JPH0342736Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] This invention relates to a vertical antenna suitable for transmitting and receiving radio waves with a wide wavelength range from medium waves to short waves.

[Conventional technology]

An antenna that resonates at wavelengths close to the radio waves being received is one of the conditions for maintaining good reception sensitivity, but when the wavelength of the radio waves spans a wide range, the reception sensitivity of radio waves that deviate from the resonance radio waves decreases. Significant degradation is typical and is a particular drawback for single vertical antennas.

The present invention relates to the structure of a vertical antenna that aims to receive or transmit radio waves in a wide wavelength band with relatively high sensitivity by providing a single antenna with a plurality of resonant wavelengths.

[Problems that this invention attempts to solve]

Antenna of the type that transmits or receives radio waves from the base of a vertical antenna fixed on the ground surface resonates with radio waves with wavelengths that are approximately one-fourth of the radio wave wavelength and integral multiples thereof, so the resonance Highly sensitive radio wave transmission and reception can be achieved by impedance matching the radio waves.

Therefore, it is necessary to increase the number of radio waves that cause the above-mentioned resonance.

[Means for solving problems]

This invention divides the vertical conductor of the antenna into two parts, and adjusts the upper and lower conductors from the dividing point so that they resonate with radio waves of different wavelengths. By utilizing the added resonance, we obtain a vertical antenna that can be used for transmitting and receiving waves in a wide wavelength band.

〔Example〕

FIG. 1 shows the main parts of the present invention, some of which are sectional and perspective views showing the structure.

The base 1 is fixed to the earth surface 13 and is grounded by a ground wire 14 to increase the electrical conductivity of the surface 13.

An insulating stand 2 such as an insulator is fixed above the base 1 to hold the lower antenna 3, but the insulating stand 2 can also be fixed directly to the surface 13 and the base 1 is installed near the insulating stand 2.

A folded portion 5 is provided at the upper end of the lower antenna 3 and is used to improve the sensitivity of the upper antenna 6 as described later.

The upper antenna 6 and the lower antenna 3 are connected to a connecting part 7
However, a portion of the connecting portion 7 is made of an insulating material to isolate the lower antenna 3 and the upper antenna 6.

The coaxial line 4 is, for example, a high frequency cable with an impedance of 75 ohms, and the upper end of its internal conductor 21 is connected to the lower end of the upper antenna 6 , and its outer conductor 22 is connected to the upper end of the lower antenna 3 .

The upper antenna 6 and the folded part 5 constitute a dipole antenna.
It resonates with radio waves depending on the length of the wave.

In other words, when the total length of the upper antenna 6 and the folded part 5 becomes approximately one-half of the wavelength of the radio wave, it resonates with radio waves of wavelengths that are integral multiples of the wavelength of the radio wave, and the distance between the inner conductor 21 and the outer conductor 22 resonates. It becomes a power feeding point suitable for transmitting and receiving radio waves.

Furthermore, resonance occurs according to the individual lengths of the upper antenna 6 and the folded portion 5, and exhibits better sensitivity to this radio wave than to non-resonant wavelengths.

At the wavelength at which the folding section 5 resonates and in the vicinity thereof, there are extremely few radio waves entering and leaving the lower antenna 3 from the feed points of the inner conductor 21 and the outer conductor 22, so that the transmission and reception of the upper antenna 6 and the folding section 5 are difficult. It's almost unrelated.

The coaxial wire 4 is inserted into the base 1 from its lower end through the inside of the lower antenna 3 as shown by the extension 23, and is wound into a coil to form a matching coil 24 of the lower antenna 3.

That is, the coaxial line 4 is used as it is, or similar coaxial lines are connected and extended to obtain a single-turn matching coil 24 as shown.

Connecting the terminal end 9 of the matching coil 24 to the base 1,
It is connected to the intermediate portion 25 of the outer conductor, which preferably matches the impedance of the output line 11 of the lower antenna.

The internal conductor 21 passing through the coaxial line 4, its extension 23, and the matching coil 24 is the internal conductor 12 of the upper antenna 6.

