GB2540800B - Antenna Array for Producing Beam Patterns Requiring a Large Phase Shift - Google Patents
Antenna Array for Producing Beam Patterns Requiring a Large Phase Shift Download PDFInfo
- Publication number
- GB2540800B GB2540800B GB1513300.2A GB201513300A GB2540800B GB 2540800 B GB2540800 B GB 2540800B GB 201513300 A GB201513300 A GB 201513300A GB 2540800 B GB2540800 B GB 2540800B
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- GB
- United Kingdom
- Prior art keywords
- antenna
- antenna resonating
- resonating element
- patch
- antenna array
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Classifications
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q3/00—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system
- H01Q3/26—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture
- H01Q3/30—Arrangements for changing or varying the orientation or the shape of the directional pattern of the waves radiated from an antenna or antenna system varying the relative phase or relative amplitude of energisation between two or more active radiating elements; varying the distribution of energy across a radiating aperture varying the relative phase between the radiating elements of an array
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q21/00—Antenna arrays or systems
- H01Q21/06—Arrays of individually energised antenna units similarly polarised and spaced apart
- H01Q21/061—Two dimensional planar arrays
- H01Q21/065—Patch antenna array
Landscapes
- Variable-Direction Aerials And Aerial Arrays (AREA)
Description
Antenna Array for Producing Beam Patterns Requiring a Large Phase Shift
Field of the Invention
The present invention relates to an antenna array.
Background of the Invention
An antenna array is a set of two or more individual antenna resonating elements (such as patch antenna elements) which work together to form a radiofrequency beam with specific beam properties. The phase and amplitude of the radiofrequency signal supplied to each of the antenna resonating elements is typically individually controlled to determine the beam pattern.
The phase and amplitude of the radiofrequency signal supplied to each of the antenna resonating elements is typically controlled by the design of a feed network supplying the antenna resonating elements.
The amplitude distribution to the antenna resonating elements is typically controlled using unequal power splitters which divert more power to certain antenna resonating elements, or by using line attenuators in a portion of the feed network supplying certain antenna resonating elements.
The phase distribution to antenna resonating elements is typically controlled by adjusting a line length of a portion of the feed network supplying particular antenna resonating elements, or using an electronically controlled phase shifter (such as, a filter, varactor diode, hybrid coupler, and vector modulators) which mostly rely on adjusting line length as well.
Adjusting the line length to control the phase distribution is undesirable because the phase shift introduced by line length adjustment is frequency dependant, and therefore unsuitable for wide frequency bandwidth antenna arrays.
To reduce side lobes, it is desirable for the spacing between each individual antenna resonating element to be half the free space wavelength of the radio frequency signal, or less.
This spacing only allows for relatively small amounts of line length adjustment and therefore only relatively small amounts of phase shifting between antenna resonating elements, making it difficult to achieve large phase shifts, like those required for some beam patterns, such as a flat topped beam pattern.
It would, therefore, be desirable to develop a way of providing a large phase shift between antenna resonating elements in an antenna array.
Summary of the Invention
There is provided an antenna array according to claim 1.
The antenna array comprises a first antenna resonating element configured to emit a first radiofrequency signal, and a second antenna resonating element configured to emit a second radiofrequency signal. The orientation of the first antenna resonating element is rotated with respect to the orientation of the second antenna resonating element to cause a phase inversion between the first radiofrequency signal and the second radiofrequency signal.
By rotating the orientation of the first antenna resonating element with respect to the orientation of the second antenna resonating element to cause a phase inversion between the first radiofrequency signal and the second radiofrequency signal, a 180 degree phase shift can be provided between the first radiofrequency signal from the first antenna resonating element and the second radiofrequency signal from the second antenna resonating element, which allows the antenna array to generate beam patterns (such as a flat topped beam) which require a 180 degree phase shift. This arrangement has the benefit of allowing a 180 degree phase shift to be incorporated into an antenna array design where it would not be possible to provide such a large phase shift by line length adjustment to a feed network because of restricted space between the antenna resonating elements.
