Hybrid optical-type antenna with dilated angles of areal scanning

FIELD: physics.

SUBSTANCE: double guidance of beam is used in hybrid optical-type antenna (HOA): electronic and mechanical. Electronic scanning in the HOA is carried out by switching method with amplitude and phase change. Periodic travel of field of electronic scanning is reached by means of mechanical scanning.

EFFECT: increase of scanning speed at reduction of sizes of active phased antenna array.

3 cl, 7 dwg, 2 tbl

The invention is a hybrid mirror antenna (GSA) with extended corners of the sector scanning in the azimuth plane is relates to antenna technique and can be used on space stations for airspace control.

In [1] the invention is intended for use in direction finding systems and maintenance and reduces the change of level crossing pattern (BOTTOM) in ravesignal direction in a wide range of frequencies. To do this in the mirror antenna containing a reflector in the form of clippings paraboloid of rotation and multi-element feed, which is made in the form of a 4-cell of the hexagonal lattice of the open ends of the N waveguides, combs N waveguides continue beyond the plane of their aperture in the form of protrusions, the distance between which increases smoothly up to 0,25-0,45 λ.

In [2] proposed an algorithm for the synthesis of hybrid reflector antenna with shaped reflector, the surface of which is formed by using a numerical optimization procedures; consider the example antenna with linear irradiating the grating is designed to scan in one plane in a limited sector of angles.

In the patent [3] considered a deployable mirror antenna mounted on the surface of the spacecraft. The antenna has parabolistical with horn exciter and the mechanical part with two DC motors. The mechanical part consists of a bearing slewing rings, two parallel rails, the sliding mechanism, the elevation mechanism and the clamping mechanism of the irradiator. Rotating the ring determines the position of the antenna in azimuth and is driven by electric motor, associated through a worm mechanism. The sliding mechanism, which is fixed to the elevation mechanism associated with the mirror is moved along the guides with the help of motor. The mechanical part provides quick and precise deployment of the antenna with the minimum level of interference waves from her protruding parts.

A prototype of the proposed antenna can be considered as GSA proposed in [4]. The article describes theory and design of antennas with a diameter of 35.5 m with scan angle, up to 200 times greater than the width of the pattern. The system operates in the Ka band at a frequency of 35.6 GHz, has a beam width of 0.02° and is used to determine hurricane centers of the circular motion of the upper-level clouds from the spacecraft, allows three-dimensional analysis of critical parameters and dynamics that control their formation and evolution. GSA consists of a spherical reflector with a radius of 56 m and rolling irradiator (spiral) in the form of a planar phased antenna array. Phased antenna grills who has 271 element, located in the nodes of a hexagonal grid with a pitch of 0.9 λ.

The lack of structures considered antennas with mechanical drive is their low scan rate. In these antennas, however, is provided by a wide area of exposure. In GSA with electronic scanning expansion of the sector scan increased the size of the active phased antenna array (AFAR).

The technical result, which is achieved by the claimed invention is to overcome the inherent prototype disadvantages, such as increasing the scanning speed when reducing the size AFAR.

To achieve the claimed technical result is offered in well-known GSA to use double beam steering: electronic and mechanical.

Figure 1 shows the block diagram of GSA dual beam made according to the invention. GSA with extended corners of the sector scanning in the azimuth plane includes a reflector (R) 1, feed 2 in the form AFAR, placed outside the focal plane, transceiver modules (MRP₁-MRP_n) 3 with phasers and attenuators in the channels of the transmit and receive microwave distribution system (PC) 4, which receives microwave energy from the exciter (OT) 5, power supply modules (FE₁-FE_n) 6, processor active phased array (PA) 7, SADUS the th amplitude and phase distribution in PPM ₁-MRP_nthe cluster radiation AFAR, and differs from prototype [4] the fact that GSA additionally introduced a mechanism for changing the position of the reflector (MPR) 8, block correction coordinate of the cluster radiation (Bq) 9 entered in the processor active phased array (PA). In the proposed design GSA MNR may be made in the form of the mechanism of rotation of the reflector, the optical axis (OO) which does not coincide with the axis of rotation (S), or in the form of a swing mechanism of the reflector in azimuth plane.

