WO2002019468A9 - Folded cavity-backed slot antenna - Google Patents
Folded cavity-backed slot antennaInfo
- Publication number
- WO2002019468A9 WO2002019468A9 PCT/US2001/026273 US0126273W WO0219468A9 WO 2002019468 A9 WO2002019468 A9 WO 2002019468A9 US 0126273 W US0126273 W US 0126273W WO 0219468 A9 WO0219468 A9 WO 0219468A9
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- antenna
- cavity
- housing
- folded
- slot
- Prior art date
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/10—Resonant slot antennas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01Q—ANTENNAS, i.e. RADIO AERIALS
- H01Q13/00—Waveguide horns or mouths; Slot antennas; Leaky-waveguide antennas; Equivalent structures causing radiation along the transmission path of a guided wave
- H01Q13/10—Resonant slot antennas
- H01Q13/18—Resonant slot antennas the slot being backed by, or formed in boundary wall of, a resonant cavity ; Open cavity antennas
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
- H01P7/00—Resonators of the waveguide type
- H01P7/06—Cavity resonators
Definitions
- the present invention relates to antennas. More specifically, the present invention relates to slot antennas used in high-power applications.
- the individual antenna elements of a wide-scan phased array antenna must typically be spaced very close together. More specifically, the individual antenna elements must generally be spaced approximately one-half of a free-space wavelength apart from one another.
- antenna elements that are of such compact design.
- Circularly polarized patch antennas can be made smaller than one-half of a free-space wavelength, but only through the use of a dielectric, thereby rendering the patch antenna inadequate for high power applications.
- a circularly polarized ridged waveguide antenna having a slot formed in a surface thereof can be made smaller than one-half of a free-space wavelength.
- a rectangular cavity-backed slot antenna can be constructed that can handle high power levels (i.e., no dielectric is required).
- the cross-sectional dimensions of the cavity must be greater than one-half of a free-space wavelength (typically, 7/1 Oth of a wavelength on edge) for the device to be operative.
- the reason that the dimensions of the cavity must be greater than one-half of a free-space wavelength is due to the fact that in order for the cavity to resonate, the rectangular dimensions must be equal to one-half of a guide wavelength, which is longer than the free-space wavelength.
- the size of a conventional cavity-backed slot antenna can be reduced by filling the cavity with a dielectric material, but this introduces substantial losses and renders the antenna inadequate for high average power applications.
- the present invention encompasses an antenna that includes a housing having a plurality of walls forming an enclosure, a slot formed in a first wall of the housing, and, a folded cavity formed in a second wall of the housing opposite the first wall.
- the folded cavity is preferably a compound cavity that includes a first cavity portion and a second cavity portion joined around their entire respective peripheries by a fold or shelf.
- Any convenient RF transmission line e.g., a waveguide or coaxial cables, can be used to inject RF energy into the folded cavity.
- the slot is cross-shaped, and coaxial cables that transmit RF signals that are 90° out-of-phase are used to feed the folded cavity in respective orthogonal directions, whereby the cross-shaped slot produces accurate, circularly polarized radiation.
- the slot is cross- dumbbell-shaped, and a ridged waveguide is used to feed the folded cavity.
- an amount of cavity fold is greater in a first direction than it is in a second direction, whereby the folded cavity resonates at different frequencies for RF energy of different polarizations.
- a coupling post is provided to coupled RF energy of a first polarization to RF energy of a second polarization, whereby the slot produces accurate, circularly polarized radiation.
- the antenna is capable of producing very accurate circular polarization and is capable of handling very high average power levels, e.g., 10 kW, thereby making it suitable for high power applications which require extremely compact antenna elements, e.g., wide-scan phased array antennas.
- the present invention also encompasses, in another of its aspects, a phased array antenna that includes a plurality of antenna elements each of which is constructed in accordance with the present invention.
- Figure 1 is an isometric view of the folded cavity-backed slot antenna of an embodiment of the present invention.
- Figure 2 is a cross-sectional view of the folded cavity of a conventional folded cavity-backed slot antenna.
- Figure 3 is a cross-sectional view of the folded cavity of the folded cavity-backed slot antenna depicted in Figure 1.
- Figure 4 is an isometric view of the folded cavity-backed slot antenna of the present invention fed with coaxial cables.
- Figure 5 is an isometric view of another embodiment of the folded cavity-backed slot antenna of the present invention fed with a ridged waveguide.
- Figure 6 is a graph plotting return loss versus frequency, at the ridged waveguide input port of the folded cavity-backed slot antenna of the present invention depicted in Figure 5. DESCRIPTION OF THE INVENTION
- the folded cavity-backed slot antenna 20 includes a housing 22 that has a folded rectangular cavity 24 formed in a bottom cavity wall 26 in accordance with a novel aspect of the present invention, and a slot 28 machined in the top cavity wall 30.
- the housing 22 may be constructed of aluminum or other suitable conductive material.