Another advantage of adjusting the orientation of the first and second antenna resonating elements is that the line lengths of a feed network do not need to be adjusted, making the adjustment of the orientation of the first and second antenna resonating elements more suitable for wide frequency bandwidth antenna arrays where a phase shift introduced by line length adjustment introduces an undesirable frequency dependency associated with the adjustment.
The orientation of the first antenna resonating element may be a mirror image of the orientation of the second antenna resonating element. This arrangement results in a phase inversion between the first radiofrequency signal and the second radiofrequency signal.
The direction of a voltage vector associated with the first antenna resonating element may be opposite the direction of a voltage vector associated with the second antenna resonating element. By rotating the orientation of the first antenna resonating element with respect to the orientation of the second antenna resonating element so that the direction of a voltage vector associated with the first antenna resonating element is opposite the direction of a voltage vector associated with the second antenna resonating element, a phase inversion is produced between the first radiofrequency signal and the second radiofrequency signal.
The first antenna resonating element may be a first patch antenna resonating element. The second antenna resonating element may be a second patch antenna resonating element. Rotating the orientation of the first and second patch antenna resonating elements is advantageous for providing a phase inversion in a patch antenna array where it is difficult to provide a large phase inversion by line length adjustment because the antenna resonating elements and feed network in a patch antenna array are typically mounted on a planar substrate with restricted space between antenna resonating elements for line length adjustment.
The first and second patch antenna resonating elements may each have a first side and a second side, wherein the second side is opposite the first side. The first and second patch antenna resonating elements may each have a centre located between the first and second sides. The first patch antenna resonating element may have a radiofrequency signal feed located between the first side and the centre. The second patch antenna resonating element may have a radiofrequency signal feed located between the centre and the second side.
By the first patch antenna resonating element having a radiofrequency signal feed located between the first side and the centre and the second patch antenna resonating element having a radiofrequency signal feed located between the centre and the second side, the orientation of the first and second patch antenna resonating elements are inverted, to cause a phase inversion between the first radiofrequency signal and the second radiofrequency signal.
The antenna array comprises a feed network.
The feed network of the first antenna resonating element may have a length which is the same as a length of the feed network of the second antenna resonating element. An advantage of adjusting the orientation of the first and second antenna resonating elements to cause a phase inversion is that the line lengths of the feed network do not need to be adjusted to cause the phase inversion, making the adjustment of the orientation of the first and second antenna resonating elements more suitable for wide frequency bandwidth antenna arrays where a phase shift introduced by line length adjustment would introduce an undesirable frequency dependency associated with the adjustment.
The first and second antenna resonating elements may each comprise a radiofrequency signal feed. A coupler may be attached to each feed to connect each feed to the feed network. Each coupler may be configured to locate an input to the respective coupler at a corresponding position and orientation on each of the first and second antenna resonating elements.
By providing a coupler which has an input at a corresponding position and orientation on each of the first and second antenna resonating elements, construction of the feed network is simplified by providing a consistent line length and connector orientation to connect the feed network to the antenna resonating element, irrespective of the fact that the orientation of the first and second antenna resonating elements is rotated. This means it is not necessary to tailor a feed network for a particular combination of antenna resonating elements. Instead, by using the coupler, antenna resonating elements can be connected at any desired position and orientation on the feed network to suit the needs of the particular antenna array that is being designed. This makes it possible to design a standard feed network which can be used with any combination of antenna resonating elements, and the antenna resonating elements can simply be plugged into the appropriate places on the feed network.
The coupler may be a right angled coupler. The input of the coupler may be aligned with a centre of a side of an antenna resonating element.
The first and second radiofrequency signals have the same linear polarisation. For example, the first and second radiofrequency signals may have the same horizontal linear polarisation or vertical linear polarisation.
The first antenna resonating element and the second antenna resonating element may be in a single plane.
The antenna resonating elements may be any kind of antenna resonating elements capable of emitting a signal having a well-defined polarisation where the relative orientation of the antenna resonating elements can be rotated to cause a phase inversion between the signals produced by the antenna resonating elements. For example, the antenna resonating elements may be one of: patch antennas, slot antennas, dipole antennas and horn antennas.
The first antenna resonating element and the second antenna resonating element are configured to emit in a direction to form a single beam.
