JP2000036707A - Loaded four-wire helical antenna - Google Patents

Abstract

PROBLEM TO BE SOLVED: To lower resonance frequency and to enable miniaturization with shortening of a loop-shaped helical conductor by loading an H-shaped or laterally long rectangular load on each loop or dipole. SOLUTION: This loaded four-wire helical antenna is prepared by preparing the pattern of conductor foil on a printed circuit board and shaping this printed circuit board cylindrical. Helical conductors 1a-1d of this loaded four-wire helical antenna compose of a pair of single wavelength loops, and H-shaped loads 2a-2d are loaded on each single wavelength loop. It is preferable for the load that each long side of each loop be loaded at the central part of the dipole, and it is also suitable that each loop or dipole and the load on them be composed of the pattern of a metal film formed on a dielectric substrate which is wound on a cylinder. By finding out the optimum shape and loading spot of the load to lower the resonance frequency, miniaturization is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a four-wire helical antenna used as an antenna of a GPS receiver and the like, and more particularly, to a four-wire helical antenna which is downsized by loading a load having a special shape. It relates to a helical antenna.

[0002]

2. Description of the Related Art A typical four-wire helical antenna has a first and second one-wavelength loops which are spirally deformed.
Each loop length is set so that circular polarization is radiated by feeding from one point (single-point feeding). FIG. 9 shows the basic configuration of this 4-wire helical antenna.
FIG. 10 shows the configuration of the power supply. The feeding portions of the first and second one-wavelength loops # 1 and # 2 are connected together, and the short-circuit portions are connected to each other.

In this specification, for convenience of explanation, the first
The load loaded on helical loop # 1 is called reverse load,
The load loaded on the second helical loop # 2 will be referred to as a forward load. In this loaded 4-wire helical antenna, the radiation direction of the radio wave is determined by the difference between the magnitude of the forward load and the magnitude of the reverse load. That is, when the forward load is larger than the reverse load, the radio wave is radiated in the power supply direction, and when the reverse load is larger than the tree load, the radio wave is radiated in the direction opposite to the power supply direction.

[0004]

Along each one-wavelength loop, there are a portion where a large amount of current flows and a portion where a large amount of charges accumulate. At locations where a large amount of current flows, magnetic energy can be increased by reducing the line width. In addition, electrical energy can be increased by loading a capacitive load in a portion where a large amount of electric charge is accumulated. Due to this property, the resonance frequency is reduced, and as a result, the resonance length of the one-wavelength loop is shortened, and the shape of the antenna can be reduced. However,
It is unknown how and where the shape of the load is loaded and how much the resonance frequency is reduced.

Accordingly, it is an object of the present invention to realize the miniaturization of this type of loaded 4-wire helical antenna by finding the optimum load shape and loading location for lowering the resonance frequency by experiments and numerical analysis. It is in.

[0006]

According to the present invention, there is provided a loaded 4-wire helical antenna comprising a pair of spirally deformed loops or dipoles, wherein each of the loops or dipoles has an H-shape. Or, by loading a horizontally long rectangular load, the resonance frequency is lowered, and the miniaturization accompanying the shortening of the loop-shaped helical conductor is realized.

[0007]

According to a preferred embodiment of the present invention, the load is loaded on each long side of each of the loops or on the tip of the dipole and the center of the arm. further,
According to a preferred embodiment of the present invention, each of the loops or dipoles and the load is constituted by a pattern of a metal film formed on a cylindrically shaped dielectric substrate.

[0008]

EXAMPLE First, for comparison with various examples described below, as shown in FIG. 3, a 2 mm wide printed board of ethylene tetrafluoride (trade name "Teflon") having a thickness of 0.2 mm was used.
An unloaded 4-wire helical antenna having the following specifications was created by forming a conductor foil pattern of m and shaping the printed board into a cylindrical shape. Then, with respect to the unloaded 4-wire helical antenna, a resonance frequency and an electrical characteristic to be compared with the loaded antenna were measured. Next, as each example, loaded 4-wire helical antennas loaded with loads of various shapes were created.