- the folded rectangular cavity 24 can be thought of as being formed by folding a standard rectangular cavity behind itself in two dimensions.
- This folded cavity design allows the antenna 20 to be less than l A wavelength on edge, making it compact enough to use as an antenna element in a large scan phased array antem a.
- This size reduction relative to the standard rectangular cavity design of the prior art is accomplished without the use of dielectric material, thereby enabling the antenna 20 to be used in high power applications.
- the antenna 20 can be fed with a waveguide, coaxial cables, or any other RF transmission line.
- the antenna 20 can be configured to produce a circularly polarized , radiation pattern.
- the slot 28 is cross-shaped, to thereby produce a circularly polarized radiation pattern.
- the slot 28 can be formed by machining two orthogonal slots in the top cavity wall 30 to form the shape of a cross.
- Figure 2 is a cross-sectional view of a standard rectangular cavity 32 of the prior art, in one dimension, e.g., the width dimension. The width of the cavity 32 is designated "w".
- Figure 3 is a cross-sectional view of the folded rectangular cavity 24 of the present invention, in one dimension, e.g., the width dimension.
- the width of the folded cavity 24 is designated " «w", to thereby indicate that the width of the folded cavity 24 of the present invention is significantly less than the width of the "non-folded" cavity 32 of the prior art.
- the total folded width of the cavity is approximately equal to "w", as shown in Fig. 3.
- this same size reduction is achieved in the orthogonal dimension, e.g., the length dimension, of the folded cavity 24, by virtue of the folded cavity being "folded back" along its length, as well as its width.
- this folding back of the standard rectangular cavity in orthogonal dimensions results in a "compound" cavity comprised of a first cavity portion 32 and a second cavity portion 34 joined around their entire peripheries by a fold or shelf 36.
- the particular shape of the cavity is not limiting to the present invention, in its broadest aspect.
- FIG 4 is an isometric view of the embodiment of the folded cavity-backed antenna 20 depicted in Figure 3 shown being fed with a pair of coaxial cables 40.
- Each of the coaxial cables 40 feeds the folded cavity 24 in a respective one of its two orthogonal directions. If the coax signals are 90° apart in phase, the folded cavity-backed slot 28 will radiate circular polarization.
- FIG. 5 is an isometric view of another embodiment of a folded cavity-backed antenna 20' of the present invention.
- the antenna 20' is fed with a ridged waveguide 44.
- the ridged waveguide 44 can be made narrower than a standard rectangular waveguide, e.g., approximately Vi wavelength on edge.
- a cross-"dumbbell"-shaped slot 28' was employed in order to produce a very broad radiation pattern.
- the ridged waveguide feed 44 only couples energy into the cavity in one polarization.
- the folded cavity 24' is required to resonate in both polarizations. This is achieved in this embodiment of the invention by inclusion of a coupling post 48 to couple energy from one polarization into the other polarization.
- the two polarizations of the folded cavity 24' are required to resonate at slightly different frequencies. This is achieved in this embodiment of the invention by making the amount of cavity fold greater for one polarization than the other polarization. This is accomplished by making the base of the folded cavity 34' unsymmetrical.
- the folded cavity-backed antenna 20' of this embodiment (i.e., the one depicted in Figure 5) was built and extensively tested.
- Figure 6 is a graph plotting return loss versus frequency, at the ridged waveguide input port of the folded cavity-backed slot antenna 20' of the present invention depicted in Figure 5.
- the return loss at the center (design) frequency is less than -20 dB, and is also less than -20 dB over approximately a 3% bandwidth.
- the double resonance nature of the return loss which is due to the two polarizations of the folded cavity 24' resonating at different frequencies in order to produce circularly polarized radiation, as explained above.
- the radiated axial ratio for this embodiment was also tested, and it was determined that at the center frequency the axial ratio was close to zero, and that further, the axial ratio for the folded cavity 24' was less than 3 dB over approximately a 2% bandwidth. Further, this embodiment (i.e., the embodiment depicted in Figure 5) was also tested under high power. In particular, average power in excess of 10 kW was applied to the antenna 20' with no resulting degradation.
