JPH01501194A - traveling wave array antenna - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Array beam position control using multiple slots Background of the invention This invention uses slot waveguide arrays, especially compound slots to control beam position. Regarding the array.

Two commonly used types of slot waveguide arrays are serpentine slot waveguide arrays. Ray and shunt slot array.

For both arrays, waveguides are used if the beam is to be tilted significantly from the side. must be operated at a wavelength close to its cutoff wavelength. Therefore, the excitation frequency The beam is scanned as the wave numbers are scanned.

Therefore, it is necessary to operate the array at a wavelength close to the cutoff wavelength of the waveguide. The beam position can be selected regardless of the waveguide size so that the Lot waveguide arrays are desired.

Regarding the properties of general tilt displacement slots (i.e., compound slots), , “The Physical Pr1ciples” by Watson aveguide Transmission and Antenna Sy stems”, Oxford at the C1aredon Press, It is described in 1947. Watson is clearly the special nature of these slots Using high quality, the array can achieve broadside frequency without the usual high voltage standing wave ratio. Each slot can be aligned with a tuning button to operate by wave number. I assembled a Yukinami array. However, as far as is known, Watso The authors did not use the phase characteristics of the compound slot to scan the beam.

Paper “Resonance slot that controls amplitude and phase independently”’Re5onance 5l ots with Independent Control of Ampli tude and Phase’ B, J, Maxum, IEEE Tra ns, Antenna and Propagation, Vol, AP -Jl, pp, 3g4-389. July, 1960 has a unique shape The phase characteristics of the composite slot are used to obtain the beam, and the approximate value accompanying the analysis is Therefore, a linear array is described in which the coupling coefficient is limited to small values.

Therefore, regardless of the size of the waveguide, the array can be adjusted to the cutoff frequency of the waveguide. Traveling wave slot waveguide array allows beam position selection without operating at close wavelengths Providing this would be an indication of technological progress.

Additionally, slot waveguiding using composite slots to obtain the desired beam position It would be beneficial to provide an array of tubes.

Summary of the invention The above benefits and objectives are such that the voltage phase of the slot provided in the floor-wall waveguide is A compound slot controlled by the slot's offset and tilt angle with respect to the vertical axis. This is accomplished in a slot waveguide array using a slotted waveguide array. Composite slot with phase control When carried out with a The system could be oriented in the desired direction relative to the broadside.

A preferred embodiment is formed by first and second bottom walls and first and second buttresses. a plurality of composite slots formed in the first bottom wall. Each slot The slope of the curve and its offset along the vertical axis are determined by the required voltage phase and amplitude distribution. to give the desired beam direction. Each slot has a resonance length. One end of the waveguide is Terminated with a matched load.

This invention operates near the waveguide cutoff frequency where unacceptable frequency sensitivity occurs. It is possible to position the beam far from the broadside direction without having to enable.

Brief description of the drawing These and other features and advantages of the invention will be apparent from the embodiments as shown in the accompanying drawings. It will become clear from the detailed description. In the attached drawings, Figures 1A and 1B show parallel, series and compound slots in the bottom wall of a rectangular waveguide. diagram showing, Figures 2A to 2C show resonant compound slots, parallel slots, and series slots, respectively. Lot's equivalent circuit diagram, Figure 3 is a diagram showing a waveguide in which multiple composite slots are formed. , Figures 4A and 4B show the dielectric charging for forward wave and backfire cases. According to an embodiment of the invention having nine resonant slots powered by a filled waveguide. This is an antenna directivity diagram of a traveling wave array, where the solid line is the experimental directivity and the dotted line is the expected theoretical directivity. showing tropism, FIG. 5 is a diagram showing a missile body in which a plurality of traveling wave arrays of the present invention are arranged on the outer edge. ,and FIG. 6 is a diagram showing the position and orientation of the composite slot.