The antenna array may comprise a plurality of first antenna resonating elements and a plurality of second antenna resonating elements.
An arrangement of the plurality of first and second antenna resonating elements may be configured to generate a desired beam pattern.
The feed network is configured to modify the amplitude distribution of a radiofrequency signal supplied to each antenna resonating element in the antenna array. The amplitude distribution may be modified by changing the impedance of one or more sections of the feed network.
Brief Description of the Drawings
The invention shall now be described, by way of example only, with reference to the accompanying figures in which:
Figure 1 is an illustration of a prior art antenna array;
Figure 2 is an antenna array according to an embodiment of the present invention; Figure 3 is an antenna array incorporating couplers according to an embodiment of the present invention; and
Figure 4 is an antenna array with a modified amplitude distribution in accordance with an embodiment of the present invention.
Detailed Description
Figure 1 illustrates a prior art antenna array 100. The antenna array 100 has eight antenna resonating elements in the form of patch antennas 110. Each patch antenna 110 has a feed 115 connected to a feed network 120 which supplies a radiofrequency signal to each patch antenna 110 causing each patch antenna 110 to emit a radiofrequency signal in response. The emissions from the patch antennas 110 combine to form a single emitted beam.
The relative phase between each patch antenna 110 of the antenna array 100 is controlled by varying the line length of the feed network 120 feeding each of the patch antennas 110.
The line length of the portion of the feed network 120 feeding patch antennas 110a is shorter than the line length of the portion of the feed network 120 feeding patch antennas 110b, adjusting the relative phase of the radiofrequency signal emitted by the patch antennas 110a and 110b.
To reduce side lobes, it is desirable for the spacing between each individual patch antenna 110 to be half the free space wavelength λ of the radio frequency signal, or less. This spacing only allows for relatively small amounts of line length adjustment and therefore only relatively small amounts of phase shifting between patch antennas 110a and 110b, making it difficult to achieve a large phase shift (such as 180° phase shift) required for some beam patterns, such as a flat topped beam pattern.
Figure 2 illustrates an antenna array 200 according to an embodiment of the present invention. The antenna array 200 has eight patch antennas 210. Each patch antenna 210 has a feed 115 connected to a feed network 220 which supplies a radiofrequency signal to each patch antenna 210 causing each patch antenna 210 to emit a radiofrequency signal in response. The emissions from the patch antennas 210 combine to form a single emitted beam.
Unlike the feed network 120 shown in Figure 1, the line length of the portions of the feed network 220 serving each patch antenna 210 are the same, which makes the antenna array 200 more suitable as a wide frequency bandwidth antenna array where a phase shift introduced by line length adjustment introduces an undesirable frequency dependency associated with the adjustment, and means that large phase shifts can be introduced.
The patch antennas 210 in this example produce horizontal linearly polarised radiofrequency emissions. The direction of a voltage vector 217 associated with each patch antenna 210 is shown by the arrows in Figure 2.
The orientation of patch antennas 210a are rotated by 180° with respect to the orientation of patch antennas 210b, so that the orientation of patch antennas 210a and 210b are a mirror image. As such, the feeds 115 of the patch antennas 210a are closer to the left hand side of patch antennas 210a, and the feeds 115 of the patch antennas 210b are closer to the right hand side of the patch antennas 210b.
The result of this arrangement of patch antennas 210a and 210b is that the phase of the radiofrequency signal emitted by patch antennas 210a is inverted with respect to the phase of the radiofrequency signal emitted by the patch antennas 210b (that is, the phases differ by 180°). This is illustrated in Figure 2 by the direction of the voltage vector 217 associated with the patch antennas 210a being inverted with respect to the direction of the voltage vector 217 associated with patch antennas 210b.
Figure 3 shows an antenna array 200 which is the same as the antenna array 200 shown in Figure 3, expect that each of the patch antennas 210 are attached to the feed network 220 using right angled couplers 230. A coupler 230 is attached to each feed 115 of a patch antenna 210. The coupler 230 positions the input of the coupler 230 at the same horizontally cantered location on each of the patch antennas 210.
