GB1572273A

GB1572273A - Aerial arrangements

Info

Publication number: GB1572273A
Application number: GB2289477A
Authority: GB
Original assignee: EMI Ltd
Current assignee: EMI Ltd
Priority date: 1977-05-31
Filing date: 1977-05-31
Publication date: 1980-07-30
Also published as: DE2824053A1; FR2393439A1

Description

(54) IMPROVEMENTS IN OR RELATING TO AERIAL ARRANGEMENTS (71) We, EMI LIMITED, a British company of Blyth Road, Hayes, Middlesex, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to aerial arrangements, and it relates especialy to such arrangements including end fed microstrip linear arrays of elements.

Such arrangements are disclosed and claimed in British Patent No. 1,294,024 and the disclosure of that patent is incorporated herein by reference.

Aerial arrangements are sometimes required with different polarization directions with respect to the array axis. It is an object of this invention to provide such arrangements.

According to the invention there is provided an aerial arrangement including a dielectric substrate bearing on one surface a ground plane conductor and on the opposite surface thereof, a strip conductor and at least one conductive element spaced therefrom and mutually coupled thereto, said at least one element being elongated and having its long dimension disposed, with respect to said strip conductor, at an attitude other than parallel.

In order that the invention may be clearly understood and readily carried into effect, some embodiment thereof will now be described, by way of example only, with reference to the accompanying drawing in which: Figure 1 shows parts of an arrangement in accordance with one example of the invention, Figure 2 shows a modification of the arrangement shown in Figure 1, Figure 3 shows part of an arrangement in accordance with another example of the invention, and Figure 4 shows a modification of the arrangement shown in Figure 2.

It will be appreciated that the following description relates to an aerial arrangement of the kind described in the aforementioned British Patent, formed of a dielectric substrate having both surfaces initially covered with copper, and in which one surface has been etched to form at least one microstrip conductor with associated elements spaced therefrom and mutually coupled thereto.

Referring now to Figure 1, the conductor is shown at 1 and the substrate at 2. The copper coating on the other surface of the substrate cannot be seen in the drawing, but it constitutes a ground plane for the arrangement in known manner. The substrate 2 can conveniently be formed of P.T.F.E. Ifibreglass or polyimide. Three elements are shown in Figure 1 at 3, 4 and 5 and it will be observed that the elements are elongated and that their elongated dimensions are all disposed at 45" to the conductor 1. The ends of the elements nearest the conductor 1 are parallel to that conductor. This arrangement produces a polarization angle of 45" relative to the array axis.

Referring to Figure 2, depending on the polarization angle required, the elements 3', 4', 5' can be disposed with their long dimensions at any non-parallel disposition to the conductor and with the ends nearest the conductor 1' parallel thereto. In Figure 2, the angle is by way of example 90".

If desired, circular polarization can be achieved by disposing elements with complementary angles of inclination in pairs on both sides of the conductor (e.g.

as shown in Figure 1 by elements 3, 4 and 5 and dotted elements 31, 41 and 51) the elements on one side e.g. 31, 41, 51 being displaced by As/ from the elements 3, 4 and 5 on the other side, where As is the wavelength in the strip line.

Circular polarization can also be achieved as shown in Figure 3, using a pair of microstrip conductors 6 and 7 supplied from a common feed 8 and disposed so that a phase difference A/4 exists at the commencement of the parallel parts of the two conductors.

Elements 9-12 are associated with conductor 6 and elements 13-16 with conductor 7, and it will be observed that the elongated dimensions of the two sets of elements have 45" inclinations > to the directions of the conductors 6 and 7, and the ends of elements nearest the conductors are parallel thereto. In principle, it is sufficient that the coupled elements lie perpendicular to each other. They need not be at 45" to the feed line-they could be 30 and 60 , for example. Some improvement in circularity may be achieved this way, over a wider angle around the array direction.

Figure 4 shows an alternative arrangement for achieving circular polarization. In this case, two conductors 17 and 18 run adjacent one another and respective sets of elements 19-21 and 22-24 are disposed adjacent the conductors and on their outsides. The /4 phase difference is still required between the two conductors, and the elements 19-21 are at right angles to the elements 22-24.

The arrangement of Figure 3 has a better lobe pattern over a wider azimuthal spread, since the radiating elements are more closely spaced than they are in the Figure 4 arrangement. If the elements of the two sets were formed in overlapping or inter-digitated form, even better results could be anticipated.

