JPS58187003A - Antenna using r-kr lens - Google Patents

Abstract

PURPOSE:To prevent reflection due to mismatching, by using two lenses of printed board constitution. CONSTITUTION:Inputted electromagnetic waves from an antenna element 21 pass through a circulator 31 and is divided into two by a coupler 61. The waves divided into two pass through R-kR lenses 51, 52 respectively and added by a coupler 60 and received by a receiver 40. Since the two R-kR lenses 51, 52 are used and they are coupled and fed through couplers 61, 61, the antenna system is symmetrical in the construction, allowing to form a multi-beam in all directions. Since reflecting waves are canceled with each other, the back lobe is reduced.

Description

[Detailed description of the invention] [Technical field of invention] The present invention relates to a radio wave lens called R-AR type.

[Technical background of the invention and its problems]

Detection equipment that can always know the direction, frequency, etc. of incoming magnetic waves uses a multi-beam antenna that receives signals in all directions (U-beam arrays). Among them, there is an antenna using a single-wave lens called the R-JR lens shown in FIG.

This is because the lens can be constructed from a printed board.
A multi-beam antenna using a matrix also has the advantage of a simple structure.

Also, multi-beam antennas using R-A ordinary lenses or Rotman lenses have the advantage that the feed system can be configured with a printed board, but they are not omnidirectional, so multiple antennas must be combined to make them omnidirectional. did not become. The antenna using the R-JR lens is said to be optimal as an omnidirectional i-multibeam antenna.

Here, the operation of the R-aR lens will be explained using FIG. 2.

In FIG. 2, it is assumed that radio waves arrive from direction 1. These radio waves are received by antenna elements 21, 22, 23, 24, 25 and circulators 31, 32, 33, 3, respectively.
It passes through 4°35° and is guided to the lens 5. Here, 1t
If + Is + Is is equal for all antenna elements, the radio wave guided to the lens 5 is focused on the terminal 50 of the circulator 30, passes through the circulator 30, and is guided to the receiver 40. Like this 1
The transfer incident from the direction will be received by the receiver 40. Furthermore, as is clear from FIG. 2, this antenna has an axially symmetrical structure and can form multiple beams as many as the number of receivers over the entire circumference. To + in
+ 1IIkAlthough it is not possible to make them all strictly equal, the relative permittivity of the dielectric material composing the lens 5 is set to 6, and the lens 5
It is known that if the diameter of d1 is v'T d /Dki2 where D is the diameter of the antenna array, 4 + ls + 1 m is constant in practice.

As explained above, the R-aR lens is an antenna that can form multi-beams in all directions, but it has the disadvantage of a high back rope and a large number of beams. The reason for this is that when the radio waves incident from the direction 11 in FIG. This is because 440 K waves are received via the circulator 30. That is,
The receiver 40, which originally receives only 9 radio waves entering from 1,
The radio waves coming from the rear 11 will be received,
The back lobe becomes higher. To eliminate this drawback, the mismatch at the terminal 50 can be reduced. For this reason, when the lens 5 is constructed of a printed board as shown in FIG. 1, the lens 5 and the circulator are connected by a triangular matching portion to avoid mismatching as much as possible. However, inconsistency is still unavoidable, and according to experiments, it is the worst.
A reflection of about 10 dB has been observed.

[Purpose of the invention]

The present invention was made in view of the upright defect, and an object of the present invention is to provide an antenna that does not cause reflection due to mismatch.

[Summary of the invention]

The present invention focuses on the fact that the lens 5 has a relatively inexpensive printed board structure, and uses two lenses to eliminate reflections due to vertical misalignment.

[Embodiments of the invention]

FIG. 3 shows an example of the configuration of the present invention. However, some of the antenna arrays, the connections between the lenses and the antenna elements are shown, and the others are omitted. As shown in the figure, the input radio wave from the antenna element 21 passes through the circulator 31t and passes through the 3dB coupler 6.
It is divided into two by 1. The two divided radio waves pass through lenses 51 and 52, are combined by a 3 dB coupler 60, and are received by a receiver 4o. In other words, the structure of the present invention is such that the conventional lens is made into two lenses, and the two lenses are fed and coupled by a 3 dB coupler, and electrically, it has an axially symmetrical structure like the conventional example. Therefore, multi-beams can be constructed in all directions. An example of the conditions for this antenna system to have desired characteristics is as follows.

