MULTIBAND RESONATOR ELEMENT FOR MAKING FILTERS, POLARIZERS AND FREQUENCY-SELECTIVE SURFACES

Abstract

A multiband resonator element which, on the one hand, compensates the components of an electromagnetic field radiated from its phase centre, located on the axis of symmetry of the resonator, to control the polarization purity of a radiating element. On the other hand, it enables the selection of the electromagnetic fields reflected and transmitted on a frequency- and multiband-selective surface. In this sense, this is an innovative element that enables the design of directive radiating elements and with an axial ratio for its circular polarization less than or equal to 1.5 dB for all the angles belonging to the hemisphere centred on broadside. Thus, it can be used in the design of reflectarrays, transmitarrays and any dichroic multiband surface, likewise on metamaterial surfaces.

Claims

1. A multiband resonator element comprising: a plurality of stubs adjusted in frequency and arranged according to a geometric shape to be selected from an ellipse or a rectangle.

2. The resonator element according to claim 1, wherein the ellipse has an aspect ratio equal to the unit and the stubs are arranged radially between inner rings and outer rings, thereby forming a ring of stubs.

3. The resonator element according to claim 1, wherein the rectangle has an aspect ratio equal to the unit and the stubs are arranged linearly on the four sides of the rectangle, with inner rings and outer rings, thus forming a rectangle of stubs.

4. The resonator element according to claim 1, comprising a discontinuous slot arranged on a base structure, wherein the slot has a shape dependent on the selected geometric shape and the frequency adjusted stubs.

5. The resonator element according to claim 1, wherein said resonator element comprises a metal material.

6. A cavity filter comprising a plurality of resonator elements according to claim 1, wherein each resonator element is disposed on a layer of dielectric material and separated from each other by a layer of foam-type material or air.

7. The cavity filter according to claim 6, wherein the dielectric materials include a variable dielectric constant to change the working frequency or its phase response, to perform low-pass, high-pass, band-pass or multiband-pass filters.

8. A radiating element formed by the filter cavity according to claim 7, for single or multiband applications.

9. A radiating element comprising a resonator element according to claim 2, wherein the stubs comprise a length, a width, a track spacing and a ring radius, configured to optimize the axial ratio with respect to the axis of symmetry thereof.

10. A dichroic subreflector comprising a first resonator element according to claim 2, wherein the stubs comprise: a length configured to adjust a central band; a track spacing configured to adjust the central band and an upper band; and a ring radius configured to adjust a lower band and the upper band.

11. The dichroic subreflector according to claim 10, further comprising a second resonator element identical to the first resonator element and arranged at an effective half-wavelength distance from the first resonator element that is dependent on the impedances and operating frequencies, resulting in a symmetrical configuration.

12. The dichroic subreflector according to claim 10, further comprising a smooth resonator ring disposed at an effective distance different from half a wavelength of the first resonator element that is dependent on the impedances and frequencies of operation, resulting in an asymmetric configuration.

13. A radiating element comprising a resonator element according to claim 1, wherein the radiating element further comprises an aperture polarizer configured to improve the axial ratio of the circular polarization of the radiating element up to angles of 90 degrees from a broadside axis.

14. A reflectarray antenna formed by a plurality of periodic cells each comprising a resonator element according to claim 1.

15. Frequency-selective surface for one or multiple bands formed by a plurality of periodic cells each comprising: a resonator element according to claim 1, wherein the frequency-selective surface further comprises a dielectric material with a variable dielectric constant.

16. A resonator element according to claim 1, further comprising an adjustable dipole to favour a polarization or application.

17. A multiband resonator element comprising: a plurality of stubs adjusted in frequency and arranged according to an ellipse, wherein the ellipse has an aspect ratio equal to the unit and the stubs are arranged radially between inner rings and outer rings, thereby forming a ring of stubs; and the resonator element comprising a discontinuous slot arranged on a base structure, wherein the slot has a shape dependent on the ellipse and the frequency adjusted stubs, wherein said resonator element comprises a metal material.

18. A multiband resonator element comprising: a plurality of stubs adjusted in frequency and arranged according to a rectangle, wherein the rectangle has an aspect ratio equal to the unit and the stubs are arranged linearly on the four sides of the rectangle, with inner rings and outer rings, thus forming a rectangle of stubs; and the resonator element comprising a discontinuous slot arranged on a base structure, wherein the slot has a shape dependent on the rectangle and the frequency adjusted stubs, wherein said resonator element comprises a metal material.

19. A cavity filter comprising a plurality of resonator elements according to claim 17, wherein each resonator element is disposed on a layer of dielectric material and separated from each other by a layer of foam-type material or air; and the cavity filter further comprising an adjustable dipole to favour a polarization or application.

