GB2202091A - Microstrip antenna - Google Patents

Microstrip antenna Download PDF

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Publication number
GB2202091A
GB2202091A GB8705430A GB8705430A GB2202091A GB 2202091 A GB2202091 A GB 2202091A GB 8705430 A GB8705430 A GB 8705430A GB 8705430 A GB8705430 A GB 8705430A GB 2202091 A GB2202091 A GB 2202091A
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GB
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Application
Patent type
Prior art keywords
region
regions
antenna according
element
side
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB8705430A
Other versions
GB8705430D0 (en )
GB2202091B (en )
Inventor
David John Gunton
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
British Gas Corp
Original Assignee
British Gas Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

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Classifications

    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q21/00Antenna arrays or systems
    • H01Q21/30Combinations of separate antenna units operating in different wavebands and connected to a common feeder system
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q5/00Arrangements for simultaneous operation of antennas on two or more different wavebands, e.g. dual-band or multi-band arrangements
    • H01Q5/40Imbricated or interleaved structures; Combined or electromagnetically coupled arrangements, e.g. comprising two or more non-connected fed radiating elements
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04Resonant antennas
    • H01Q9/0407Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H01Q9/0414Substantially flat resonant element parallel to ground plane, e.g. patch antenna in a stacked or folded configuration
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01QANTENNAS, i.e. RADIO AERIALS
    • H01Q9/00Electrically-short antennas having dimensions not more than twice the operating wavelength and consisting of conductive active radiating elements
    • H01Q9/04Resonant antennas
    • H01Q9/0407Substantially flat resonant element parallel to ground plane, e.g. patch antenna
    • H01Q9/045Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular feeding means
    • H01Q9/0457Substantially flat resonant element parallel to ground plane, e.g. patch antenna with particular feeding means electromagnetically coupled to the feed line

Abstract

An antenna assembly comprises a first laminar structure which includes a sheet of dielectric material 1 having on one side a contiguous metal sheet 3 and on the other side a strip transmission line 2 adapted to be coupled with signal feeding means, and a second laminar structure, one side of which is in contact with the transmission line, and having on the other side, at least one region but preferably at least two concentrically arranged regions of a coated or cladded metal which serves as a radiator, characterised in that the transmission line is non-symetrically disposed with respect to the radiator. <IMAGE>

Description

BROADBAND MICROSTRIP ANTENNAS This invention relates to radar antennas and, more particularly, to microstrip antennas for broadband transmission.

Known log periodic micros trip antennas are known which consist of a set or series of isolated metal patches on the surface of a thin dielectric sheet. The area of each of the particles varies with its neighbours by some log periodic progression. The thin dielectric sheet is placed above a second sheet, on the lower surface of which is an earth plane and on the upper surface is provided a straight transmission line. A signal is applied to the transmission line and energy is coupled by E & BR< H fields to the metal patches which resonate and radiate.

Such known antennas suffer from the disadvantage that they are large and are not readily amenable for use in portable applications such as ground probing radar for locating buried objects such as non metallic pipework.

We have found that more compact structures can be produced which take the advantages of microstrip antennas i.e. the inherent shielding from transission or reception in the backward direction and yet are portable.

According to the present invention there is provided a broadband antenna assembly comprising a first laminar structure which includes a sheet of a dielectric material, on one side of which is mounted a contiguous metal sheet and on the opposing side is mounted a strip transmission line adapted to be coupled with signal feeding means, and a second laminar structure comprising a laminar dielectric sheet, one side of which is in contact with the strip transmission line and on the other side, in at least the peripheral regions, is a coating or clading of a metal which serves as the radicator, characterised in that the transmission line is non-symetrically disposed with respect to the radiator.

The upper surface of the second laminar structure may be clad or coated with a single sheet of metallic radiator or the radiators may be in the form of a series of concentrically formed regions.

Alternatively the second laminar structure may be a multi-laminate structure comprising layers of dielectric sheets, the lower surfaces of which contact the strip transmission line and the upper surfaces of which bear metallic sheets of radicators.

The invention will be illustrated by reference to the accompanying drawings.

Referring to the drawings, a typical antenna assembly was constructed as follows : All circuits are made in etched copper film mounted on 1.6 mm GRP boards, whose relative permitivity is 4.7.

