JPH075692Y2 - Communication antenna - Google Patents

Description

The present invention relates to a vertical antenna that radiates vertically polarized waves in the horizontal direction or receives vertically polarized waves, and its purpose is simple and rational. It is intended to provide a communication antenna that has a wide half-value angle, a high gain, a large front-back ratio, a simple structure, and is easy to mount by the configuration.

(B) Conventional technology As means for ensuring high gain, Japanese Patent Laid-Open No. 53-87150
There is a technique in which radiation elements are vertically stacked in multiple stages as described in Japanese Patent Publication No. 60-192504 and Japanese Utility Model Publication No. 59-140508. Also, Japanese Examined Sho 31-7710
As described in Japanese Utility Model Publication No. 49-132744, in front of the radiator, a plurality of waveguide elements are arranged in parallel with the radiation element at a predetermined interval and each waveguide element is placed on the center of each arm. A technique for mounting and arranging is known.

(C) Problems to be solved by the invention An antenna that stacks radiation elements vertically to ensure high gain has a characteristic of 360 ° uniform in the horizontal direction and has a small front-to-back ratio. When installed on the balcony, radio waves are blocked on the building side and only the first half is used. Therefore, radiating the radio wave to the rear side where it is not used unnecessarily sacrifices the frontward gain, which hinders securing a high gain.

The so-called Yagi-type antenna with a plurality of waveguide elements arranged in the front is dedicated to a directional antenna in the ultra-high frequency band such as a television receiving antenna, and is applied to a communication antenna that radiates vertically polarized waves in the horizontal direction. Have difficulty. Even if it is applied, it extends in the horizontal direction and becomes heavy at the front, and the metal handrail is apt to be adversely affected by radio wave interference and the like, so that the installation position and posture are limited and the support structure becomes complicated. Since the half-value angle becomes extremely narrow,
Although the gain is improved, the communication range is limited. Also, since the cable connection terminal is provided in the center of the arm,
It causes electromagnetic induction between the coaxial cable and the antenna element, which adversely affects the antenna characteristics.

The present invention has a half-value angle of about 180 ° and has a large front-to-back ratio to suppress radio wave radiation in unnecessary directions to ensure high gain. It is a communication antenna developed as a result of earnest research to prevent electromagnetic induction between the radiation elements. And a plurality of reflecting elements each having a half wavelength length of the first frequency among the different frequencies, and each of the reflecting elements being the radiation element. Of the first reflector and the second reflector of 1/2 wavelength length of the second frequency, which are stacked so as to correspond to each other, respectively on the horizontal boom. Are parallel to each other and the first reflector keeps a distance of 1/4 wavelength of the first frequency with respect to the radiator, and the second reflector has a second frequency with respect to the radiator. The antenna is vertically installed so as to maintain the interval of 1/4 wavelength, and a matching circuit, a ground wire, and a cable connecting terminal are provided at the lower end of the radiation element.

The action radiator operates at different frequencies depending on the length of the one radiation element and the total length of the plurality of radiation elements. A first reflector in which a plurality of reflective elements each having a half wavelength of the first frequency among the different frequencies are stacked so that each reflective element corresponds to each of the radiating elements; A second reflector having a half wavelength of two frequencies, each parallel to one another on a horizontal boom, and said first reflector being 1/4 of the first frequency with respect to said radiator. By keeping the wavelength intervals, and further arranging the second reflector so as to maintain an interval of 1/4 wavelength of the second frequency with respect to the radiator, the half-value angle of each operating frequency is approximately 180. In addition to being able to set to °, it is possible to suppress the emission of radio waves in unnecessary directions, to secure a large front-to-back ratio and to improve gain. Moreover, since the vertical antenna and the reflection element are vertically hung on the horizontal boom, if the horizontal boom is attached along the metal handrail and the antenna is projected above the metal handrail,
The half-value angle is not extremely narrowed due to adverse effects such as radio wave interference, and the communication range is not limited. Furthermore, since the cable connection terminal is provided at the lower end of the radiation antenna, it is possible to prevent the electromagnetic characteristics between the cable and the antenna element from adversely affecting the antenna characteristics.