20. A cavity filter comprising a plurality of resonator elements according to claim 18, wherein each resonator element is disposed on a layer of dielectric and separated from each other by a layer of foam-type material or air; and the cavity filter further comprising an adjustable dipole to favour a polarization or application.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0034] With reference to the numbering adopted in the figures described above, the description of the present invention will be described in greater detail, which is based on a multiband resonator element, such as that represented in FIG. 1, which is formed by a series of stubs (13.a or 13.b) adjusted in frequencies and arranged on what would be a ring or a rectangle, thus making a ring or rectangle of stubs.

[0035] This element may be implemented to improve the axial ratio within an enlarged viewing cone of the radiating element under analysis, such as that shown in FIG. 2, consisting of an iris filter 23.a, 23.g, 23.d, and 23.k, in the dielectric load at aperture 22 which may be a shaped or corrugated cone, in a cavity 24 containing the foregoing elements, for working at two separate frequencies, and the multiband resonator element at aperture 21 which improves the ratio between the field components for large angles relative to the axis or elevation angles. This improvement of the axial ratio consists of obtaining a circular polarization purity less than or equal to 1.5 dB for an observation range of +/−75 degrees, or less than or equal to 2 dB for an observation range of +/−85 degrees, with respect to the axis or “broadside” or axis.

[0036] This element can also be implemented in multiband dichroic subreflector designs. These multiband subreflectors can be made for virtually any band ratio with the normalized frequency response shown in FIGS. 6 and 7, for the non-symmetrical and symmetrical configurations, respectively. These bands may be, for example: [S, C, X], [Ku, K, Ka], [X, K, Ka], etc. These implementations in dichroic subreflectors being limited in the upper bands by the physical dimensions and manufacturing technologies available.

[0037] For the case of application in the aperture of radiating elements to improve the axial ratio of radiating elements or antennas, the length of the stubs in FIG. 2, the width and spacing of the nearest tracks in FIG. 1, and the radius of the ring that the set of stubs forms, are adjusted to improve adaptation of the resonant patch or cavity with the medium at the antenna aperture. In addition, they optimize the axial ratio with respect to the axis of symmetry or direction of “broadside” as explained above.

[0038] In the case of application in dichroic subreflectors, we can start from the resonator of FIG. 1, but now adding to this element (32) the layers corresponding to the dielectric materials, which can be, according to design and for a manufacture with classic technology of the embodiment presented in FIG. 3: Kapton (31), Kevlar (33), Foam or Honeycomb (34), Kevlar (35), and Kapton (36). These materials may change depending on the selected manufacturing technique or technology. Now, the length of the stubs adjusts the central band of FIG. 6, while the separation of the tracks of the stubs adjusts the central and upper bands of FIG. 6. The radius of the ring formed by the stubs adjusts the lower and upper bands of FIG. 6. Finally, another important variable for the design of a dichroic subreflector, using any resonator, is that of the period of the cell used (symmetrical sides of the cell of FIGS. 3, 4 and 5). This variable, for the specific case of the invention presented here, adjusts all the bands, but it is its greatest impact on the lower and upper bands. With this set of parameters and knowing its effects on the response of the element, it is possible to design the resonant element within a periodic cell for implementation in a dichroic subreflector working on a set of specific bands.

[0039] In order to maximize transmission in a dichroic subreflector, it is demonstrated that it must have symmetry with respect to the impedances seen on both sides thereof, and these must be spaced at an effective distance of approximately half a wavelength in practice as depicted in FIGS. 4 and 5. Thus, it is possible to implement two classes of dichroic subreflectors based on the multiband resonator elements of FIG. 1 and the periodic cell of FIG. 3. That is, a symmetrical one with two resonators formed by “stubs” 41.b and 42.e on both sides in FIG. 4, or a non-symmetrical one with a resonator formed by “stubs” 51.b on one side and a smooth resonator ring 52.e on the other side in FIG. 5.

[0040] The symmetrical configuration allows the lower and upper bands to be adjusted in reflection, while the central one is adjusted in transmission as can be seen in FIG. 7. On the other hand, the non-symmetrical configuration allows adjusting the lower band in transmission, while the central and upper bands in reflection as can be seen in FIG. 6.

[0041] For the above, the slots shown in FIG. 9 can also be implemented, to implement different designs and manufacturing techniques. Likewise, the adjustable dipole of FIG. 10 can be introduced into the above elements depending on the polarization of the system and its multiband application.

REFERENCES

[0042] [1] W. C. G. S. a. N. S. L. Shafai, «Dual Band Dual Polarized Radiating Element Development,» de ANTEM'96, 1996.

[0043] [2] A. Imran Sandhu, E. Arnieri, G. Arriendóla, L. Boccia, E. Meniconi y V. Ziegler, «Radiating Elements for Shared Aperture Tx/Rx Phased Arrays at K/Ka Band,» IEEE Transactions on Antennas and Propagation, vol. 64, no 6, pp. 2270-2282, 2016.

