A device for reducing the influence of masts and stands on the parameters of antennas installed on them

Abstract

The utility model relates to the field of antenna technology and can be used, for example, in corporate and mobile communications, as well as in special-purpose communication systems. The technical result is a reduction in the influence of antenna masts or racks on the electrical and electrodynamic parameters of the antennas installed thereon while relaxing the restrictions on the transverse size of the masts or racks. The technical result is achieved in that at least a second conductor (2) of about 0.5λ in length with a gap in the middle is placed on the antenna mast or rack (1) with an antenna (3) coaxially installed thereon, the second conductor (2) is made in the form of a metal cylindrical tube, the ends of which are permanently electrically connected along the perimeter to the corresponding section of the antenna mast or rack (1), wherein this section of the mast or rack is used as the first conductor. 3 ill.

Description

[0001] The utility model relates to the field of antenna technology and can be used in corporate, mobile communications, as well as in special-purpose communication systems.

[0002] Antenna devices used in the construction of various types of communication systems are typically mounted on antenna masts or small-diameter posts. Antenna masts and posts are often relatively simple tubular metal structures that are sufficiently resistant to mechanical stress.

[0003] Being conductors of electric current, under certain conditions, they can become a good medium for currents caused by the operation of an antenna device installed on an antenna mast or stand.

[0004] When an antenna mast or strut and an antenna device (e.g., a coaxial antenna) are galvanically connected to each other, current leakage onto the outer surface of the antenna mast or strut occurs. To reduce this leakage, the lower arm of the coaxial antenna's dipole is made longer than the upper arm, and the length of the current path along its inner surface is adjusted. However, this is insufficient, and without additional special measures, completely eliminating current leakage onto the outer surface of the antenna mast or strut is difficult. These leaking currents generate a secondary field, which, when combined with the antenna's radiation field, alters the antenna device's parameters, primarily the matching parameters and the radiation pattern.

[0005] If an antenna mast or pylon is irradiated by an electromagnetic wave reflected from a reflector, or if the radiation source is located some distance from the antenna mast or pylon, such as in a ring antenna array, currents are induced in the mast or pylon, causing secondary radiation. This secondary radiation, combined with the antenna's radiation field, alters the antenna's parameters, primarily its matching parameters and radiation pattern. The radiation pattern under these conditions depends significantly on the geometric parameters of the mast or pylon, primarily its length.

[0006] There are a number of devices that interrupt the currents flowing along the surface of a conductor.

[0007] An antenna device is known that has the ability to reduce its influence on the parameters of nearby antennas by mechanically dividing the vibrator into parts significantly smaller than the wavelength [1]. Structurally, the antenna device is a vibrator, along the length of which switching devices (e.g., pin diodes, HF relays) are installed. When working with a given antenna, on command from the control device, the switching devices are closed, combining the vibrator sections into a single whole with a resonant frequency in accordance with the overall geometric length. When working with a given antenna, then, in order not to interfere with nearby antennas, on command from the control device, the switching devices are opened, dividing the vibrator into short sections that are galvanically unconnected, ensuring a break in the current along the vibrator at the operating frequency. The short sections, having a higher resonant frequency, do not interfere with the operation of the antenna.The antenna ceases to be a source of secondary radiation and does not affect the parameters of neighboring antennas.

[0008] The disadvantages of this device are that, to prevent current leakage into adjacent sections due to capacitive coupling, the gap between the switching devices located in the high-current region must be significant when open, which standard switching devices do not provide. Furthermore, dividing the solid metal vibrator into individual sections reduces its mechanical strength.

[0009] There are a number of different types of baluns that ensure proper operation of antenna devices when fed by an unbalanced (coaxial) RF cable by interrupting the currents flowing along its outer surface. For example, a balun [2] is a ferrite ring, either simply placed on the cable braid or attached to several turns of the braid. With its high inductance, the device creates a high resistance on the outer surface of the RF cable, thereby interrupting the currents flowing.

[0010] The disadvantage of such devices is the low mechanical strength of the materials used in them in relation to impact loads, as well as the spread of their parameters.

[0011] The closest analogue in technical essence to the proposed device is the design of an antenna mast with a reduced impact on the parameters of the installed antennas [3], adopted as a prototype.

[0012] Fig. 1 shows an antenna mast 1, on which, parallel to it, at least one second conductor 2 is installed with a gap in the middle, with a length of ~0.5λ, and having a permanent electrical connection with the antenna mast at the ends. Conductor 2 is attached to the antenna mast 1 by any method that ensures reliable electrical contact: welding, soldering, etc. In this case, this section of the antenna mast 1 with the installed second conductor 2 actually represents an antenna "controlled passive element with variable characteristics" according to patent [4], operating only in the mode of low interaction with the incident electromagnetic wave ("invisibility").

[0013] The prototype device operates as follows.