Detailed description of disclosure A preferred embodiment of the invention includes a plurality of compound slots formed along a single bottom wall. This is a slot waveguide array with waveguides that are connected to each other. The basic principle of this invention is The flatness of the various slots formed in wave tubes 20 (FIG. 1A) and 30 (FIG. 1B) It will be appreciated that FIGS. 1A and 1B show top views.

Composite slots such as slots B, D in Figure 1A and B-, D- in Figure 1B are Both are offset and tilted with respect to the centerline 25 of the bottom wall. resonance complex The equivalent circuit of the joint slot is W, a T network as shown in Figure 2A. child In contrast, slots A and E are arranged parallel to the axis 25 but offset from the axis. Therefore, as shown in Figure 2B, it can be expressed by pure parallel admittance. Let's do it. The slots C9C' are arranged on the axis 25, but are tilted to the axis. Therefore, it can be expressed as a pure series impedance as shown in Figure 2C.

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The characteristics of the composite slot can be understood by the following analysis. Figures 1A and 2A All slots shown in the figure have a resonance length (half the wavelength of the excitation energy). do. In this case, if the TE of unit amplitude and zero phase (with reference to the cross section z-z') ,.

The mode excitation signal travels through the waveguide 20.30 in the direction of arrow 26 while these If it is incident on any of the slots, the electric field induced in slot A will be on axis 25. It has an amplitude determined by the offset XA between them and a phase of 90°. slot The electric field induced in slot E has the same amplitude as in slot A, but the phase is -90 It is @. The electric field induced in the slot C is determined by the inclination angle θC with respect to the axis 25. It has an amplitude of 0° and a phase of 0°.

Composite slots B and D are from slot A to slot C1 to slot C, respectively. Since it is seen as a transition to slot E, the electric field induced in composite slots B and D is The phases are in the range of (90', o@) and (0°, -90') respectively . The amplitude and phase of these induced electric fields depend on the slot BSD offsets X, , XD and the slope. It depends on the oblique angle θB1θp.

Similarly, since the phase of the electric field induced in slot C' is 180', the composite slot The phases of the electric fields induced at B” and D= are (90” and 180’), respectively. and (18'0", -90°).The amplitude and phase of these induced electric fields depends on the offsets XB・, XD− and the inclination angles θB・, θp− of slots B′, D′. will exist.

From the above explanation, it can be seen that the TEIO mode is induced into the resonant composite slot by the excitation signal. The phase of the electric field can be changed over 360° by selecting the slot offset and tilt angle. An important conclusion is that it can be tuned over the entire range. this conclusion '+t, adjust the phase of the compound slot to scan the beam at a given angle It can be used for overall phase control of the array, which not only compensates for the effects of mutual coupling. This shows that it is possible to do this.

For the design of slot arrays with mutual coupling effects, see Kurt L. z and R,s, “The Deslgn of Small” by Elliot Slot Array’ (Small slot array design) IEEE Tra ns.

Antennas and Propagation, Vol, AP-28 , pp. 214-219, March 1978, and M, 0refice and R,S, Des1gn of Inclined 5eries by Elliot 5lot Arrays’ (Design of tilted serial slot array) UCLA Department of Electrical Sciences Re Port, October 1979.

In these designs, the equivalent dipole array is the original Bablnet. proposed by the theory that the aperture excitation weighted sum of dipole initial impedances is mutually exclusive. It was confirmed that they represent mutual bonds. The length of the dipole is also the length of the slot. ), but the sum of the self-impedance term and the mutual coupling term of the loaded Guy pole is a pure real and was adjusted to a level that yielded adequate excitation and input matching.

Therefore, for a parallel slot array, the design parameters are (Xn, 2Ln )Met.

Xn and 2Ln represent the offset and length of the nth slot, respectively. Series For the lot array, the design parameters were (θn, 2Ln). θ n and 2Ln represent the inclination angle and length of the nth slot, respectively.

Unlike these earlier designs, this invention utilizes resonant length compound slots and In addition to adjusting the phase that determines the beam scanning angle, there are two The parameters Xn and θn are adjusted.