The proposed design GSA works as follows. Electronic scanning in azimuth and elevation provides an overview within a given number (for example, 30 20) widths of the directional diagrams (SDN) and is switching the way with the change of amplitude and phase. The essence of this method consists in the following. Each position of the beam of GSA corresponds to the inclusion of a specific set MRP AFAR (cluster emission) with the corresponding values of amplitude and phase, set the attenuators and phasers. Moving the beam is achieved by changing the position of the cluster and set the new values of the amplitude and phase of the MRP. Switching control, the amplitude and the phase of the MRP is on the codes of the processor. Additional scan (from minus 30 to 30 SDN) is achieved by changing the position of the reflector by rotating vatrogasci (S), normal to the plane AFAR and not coincident with the optical axis (PA) of the reflector, or the swing of the reflector in azimuth plane. MNR changes the position of the reflector and is controlled by the processor (PA).

Bq entered in the processor AFAR, performs the correction table of the coordinates of clusters of radiation that is loaded in the processor, depending on the position of the reflector. Correction occurs for the current position of the MPR on the ratios of (13), (14) while rotating and swing accordingly.

Figure 2 shows the graphs of the amplitude of the field distribution in AFAR depending on the deflection of the beam, obtained by mathematical modeling. Curve 10 corresponds neuklonnogo beam, curve 11 - deviation 30 SHDN, curve 12 - deviation 60 SDN. The shape of the distribution will be close to rectangular (Fresnel) when the deviation of the beam to 8 SDN. Most of the distortion caused by caustical, will be the removal of stains AFAR more than 20 SDN. To reduce the effect of distortion to increase the size AFAR.

Large size AFAR, on the one hand, lead to an increase in the mass of the antenna and the shading of the reflector, on the other hand, allow you to concentrate power in one or a small number of antipersonnel mines. The ratio of focal length to the diameter of the mirror is chosen so as to ensure minimum dimensions AFAR.

If still the reflector in one cycle the beam is within the scan N _xprovisions in azimuth and N_yprovisions in elevation. At this time of the beam in each of the fixed positions is

where N_xa number of provisions of the beam in azimuth;

N_ya number of provisions of the beam in elevation;

T - the time of the review.

The time dependence of the position of the beam in azimuth during one cycle of the review are presented in figure 3 and is defined by the expression

where δ - step scanning in azimuth;

Δ - limit scan in azimuth;

i - the position number of the beam in azimuth;

where floor {...} is the integer part of the fraction;

N_xa number of provisions of the beam in azimuth;

δt is the time of the beam in a fixed position;

t - time.

The time dependence of the position of the beam in elevation for one cycle of the review are presented in figure 4 and is defined by the expression

where δ - step scanning in elevation;

Δ - limit scanning in elevation;

j is the position of the beam in elevation.

where floor {...} is the integer part of the fraction;

N_ya number of provisions of the beam in elevation;

δt is the time of the beam in a fixed position;

t - time.

Shown in figure 4 marks the provisions of the rays meet the t table 1.

The calculated position of the center of the cluster distribution fields AFAR expressed as

X_i=-F·tg(A_iand

Y_j=-F·tg(B_j) (6)

where F is the focal length of the reflector;

And_i- the position of the beam in azimuth;

B_j- the position of the beam in elevation;

In the proposed variant of construction of GSA with a movable reflector when browsing in azimuth beam moves in two directions - half cycle (rays i=1÷N_x'/2) - right and the second half cycle (rays i=N_x'/2+l-N_x') - left (a total of N_x' provisions). When moving to the right scanning in elevation in negative angles (rays j=1÷N_y'/2), and moving to the left for positive angles (rays j=N_y'/2+1 the N _y'). The time dependence of the position of the beam in azimuth for the variant with a moving reflector is presented on figure 5 and is defined by the expression

where δ' - step scanning in azimuth;

Δ' limit scanning in azimuth;

i - the position number of the beam in azimuth,

N_x' is the number of positions the beam in azimuth;

floor{...} is the integer part of the fraction;

N_x'is the number of positions the beam in azimuth;

δt is the time of the beam in a fixed position;

t - time.

Shown in figure 5 letter designations curve plots correspond to the positions of the rays: the plot And_i1' - i=1÷N_x'/2, plot And_i2' -i=N_x'/2+1÷N_x'.

The time dependence of the position of the beam in elevation of a variant with a moving reflector is presented on Fig.6 and is determined by the expression,

& Delta; b' is the step of scanning in azimuth;

Δ' limit scanning in azimuth;

j is the position of the beam in elevation;

floor{...} is the integer part of the fraction;

N'_ya number of provisions of the beam in azimuth;

δt is the time of the beam in a fixed position;

t - time.