The feed line 2 was of width 2.5 mm, was mounted in or on a GPR board 1, (Fig. 1) approximately 30 x 30 Ocm. A continuous metal film 3 was present on the back of the board. On the top of the board 1 is found a conventional microstrip transmission line 2. Its impedance was measured as approximately 75 ohm and the velocity of propagation along it measured as 0.55C, where C is the velocity of light (3 x 108 ms1). The signal was introduced to the line through a SMA-style microstrip connector (not shown) mounted with its axis perpendicular to the plane of the board. A like connector at the other end of the stripline carried a 50 ohm load.

On a metal coated GPR board 4 of dimensions 21 cm x 21 cm a gap 7 of 1.0 mm was etched to define two regions (Figure 2). The inner region 5 was a 10 x 10 cm square and was surrounded by a concentric region 6 whose outer edges were 14.5 cm. There was no metal backing to the board.

The two boards 1 and 4 were clamped together with a film of petroleum jelly between them to aid dielectric continuity. Short wires were soldered at A, B and C so as to give electrical continuity. The performance of the antenna varied depending on the positioning of the pattern relative to the stripline below it. Useful configurations are shown in figures 3(a), (b) (c).

Two identical antennas were produced, one used as transmitter and one as receiver. Transmission was observed to occur at 550 MHz and 760 MHz. These frequencies corresponded to those at which the overall length (14.7 cm) and the length of the inner rectangle (10 cm) corresponded to a half-wavelength, taking account of the dielectric slowing properties of the substrate.

Thus the frequency response of structure 3(c) (550 MHz) could be extended through the addition of a second passband at 760 MHz by the use of structure 3(c). (Structure 3B had a response at 760 NHz with no appreciable transmission at 550 MHz).

It was also observed that if the connection at Y was removed then the structure still radiated at two frequencies, but these were now 480 MHz and 870 MHz, with a smaller response at 760 MHz.

In addition to all the results described above there were the harmonics (multiples) at higher frequencies.

The power of the method of coupling of the input signal by fields rather than by direct connection, as in conventional microstrip 'patch' antennas, is that the feeding transmission line can itself be adjusted in its properties. For example, it need not be straight, it could divide so as to feed several parts of the radiator at once, it could include frequency sensitive components such as filters or directional couplers. Examples are illustrated in figures 4(a), (b) (c).

For an extended passband the sections into which the antenna is divided are suitably formed. For example, the width of the transmission peaks observed experimentally was approximately 10% of the centre frequency.

Thus, if the ratio of successive sections is approximately 5% the passbands will merge, and the total number of sections will determine the overall bandwidth.

In a further example (Fig. 5), the upper GPR board was configurated to provide three regions 8,9,10.

Metallic links were soldered at X,X',X", and the position of the feeding transmission line is shown at 21.

The antenna was observed to transmit in frequency bands (of width between 50 and 100 MHz) centered on 550MHz, 700 MHz and 950 MHz, which approximately correspond to the frequencies at which the length of each rectangle is a half-wavelength.

Figure 7 illustrates the multilaminate structure arrangement. In this embodiment, the upper GRP board is provided as a stacked layer of boards 14,15,16. In alternate interlayers are a plurality of radiators 11,12,13 whose sizes conform to a log periodic progression, and the transmission strip 2.

Claims (12)

