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EP-3993162-B1 - PARASITIC ELEMENTS FOR ANTENNA SYSTEMS

EP3993162B1EP 3993162 B1EP3993162 B1EP 3993162B1EP-3993162-B1

Inventors

  • LIN, JESSE
  • GUNNELS, ROBERT

Dates

Publication Date
20260506
Application Date
20210729

Claims (9)

  1. An antenna system (20A; 20B; 20C; 20D; 20E) comprising: a ground plane (22); an antenna (22A; 22B, 22C; 22D) disposed on a top side of the ground plane (22) and configured to produce a radiation pattern; and a plurality of parasitic elements (24A; 24B) connected to and extending from the top side of the ground plane (22), wherein a respective proximal end of each of the plurality of parasitic elements (24A:24B) is connected to the ground plane (22), wherein a respective distal end of each of the plurality of parasitic elements (24A; 24B) is displaced from the ground plane (22), wherein each of the plurality of parasitic elements (24A; 24B) is positioned at a uniform distance from a center of the antenna (22A; 22B, 22C; 22D), wherein each of the plurality of parasitic elements (24A; 24B) is oriented at a common pitch angle relative to the ground plane (22), and wherein a respective length of each of the plurality of parasitic elements (24A; 24B) is between approximately 0.2 and approximately 0.25 times a wavelength of a frequency of the antenna (22A; 22B, 22C; 22D), the common pitch angle is between 35° and 55°, and the uniform distance is equal to approximately one quarter of the wavelength, λ/4, of the frequency of the antenna (22A; 22B, 22C; 22D), the respective length of each of the plurality of parasitic elements (24A; 24B), the common pitch angle, and the uniform distance being configured to broaden a beamwidth of the radiation pattern.
  2. The antenna system of claim 1 wherein the plurality of parasitic elements (24A; 24B) includes metal wire elements, or copper strips embedded in a printed circuit board.
  3. The antenna system of claim 1 or 2 wherein the plurality of parasitic elements (24A; 24B) includes between 6 and 16 elements.
  4. The antenna system of any preceding claim wherein each of the plurality of parasitic elements (24A; 24B) is placed in an equidistant manner around the antenna (22A; 22B, 22C; 22D).
  5. The antenna system of any preceding claim wherein the antenna (22A; 22B, 22C; 22D) includes one or more patch antennas (22A), a crossed-dipole antenna (22D), one or more single band elements (22B, 22C), a dual-band element, or a multi-band element.
  6. The antenna system of any preceding claim wherein the antenna's radiation is circularly polarized, and wherein the plurality of parasitic elements (24A; 24B) includes helical-shaped elements.
  7. The antenna system of claim 6 wherein the radiation is right hand circularly polarized, and wherein the respective distal end of each of the plurality of parasitic elements (24A; 24B) extends in a counter-clockwise direction relative to the respective proximate end of a respective one of the plurality of parasitic elements (24A; 24B).
  8. The antenna system of claim 6 wherein the radiation is left hand circularly polarized, and wherein the respective distal end of each of the plurality of parasitic elements (24A; 24B) extends in a clockwise direction relative to the respective proximate end of a respective one of the plurality of parasitic elements (24A; 24B).
  9. The antenna system of any preceding claim wherein a respective top section of each of the plurality of parasitic elements (24A; 24B) is bent down towards the ground plane (22).

Description

FIELD The present invention generally relates to radio frequency (RF) communications hardware. More particularly, the present invention relates to antenna systems. BACKGROUND In many global navigation satellite system ("GNSS") antenna applications, it is beneficial for a radiation pattern of an antenna to have a broad beamwidth. In particular, it is beneficial for the antenna to provide hemispheric coverage centered about the zenith and for a gain of the antenna to be as high as possible near the horizon without significant gain loss at or near the zenith while maintaining the gain as low as possible below the horizon. However, known antenna systems that provide the above-identified features suffer from several known drawbacks. For example, some known antenna systems provide the broad beamwidth by employing an antenna element with a large height dimension that is not suitable for applications requiring antennas with low physical profiles. Furthermore, other known antenna systems require the use of resistors, capacitors, and/or inductors to create a loading circuit. Regardless, all of these known antenna systems require a large volume or additional loading components to implement and only broaden the beamwidth by a small degree. US2017/047665A1 discloses a central fixed patch antenna surrounded with reactively or resistively loaded peripheral monopoles as surface-wave excited parasitic radiators. The surrounding monopoles may be printed on the same substrate as the patch, and may take a spiral (pin-wheel) shape. US2004/070545A1 discloses a circular polarized wave reception antenna having a monopole antenna having a pole portion and a ground plate for grounding one terminal of the pole portion and a polarization converting arrangement disposed around the monopole antenna. The polarization converting arrangement has a plurality of helical leads extending in a helical fashion along the pole portion set apart from the pole portion by a predetermined distance. Each of the helical leads has an end grounded in said ground plate. The helical leads are disposed at equal angular spaces around the pole portion. When a resonance wavelength lambda is equal to 128.3 mm, the predetermined space is equal to 20 mm. Each helical lead has a length of lambda/4. A pitch angle included between the ground plate and each helical lead is equal to 40 degrees. US2002/158808A1 discloses dipole antennae disposed so as to be approximately orthogonal at approximately lambda/4 intervals on a reflecting plate having a diameter of approximately lambda/2 or more. By disposing a plurality of non-feeding elements around the dipole antennae and isolating them by approximately lambda/4, the transmission gain and axial ratio in a low elevation angle can be improved. In view of the above, there is a continuing, ongoing need for improved antenna systems. SUMMARY OF THE INVENTION The present invention is defined in claim 1, to which reference should now be made. Optional embodiments are defined in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an antenna system according to disclosed embodiments;FIG. 2 is a perspective view of an antenna system according to disclosed embodiments;FIG. 3 is a perspective view of an antenna system according to disclosed embodiments;FIG. 4 is a perspective view of an antenna system according to disclosed embodiments;FIG. 5 is a perspective view of an antenna system according to disclosed embodiments; andFIG. 6 is a graph of a radiation pattern for an antenna system according to disclosed embodiments. DETAILED DESCRIPTION While this invention is susceptible of an embodiment in many different forms, there are shown in the drawings and will be described herein in detail specific embodiments thereof with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention. It is not intended to limit the invention to the specific illustrated embodiments. Embodiments disclosed herein can include an antenna system that can produce a radiation pattern with a broad beamwidth, hemispheric coverage centered about the zenith, and a gain as high as possible near the horizon without significant gain loss at or near the zenith while maintaining the gain as low as possible below the horizon. The antenna system disclosed herein includes a ground plane, an antenna disposed on a top side of the ground plane and configured to produce a radiation pattern, and a plurality of parasitic elements connected to and extending from the top side of the ground plane and positioned at a uniform distance from a center of the antenna. A respective proximate end of each of the plurality of parasitic elements is connected to the ground plane, and a respective distal end of each of the plurality of parasitic elements is displaced from the ground plane. Each of the plurality of parasitic elements is oriented at a common pitch angle relative to the ground plane. A