See figure 6 letter designations provisions rays correspond to table 2.

The current offset of the beam in azimuth and elevation, caused by displacement of the reflector antenna in the case of rotation around the axis normal to the plane, and in which the optical axis of the reflector is rotated at an angle relative to the axis of rotation, respectively:

AV=-Rcos{Ωt);

where R is the angle of deflection of the beam;

Ω - angular frequency of rotation of the reflector;

t - time

in the case of swing of the reflector in azimuth plane, characterized by the expression

where A_IK- current displacement of the beam in azimuth, caused by the swing of the reflector antenna;

And_max- the maximum deviation of the beam caused by the swing of the reflector;

V is the velocity of the swing.

T - the time of the review;

t - time.

The calculated position of the center of the cluster distribution fields AFAR in the case of rotation of the reflector is determined by the expression:

XI C=-Ftg(Ai+Rcos(Ωt))

in the case of swing of the reflector is defined expressions

HK=-Ftg(A_i-AK)

,

where F is the focal length of the reflector;

And_i- the position of the beam in azimuth for the antenna with a movable reflector;

In_i- the position of the beam in elevation for the antenna with a movable reflector;

R is the angle of deflection of the beam;

Ω - angular frequency of rotation of the reflector;

t - time;

Shown in figure 5 and 6 positions of the beams are formed in the resultant action of the mechanical movement of the reflector and electronic offset of the cluster area AFAR-irradiator.

Accordingly, the scanning should work out the difference between the values of the angles and offsets of the beam caused by the rotation or swing of the reflector. Figure 7 presents the time dependence of the cluster centers on AFAR for the review cycle for the formation of the desired geometry is generowania. Points a', b', C', d', e, f in the graphs (X, Y) is the variance of cluster AFAR in mutually perpendicular directions by changing the position of the reflector indicate the position of the beam in accordance with table 2.

Required for the proposed version of GSA square AFAR-irradiator significantly less than that required for the variant with a fixed reflector:

S~X_maxY_max,

S_in~X_vmagY_vmag

S_to~X_kmahY_kmah

where X_max, Y_max, X_vmag, Y_vmag, X_kmah, Y_kmah- the maximum deviation of the cluster AFAR in mutually perpendicular directions for fixed, rotating and tilting the reflector, respectively;

S, S_in, S_tosquare AFAR in the case of stationary, rotating, tilting reflector, respectively.

References:

1. Bobkov NI, Bocharnikov A.A., Kashubin BT, Logvinenko EL, Shevelenko A.A., Starov A.G., Yashin I.E. Broadband four-beam mirror antenna (options). Pat. No. 2099836, Russia, H01Q 19/17.

2. Reutov A.S., A.V. Shishlov Constructive synthesis and evaluation of the effectiveness of the hybrid reflector antennas with shaped reflector antenna. 2005, N 1, p.63-67.

3. Sherwood William J. Rodeffer Charles E., Rodeffer Mark A. Deployable antenna for spacecraft. Deployable satellite antenna for use on vehicles. PA is. 5528250 USA, H01Q 1/32.

4. Keyvan Badahory, Yahya Rahmat-Samii. An Array-Compensated Spherical Reflector Antenna for a Very Large Number of Scanned Beams. IEEE Trans on AES, vol 53, No 11, November 2005, p.3547-3555

1. Hybrid reflector antenna (GSA) with extended corners of the sector scanning in the azimuth plane, including the reflector, the feed in the form of an active phased antenna array (AFAR), placed outside the focal plane, transceiver modules (MRP) with phasers and attenuators in the channels of the transmit and receive microwave distribution system (PC), exciter (EOI), the sources of supply (PS) modules, and the processor AFAR, specifying the amplitude and phase distribution in PPM on cluster radiation AFAR, characterized in that GSA additionally introduced a mechanism for changing the position of the reflector (WORLD), and the processor AFAR entered the block coordinates correction cluster of the radiation depending on the position of the reflector.

2. GSA according to claim 1, characterized in that the mechanism for changing the position of the reflector is made in the form of the mechanism of rotation of the reflector, and the optical axis of the reflector does not coincide with the axis of its rotation.

3. GSA according to claim 1, characterized in that the mechanism for changing the position of the reflector is made in the form of a swing mechanism of the reflector in azimuth plane.