C1, ε,: relative dielectric constant, λ: wavelength used, dl, d,
: Lens diameter.

The operation of this embodiment of the invention will be described with reference to FIG. FIG. 4 shows the main parts extracted from FIG. 3 in a simplified manner.

The radio waves incident from the antenna element 21 are sent to the circulator 3
1 = passes through and is divided into two by the 3 dB coupler 61. At the output of 61, the radio waves incident on the lens 51 are
It is also assumed that the phase of the radio waves incident on the signal is delayed by 90 degrees (Condition I). The divided radio waves pass through the lens 51 and the lens 52'fr: (1) The phase difference is different from K and the phase difference is 50 at the output ends 501 and 502 of the lens.
The output of 1 leads the output of 502 by 90° in phase.

Therefore, when the outputs of 501 and 502 are added together at 3 dB Cubflow 0, the output appears toward the circulator 30 and does not appear at the terminal of the non-reflection termination 70. Therefore, it is guided to the receiver 40 via the circulator 30 without loss. On the other hand, the radio waves incident from the antenna element 20 are reflected by the lens 0 terminals 501 and 502, but the electrical lengths from the output end of the 3 dB coupler 60 to 501 and 502 are equal (
Due to condition (2), the reflected wave appears at the non-reflection termination 70 and does not appear at the receiver 40 until t.

According to the following explanation, F'L-, which had a high back lobe in the past,
It has been found that an antenna using an An lens can be improved to provide a full image of the pack rope, but it is not possible to form a sharp forward beam as is. In order to form a sharp beam forward, press A! in Figure 2. ! ＋l
s + 16 had to be approximately constant for the front group of antenna elements. For that purpose v'T d':
He said it needs to be s 2 D.

Consider how this relationship is modified in the configuration of FIG. 3 according to the present invention.

In Figure 2, Ass is constant for all elements! , +7. may be kept constant. This is l,
! .

This means that the phase term of is constant. Assuming that 0 is smaller than this, JT' d :2 D is obtained. If we apply the same idea to Fig. 4, it will be sufficient to keep the phase term in (1) constant. So J, d
H+v′T? Equation (1) is transformed by assuming that d, == 2dt. It suffices to keep the phase term of the equation constant, so d′ta2
D, that is, V"t d+ + v' also becomes d, = 4D, and condition (2) is obtained. In this way, condition (2) forms a sharp beam forward.

As stated above, if the antenna with the configuration shown in Figure 3 satisfies the conditions (■), (III), and (IV), the second
A low-backdrop omnidirectional multi-beam antenna, which cannot be obtained with the conventional type shown in the figure, can be obtained.

In the above embodiment, an example in which a 90' kagura was used as a 3 dB kagura was explained, but as shown in FIG.
A similar effect can be obtained by using a ° coupler.

In this case, the electrical length between the output end of the turnip 2 and the lens terminal requires a difference of % of the wavelength used. In addition, there is V'r1d4 between the diameters d, , d of the lenses 51 and 52.
+v"1 d2'::4 Only the condition D is necessary.

〔Effect of the invention〕

According to the present invention, it is possible to obtain a multi-beam antenna with all directions P[t having a low back rope.

[Brief explanation of drawings]

3 is a diagram showing a configuration example of the present invention, FIG. 4 is a diagram explaining the operation of the present invention, and FIG. 5 is a diagram showing another embodiment of the present invention.

Claims (1)

[Claims] A circular antenna array with a diameter of D9, and nine circulators connected to antenna elements constituting this antenna array;
A receiver connected to this circulator, a 3 dB coupler connected to the circulator, and a relative dielectric constant ε! ,
a first 1l-aR lens with a diameter d1 and a relative dielectric constant ε7,
Diameter d! and a second R-aR lens of 3 dB.
between one of the output ends of the wig and the terminals of the first R, -JR lens, and between the other output end of the 3dB coupler and the second R-A
If the coupler is a 90° turnip 2, connect the terminals of the R lens with a line of equal length, or if the coupler is an 1800 coupler, connect the terminals of the R lens with a line with a length of 1/4 of the wavelength used, and connect the input of the 3 dB coupler. Non-reflective P: Connect the end to the terminal separated from the end,
When the constant of the lens is selected to be V d+ + v" x d2:4D, and the coupler is a 90° angle, Iv"-@
R, -A characterized in that the dimensions are selected such that d Hsr'g dl l is approximately an odd multiple of half the wavelength used.
Antenna using R lens.