Abstract
Description
Claims
Priority Applications (8)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AU2001288354A AU2001288354B2 (en) | 2000-08-27 | 2001-08-24 | Folded cavity-backed slot antenna |
KR1020037005647A KR100870583B1 (en) | 2000-08-27 | 2001-08-24 | Folded cavity-backed slot antenna |
AU8835401A AU8835401A (en) | 2000-08-27 | 2001-08-24 | Folded cavity-backed slot antenna |
DE60123454T DE60123454T2 (en) | 2000-08-27 | 2001-08-24 | FOLDED CAVITY-BASED SLOTTED ANTENNA |
IL15397801A IL153978A0 (en) | 2000-08-27 | 2001-08-24 | Folded cavity-backed slot antenna |
JP2002524257A JP4933020B2 (en) | 2000-08-27 | 2001-08-24 | Slot antenna with folded cavity at the back |
EP01968077A EP1334536B1 (en) | 2000-08-27 | 2001-08-24 | Folded cavity-backed slot antenna |
IL153978A IL153978A (en) | 2000-08-27 | 2003-01-15 | Folded cavity-backed slot antenna |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US38564600A | 2000-08-27 | 2000-08-27 | |
US09/385,646 | 2000-08-27 |
Publications (3)
Publication Number | Publication Date |
---|---|
WO2002019468A2 WO2002019468A2 (en) | 2002-03-07 |
WO2002019468A3 WO2002019468A3 (en) | 2002-06-27 |
WO2002019468A9 true WO2002019468A9 (en) | 2004-03-04 |
Family
ID=23522285
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2001/026273 WO2002019468A2 (en) | 2000-08-27 | 2001-08-24 | Folded cavity-backed slot antenna |
Country Status (7)
Country | Link |
---|---|
EP (1) | EP1334536B1 (en) |
JP (1) | JP4933020B2 (en) |
KR (1) | KR100870583B1 (en) |
AU (2) | AU8835401A (en) |
DE (1) | DE60123454T2 (en) |
IL (2) | IL153978A0 (en) |
WO (1) | WO2002019468A2 (en) |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2016174930A1 (en) * | 2015-04-30 | 2016-11-03 | 古野電気株式会社 | Circularly polarized wave antenna and orientation calculation device |
CN107069188B (en) * | 2016-12-29 | 2019-12-20 | 北京遥测技术研究所 | Low-profile high-efficiency dual-polarized panel antenna |
Family Cites Families (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4131893A (en) * | 1977-04-01 | 1978-12-26 | Ball Corporation | Microstrip radiator with folded resonant cavity |
US4130823A (en) * | 1977-08-05 | 1978-12-19 | The United States Of America As Represented By The Secretary Of The Navy | Miniature, flush mounted, microwave dual band cavity backed slot antenna |
US5049895A (en) * | 1985-01-24 | 1991-09-17 | Yoshiharu Ito | Flat circular waveguide device |
JPH02156707A (en) * | 1988-12-08 | 1990-06-15 | Yagi Antenna Co Ltd | Planer antenna |
JP3341292B2 (en) * | 1991-02-18 | 2002-11-05 | 凸版印刷株式会社 | Dual-polarized radial line slot antenna |
JP3021752B2 (en) * | 1991-04-26 | 2000-03-15 | 凸版印刷株式会社 | Composite structure radial line slot antenna |
US5581266A (en) * | 1993-01-04 | 1996-12-03 | Peng; Sheng Y. | Printed-circuit crossed-slot antenna |
JP3026711B2 (en) * | 1993-07-07 | 2000-03-27 | 凸版印刷株式会社 | Dual-polarization feeder |
JP3340958B2 (en) * | 1998-04-17 | 2002-11-05 | 株式会社ヨコオ | Array antenna |
US6304226B1 (en) * | 1999-08-27 | 2001-10-16 | Raytheon Company | Folded cavity-backed slot antenna |
-
2001
- 2001-08-24 IL IL15397801A patent/IL153978A0/en unknown
- 2001-08-24 AU AU8835401A patent/AU8835401A/en active Pending
- 2001-08-24 AU AU2001288354A patent/AU2001288354B2/en not_active Ceased
- 2001-08-24 DE DE60123454T patent/DE60123454T2/en not_active Expired - Lifetime
- 2001-08-24 KR KR1020037005647A patent/KR100870583B1/en not_active IP Right Cessation
- 2001-08-24 EP EP01968077A patent/EP1334536B1/en not_active Expired - Lifetime
- 2001-08-24 WO PCT/US2001/026273 patent/WO2002019468A2/en active Search and Examination
- 2001-08-24 JP JP2002524257A patent/JP4933020B2/en not_active Expired - Fee Related
-
2003
- 2003-01-15 IL IL153978A patent/IL153978A/en not_active IP Right Cessation
Also Published As
Publication number | Publication date |
---|---|
IL153978A0 (en) | 2003-11-23 |
AU2001288354B2 (en) | 2005-08-18 |
KR20030051739A (en) | 2003-06-25 |
JP2004508751A (en) | 2004-03-18 |
JP4933020B2 (en) | 2012-05-16 |
DE60123454D1 (en) | 2006-11-09 |
DE60123454T2 (en) | 2007-08-23 |
WO2002019468A2 (en) | 2002-03-07 |
AU8835401A (en) | 2002-03-13 |
EP1334536A2 (en) | 2003-08-13 |
WO2002019468A3 (en) | 2002-06-27 |
EP1334536B1 (en) | 2006-09-27 |
IL153978A (en) | 2008-12-29 |
KR100870583B1 (en) | 2008-11-25 |
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