F. Example An example in which the communication antenna according to the present invention is implemented as a ground plane type antenna will be described with reference to the drawings.

In FIG. 1, 1 is a radiator, 2 is a first reflector, and 3 is a second reflector, which are arranged parallel to each other and vertically and are connected by horizontal booms 4 and 4 at their lower ends. . The radiator 1 is 430MHz which is an example of the first frequency.
Radiating elements 1a, 1b, 1c with a length corresponding to approximately 5 / 8λ
However, a coil 5 for changing the phase of the current flowing through the element with respect to 430 MHz for synthesis and a capacitor 6 for shortening the electrical length are connected in series under the radiation element 1a in order from the top. The radiating element 1b is connected below the radiating element 1b, and the radiating element 1c is further connected below the radiating element 1b via the coil 5. At the lower end of the radiating element 1c, 430 MHz, and the total length of the radiating elements 1a, 1b, 1c corresponds to 7 / 8λ.
A matching unit 7 for matching with MHz is connected, and the matching unit 7 is composed of a resonance circuit of a coil 12 and a capacitor 13. In addition, in order to prevent unnecessary current from flowing to the outer conductor, the tip should be slightly downward in the radial direction.
The ground lines 8, 8, 8 of the book are projected. The length of the ground wire 8 is 1 / 4λ of 144MHz (3/4 of 430MHz) which is an example of the second frequency.
λ). The radiating elements 1a, 1b, 1c are formed by thin metal pipes made of brass having high conductivity, and they are housed in a glass fiber cylinder body with less inductive loss. The matching circuit 7 is housed in the lower end of the cylindrical body, and the connection terminal 9 of the coaxial cable is fixed below the matching circuit 7. Further, a ground wire mounting member 8a is fitted around the lower end portion of the cylinder body, and the ground wires 8, 8 and 8 are mounted through the ground wire mounting member 8a, and further the ground wire at the lower end portion of the cylinder body is mounted. The lower part of the wire attachment member 8a is covered with a waterproof tube 10 made of aluminum. The matching circuit 7, the ground wire 8, the outer conductor of the cable connection terminal 9, and the waterproof tube 10 are electrically connected. The first reflector 2 is a joint in which the reflective elements 2a, 2a, 2a made of aluminum pipe are made of a highly insulating material such as ABC resin or vinyl chloride.
11 and 11 are connected in a straight line, and each reflecting element 2a, 2a, 2a has a length corresponding to 1 / 2λ of 430 MHz, and for each of the radiating elements 1a, 1b, 1c is 430 MHz.
Are arranged with an interval corresponding to 1/4 λ. Further, the second reflector 3 is provided with a reflecting element 3a corresponding to a 1 / 2λ length of 144 MHz, keeping a distance corresponding to 1 / 4λ of 144 MHz with the radiator 1. For amateur radio, 14
4MHz usually means a band of 144 to 146MHz, and 430MHz means a band of 430MHz to 440MHz.

The distribution of the current flowing through each element in the communication antenna thus formed is shown in FIG. And in the case of a single radiator that does not include the reflector 2 (3), the radio wave is uniformly radiated in all directions of 360 ° with respect to the horizontal direction, whereas by providing the reflector 2 (3), At 440 MHz, as shown in the third illustration, the reflector 2 (3) and the opposite side are almost
Along with having a half-value angle of 180 °, a front-back ratio of about 12 dB was obtained, and a gain improvement of 2.5 dB at 144 MHz and 3 dB at 430 MHz was confirmed. In terms of shape, the reflector 2 (3) is arranged behind the radiator 1, and the reflectors 2 (3) are the horizontal booms 4 and 4.
Since the lower end portion is connected by, the horizontal boom 4 can be mounted in a well-balanced manner by supporting it in the vicinity of the center of the horizontal boom 4, and by being attached to an upper position such as a handrail, it is less likely to be affected by them. Moreover, since the cable connection terminal 9 is provided at the lower end of the radiator 1, electromagnetic induction that adversely affects the antenna characteristics is not caused between the coaxial cable and the antenna element.

