Suppression of surface waves in printed circuit board-based phased-array antennas

Patent metadata

Field	Value
Publication number	US-10490907-B2
Application number	US-201615277149-A
Country	US
Kind code	B2
Filing date	Sep 27, 2016
Priority date	Sep 27, 2016
Publication date	Nov 26, 2019
Grant date	Nov 26, 2019

Abstract

A phased-array antenna includes an antenna layer of a stacked printed circuit board, a ground plane layer of the stacked printed circuit board spaced apart from the antenna layer, and a first dielectric layer of the stacked printed circuit board disposed between and in opposed contact with the antenna layer and the ground plane layer. The antenna layer includes an associated metal patch pattern defined by a series of slots. The stacked printed circuit board defines a thickness extending between a top end of the stacked printed circuit board and a bottom end of the stacked printed circuit board. The phased-array antenna includes a series of ground vias extending between the top and bottom ends of the stacked printed circuit board. The ground vias are configured to suppress surface waves propagating across the stacked printed circuit board.

First claim

What is claimed is:

1. A phased-array antenna assembly, comprising:
an antenna board stack defining a thickness between a bottom end and a top end, the antenna board stack comprising:
a central core layer including a bottom surface and a top surface disposed on an opposite side of the central core layer than the bottom surface, and defining an axis of symmetry bisecting the bottom surface and the top surface to divide the thickness of the antenna board stack in half;
a bottom multilayer antenna unit defining a bottom thickness between the bottom surface of the central core layer and the bottom end of the antenna board stack, the bottom multilayer antenna unit comprising a first bottom metal layer in opposed direct contact with the bottom surface of the central core layer and a second bottom metal layer spaced apart from both the first bottom metal layer and the bottom end of the antenna board stack;
a top multilayer antenna unit defining a top thickness between the top surface of the central core layer and the top end of the antenna board stack, the top multilayer antenna unit comprising two spaced apart top metal layers; and
a series of metal-filled ground vias formed through the antenna board stack, the metal-filled ground vias extending in a direction substantially perpendicular to the axis of symmetry and configured to suppress surface waves propagating across the antenna board stack; and

a radome configured to cover the top end of the antenna board stack, the radome including an outer surface and an inner surface disposed on an opposite side of the radome than the outer surface and opposing the top end of the antenna board stack.

2. The antenna assembly of claim 1 , wherein:
the bottom multilayer antenna unit comprises:
a first bottom dielectric spacer disposed between the first bottom metal layer and the second bottom metal layer; and
a second bottom dielectric spacer disposed at the bottom end of the antenna board stack; and

the top multilayer antenna unit comprises:
a first top metal layer disposed on the top surface of the central core layer;
a second top metal layer;
a first top dielectric spacer separating the first top metal layer and the second top metal layer; and
a second top dielectric spacer disposed on an opposite side of the second top metal layer than the first top dielectric spacer,

wherein the first and second bottom metal layers and the first and second top metal layers are connected by at least one probe fed via extending between the top and bottom ends of the antenna board stack.

3. The antenna assembly of claim 2 , wherein the first bottom metal layer, the first top metal layer, and the second top metal layer each comprise a corresponding antenna, and the second bottom metal layer comprises a ground plane shared by each of the antennas.

4. The antenna assembly of claim 3 , wherein each ground via is formed through a corresponding metal patch of each of the antennas.

5. The antenna assembly of claim 3 , wherein a first portion of the ground vias are formed through corresponding metal patches in vertical feeds of the antennas, and a second portion of the ground vias are formed through corresponding metal patches in horizontal feeds of the antennas.

6. The phased-array antenna of claim 5 , wherein the number of ground vias in the first portion is equal to the number of ground vias in the second portion.

7. The antenna assembly of claim 2 , wherein the metal-filled ground vias are grounded to the second bottom metal layer.

8. The antenna assembly of claim 2 , wherein one or more of the metal-filled ground vias are grounded to at least one of the first bottom metal layer, the first top metal layer, or the second top metal layer.

9. The antenna assembly of claim 2 , wherein a portion of the metal filling of at least one of the ground vias is removed proximate to the first bottom dielectric spacer to electrically isolate the metal filling from the first bottom dielectric spacer.

10. The antenna assembly of claim 2 , wherein each ground via is spaced apart from the at least one probe fed via by at least a predetermined distance to prevent an impedance mismatch.

11. The antenna assembly of claim 2 , wherein a radio frequency manifold layer comprising a passive splitter/combiner is formed by a conductive micro-strip line formed on the second bottom dielectric spacer.

12. The antenna assembly of claim 1 , wherein the series of metal-filled ground vias formed through the antenna board stack comprises at least ten metal-filled ground vias.

13. The antenna assembly of claim 1 , wherein the radome is formed from one or more plastic materials.

14. The antenna assembly of claim 13 , wherein the outer surface of the radome is coated with a hydrophobic material.

15. The antenna assembly of claim 1 , wherein the radome and the top end of the antenna board stack are separated by a top air gap.

16. The antenna assembly of claim 1 , wherein the radome comprises a C-sandwich radome structure.

Assignees

• Google Inc
• Google Llc

Inventors

• Feldman Arnold
• Noujelm Leesa Marle
• Buckley Michael J

Classifications

• H01Q5/20

  characterised by the operating wavebands · CPC title

• H01Q1/42

  Housings not intimately mechanically associated with radiating elements, e.g. radome · CPC title

• H01Q21/24

  Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction {(circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001)} · CPC title

• H01Q9/0407

  Substantially flat resonant element parallel to ground plane, e.g. patch antenna (dipole H01Q9/285; monopole H01Q9/40) · CPC title

• H01Q21/0075

  Stripline fed arrays (H01Q21/065 takes precedence) · CPC title