Resonant length arrays are useful for important applications where parallel and series slots are inadequate, i.e. This has important advantages when used in traveling wave arrays. These advantages of rectangular waveguide The tube 40 has non-resonantly spaced slots 5l-8n formed in one of its bottom walls 41. This will be understood by referring to FIG. The waveguide 40 terminates at a load 43. It's on the edge. Continuous slots are essentially the same in each slot, but two slots It is assumed that the phase is excited in the TE+o mode, which differs in phase by B+od radians. . d is the slot spacing and BIO is the phase velocity of the mode (2π/λ).

Aperture excitation means that the main beam has an energy given by kd cos θ0 + mB1゜d. The natural phase progression (na tural phase progression) at 0k-2π/λ be. (Load phase control provided by composite slots is not considered.) Therefore, θo − arccos (B lo C). Size of bottom wall 41 of waveguide 40 Whatever you do with it. Therefore, it corresponds to any beam direction θ0. You might think that you can adjust it to It is not possible in practice if consideration must be given.

This invention describes how to perform a step from a slot other than B1゜d in a traveling wave array. Aperture excitation is performed with phase progression to the lot, and the beam is The present invention provides a solution to the problem of whether it is possible to set the position at a certain degree. Theoretically this Adjust the slot length of pure series or parallel slots to adjust the phase to aperture excitation. This can be achieved by providing a phase difference that, when applied to the beam, sets the beam at the desired angle. It may become Noh.

However, for arrays of practical length, this phase increase can be significant. The more the dynamic range for self-admittance and self-impedance There is not enough ji. Composite slots are not subject to this restriction. Because compound slot This is because it allows a full phase range of 360@ when exciting the individual slots. . The direction of the composite slot is determined by the beam position θ0 (Figure 3) using equation (1). Add an additional phase shift α such that

eOsθo = B 1o/k + a/kd (1) As a result, using compound slots The traveling wave slot array used in this application does not require an excitation signal close to the cutoff wavelength of the waveguide. In most cases, the beam is produced at the end fire (90” from the broadside). It is possible to

An exemplary procedure for designing a composite slot array is outlined below. waveguide The size, slot spacing, operating frequency and dielectric constant of the waveguide dielectric filling all depend on Assume that it is selected. In this example, a composite of nine resonant lengths is used in the array. There are slots with a common spacing d, with the nth slot being furthest from the excitation source.

Additionally, the desired radiation pattern is specified, so that the total voltage of each slot is It is assumed that the relative amplitude and phase have been determined using known techniques.

The total voltage at the nth slot is expressed as V°, and there are four voltages as shown in equation (3). It consists of the following ingredients.

■A゛-■ゎr” +V, 2a +vゎ3” +V-4’ (3) Here, Va” is the partial slot due to the wave A incident from the left, that is, Z < Z s’. is the cut voltage and ■. 2° is incident from the right, that is, from Z)Z　fi　” The wave is the partial voltage, and v,3'' is the voltage difference between all other slots of the array. V a4° is the partial voltage due to the mutual coupling between the two adjacent waveguides. Partial voltage due to internal TE20 mode coupled with lot.

Similarly, the total backscattered and forwardscattered TEIO modules away from the nth slot The code has the amplitude shown in equations (4) and (5).

B, -BゎI+B I+2+B a3+8114 (4) C, -C=++C, 2+C-300-a (5) The relationship that connects the quantities in equations (4) and (5) is Ape. shown in the index.

The desired slot voltage and slot offset from the waveguide centerline (Xゎ) and its The central design formula that ultimately leads to the relationship between the inclination angle (θ.) and the center line of is shown as follows.

In the above formula, However, n is the free space impedance, λ - λ, bar ε) 1/2, and the dielectric The rate is ε, -ε/ε. A plane wave propagating in an unbounded area is the wavelength.