It should be noted that the reception has the same characteristics as the transmission according to the principle of reversibility of the antenna characteristics.

Although the above embodiment shows the ground plane antenna in which the radiation elements 1a, 1b, 1c are stacked in three stages via the coil, as shown in the fourth drawing, the radiation elements 1a, 1b, 1c are shown.
In order to change the phase of the electric current between different frequencies and to synthesize the phase adjusting element 1d wound in a single layer, the radiation element 1e is connected under the coil 5 through the coil 5 to form five stages. The mechanism and operating frequency can be changed according to the embodiment, such as appropriately changing the number of stages, making the radiation element a length adapted to, for example, 50 MHz and 144 MHz, or 430 MHz and 1.2 GHz, and stacking by connecting means other than interposing a coil. The present invention is not limited, and can be used for a collinear antenna, a sleeve antenna, a whip antenna, etc. other than the ground plane antenna. When the number of stacked stages is 5, the distribution of the current flowing through each element is as shown in FIG. Further, in the embodiment, the ground wire is set slightly downward and the directional characteristic with respect to the vertical direction is set upward. However, changing the mounting angle of the ground wire, increasing or decreasing the number of wires, or changing the material of each member is effective in the present invention. It may be changed appropriately within the range in which is achieved.

Advantages According to the present invention, it is possible to realize a communication antenna with a high gain and a wide half-value angle of 180 ° and a large front-to-back ratio. Moreover, since the electromagnetic induction between the cable and the antenna element does not occur, the original characteristics of the antenna are not deteriorated. Further, even when it is attached to a veranda, it is a perfect form for use in a well-balanced position at a position where it is unlikely to be affected by handrails, etc. Therefore, considering the housing situation in Japan, it can be said that it is a great antenna with great demand.

[Brief description of drawings]

FIG. 1 is a perspective view showing an external appearance of an antenna in which a communication antenna according to the present invention is implemented as a ground plane antenna, FIG. 2 is an explanatory view showing the structure of the antenna, and FIG. 3 shows characteristics of the antenna at 440 MHz. FIG. 4 is an explanatory view of the lower end of the radiator, FIG. 5 is an explanatory view of a modified example, and FIGS. 6 and 7 are currents of 144 MHz and 440 MHz flowing through each element in the antenna of the embodiment. It is a current distribution diagram which shows distribution. 1 ... Radiator, 1a, 1b, 1c, 1e ... Radiant element, 1d
...... Phase adjusting element, 2 …… First reflector, 3 …… Second reflector, 2a, 3a …… Reflecting element, 4 …… Horizontal boom, 5 …… Coil, 6 …… Capacitor, 7 ・ ・ ・… Matcher,
8 ... Ground wire, 8a ... Ground wire mounting member, 9 ... Cable connection terminal, 10 ... Waterproof tube, 11 ... Joint, 12 ... Coil, 13 ... Capacitor.

Claims (1)

[Scope of utility model registration request] 1. In a communication antenna for radiating vertically polarized waves in the horizontal direction or receiving vertically polarized waves, radiation elements are vertically stacked in multiple stages, and the length of one radiation element of the stacked elements and a plurality of radiation elements are stacked. Each of the reflecting elements is provided with a radiator that can operate for different frequencies according to the total length of the radiating elements and a plurality of reflecting elements having a half wavelength length of the first frequency among the different frequencies. A first reflector and a second reflector having a half wavelength of a second frequency, which are stacked so as to correspond to the radiating elements, are parallel to each other on the horizontal boom, and the first reflector is provided. Of the reflector keeps a distance of 1/4 wavelength of the first frequency with respect to the radiator, and the second reflector has a distance of 1/4 wavelength of the second frequency with respect to the radiator. Vertically to keep Radiator lower end to the matching circuit and the ground wire and a communication antenna formed by providing a cable connection terminals.