An alternative substrate, which has advantage if the arrangement is to be operated at high temperatures (say in excess of 600"C) is ceramic, but in this case the conductive components (microstrip conductors and elements and ground plane conductor) have to be fired on.

WHAT WE CLAIM IS:- 1. An aerial arrangement including a dielectric substrate bearing on one surface a ground plane conductor and on the opposite surface thereof, a strip conductor and at least one conductive element spaced therefrom and mutually coupled thereto.

said at least one element being elongated and having its long dimension disposed, with respect to said strip conductor, at an attitude other than parallel.

2. An aerial arrangement according to Claim 1, comprising a plurality of strip conductors on the said opposite surface, and at least one conductive element spaced from each strip conductor and mutually coupled thereto, each element being elongated and having its long dimension disposed, with respect to the strip conductor to which it is coupled, at an attitude other than parallel.

3. An aerial arrangement according to Claim 1, or Claim 2 comprising a plurality of conductive elements spaced from the or each strip conductor and mutually coupled thereto, each element being elongated and having its long dimension disposed with respect to the strip conductor with which it is coupled, at an attitude other than parallel.

4. An aerial arrangement according to Claim 3 when appended to Claim 1 or 2 wherein all the elements coupled with the said strip conductors are arranged on the same side thereof.

5. An aerial arrangement according to Claim 3 when appended to Claim 1 or 2, wherein the elements coupled with the said conductor or one of the said strip conductors are arranged on both sides thereof.

6. An aerial arrangement according to Claim 4, comprising two strip conductors having parallel portions connected to common feed strip conductor by strip conductor means arranged to establish a predetermined phase difference between electromagnetic waves fed to the parallel portions.

7. An aerial arrangement according to Claim 6, wherein the said elements are coupled to the parallel portions, and are arranged therebetween.

8. An aerial arrangement according to Claim 6, wherein the said elements are coupled to the parallel portions and are arranged on opposite sides of the respective portions.

9. An aerial arrangement according to Claim 6, 7 or 8 wherein the elements coupled to one of the two conductors have their long dimensions at right angles to the long dimensions of the elements coupled

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. and 5 on the other side, where As is the wavelength in the strip line. Circular polarization can also be achieved as shown in Figure 3, using a pair of microstrip conductors 6 and 7 supplied from a common feed 8 and disposed so that a phase difference A/4 exists at the commencement of the parallel parts of the two conductors. Elements 9-12 are associated with conductor 6 and elements 13-16 with conductor 7, and it will be observed that the elongated dimensions of the two sets of elements have 45" inclinations > to the directions of the conductors 6 and 7, and the ends of elements nearest the conductors are parallel thereto. In principle, it is sufficient that the coupled elements lie perpendicular to each other. They need not be at 45" to the feed line-they could be 30 and 60 , for example. Some improvement in circularity may be achieved this way, over a wider angle around the array direction. Figure 4 shows an alternative arrangement for achieving circular polarization. In this case, two conductors 17 and 18 run adjacent one another and respective sets of elements 19-21 and 22-24 are disposed adjacent the conductors and on their outsides. The /4 phase difference is still required between the two conductors, and the elements 19-21 are at right angles to the elements 22-24. The arrangement of Figure 3 has a better lobe pattern over a wider azimuthal spread, since the radiating elements are more closely spaced than they are in the Figure 4 arrangement. If the elements of the two sets were formed in overlapping or inter-digitated form, even better results could be anticipated. An alternative substrate, which has advantage if the arrangement is to be operated at high temperatures (say in excess of 600"C) is ceramic, but in this case the conductive components (microstrip conductors and elements and ground plane conductor) have to be fired on. WHAT WE CLAIM IS:-

1. An aerial arrangement including a dielectric substrate bearing on one surface a ground plane conductor and on the opposite surface thereof, a strip conductor and at least one conductive element spaced therefrom and mutually coupled thereto.

to the other conductor.

10. An aerial arrangement according to any preceding claim, wherein the end of the or each element nearest the conductor with which it is coupled is parallel to that conductor.

11. An aerial arrangement according to Claim 1, 2 or 3 wherein the or each element is disposed with its long dimension at 90" to the strip conductor with which it is coupled.

12. An aerial arrangement according to Claim 1, 2 or 3, wherein the or each element is disposed with its long dimension at 45" to the strip conductor with which it is coupled.

13. An aerial arrangement substantially as hereinbefore described with reference to Figure 1, Figure 2, Figure 3 or Figure 4 of the accompanying drawing.