1. An antenna assembly is provided which comprises a first laminar structure which includes a sheet of dielectric material having on one side a contiguous metal sheet and on the other side a strip transmission line adapted to be coupled with signal feeding means, and a second laminar structure, one side of which is in contact with the transmission line, and having on the other side, at least one region but preferable at least two concentrically arranged regions of a coated or cladded metal which serves as a radiator, characterised in that the transmission line is non-symetrically disposed with respect to the radiator.
2. An assembly as claimed in claim 1, wherein the other side of said second laminar structure has at least two regions concentrically arranged.
3. An assembly as claimed in claim 2 wherein said regions are in direct electrical contact.
4. An assembly as claimed in any of the preceding claims wherein said second laminar structure is a multi-laminate structure comprising a plurality of laminar structures having a radiator provided on one surface and the other surface is in contact with the transmission line.
5. An antenna assembly according to claim 1 and substantially as hereinbefore described with reference to the accompanying drawings. CLAIMS 1. An antenna comprising a laminar conductive earth plane region, laminar conductive element regions above and parallel to said earth plane region and spaced from it, a conductive feed strip extending beneath at least one of said element regions in electric field coupling relationship therewith, any remaining element region being conductively connected to a region thus coupled, and dielectric material interposed between said earth plane region and said element regions and between said feed strip and said regions, said element regions as viewed in plan being mutually concentric of progressively decreasing area and lying within the outline of said earth plane region, each element region except the largest lying within the outline of the largest and the or each element region in said field coupling relationship with said feed strip being divided thereby non-symmetrically as viewed in said plan.
2. An antenna according to claim 1 said element regions being coplanar.
3. An antenna according to claim 1 said element regions being mutually parallel, spaced apart and decreasing in area in the direction away from said earth plane region.
4. An antenna according to claim 2 said element regions comprising a square region and one or more encircling regions each bounded by an outer square boundary, the inner boundary of each encircling region being spaced from the outer boundary of the adjacent inner region by a gap which is uniform throughout itself.
5. An antenna according to claim 3 each element region being square.
6. An antenna according to claim 3 the areas of said element regions conforming to a log periodic progression.
7. An antenna according to claim 3 or claim 6 feed strip extending in zig-zag manner and having runs interleaved between said element regions.
8. An antenna according to any claim of claims 1 to 6 said feed strip comprising a branch or branches.
9. An antenna according to claim 1 substantially as herein described with reference to Figures 1 & 2 of the accompanying drawings.
10. An antenna according to claim 1 substantially as herein described with reference to Figures 1 & 5 of the accompanying drawings.
11. An antenna according to claim 1 substantially as herein described with reference to Figure 6 of the accompanying drawings.
12. An antenna according to claim 9 substantially as herein described with reference to Figure 3(a), Figure 3(b) or Figure 3(c) of the accompanying drawings.
GB8705430A 1987-03-09 1987-03-09 Broadband microstrip antennas. Expired - Fee Related GB2202091B (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB8705430A GB2202091B (en) 1987-03-09 1987-03-09 Broadband microstrip antennas.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB8705430A GB2202091B (en) 1987-03-09 1987-03-09 Broadband microstrip antennas.

Publications (3)

Publication Number Publication Date
GB8705430D0 GB8705430D0 (en) 1987-04-15
GB2202091A true true GB2202091A (en) 1988-09-14
GB2202091B GB2202091B (en) 1990-11-28

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB8705430A Expired - Fee Related GB2202091B (en) 1987-03-09 1987-03-09 Broadband microstrip antennas.

Country Status (1)

Country Link
GB (1) GB2202091B (en)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0398554A2 (en) * 1989-05-16 1990-11-22 Hughes Aircraft Company Multiband gridded focal plane array antenna
US5165109A (en) * 1989-01-19 1992-11-17 Trimble Navigation Microwave communication antenna
FR2692404A1 (en) * 1992-06-16 1993-12-17 Aerospatiale elementary pattern antenna bandwidth and the antenna array with.
GB2308012A (en) * 1995-12-05 1997-06-11 Northern Telecom Ltd Antenna assembly

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1413041A (en) * 1973-02-07 1975-11-05 Mel Equipment Co Ltd Dipole aerial
GB1550809A (en) * 1977-04-18 1979-08-22 Bendix Corp Symmetrical balanced stripline dipole

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1413041A (en) * 1973-02-07 1975-11-05 Mel Equipment Co Ltd Dipole aerial
GB1550809A (en) * 1977-04-18 1979-08-22 Bendix Corp Symmetrical balanced stripline dipole

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5165109A (en) * 1989-01-19 1992-11-17 Trimble Navigation Microwave communication antenna
EP0398554A2 (en) * 1989-05-16 1990-11-22 Hughes Aircraft Company Multiband gridded focal plane array antenna
EP0398554A3 (en) * 1989-05-16 1991-11-06 Hughes Aircraft Company Multiband gridded focal plane array antenna
FR2692404A1 (en) * 1992-06-16 1993-12-17 Aerospatiale elementary pattern antenna bandwidth and the antenna array with.
EP0575211A1 (en) * 1992-06-16 1993-12-22 AEROSPATIALE Société Nationale Industrielle Radiating element of an antenna with wide bandwidth and antenna array comprising such elements
US5565875A (en) * 1992-06-16 1996-10-15 Societe Nationale Industrielle Et Aerospatiale Thin broadband microstrip antenna
GB2308012A (en) * 1995-12-05 1997-06-11 Northern Telecom Ltd Antenna assembly
GB2308012B (en) * 1995-12-05 1999-11-17 Northern Telecom Ltd A radiation shielding device
US6239766B1 (en) 1995-12-05 2001-05-29 Nortel Networks Limited Radiation shielding device

Also Published As

Publication number Publication date Type
GB8705430D0 (en) 1987-04-15 grant
GB2202091B (en) 1990-11-28 grant

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 19930309