[0044] [3] S. G. Fan Qin, L. Qi , M. Chun-Xu, G. Chao, W. Gao , X. Jiadong y L. Janzhou, «A Simple Low-Cost Shared-Aperture Dual-Band Dual-Polarized High-Gain Antenna for Synthetic Aperture Radars,» IEEE Transactions on Antennas and Propagation, vol. 64, no 7, pp. 2914-2922, 2016.

[0045] [4] K. Naishadham, R. Li, L. Yang, T. Wu y W. Hunsicker, «A Shared-Aperture Dual-Band Planar Array With Self-Similar Printed Folded Dipoles,» IEEE Transactions on Antennas and Propagation, vol. 61, no 2, pp. 606-613, 2013.

[0046] [5] M. Ferrando-Rocher, A. U. Zaman, J. Yang y A. Valero-Nogueira, «A Dual-Polarized Slotted-Waveguide Antenna Based on Gap Waveguide Technology,» de 11 th European Conference on Antennas and Propagation EUCAP, Paris, 2017.

[0047] [6] R. J. Coe, «Parasitically Coupled Complementary Slot-dipole Antenna Element». U.S. Pat. No. 4,710,775, December 1987.

[0048] [7] B. Kuan M. Lee, F. Nam S. Wong, C. Ruey S. Chu y F. Ray Tang, «DUAL BAND PHASED ANTENNA ARRAY USING WIDEBAND ELEMENT WITH DIPLEXER». U.S. Pat. No. 4,689,627, August 1987.

[0049] [8] C.-H. A. T. Saratoga, «Dual Frequency Circularly Polarized Microwave Antenna». U.S. Pat. No. 5,241,321, 31 August 1993.

[0050] [9] P. C. Strickland, «POLARIMETRIC DUAL BAND RADIATING ELEMENT FOR SYNTHETIC APERTURE RADAR». U.S. Pat. No. 5,952,971, 14 September 1999.

[0051] [10] B.-j. Lee y et al., «BROADBAND DUAL-POLARIZED MICROSTRIP ARRAY ANTENNA». U.S. patent application Ser. No. 10/476,410, 24 June 2004.

[0052] [11] B. Carmen y A. Teillet, «DUAL-POLARIZED RADIATING ELEMENT, DUAL-BAND DUAL-POLARIZED ANTENNA ASSEMBLY AND DUAL-POLARIZED ANTENNA ARRAY». U.S. Pat. No. 8,354,972 B2, 15 January 2013.

[0053] [12] Przemyslaw Gorski, Joana S. Silva, y Juan R. Mosig, «Wideband, Low Profile and Circularly Polarized K/Ka Band Antenna». IEEE European Conference on Antennas and Propagation (EuCAP), Lisbon (Portugal), 13-17 April. 2015.

[0054] [13] M. Salas-Natera, M. Barba Gea, y J. Encinar Garcinuño, «Elemento Radiante de Doble Banda y Doble Polarización Multi-propósito», Referencia de patente: ES-2017003144220171220, 2017

[0055] [14] R. Martinez-Lopez, J. Rodriguez-Cuevas, A. E. Martynyuk y J. I. Martinez-Lopez, «An active Ring Slot With RF MEMS Switchable Radial Stubs for Reconfigurable frequency Selective Surface Applications», México D.F.: Factulty of Engineering, National Autonomous University of México , 2012.

[0056] [15] D. Singh y V. M. Srivastava, «Dual resonance shorted stub circular rings metamaterial absorber». International Journal of Electronics and Communications, 2017.

[0057] [16] Peng-Chao Zhao, Zhi-Yuan Zong, Wen Wu, Bo Li, y Da-Gang Fang, «An FSS Structure Based on Parallel LC Resonators for Multiband Applications». IEEE Transactions on Antennas and Propagation, vol. 65, no 10, pp. 5257-5266, 2017.

[0058] [17] Raymond Dickie, Steven Christie, Robert Cahill, Paul Baine, Vincent Fusco, Kai Parow-Souchon, Manju Henry, Peter G. Huggard, Robert S. Donnan, Oleksandr Sushko, Massimo Candotti, Rostyslav Dubrovka, Clive G. Parini, and Ville Kangas, «Low-Pass FSS for 50-230 GHz Quasi-Optical Demultiplexing for the MetOp Second-Generation Microwave Sounder Instrument». IEEE Transactions on Antennas and Propagation, vol. 65, no 10, pp. 5312-5321, 2017.

[0059] [18] M. Sharifian Mazraeh Mollaei and S. H. Sedighy, «Three Bands Substrate Integrated Waveguide Cavity Spatial Filter With Different Polarizations». IEEE Transactions on Antennas and Propagation, vol. 65, no 10, pp. 5628-5632, 2017.