That is, it is the same as if the feeding point of the tablet-type antenna constituted by the upper antenna 6 and its folded portion 5 is drawn out to the output line 12 of the upper antenna 6, and becomes the feeding point for transmitting and receiving radio waves.

In addition, for radio waves with long wavelengths that are out of the resonance of the upper antenna 6, the upper antenna 6 is connected to the coaxial line 4.
Since the characteristics are the same as those connected to the upper end of the lower antenna 3 through the capacitance of the connecting part 7, etc.,
The matching coil 24 is adjusted to match the antenna obtained by adding the lower antenna 3 and the upper antenna 6.

When this embodiment is used for transmitting and receiving radio waves with a minimum wavelength of 10 meters and longer wavelengths, the sum of the lengths of the upper antenna 6 and the folded part 5 is 5 meters, and the length of the upper antenna 6 and the lower antenna 3 is 5 meters. 15 heads of
If you select meters, the output line 1 of the upper antenna
2 exhibits resonance characteristics of half the wavelength of radio waves with a wavelength of approximately 10 meters.

Further, the output line 11 of the lower antenna will exhibit a quarter wavelength resonance characteristic for radio waves having a wavelength of approximately 60 meters.

Also, if the sum of the lengths of the upper antenna 6 and the folded part 5 is 10 meters, the output line 1 of the upper antenna
2, one wavelength resonates for a radio wave with a wavelength of approximately 10 meters, and two resonates for a radio wave with a wavelength of 20 meters.
Shows resonance characteristics of 1/2 wavelength.

If the total length of the upper antenna 6 and lower antenna 3 is 30 meters, the output line 11 of the lower antenna is
It exhibits quarter wavelength resonance for radio waves with a wavelength of 120 meters and half wavelength resonance for radio waves with a wavelength of 60 meters.

Therefore, the upper antenna 6, the folded portion 5, the lower antenna 3, and the matching coil 24 are arranged so that the radio waves to be used resonate or are in a state close to this.
By adjusting these factors, it is possible to obtain a vertical antenna with good sensitivity over a wide wavelength band.

Note that the top loading 17 can be added when it is necessary to increase the capacitance in order to improve the distribution of radio waves of the upper antenna 6.

The stabilizing resistors 15 and 16 are resistors inserted in order to limit fluctuations in insulation resistance around the inner conductor 21 and outer conductor 22 and stabilize the operation of the present invention.
Its value may be several kiloohms.

In order to improve the coupling coefficient of the matching coil 24, a ferrite magnetic core or the like may be inserted, and instead of the single-turn coil and its intermediate portion 25 as shown in the figure, a compound winding may be used to connect the output line of the lower antenna. A matching coil of a transformer provided with 11 can be used.

[Brief explanation of the drawing]

FIG. 1 shows the main parts of the present invention, some of which are shown in cross-sectional and perspective views. 1... Base, 2... Insulating stand such as insulator, 3... Lower antenna, 4... Coaxial line, 5... Folded part, 6
. . . Upper antenna, 7 . . . Connection portion, 9 . Lines, 15, 16... Stabilizing resistor, 17... Top loading, 21... Inner conductor of coaxial line 4, 22... Outer conductor of coaxial line 4, 23... Extension of coaxial line 4, 24... ...Matching coil, 25...Middle portion to be matched.

Claims (1)

[Claims for Utility Model Registration] A lower antenna 3 having a folded portion 5 on the upper side is fixed to a base 1 which is grounded with a ground wire 14 via an insulating stand 2, and an upper antenna 6 is attached above the lower antenna 3. In a vertical antenna coupled with a fixed connection part 7, a. Connecting the upper end of the inner conductor 21 of the coaxial line 4 and the outer conductor 22 of the coaxial line 4 to the lower end of the upper antenna 6 and the upper end of the lower antenna 3, respectively; b forming the extension 23 of the coaxial line 4 into a matching coil 24; c connecting the terminal end 9 of the matching coil 24 to the base 1; d connecting the output line of the lower antenna 3 to the middle part 25 of the outer conductor of the matching coil 24. 11; and e) The internal conductor 12 of the coaxial line 4 passing through the matching coil 24 is used as an output line of the upper antenna 6.