JPH0524682B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an antenna mounted on a fixed or mobile body for satellite communication, and more particularly to a planar printed antenna using a printed circuit board.

[Description of Prior Art] Conventionally, this type of planar printed antenna is
Multiple radiating elements arranged on a printed circuit board,
The electrolysis was excited so that the phases were aligned, and the desired direction was the maximum radiation direction.

FIG. 2 shows an example of a planar antenna using a microstrip patch antenna as a radiating element.

In the antenna shown in the figure, each microstrip patch antenna 1 has a ground plate 2 made of a conductor.
Each microstrip patch antenna 1 has microstrips arranged in a row in a plane on the upper dielectric layer 3 to give a predetermined excitation phase so as to form a sharp pencil beam in a desired direction. A stripline 4 is connected.

Now, the z-axis is perpendicular to the printed circuit board, the x-axis is in the direction in which the radiating elements (microstrip patch antennas in this case) 1 are arranged, and the y-axis is perpendicular to this x-axis and parallel to the printed board. Take.

When the desired radiation direction is a direction shifted by θ (rad) in the x-axis direction from the z-axis within the xz plane, the excitation phases n ₁ to n ₄ in each radiation direction are expressed by the following equations.

n _o =-2πα (n-1)/λ ₀ sin θ (rad) (n=1, 2...4) where λ ₀ is the free space wavelength and α is the element spacing.

[Problems to be Solved] In the conventional planar antenna described above, the excitation phase to each radiating element 1 is determined by the path length difference between the microstrip lines 4. Once the etching pattern of the radiating element 1 is determined, the maximum radiation direction is determined, and the angle of the maximum radiation direction cannot be changed unless the printed circuit board is physically moved.

Therefore, when performing satellite communications using this antenna, the satellite must be tracked using a step track, and the entire antenna must be moved. Furthermore, if the antenna is mounted on a rapidly moving object such as a car, a very high-speed servo mechanism is required, which may be impractical or expensive.

The present invention has been made in view of the above problems, and provides a printed antenna that can change the angle of the maximum radiation direction without physically moving the antenna itself and can perform electrical high-speed beam scanning. With the goal.

[Means for Solving Problems] In order to achieve the above object, the present invention provides a printed antenna equipped with a microstrip line for serially feeding radiating elements arranged on a printed board or an array antenna of radiating elements. Two branch lines are formed that branch at two branch points that are each offset by a predetermined amount from the center of the lip line, and on these two branch lines, a distance of 1/4 wavelength or an odd number multiple thereof from each branch point is formed. , a switching diode is loaded between each branch line and the ground conductor, and a power supply circuit is provided in which the branch lines are joined at a distance of 1/4 wavelength or an odd number of times from the loading point. .

[Example] Next, an example of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of an embodiment of the present invention.

In the printed antenna of this embodiment, microstrip patch antennas 1 as radiating elements are arranged on a dielectric layer 3 on a ground plate 2 made of a conductor.
is supplied with power from the microstrip line 4.

The microstrip line 4 is ±d from the center.
It branches at branch points a and b with a distance of , and has two branch lines 4a and 4b, and these two branch lines 4
On a and 4b, diodes 5 and 6 are loaded at positions 1/4 wavelength away from the branch points a and b, respectively. These diodes 5 and 6 are loaded in parallel with the circuit between the stripline 4 and the ground plate 2, and perform high frequency switching by applying a bias voltage. Note that the cold ends of the diodes 5 and 6 are connected to the ground plate 2 at high frequency by capacitors 7 and 8, respectively.

The branch lines 4a and 4b join together at a branch point c, which is further 1/4 wavelength away from the location where the diodes 5 and 6 are loaded, and serve as a power feeding location for the present antenna.

Next, the operation of this antenna will be explained.

In this antenna, by alternately switching the diodes 5 and 6, the beam direction of the antenna is switched in the ±θ direction with respect to the z-axis within the xz plane.

Now, if a bias voltage is applied to one diode 6 to short-circuit the circuit, branch point b and branch point c
The impedance viewed from the side of the diode 6 becomes very large, and the branch line 4b from the branch point b to the branch point c including the diode 6 is electrically equivalent even if it does not exist. At this time, power is supplied from the branch line 4 passing through the hot end of the diode 5 from the branch point c.
The process is carried out from branch point a through a. Branching point a
is offset by d from the center of the microstrip line 4 in the x-axis direction, and the combined electrolysis from each element is adjusted to be maximum in the -θ direction.

Note that at this time, the diode 5 exhibits a very high impedance in the off state and does not affect the impedance of the stripline.

Similarly, when a bias voltage is applied to diode 5 to turn it on and diode 6 is turned off, power is supplied from branch point b through branch line 4b, and at this time, the maximum radiation direction of the combined electric field from each element is +θ It has been adjusted so that

As mentioned above, the printed antenna of this example is
By providing two branches in the microstrip line 4 that serially feeds a plurality of microstrip patch antennas 1 arranged on a printed board, two branches with different excitation phases are provided to each microstrip patch antenna 1. A switching circuit that has a feed line and uses diodes 5 and 6 allows the use of two pencil beam radiation patterns with slightly different beam peak angles by switching between the two feed lines. Electrical high-speed beam scanning can be performed without moving the beam.

In addition, in the above embodiment, for convenience of explanation,
Although a so-called disk-shaped patch antenna was used as the radiating element, any radiating element may be used, such as a linearly polarized wave element such as a dipole antenna or a slot antenna, or a circularly polarized wave element such as a spiral antenna. Of course.

In addition, by arranging the array antennas of the above embodiment symmetrically and connecting the two array antennas using the same feeding circuit as in the above embodiment, it is also possible to connect the two array antennas in a direction perpendicular to that of the above embodiment. It is possible to switch between pencil beam radiation patterns having two adjacent maximum radiation directions, and it is also possible to switch and use pencil beam radiation patterns having a total of four adjacent maximum radiation directions.

Further, from branch point b to diode 6, branch point c
from diode 6, from branch point a to diode 5,
Since the distance from the branch point c to the diode 5 is to short-circuit one of the branch lines, it may be set to an odd multiple of 1/4 wavelength, and it is clear that the same effect can be obtained in this case as well.

[Effects of the Invention] As explained above, the present invention provides two branches in a microstrip line that series-feeds a plurality of radiating elements arranged on a printed board, so that the excitation phases to each element are different. A switching circuit that has two feed lines and uses diodes can switch between the two feed lines to use two pencil beam radiation patterns with slightly different beam peak angles.

Therefore, the printed antenna of the present invention can perform electrical high-speed beam scanning without physically moving the antenna itself.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a perspective view of a conventional example. 1: Microstrip patch antenna, 2:
Ground plate, 3: dielectric, 4: microstrip line, 4a: branch line, 4b: branch line, 5: diode, 6: diode, 7: capacitor, 8: capacitor.

Claims (1)

[Scope of Claims] 1. In a printed antenna equipped with a microstrip line for serially feeding a radiating element or an array antenna of radiating elements arranged on a printed board, 2 elements offset by a predetermined amount from the center of the microstrip line, respectively. Two branch lines are formed that branch at one branch point, and on these two branch lines, a switching line is placed between each branch line and the ground conductor at a distance of 1/4 wavelength or an odd number of times from each branch point. 1. A printed antenna comprising a feeding circuit in which each branch line is loaded with a diode and the branch lines are joined at a distance of 1/4 wavelength or an odd number of times from the loading point. 2. The printed antenna according to claim 1, wherein the array antenna is two array antennas placed symmetrically.