ground plane. Fig. 11 is a graph of the return loss in VSWR as a function of frequency in a conventional batch antenna; Fig. 12 is a graph of the return loss of the conventional batch antenna as a function of frequency; 1 is a graph of return loss in VSWR as a function of frequency for an antenna constructed in accordance with the invention; 20... Base plate 22... Mast or balloon 24, 26, 24', 26'... Dipole element 2
4 and 26...a pair of dipoles 24' and 26'...a pair of dipoles 36.38...
・Passive element or parasitic resonator 40...Central conductor 42...Outer conductor

Claims (14)

[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; each at a first position a predetermined distance from the ground plane; a pair of dipole elements having a first end connected to and supported by the mast and a second end disposed proximate the ground plane, each dipole element having a first end connected to and supported by the mast; A curved dipole element antenna that is curved on a plane containing. (2) a second pair 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; dipole elements of the second pair, each dipole element of the second pair being curved in a plane perpendicular to a plane containing the mast and containing the first named dipole element. Antenna as described. (3) The antenna according to claim 1, wherein the curve is convex. (4) The annularte according to claim 1, wherein the curve is concave. (5) cooperating with the pair of dipole elements, each of which is curved in a plane containing the mast;
The antenna of claim 1 further comprising a pair of elongate parasitic elements. (6) The antenna of claim 5, wherein each of the parasitic elements is substantially parallel to each of the dipole elements. (7) The antenna according to claim 1, wherein the second end portion contacts the ground plane. (8) The antenna according to claim 1, wherein the second end portion is separated from the ground plane. (9) a base plate forming a ground plane XY defined by an X-axis and a Y-axis that intersect each other at right angles 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 the X-axis and the Z-axis;
a pair of dipole elements extending on an XZ plane defined by an axis, each of the dipole elements being connected to the mast at a first position a predetermined distance from the ground plane. a supported first end and a second end disposed near the ground plane, each of the dipole elements being curved on the XZ plane, and the curvature being continuous. A curved dipole element antenna with a first derivative of constant sign. (10) further comprising a second pair of dipole elements extending on a YZ plane defined by the Y-axis and the Z-axis, each of the second pair of dipole elements being located near the first position; a first end connected to and supported by the mast, and a second end disposed near the ground plane, each of the second pair of dipole elements disposed on the YZ plane. 10. The antenna of claim 9, wherein the curvature of the second pair of dipole elements has a continuous and constant sign first derivative. (11) Let x be the distance from the origin along the X axis, and z be Z
The initially named curvature is given by the following equation (X Antenna according to claim 10, given by ^n/a)+(Z^n/b)=1. (12) When y is the distance from the origin along the Y axis, the second designated curvature is expressed by the following formula (y^n/a)
Antenna according to claim 11, given by +(Z^n/b)=1. (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 dipole elements in an orthogonal relationship connected to and supported by the mast. A curved dipole element antenna, wherein the mast is a coaxial cable feeder. (14) The first dipole element of the first pair is connected to the first dipole element of the second pair and the inner conductor of the coaxial cable feeder, and the second dipole element of the first pair 14. The antenna of claim 13, wherein an element is connected to a second dipole element of the second pair and an outer conductor of the coaxial cable feed.