Example 1 A loaded 4-wire helical antenna loaded with a vertically rectangular load shown in FIG. 4 was prepared, and various characteristics including a resonance frequency were measured.

Embodiment 2 A loaded 4-wire helical antenna loaded with a horizontally long rectangular load shown in FIG. 5 was prepared, and various characteristics including a resonance frequency were measured.

Example 3 A thin wire-loaded 4-wire helical antenna loaded with a horizontally long rectangular load shown in FIG. 5 was prepared, and various characteristics including a resonance frequency were measured.

Embodiment 4: The area of a vertically long rectangular shape shown in FIG.
A loaded 4-wire helical antenna loaded with 1.5 times the load was created and its characteristics were measured.

Example 5 A loaded 4-wire helical antenna loaded with an H-shaped load shown in FIG. 6 was prepared, and various characteristics were measured. However, the dimensions of the forward load and the reverse load are the dimensions of four deleted portions defined as shown in FIG. Less than,
The same applies to other H-shaped loads.

Example 6 A loaded 4-wire helical antenna loaded with an H-shaped load similar to that of FIG. 6 was prepared, and various characteristics were measured. However, the dimensions of the forward load and the reverse load are different.

Example 7 A loaded 4-wire helical antenna loaded with an H-shaped load as shown in FIG. 7 was prepared, and various characteristics were measured. However, the dimensions of the forward load and the reverse load are different, and an arc plate for impedance matching is added to the power supply unit.

Example 8 A loaded 4-wire helical antenna loaded with an H-shaped load as shown in FIG. 8 was prepared, and various characteristics were measured. However, the dimensions of the forward load and the reverse load are different, and an arc plate and a stub for impedance matching are added to the power supply unit. The addition of the arc plate and the stub improved the VSWR to about 1.2 at the resonance frequency.

FIG. 1 is a front view (A) showing the external appearance of the loaded 4-wire helical antenna of the eighth embodiment, and a plan view (B) showing the shape and dimensions of the load loaded on the helical conductor. 1a to 1d are helical conductors forming a pair of one-wavelength loops, 2a to 2d are H-shaped loads loaded on each one-wavelength loop, 3 is a disk-shaped dielectric substrate forming a feeding unit, 4 Is a disk-shaped dielectric substrate constituting a short-circuit portion, 5 is a stub for impedance adjustment, and 10 is a coaxial cable.

FIG. 2 is a diagram showing a connection point with an upper feed line and a lower interconnection point of a loaded 4-wire helical antenna common to the above embodiments. The hatched portions are soldered portions between the core conductor 11 and the outer cover 12 and each helical conductor.

A. Unloaded characteristics shown in Table 1 and Example 2
With reference to the results from Nos. To 8, it has been demonstrated that the loading frequency reduces the resonance frequency of the loaded 4-wire helical antenna and enables downsizing in any shape. B. When the results of Examples 1 to 4 are compared, the reduction rate of the resonance frequency of the loaded 4-wire helical antenna from the resonance frequency in the case of no loading (hereinafter referred to as “horizontal rectangular load”) is lower than that of the vertical rectangular load. , Simply "decrease rate") is 10%
Approximately 15% larger than that, it is clear that it contributes to size reduction.

C. Comparing Examples 2 and 3, when the width of the helical conductor foil is reduced from 2 mm to 1 mm in a horizontally elongated rectangular load, the reduction rate of the resonance frequency is increased by about 5%. It turns out that. D. A comparison between Example 1 and Example 4 reveals that, for a vertically long rectangular load, the reduction rate of the resonance frequency no longer increases even if the area is increased by about 50%.

E. Comparing Examples 2, 3, 5, and 6, it is clear that the reduction rate of the resonance frequency is substantially the same between the horizontally rectangular load and the H-shaped load. F. Comparing Examples 5, 6, and 7, when the forward load and the reverse load have the same H-shape, the dimensions are the same, the forward load is larger, or the reverse load is larger. Regardless, the reduction rate of the resonance frequency is around 40%. This means that, as described above, the radiation direction can be arbitrarily changed based on the difference between the magnitude of the forward load and the magnitude of the reverse load in the 4-wire helical antenna that has been reduced in size by loading an H-shaped load. This means that unidirectional radiation characteristics can be easily realized.