The important terms related to the slot direction are h, (X, , θ., 2L,) . This section is However, 2L is the resonance length of the n-th composite slot.

2L, is a function of the offset of the nth slot, and perhaps also of its tilt angle. It is a number. In equation (7), i − arcsin(λ/2a), and In order to solve the design formula (6), constants L −, Kr, −, K 2. . is given an initial value It will be done. Also, the mutual coupling between the outside and the inside, Vm3's and Vm4' are the first of these. Calculated for period value. The design formula is as follows, from X, and θ. Of new Derive values that lead to values. This process is repeated, and each iteration yields Xゎ and θ. of getting closer to the true value.

The compound slots used in embodiments of the invention are of resonant length. For those skilled in the art As is well known, the resonance length can be measured empirically or by the moment method. It is a parameter that can be determined by calculation using the method of Suitability of resonance length parameters A reasonable approximation is that of a purely parallel slot with the same offset as this composite slot. It is known that

Design equation (6) was tested for experiments conducted on an S-band antenna.

Each of these antennas consists of 9 compound slots with a 0.55λ center 0, and the traveling wave was supplied by a dielectric-filled TEIO wave waveguide. each The waveguide was terminated with a matched load that absorbed 10% of the input power. waveguide floor wall The size is 1.3 inches, and the buttress is 150 inches. The waveguide has a dielectric constant was filled with a dielectric of 2.5. The waveguide is a stripline with copper coating on both sides. Made of Duroid 587B, which is a board material, butted The bagged ends are coated with copper to form a sealed waveguide. Both of these antennas were early Designed using less precise design procedures. The array is directed from input to load A beam at an angle of 60° and 120” from the forward endfire defined as being at designed to generate a

Slot designed to generate main beam at 60″ from forward endfire The dimensions and orientation of the nine slots S1 of the array are shown by way of example in Table 3.

Table 1 Slot #X, (inch) θ, (degree) length (inch) 1 +, 003 −． 7B @ 1.1722 +, 018 -. 35' 1.1743 +, 02 2 +1.4° 1.1754 0.0 +3.8' 1.172 5 -. 038 +3.3" 1.1816 -.069 -i, o@1.20 07 -. 052 -5.5' 1.1888 +, 011 -5.2' 1. 1739 10.41 -2.3" 1.182 Target aperture distribution is tiller The distribution was -30 dB, n = 8. Main beam ±3 from broadside 0'' and if the element factor is included, this is -26dB theoretical sidelobe level. Patterns obtained from experiments with these antennas is shown in FIGS. 4A and 4B, with the actual slot dimensions and modified design described above. The pattern calculated using the formula is compared. Unique features of this invention Although the waveguide size and slot spacing are the same, the beams of the two antennas on both sides of the broadside. Only the direction of the slot is different.

The example above shows ±60″ and 120’ from the front end fire, or a broad This invention concerns an array that generates a beam at ±30'' from the side. The maximum beam scanning angle that can be achieved is determined by the shape of the radiation pattern of the slot element and the quadratic limited only by the beam rise and the limitations on possible interelement phase shifts. Therefore, it should be understood that there is no limit.

As will be understood by those skilled in the art, the longer the array, the narrower the beam; The system can be scanned closer to the end fire.

A particularly suitable application of this invention is as a missile target detection system or fuse antenna. It is. A schematic perspective view of a portion of the missile body with the slot array is shown in FIG. is shown.

One piece designed to emit a beam far from the broadside. The above slot arrays 62 are arranged in the longitudinal direction along the outer surface of the missile body 60. be able to. The beams of these antennas are placed on the missile at some distance from the target. Can sometimes be used to locate targets that are being approached by missiles It is. This allows, for example, to detonate the explosives loaded on the missile and destroy the target. You will be given enough time to do so. The number of arrays placed around the missile is It depends on the application.

The embodiments described above are merely illustrative of specific embodiments that utilize the principles of the invention. will be understood. Any person skilled in the art may follow the principles of this invention without departing from the scope of this invention. It is possible to devise various arrangements.