The feed 115 on patch antennas 210a and 210b are on opposite sides of their respective patch antenna, so the couplers 230 attached to patch antennas 210a are a mirror image of the couplers 230 attached to patch antennas 210b, in order to provide an input to both the patch antennas 210a and 210b that is horizontally centered.
This coupler arrangement simples construction of the feed network 220 by providing a consistent line length and orientation to allow any output on the feed network 220 to be connected to any patch antennas 210, regardless of the orientation of the patch antenna 210 (that is, regardless of whether the patch antenna is a patch antenna 210a or 210b). This means that it is not necessary to tailor the feed network 220 for the particular combination of patch antennas 210a and 210b, so a standard feed network 220 can be used with any combination of patch antennas 210a and 210b by simply plugging the patch antennas 210a and 210b into desired places on the feed network 220 with a coupler 230.
Figure 4 shows another example of an antenna array 200. This example is generally the same as antenna array 200 shown in Figure 3, expect that the arrangement of patch antennas 210a and 210b differs to provide a different desired beam pattern.
Also, additional amplitude modifying elements 225 and 226, which are a quarter wavelength long, have been placed in the feed network 230 to modify the amplitude distribution of a radiofrequency signal supplied to patch antennas 410a and 410b respectively, by altering the impedance of the elements 225 and 226 relative to the impedance of the standard feed network.
The elements 225 have a wider line width than the standard feed network line width which reduces the impedance of the element 225 relative to the standard feed network and increases the amplitude supplied to the patch antennas 410b. Conversely, the elements 226 have a narrower line width than the standard feed network line widths which increases the impedance of the element 226 relative to the standard feed network and decreases the amplitude supplied to the path antennas 410a.
Although the invention has been described in terms of certain preferred features, the skilled person will appreciate that various modifications could be made without departing from the scope of the appended claims.
Although the antenna array 200 has been described as having eight patch antennas 210, the antenna array 200 could have any number patch antennas 210 to create desired beam properties, such as one or more of: a desired beam power, beam bandwidth, beam shape, and beam pattern.
The antenna array 200 could have any arrangement of patch antennas 210a and 210b with inverted phase as may be necessary to produce a desired beam pattern, or beam phase profile.
Although the invention has been described in terms of patch antenna resonating elements, the antenna resonating elements could be any other kind of antenna resonating elements capable of emitting a radiofrequency signal having a well-defined polarisation where the relative orientation of the antenna resonating elements can be rotated to cause a phase inversion between the radiofrequency signals produced by the antenna resonating elements. For example, the antenna resonating elements may be one of: slot antennas, dipole antennas and horn antennas.
Although the polarisation has been described as being horizontal linearly polarised, the polarisation could also be vertical linearly polarised.
Any arrangement of elements 225 and 226 may be used to create a desired beam amplitude profile.
Claims (11)
1. An antenna array comprising: a first antenna resonating element configured to emit a first radiofrequency signal and a second antenna resonating element configured to emit a second radiofrequency signal, wherein the first and second radiofrequency signals have the same linear polarisation; wherein the orientation of the first antenna resonating element is rotated with respect to the orientation of the second antenna resonating element to cause a phase inversion between the first radiofrequency signal and the second radiofrequency signal; wherein the first antenna resonating element and the second antenna resonating element are configured to emit in a direction to form a single beam; and the antenna array further comprising a feed network configured to modify the amplitude distribution of a radiofrequency signal supplied to each antenna resonating element in the antenna array.
2. The antenna array of claim 1, wherein the orientation of the first antenna resonating element is a mirror image of the orientation of the second antenna resonating element.
3. The antenna array of either of claims 1 or 2, wherein the direction of a voltage vector associated with the first antenna resonating element is opposite the direction of a voltage vector associated with the second antenna resonating element.
4. The antenna array of any preceding claim, wherein the first antenna resonating element is a first patch antenna resonating element and the second antenna resonating element is a second patch antenna resonating element.
5. The antenna array of claim 4, wherein the first and second patch antenna resonating elements each have corresponding first and second sides, wherein the second side of each patch antenna resonating element is opposite the first side of that patch antenna resonating element; and each of the first and second patch antenna resonating elements have a centre located between the first and second sides; and the first patch antenna resonating element has a radiofrequency signal feed located between the first side and the centre; and the second patch antenna resonating element has a radiofrequency signal feed located between the centre and the second side.