G. Comparing Examples 6, 7, and 8, the reduction rate of the resonance frequency is kept at a value of about 40% regardless of whether or not the impedance matching between the feeding unit and the antenna is improved. This means that sufficient impedance matching is possible in a loaded 4-wire helical antenna that has been downsized by loading an H-shaped load.

The loaded 4-wire helical antenna according to the present invention has been described above, taking the case where the loop length is an electrical length of one wavelength as an example. However, the loaded four-wire helical antenna of the present invention can also be applied to a loop having a length that is an integral multiple of the electrical length of one wavelength.

Further, the present invention has been described by taking a four-wire helical antenna constituted by a pair of loops as an example.
However, instead of a loop shape, a short-circuit part on the opposite side from the power supply side can be cut off to form a dipole. However, in this dipole, the dipole length is an integral multiple of the electrical length of one wavelength. It is set to (integer + 0.5) times the electrical length.

[0025]

As described in detail above, the loaded four-wire helical antenna of the present invention has an H loop on each loop or dipole.
Because it is a configuration in which a load in the shape of a letter or a horizontally long rectangle is loaded, as verified from the experimental results shown in the examples, the resonance frequency is reduced by about 40% even in the case of no loading, and the electrical length is reduced. The accompanying miniaturization is realized.

[Brief description of the drawings]

FIG. 1A is a front view showing the appearance of a loaded 4-wire helical antenna according to one embodiment of the present invention, and FIG. 1B is a plan view showing the shape and dimensions of a load loaded on a helical conductor.

FIG. 2 is a diagram showing a connection point with an upper feed line of a loaded 4-wire helical antenna common to each embodiment of the present invention and an interconnection point of a short-circuit part below.

FIG. 3 is a developed view showing a configuration of an unloaded 4-wire helical antenna to be compared with each embodiment of the present invention.

FIG. 4 is a developed view showing a configuration of a loaded 4-wire helical antenna according to the first embodiment of the present invention.

FIG. 5 is a developed view showing a configuration of a loaded 4-wire helical antenna according to a second embodiment of the present invention.

FIG. 6 is a development view showing a configuration of a loaded 4-wire helical antenna according to a fifth embodiment of the present invention.

FIG. 7 is a developed view showing a configuration of a loaded 4-wire helical antenna according to a seventh embodiment of the present invention.

FIG. 8 is a developed view showing a configuration of a loaded 4-wire helical antenna according to an eighth embodiment of the present invention.

FIG. 9 is a perspective view showing a configuration of a general four-wire helical antenna.

FIG. 10 is a connection diagram of a feed unit of a general one-point feed four-wire helical antenna.

[Explanation of symbols]

 1a to 1d Helical conductors forming a pair of one-wavelength loops 2a to 2d Load 3 Dielectric substrate forming a feeding part 4 Dielectric substrate forming a short circuit part 5 Stub for impedance adjustment 10 Semi-rigid coaxial cable 11 Semi-rigid coaxial cable Metal sheath of 12-core semi-rigid coaxial cable

Claims (5)

[Claims] 1. A four-wire helical antenna comprising a pair of spirally deformed loops or dipoles, wherein each loop or dipole is loaded with an H-shaped or horizontally long rectangular load. Loaded 4-wire helical antenna. 2. The loaded four-wire helical antenna according to claim 1, wherein each of the long sides of each of the loops is loaded on a central portion of a dipole. 3. In each of the first and second aspects, each of the loops or dipoles and the load loaded thereon are constituted by a pattern of a metal film formed on a dielectric substrate wound on a cylindrical body. A loaded 4-wire helical antenna. 4. The loaded four-wire helical antenna according to claim 1, wherein each of the loops has an electrical length that is an integral multiple of one wavelength. 5. The loaded four-wire helical antenna according to claim 1, wherein each of the dipoles has an electrical length of (integer + 0.5) times one wavelength.