碕 dawn % Special table Hei 1-son:)4(6) Special table Hei 1-501194 (8) FIG. 4A international search report mvm41 A#5llcsbee Na, PCT/υS 87102380 SA　19066

Claims (13)

[Claims] 1. formed by first and second conductive wide walls and first and second conductive narrow walls; a rectangular waveguide and propagation in TE10 mode from the first end of the waveguide to the second end. means for exciting the waveguide with an excitation signal that a plurality of compound slots having a substantially resonant length formed along the The slope and offset from the longitudinal centerline of the wide wall 1 Control the phase and amplitude of the pressure to position the beam resulting from the excitation signal in a predetermined direction and means for terminating the waveguide at the second short section. A traveling wave array for providing an array beam in a predetermined direction, characterized by: 2. The resonance length of each compound slot is the same off centerline as each compound slot. It is characterized by being selected as the resonance length of pure parallel slots arranged in a set. An array according to claim 1. 3. The slope and offset of each of the composite slots may further be adjusted between multiple composite slots. selected to provide phase and amplitude corrections for the mutual coupling effects of 3. The array of claim 2. 4. characterized in that the waveguide is filled with a dielectric material having a dielectric constant greater than 1; 3. The array of claim 2. 5. Claim 1, characterized in that the means for terminating the waveguide comprises a matched load. Array according to item 2. 6. The center-to-center spacing of the slots is approximately .000, where λo is the wavelength of the characteristic waveguide. 5λo 3. An array according to claim 2, characterized in that: 7. A fuse antenna array for a missile with an elongated missile body. , comprising a plurality of slot waveguide arrays arranged around the perimeter of the missile body; Each of the arrays is generally aligned parallel to the longitudinal axis of the missile body, and each array to provide a tilted beam from a broadside direction in response to an array excitation signal. each array includes first and second conductive wide walls and first and second conductive wide walls. a rectangular waveguide formed by a conductive narrow wall, and a rectangular waveguide formed by a conductive narrow wall; means for exciting the waveguide with an excitation signal propagating in TE10 mode to the end; a plurality of complexes having a substantially resonant length formed along the first wide wall with a center-to-center spacing of the slope and offset from the longitudinal centerline of the first wide wall of each slot. controls the phase and amplitude of the voltage in each slot to reduce the beats resulting from the excitation signal. the waveguide is selected to position the waveguide in a predetermined direction. A fuse antenna array comprising: means for terminating. 8. The resonance length of each compound slot is the same off centerline as each compound slot. It is characterized by being selected as the resonance length of pure parallel slots arranged in a set. The antenna array according to claim 7. 9. The slope and offset of each of the composite slots may further be adjusted between multiple composite slots. selected to provide phase and amplitude corrections for the mutual coupling effects of An antenna array according to claim 7. 10. characterized in that the waveguide is filled with a dielectric material with a dielectric constant greater than 1 An antenna array according to claim 7. 11. Claims characterized in that the means for terminating the waveguide comprises a matched load. The antenna array according to item 7. 12. The center-to-center spacing of the slots is approximately .000, where λo is the wavelength of the characteristic waveguide. At 5λo 8. An antenna array according to claim 7, characterized in that: 13. in a traveling wave array to give a tilted array beam from the broadside. Yes, formed by first and second conductive wide walls and first and second conductive narrow walls. a rectangular waveguide filled with a dielectric material, and from the first end of the waveguide to the second end. means for exciting the waveguide with an excitation signal propagating in TE10 mode; a matched load terminating in the second short section and formed along the first wide wall at a predetermined center-to-center spacing; a plurality of composite slots having a substantially resonant length, the length of the first wide wall of each slot; The slope and offset from the centerline in the hand direction determine the phase and amplitude of the voltage at each slot. selected to control the width and position the beam resulting from the excitation signal in a predetermined direction. A traveling wave array comprising: