GB1591643A

GB1591643A - Aerial arrangements

Info

Publication number: GB1591643A
Application number: GB2289377A
Authority: GB
Original assignee: EMI Ltd
Current assignee: EMI Ltd
Priority date: 1977-05-31
Filing date: 1977-05-31
Publication date: 1981-06-24
Also published as: FR2393438A1; FR2393438B3; DE2824052A1

Description

(54) IMPROVEMENTS IN OR RELATING TO AERIAL ARRANGEMENTS (71) We, EMI LIMITED, a British company of Blythe 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 per formed, to be particularly described in and by the following statement : - The present invention relates to microstrip antenna arrangements.

British Patent No. 1,294,024 relates to such arrangements incorporating endued microstrip linear arrays, including one feed line and a plurality of dipole elements .spaced therefrom and not conductively con nected and the disclosure of that Patent is incorporated herein by way of reference.

It is an object of this invention to provide an aerial arrangement which exhibits im proved coupling between the elements and the feed line.

According to the invention there is pro vided a microstrip antenna arrangement comprising an insulative substrate; a con .ductive layer defining a ground plane :on one face of the substrate; and, on the other face of the substrate, a conductive strip defining a feed line and at least one elongate element of conductive material spaced from, but not.conductively connected to, the strip, said element comprising 9 rectangular cen tral portion which is elongated substantially parallel to the said line, and a pair of' end portions integral with the central portion and extending in opposite directions from the ends of the central portion which are perpendicular to the said line, each end por tion being either substantially semidrcular, the said ends forming diameters of the semi circles or each end portion being substan tially triangular the said ends of the central portion forming the bases of the triangles, all the internal angles on the said bases of the triangles being acute.

In order that the invention may be clearly understood and readily carried into effect, some embodiments thereof will now be described, by way of example only, with reference to the accompanying drawings, of which: Figure 1 is a plan view of a portion of a microstrip antenna arrangement in accordance with one example of the invention, Figure 2 is a plan view portion of an arrangement in accordance with another example of the invention, Figure 3 is a plan view of an advantageous configuration for an arrangement in accord -ance with either of the aforementioned examples of the invention, and Figure 4 shows a detail of a modification of the arrangements of Figures 1 to 3. - Referring now to Figure 1, a microstrip conductor 1 is provided on, a dielectric substrate 2; for example, by etching as described in the aforementioned British Patent.

The other surface of the dielectric substrate 2 is, in this ' example, fully coated with -electrically conductive material (not shown) to form a ground plane in known manner.

An element 3 of electrically conductive material is disposed on the substrate 2 so that it is spaced from the conductor 1. This element may also be formed by etching.

The element 3 is lozenge-shaped and is disposed generally parallel to the conductor 1.

The ends of the element 3, however, con tain regions 4, - 5, 6 and 7, which are all obliquely inclined-to the direction perpendi cular to the conductor 1 and in the plane of the arrangement. In the example shown, the angle of inclination in each case is 209.

'This angle of inclination is not, however, the only angle which can be used, and angles in the range from 10 to 800 may be used, if desired. Moreover, the angles of inclina tion of all four regions 4-7 need not be the same.

The inventors have discovered that the formation of elements such as 3 as lozenge shaped elements effects substantial improve- ment in mutual coupling of the elements to the conductor 1 and this improves the power output from the arrangement when it is used as a transmitting aerial.

In principle, the two inclined regions at one or both ends of the element could be replaced by an arcuate region having a semicircular boundary (Figure 4) but this con figuration is more difficult to form than the configuration shown in Figure 1.

As will be appreciated from the aforementioned British Patent, an aerial arrangement may include a number of substantially parallel microstrip conductors, each fed from a common point and each terminated individually. Associated with each conductor are a number of elements in this example, lozenge-shaped elements, which may, if desired, vary in size and/or spacing from the conductor.

If desired, as shown in Figure 2, lozengeshaped elements 8, 9 can be disposed in pairs on opposite sides of a microstrip conductor 10. The elements on one side of the line can be of one length (measured parallel to the conductor) and those on the other side of another length so as to cause the dipoles, caused by mutual coupling of the elements with the conductor, to be tuned to different frequencies on the two sides of the conductor. This increases the bandwidth of 'the arrangement when used as an aerial.

When an arrangement in accordance with the invention is to be mounted on a surface subject to aerodynamic drag, the configura 'tion shown in Figure 3 is useful because the upper surface of the microstrip is uncluttered owing'to the use of a slot feed 1:1 to the line and the use of a lossy section 12 of ground plane at the load end of the array.

'WHAT WE CLAIM IS: '1. A microstrip antenna arrangement comprising an insulative substrate; a conductive layer defining a ground plane on one'face of the sutbstrate, and, on the other face of the substrate a conductive strip defining a feed line and at least one elongate 'eiemen't of conductive material spaced'from, 'but not conductively connected to, the strip, 'said element comprising a rectangular centrial portion which lis elongated substantially para' lel to the said line, and a pair of end portions integral with the central portion and extending in opposite directions from the ends of the central ,portion which are perpendicular to the said line, each end for 'tion being éither substantially semicircular, "the said ends'forming diameters of the semicircles or each end portion being substantially triangular the said ends of the central portion forming the bases of the triangles, all the internal angles on the said bases of the triangles being acute.

2. An arrangement according to claim 1, wherein the end portions are substantially triangular and the said internal angles are in the range 10 to 80".

3. An arrangement according to claim 2 wherein the said internal angles are not all the same.

4. An arrangement according to claim 2, wherein all the said internal angles are the same.

5. An arrangement according to claim 4, wherein the said internal angles are 20 .

6. An arrangement according to any preceding claim, comprising a plurality of such elements spaced from, but not conductively connected to, the feedline.

7. An arrangement according to claim 6 wherein the elements vary in size and/or spacing from the said line.

8. An arrangement according to claim 6 or 7 comprising a plurality of elements on one side of the line,- and a plurality of the elements on the other side of the line.

9. An arrangement according to claim 8, comprising a plurality of elements on one side of the line having a one length (measured parallel to the line) and a plurality -of elements of another length on the other side of the line.

:10. An arrangement according to any preceding claim, comprising a slot feed to the said line, and lossy load at the load end of the arrangement.

'11. ,An arrangement :according to claim 10, wherein the lossy load comprises a section of ground plane.

:12. A microstrip antenna arrangement substantially as hereinbefore described with reference to !Figure 1, 2 or 3 .of the accompanying -drawing.

13. A microstrip antenna .arrangement substantia-lly.as hereinbefore described with reference to Figure 1, 2 or 3.as modified by figure 4-of the accompanying .drawing.

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

Claims

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

figuration is more difficult to form than the configuration shown in Figure 1.

As will be appreciated from the aforementioned British Patent, an aerial arrangement may include a number of substantially parallel microstrip conductors, each fed from a common point and each terminated individually. Associated with each conductor are a number of elements in this example, lozenge-shaped elements, which may, if desired, vary in size and/or spacing from the conductor.

If desired, as shown in Figure 2, lozengeshaped elements 8, 9 can be disposed in pairs on opposite sides of a microstrip conductor 10. The elements on one side of the line can be of one length (measured parallel to the conductor) and those on the other side of another length so as to cause the dipoles, caused by mutual coupling of the elements with the conductor, to be tuned to different frequencies on the two sides of the conductor. This increases the bandwidth of 'the arrangement when used as an aerial.

When an arrangement in accordance with the invention is to be mounted on a surface subject to aerodynamic drag, the configura 'tion shown in Figure 3 is useful because the upper surface of the microstrip is uncluttered owing'to the use of a slot feed 1:1 to the line and the use of a lossy section 12 of ground plane at the load end of the array.

'WHAT WE CLAIM IS: '1. A microstrip antenna arrangement comprising an insulative substrate; a conductive layer defining a ground plane on one'face of the sutbstrate, and, on the other face of the substrate a conductive strip defining a feed line and at least one elongate 'eiemen't of conductive material spaced'from, 'but not conductively connected to, the strip, 'said element comprising a rectangular centrial portion which lis elongated substantially para' lel to the said line, and a pair of end portions integral with the central portion and extending in opposite directions from the ends of the central ,portion which are perpendicular to the said line, each end for 'tion being éither substantially semicircular, "the said ends'forming diameters of the semicircles or each end portion being substantially triangular the said ends of the central portion forming the bases of the triangles, all the internal angles on the said bases of the triangles being acute.
2. An arrangement according to claim 1, wherein the end portions are substantially triangular and the said internal angles are in the range 10 to 80".
3. An arrangement according to claim 2 wherein the said internal angles are not all the same.
4. An arrangement according to claim 2, wherein all the said internal angles are the same.
5. An arrangement according to claim 4, wherein the said internal angles are 20 .
6. An arrangement according to any preceding claim, comprising a plurality of such elements spaced from, but not conductively connected to, the feedline.
7. An arrangement according to claim 6 wherein the elements vary in size and/or spacing from the said line.
8. An arrangement according to claim 6 or 7 comprising a plurality of elements on one side of the line,- and a plurality of the elements on the other side of the line.
9. An arrangement according to claim 8, comprising a plurality of elements on one side of the line having a one length (measured parallel to the line) and a plurality -of elements of another length on the other side of the line.

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10. An arrangement according to any preceding claim, comprising a slot feed to the said line, and lossy load at the load end of the arrangement.

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11. ,An arrangement :according to claim 10, wherein the lossy load comprises a section of ground plane.

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12. A microstrip antenna arrangement substantially as hereinbefore described with reference to !Figure 1, 2 or 3 .of the accompanying -drawing.
13. A microstrip antenna .arrangement substantia-lly.as hereinbefore described with reference to Figure 1, 2 or 3.as modified by figure 4-of the accompanying .drawing.