Frequency-controlled antenna

FIELD: microwave radio engineering; radar frequency-controlled antennas.

SUBSTANCE: proposed antenna is made in the form of flat array of linear radiators connected to power splitter in the form of sine-wave configured line. Components coupling power splitter with linear radiators are divided at antenna input into two groups so that longitudinal axis incorporating all even-numbered coupling members is offset relative to axis incorporating all odd-numbered coupling members by integer odd number of quarter-wavelengths in sine-wave line of power splitter. Phase mismatch occurring in this case is compensated for by respective difference in input section lengths of even- and odd-numbered linear radiators.

EFFECT: reduced space requirement, improved matching and performance characteristics of antenna and radar as a whole.

2 cl, 2 dwg

 

The invention relates to radio ultra high frequency (UHF) and can be used in radar antennas frequency scan.

Widely known and used in radar antenna frequency scan are flat lattice of linear emitters connected to the power splitter in the form of a transmission line microwave sinusoidal ("the kite" or serpentine) configuration. Description of the principle of the device and the validity of such antenna is in many literary sources, in particular in the "Scanning antenna systems microwave" Vol.3, translation edited Getmanova and Apply, ed. "Soviet radio", M, 1971

Significant disadvantages of the known antennas is that the frequency of the signal corresponding to the formation pattern with a maximum in the direction normal to the longitudinal axis of the sinusoidal line (hereinafter frequency normals), the standing wave ratio voltage (hereinafter VSWR) at the input sinusoidal line power splitter increases dramatically in the in-phase summation of a large number of even small magnitude of reflections from the tap - connection elements of the power splitter with in-line emitters. This phenomenon in the literature is called "the effect of normals.

As a prototype of the invention, in principle, can the t to be taken antenna frequency scan radar, AN/SPS-48 company ITT Gilfillan, U.S. ("Foreign military review", 1980, No. 5; "Aviation Wee, 1984, 121, No. 24; TIER, t, No. 2), which is a flat grid of 76 waveguide-slot horizontal line emitters (lines)connected to vertical sinusoidal (serpentine) line of the power divider. VSWR at the input of this antenna at the frequency of the normal is 3.5, which leads to deterioration of antenna characteristics and radar in General at this frequency. However, this antenna can not be adopted for the prototype of the present invention in terms of design, as the specific location of linear emitters and sinusoidal line power splitter in two mutually perpendicular planes is not possible to implement proposed in the invention idea.

As a prototype in the design of the present invention may be adopted antenna frequency scan with the above principle, in which, to ensure a compact design, sinusoidal line power splitter is located in a plane parallel to the plane containing the linear emitters, and the relationship of linear emitters with taps divider power lines is a line perpendicular to both of the aforementioned planes.

Such designs are, in particular, the ship's three-coordinate radar station, otrabotannye and manufactured FSUE "HMP "salute" (claim 1 of the formula for a utility model patent of the Russian Federation No. 35688). In these antennas all taps are located on the same longitudinal axis of the attenuator, which is its axis of symmetry, the distance between all neighboring taps equally, RAID phases for each period of the power splitter are the same; at a frequency of normals all linear emitters of the common-mode (if necessary, invert the phase on them 180 degrees), but also the reflections coming from the taps to the input of the power splitter - phase (Figure 1). This leads to poor matching at the input of the power splitter at the frequency corresponding to the formation of the beam normal to this axis, when the distance between the taps on the power lines are multiples of a whole number of half-waves in the line.

The task to be solved by the invention, is expanding Arsenal of technical means of designing antenna frequency scanning with simultaneous improvement of its operational characteristics. Technical results when implementing the present invention are, in particular, ensuring a compact design, improved coordination, i.e. reducing the VSWR at the antenna input on the frequency of "normals", the improvement of the operational characteristics of the antenna and radar in General.

The essence of the invention lies in the fact that to improve coordination (slimming is VSWR) at the antenna input frequency scanning frequency of the normal elements of communication (taps) divider output lines divided into two groups so that a longitudinal axis that contains all the even-numbered elements, displaced about the axis containing all the odd elements of communication, on the whole odd number of quarter wave length of the sinusoidal line power splitter, and the resulting inconsistency of the phase offset corresponding to the difference of the lengths of the inlet pipe even and odd linear emitters.

2 shows the scheme of the antenna frequency scan. Antenna frequency scan consists of a power splitter 1 in the form of a transmission line microwave sinusoidal (kite or serpentine) configuration and radiant paintings of linear emitters 2, each of which is associated with power splitter 1 through the elements of communication - taps 3, 4, 5, 6, which can be both directed and undirected. The number of taps and the size of their connection with the power splitter provides the amplitude distribution of microwave energy between the linear emitters 2, necessary for the formation of in-plane frequency scanning pattern with the given parameters, and the length of the line sections between adjacent taps provides a phase distribution between the linear emitters required to implement swing beam antenna frequency scanning in a given sector angles when changing the frequency of the signal in the acceptable frequency range.

To ensure good coordination (low VSWR) at the antenna input frequency scan during formation of the pattern with a maximum in the direction normal to the axis of the attenuator 1 taps are divided into two groups (even and odd) so that the section containing all the even-numbered taps, separated from the section containing all the odd-numbered taps, distance And equal odd number of quarter wavelengths in the line of the power divider, the frequency of the signal corresponding to the formation of a beam in the direction normal to the axis of the attenuator. Due to the offset axis, containing the even-numbered taps relative to the axis containing the odd-numbered taps, at value:

Δ=(2n+1)ΛN/4,

where n=0,1,2 and so on, a Λn- wave length in the channel divider power at the frequency corresponding to the formation of a beam in the direction normal to the longitudinal axis of the power splitter is almost complete mutual compensation coming in on the antenna input and strongly out of phase with respect to each other reflections from the even-numbered and odd-numbered taps. The resulting inconsistency of the phases of the even-numbered taps relative to odd offset by a corresponding difference of the lengths of the inlet pipe odd and even lines 2 provided the same con is e.g. the elements they connect to the taps. In case of differences between the phase velocity of wave propagation in channels of the attenuator 1 and the linear emitters 2 compensation of reflection and correction of the phase distribution is achieved by the corresponding correction value Δ.

The proposed scheme was tested experimentally on the antenna containing 68 linear emitters. The distance between the longitudinal axes of the power splitter, containing even and odd taps was 5/4 ΛN. Sinusoidal line power splitter and line have a cross-section of the waveguide channel of 28.5×12,6 mm

VSWR at the antenna input over the entire operating frequency range is not exceeded 1.8, and at a frequency of normal VSWR equal to 1.3.

In addition, experimentally verified power splitter with the same cross-section of the channel used for feeding the antenna from 94 linear emitters. The spacing of the axes containing the even-numbered and odd-numbered taps, as in the previous case, is 5/4 ΛN. When installed on the outputs of the taps of the power splitter agreed load VSWR at the input over the entire operating range of frequencies, including the frequency of normal, is not exceeded 1.2.

1. Antenna frequency scan, performed in the form of a flat grid of linear emitters connected to the power splitter in a line of sinusoidal configuration, layout is defined in the plane parallel to the plane containing the linear emitters, characterized in that the connection elements of the power splitter with in-line emitters are divided into two groups in such a way that the longitudinal axis of the attenuator containing all the even elements, displaced about the axis containing all the odd elements of communication, on the whole odd number of quarter wave length of the sinusoidal line.

2. The device according to claim 1, characterized in that the difference of the lengths of the inlet pipe even and odd linear emitters is selected from the condition of matching the phases of the even outputs of the power splitter relatively odd.



 

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