Multi-segmented dielectric resonator antenna

Details Multi-segmented dielectric resonator antenna Multi-segmented dielectric resonator antenna

2002-12-19

2004-11-09

Nguyen, Hoang V. (Department: 2821)

Communications: radio wave antennas

Antennas

Microstrip

C343S873000, C342S368000

Reexamination Certificate

active

06816118

ABSTRACT:

The present invention relates to dielectric resonator antennas (DRAs) composed of several adjacent segments, which may be excited simultaneously to provide steerable receive and transmit beams and very low backlobes.
Since the first systematic study of dielectric resonator antennas (DRAs) in 1983 [LONG, S. A., McALLISTER, M. W., and SHEN, L. C.: “The Resonant Cylindrical Dielectric Cavity Antenna”, IEEE Transactions on Antennas and Propagation, AP-31, 1983, pp 406-412], interest has grown in their radiation patterns because of their high radiation efficiency, good match to most commonly used transmission lines and small physical size [MONGIA, R. K. and BHARTIA, P.: “Dielectric Resonator Antennas—A Review and General Design Relations for Resonant Frequency and Bandwidth”, International Journal of Microwave and Millimetre-Wave Computer-Aided Engineering, 1994, 4, (3), pp 230-247].
The majority of configurations reported to date have used a slab of dielectric material mounted on a ground plane excited by either an aperture feed in the ground plane [ITTIPIBOON, A., MONGIA, R. K., ANTAR, Y. M. M., BHARTIA, P. and CUHACI, M: “Aperture Fed Rectangular and Triangular Dielectric Resonators for use as Magnetic Dipole Antennas”, Electronics Letters, 1993, 29, (23), pp 2001-2002] or by a probe inserted into the dielectric material [McALLISTER, M. W., LONG, S. A. and CONWAY G. L.: “Rectangular Dielectric Resonator Antenna”, Electronics Letters, 1983, 19, (6), pp 218-219]. Direct excitation by transmission lines has also been reported by some authors [KRANENBURG, R. A. and LONG, S. A.: “Microstrip Transmission Line Excitation of Dielectric Resonator Antennas”, Electronics Letters, 1994, 24, (18), pp 1156-1157].
Further analysis of steerable-beam DRAs is to be found in the present applicant's co-pending U.S. patent application Ser. No. 09/431,548, from which the present application claims priority and the disclosure of which is incorporated into the present application by reference.
Two of the most commonly described geometries are cylindrical and rectangular dielectric slabs. Several publications describe how these may be bisected through an image plane by a conducting sheet [TAM, M. T. K. and MURCH, R. D.: “Half volume dielectric resonator antenna designs”, Electron. Lett., 1997, 33, (23), pp. 1914-1916; MONGIA, R. K.: ‘Half-split dielectric resonator placed on metallic plane for antenna applications’. Electron. Lett., 1989, 25, (7), pp 462-464]. To the applicant's knowledge, only one publication describes antennas made from segments smaller than a half volume [TAM, M. T. K. and Murch, R. D.: “Compact Circular Sector and Annular Sector Dielectric Resonator Antennas”, IEEE Transactions on Antennas and Propagation, AP-47, 1999, pp 837-842].
According to a first aspect of the present invention, there is provided a compound dielectric resonator antenna comprising a plurality of individual dielectric resonator antennas, each including a grounded substrate, a dielectric resonator element having side faces and associated with the rounded substrate, and a feeding mechanism for transferring energy into and from the dielectric resonator element, characterised in that the dielectric resonator elements are arranged such that at least one side face of each dielectric resonator element is adjacent to at least one side face of a neighbouring dielectric resonator element and in that the antenna further includes electronic circuitry provided to activate the dielectric resonator elements individually or in combination so as to produce at least one incrementally or continuously steerable beam, which may be steered through a predetermined angle.
According to a second aspect of the present invention, there is provided a compound dielectric resonator antenna comprising a plurality of individual dielectric resonator antennas, each including a dielectric resonator element having side faces, and a feeding mechanism for transferring energy into and from the dielectric resonator element by way of at least one dipole feed. characterised in that the dielectric resonator elements are arranged such that at least one side face of each dielectric resonator element is adjacent to at least one side face of a neighbouring dielectric resonator element and in that the antenna further includes electronic circuitry provided to activate the dielectric resonator elements individually or in combination so as to produce at least one incrementally or continuously steerable beam, which may be steered through a predetermined angle.
It is preferred that the adjacent side faces are substantially contiguous. in that they contact each other. Alternatively, small gaps may be present between the adjacent side faces, these gaps being filled with air or another dielectric material.
Advantageously, the adjacent side faces of at least one pair of neighbouring dielectric resonator elements are separated by an electrically conductive wall which contacts both adjacent side faces. Preferably, all adjacent side walls are separated by an electrically conductive wall.
The dielectric resonator elements may be disposed directly on, next to or under the grounded substrate, or a small gap may be provided between the elements and the grounded substrate. The gap may comprise an air gap, or may be filled with another dielectric material of solid, liquid or gaseous phase.
The present invention seeks to provide an antenna having several elements, each of which is a segmented DRA. These elements may be excited simultaneously in order to provide steerable receive and transmit beams, radio direction finding capabilities, intelligent (or ‘smart’) antenna capabilities, low radiation backlobes and narrower radiation main lobes. The present invention also seeks to provide a significant further reduction in the backlobes by using extensions to the conducting walls that define the sides or edges of the DRA elements. Low backlobes are of particular importance to the application of these antennas to mobile telephones. Furthermore, an original geometry for the elements is proposed.
In some embodiments, a 90 degree sector of a cylindrical or annular DRA is resonated in its fundamental HEM
21&dgr;
mode, but there are several other resonant modes that may be used with this and with other geometries. An example of another combination is a 60 degree sector and its associated fundamental HEM
31&dgr;
mode.
The preferred HEM
11&dgr;
, HEM
21&dgr;
and HEM
31&dgr;
modes are hybrid electromagnetic resonance modes, radiating like a horizontal magnetic dipole, which give rise to a vertically polarised radiation pattern with a cosine or figure-of-eight shaped pattern.
It has been noted by the present applicants that the results described in the above reference apply equally to DRAs operating at any of a wide range of frequencies, for example from 1 MHz to 100,000 MHz and even higher for optical DRAs. The higher the frequency in question, the smaller the size of the DRA, but the general beam patterns achieved by the probe/aperture and segment combination geometries described hereinafter remain generally the same throughout any given frequency range. Operation at frequencies substantially below 1 MHz is also possible, using dielectric materials with a high dielectric constant.
Advantageously, the antenna and antenna system of the present invention are adapted to produce at least one incrementally or continuously steerable beam, which may be steered through a complete 360 degree circle.
Advantageously, there is additionally or alternatively provided electronic circuitry to combine the feeds to form sum and difference patterns to permit radio direction finding capability of up to 360 degrees.
The electronic circuitry may additionally or alternatively be adapted to combine the feeds to form amplitude and/or phase comparison radio direction finding capability of up to 360 degrees.
In a first preferred embodiment, radio direction finding and beamforming capability is a complete 360 degree circle, with the indi

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