6. The antenna array of any preceding claim, wherein the feed network of the first antenna resonating element has a length which is the same as a length of the feed network of the second antenna resonating element.
7. The antenna array of any preceding claim, wherein: the first and second antenna resonating elements each comprise a radiofrequency signal feed; a coupler is attached to each feed to connect each feed to the feed network, and each coupler is configured to locate an input to the respective coupler at a corresponding position and orientation on each of the first and second antenna resonating elements.
8. The antenna array of any preceding claim, wherein the first antenna resonating element and the second antenna resonating element are in a single plane.
9. The antenna array of any preceding claim, wherein the antenna array comprises a plurality of first antenna resonating elements and a plurality of second antenna resonating elements.
10. The antenna array of claim 9, wherein an arrangement of the plurality of first and second antenna resonating elements is configured to generate a desired beam pattern.
11. The antenna array of any preceding claim, wherein the amplitude distribution is modified by changing the impedance of one or more sections of the feed network.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1513300.2A GB2540800B (en) | 2015-07-28 | 2015-07-28 | Antenna Array for Producing Beam Patterns Requiring a Large Phase Shift |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1513300.2A GB2540800B (en) | 2015-07-28 | 2015-07-28 | Antenna Array for Producing Beam Patterns Requiring a Large Phase Shift |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB201513300D0 GB201513300D0 (en) | 2015-09-09 |
| GB2540800A GB2540800A (en) | 2017-02-01 |
| GB2540800B true GB2540800B (en) | 2019-09-11 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1513300.2A Active GB2540800B (en) | 2015-07-28 | 2015-07-28 | Antenna Array for Producing Beam Patterns Requiring a Large Phase Shift |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2540800B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108333563A (en) * | 2017-01-20 | 2018-07-27 | 北京行易道科技有限公司 | Radar and the vehicles |
| CN109921184B (en) * | 2019-02-01 | 2020-10-16 | 东南大学 | Substrate integrated electric dipole antenna and array based on low-profile microstrip feed structure |
Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4543579A (en) * | 1983-03-29 | 1985-09-24 | Radio Research Laboratories, Ministry Of Posts And Telecommunications | Circular polarization antenna |
| US5181042A (en) * | 1988-05-13 | 1993-01-19 | Yagi Antenna Co., Ltd. | Microstrip array antenna |
| WO1997038465A1 (en) * | 1996-04-03 | 1997-10-16 | Johan Granholm | Dual polarization antenna array with very low cross polarization and low side lobes |
| WO2002084797A1 (en) * | 2001-04-12 | 2002-10-24 | Marius Du Plessis | Antenna |
| US6552695B1 (en) * | 2002-02-22 | 2003-04-22 | Ems Technologies Canada, Ltd. | Spin-scan array |
| KR20080093645A (en) * | 2007-04-17 | 2008-10-22 | 삼성탈레스 주식회사 | Directional array structure antenna |
-
2015
- 2015-07-28 GB GB1513300.2A patent/GB2540800B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4543579A (en) * | 1983-03-29 | 1985-09-24 | Radio Research Laboratories, Ministry Of Posts And Telecommunications | Circular polarization antenna |
| US5181042A (en) * | 1988-05-13 | 1993-01-19 | Yagi Antenna Co., Ltd. | Microstrip array antenna |
| WO1997038465A1 (en) * | 1996-04-03 | 1997-10-16 | Johan Granholm | Dual polarization antenna array with very low cross polarization and low side lobes |
| WO2002084797A1 (en) * | 2001-04-12 | 2002-10-24 | Marius Du Plessis | Antenna |
| US6552695B1 (en) * | 2002-02-22 | 2003-04-22 | Ems Technologies Canada, Ltd. | Spin-scan array |
| KR20080093645A (en) * | 2007-04-17 | 2008-10-22 | 삼성탈레스 주식회사 | Directional array structure antenna |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2540800A (en) | 2017-02-01 |
| GB201513300D0 (en) | 2015-09-09 |
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