SU1555740A1 - Dipole antenna - Google Patents

Abstract

The invention relates to antenna technology. The purpose of the invention is to match at a second frequency, two times less than the main frequency. The dipole antenna contains a metal mast 1 with a base 2 and holes 10, lower and upper quarter-wave glasses 3 and 5, each of which is made of four U-shaped rods 4 and 6, a coaxial feeder 7 connected to a coaxial connector 8, and U- knee 9. At a wavelength twice as large as the main λ, glasses 3 and 5 cease to be quarter-wave. Each of them is a large reactance, and the electric length of the U-bend 9 is 0.75 λ. This gives U-bend 9 the properties of a quarter-wave transformer. Therefore, the energy of an electromagnetic wave propagating through the feeder 7 almost completely passes into U-bend 9 and excites cups 3 and 5, having a total length of 0.25 λ. The bandwidth is determined by the band of the U-bend 9 in the quarter-wave transformer mode, which is narrower than the generally known length of 0.25 λ. 1 il.

Description

The invention relates to antenna technology and can be used as an antenna of vertical polarization.

The purpose of the invention is to match at a second frequency, two times less than the main frequency.

The drawing shows a dipole antenna, a general view.

The dipole antenna contains a metal mast 1 with a base 2 connected in a grounded screen (not shown) lower quarter-wave glass 3, made of four U-shaped rods 4, upper quarter-wave glass 5, made of four U-shaped rods 6, coaxial feeder 7, connected to the coaxial connector 8, and U-knee 9. The peripheral ends of the U-shaped rods 4 and 6 are closed on the metal mast 1, and the central ends through the holes 10 in the metal mast 1 are inserted inside it, where the U-different rods 4 are connected with the central conductor of the coaxial feeder 7, and the U-shaped rods 6 with the central conductor of U-bend 9, the second end of which is connected to the central conductor of the coaxial feeder 7, and the outer conductors of the coaxial feeder 7 at its end and U-bend 9 at its two ends The common point 11 is connected to the metal mast 1 inside it, the dipole antenna has the following parameters: diameter of the metal mast d 0.033ft cut, diameter of the U-shaped rods 0.125d, distance of the middle part of the U-shaped rod from the axis of the metal mast 1, 5d , the length of the U-knee 1, 5 ft cut / 41, where Npev is the main wavelength of the dipole antenna, 6 is the relative dielectric constant of the coaxial

five

0

35

Q

before

45

50

55

the cable from which the U-bend is made.

Wave resistances of the coaxial feeder and the U-bend are 75 Ohms.

Dipole antenna works as follows.

At the main wavelength, electromagnetic energy, propagating in the form of a TEM wave, at the output of the coaxial feeder 7 is divided in half between the entrance of the lower quarter-wave cup 3 and the input of the U-leg 9, having an electrical length of 1.5 ft and connected to the output an upper quarter-wave cup 5. The shoulders of a dipole antenna, formed by quarter-wave glasses 3 and 5, are excited in antiphase in half-wave resonance mode and intensely radiate. Performing quarter-wave cups 3 and 5 from U-shaped rods 4 and 6 increases the radiation resistance of the antenna, just as it does in a loop vibrator with different diameters of solid and excitable conductors, which allows the 75-ohm coaxial feeder 7 to match the dipole antenna through and -colo about 9, having a transformation ratio of 1: 4. The bandwidth is determined in the main band of the U-leg 9, which, with a length of 1.5 ft, is narrower than with a generally known length of 0.5 ft.

At a wavelength twice as large as the main wave, glasses 3 and 5 cease to be quarter-wave. Each of them is a large reactance, and the electric length of the U-bend 9 is 0.75ft, which gives the U-bend 9 the properties of a quarter-wave transformer. Therefore, the energy of an electromagnetic wave propagating along a coaxial feeder 7,

almost completely goes to the U-knee

9 and excites cups 3 and 5, having a total length of 0.25 ft, and the current distribution, having a maximum current g at the grounded shield, is similar to the current distribution during excitation in the transient. days, the point of an asymmetrical resonant vibrator, which, with such excitation, has an increased input resistance of an active nature. The bandwidth is determined by the band of the U-bend 9 in the quarter-wave transformer mode, which is narrower than the generally known length of 0.25. 15

The dipole antenna with a height of 0.53 m provides coordination in the band (300-350) MHz and in the band (150-180) MGSch with VSWR not more than 2.0, i.e. additionally at a frequency two times smaller, beyond the 20 limits of the frequency range of the known antenna.

Claims (1)

Invention Formula A dipole antenna containing a metal mast with two quarter-wave cups coaxially mounted on it, the outer ends of which are closed on a metal mast and the inner ones are connected through a balancing element with a coaxial feeder, which is different in order to match at the second frequency, two times smaller than the main frequency, quarter-wave glasses are made each of four U-shaped rods located at a distance of 1.5 d from the axis of the metal mast, de d - diameter of the metal mast, wherein the free ends of the U-shaped cores each quarter cup inserted through openings in the metal mast inside it, and a balancing member is a U-knee length 1,5 ft, where ft. - the length of the main wave in the U-bend, and the outer conductors of the U-bend and coaxial feeder are closed at one point inside the metal mast.