[0014] Antenna mast section 1, together with second conductor 2, installed parallel to the mast, forms an antenna element operating in a low-interaction mode with the incident electromagnetic wave ("invisibility"). This ensures the absence (or at least a significant reduction) of currents flowing through the mast, thereby significantly reducing the mast's influence on the parameters of antennas mounted on it. Second conductors 2 are installed along mast 1 in close proximity to each other.

[0015] A drawback of the prototype device is that to effectively reduce the influence of antenna masts or racks on the electrical and electrodynamic parameters of antennas mounted on them, the cross-sectional dimension of the second conductor must be comparable to that of the first conductor, otherwise the device's performance is reduced. In practical implementation, with a relatively large cross-sectional dimension of the first conductor, i.e., with a large cross-sectional dimension of the antenna mast or rack (which may be required, for example, to increase mechanical strength), this leads to a significant bulkiness of the entire antenna mast or rack structure.

[0016] The objective of the proposed device is to reduce the influence of antenna masts or racks on the electrical and electrodynamic parameters of antennas installed on them while loosening restrictions on the transverse size of the masts or racks.

[0017] To solve the stated problem in a device for reducing the influence of antenna masts and racks on the parameters of antennas coaxially mounted on them, which is an antenna element consisting of a first conductor, which is a section of the mast or rack, and at least one second conductor located parallel to it, with a length of about 0.5λ with a gap in the middle, constantly electrically connected by its ends to this section of the antenna mast, according to the utility model, the second conductor is made in the form of a metal cylindrical pipe located on the first conductor coaxially with it, wherein the antenna element is located below the antenna, having current flowing onto the mast or rack.

[0018] In Fig. 2 a, b) the proposed device is shown, where it is indicated:

[0019] 1 - antenna mast or stand;

[0020] 2 - second conductor with a gap;

[0021] 3 - installed antenna.

[0022] The device comprises an antenna mast or post 1, on which an antenna 3 is mounted coaxially, having a current leakage onto the mast or post 1. Below the antenna 3, an antenna element is located, consisting of a first conductor 1, which is this section of the mast or post 1, and at least one second conductor 2 located parallel to it, with a length of about 0.5 λ and a gap in the middle. Moreover, the second conductor 2 is a metal cylindrical tube, located coaxially with the first conductor 1, with a length of about 0.5 λ, with a gap in the middle, permanently electrically connected at its ends to the antenna mast or post 1 by any method that ensures mechanical strength and reliable electrical contact - welding, soldering, etc.

[0023] The proposed device operates as follows.

[0024] The second conductor (a metal cylindrical tube) 2, together with a section of the antenna mast or stand 1, creates an antenna "controlled passive element with variable characteristics" according to patent [4], but operating only in one mode of low interaction with the incident electromagnetic wave ("invisibility"). The antenna element formed in this way ensures the interruption of currents that inevitably occur due to current flowing onto the mast or stand 1 from the antenna 3 located coaxially with the mast or stand. This, as a consequence, results in a significant reduction in the influence of the mast or stand 1 on the parameters of the antennas 3 installed on them.

[0025] Fig. 3a) shows the power directivity pattern in the vertical plane for a coaxial antenna located coaxially with a mast or stand, for the case of a relatively large (about 0.08λ) transverse size of the mast or stand in the absence of an antenna element that breaks the currents flowing on the mast or stand.

[0026] Fig. 3 b) shows the power directivity pattern in the vertical plane for a coaxial antenna located coaxially with a mast or stand, for the case of a relatively large (about 0.08λ) transverse size of the mast or stand in the presence of an antenna element that breaks the currents flowing on the mast or stand.

[0027] As can be seen from the radiation patterns shown in Fig. 3a) and 3b), the installed antenna element makes it possible to reduce the radiation level in the vertical plane in a direction different from the main one.

[0028] The technical result is a reduction in the influence of antenna masts or racks on the electrical and electrodynamic parameters of antennas installed on them while loosening restrictions on the transverse size of the masts or racks.

[0029] Sources of information.

[0030] 1. Russian Federation Patent 2207671, H01Q 1 / 52.

[0031] 2. USSR Author's certificate 150886 Balancing device Medinets Yu.R., published 01.01.1962.

[0032] 3. Russian Federation Patent 2801435, H01Q 3 / 00, Design of an antenna mast with reduced impact on the parameters of installed antennas (prototype).

[0033] 4. Russian Federation Patent 2695026, H01Q 3 / 00, H 01Q 3 / 242.

Claims

A device for reducing the influence of masts and racks on the parameters of antennas coaxially mounted thereon, which is an antenna element consisting of a first conductor, which is a section of a mast or rack, and at least one second conductor located parallel to it, with a length of about 0.5λ and a gap in the middle, constantly electrically connected at its ends to this section of the antenna mast, characterized in that the second conductor is made in the form of a metal cylindrical tube located on the first conductor coaxially with it, wherein the antenna element is located below the antenna, having current flowing onto the mast or rack.

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