EP-4742450-A2 - MULTI-ELEMENT FILAR ANTENNA STRUCTURES

EP4742450A2EP 4742450 A2EP4742450 A2EP 4742450A2EP-4742450-A2

Abstract

Single band and multiband wireless antennas are an important element of wireless systems. Competing tradeoffs of overall footprint, performance aspects such as impedance matching and cost require not only consideration but become significant when multiple antenna elements are employed within a single antenna such as to obtain circular polarization transmit and/or receive. Accordingly, it would be beneficial to provide designers of a wide range of electrical devices and systems with compact single or multiple frequency band antennas which, in addition to providing the controlled radiation pattern and circular polarization purity (where required) are impedance matched without substantially increasing the footprint of the antenna and/or the complexity of the microwave / RF circuit interfaced to them, whilst supporting multiple signals to/from multiple antenna elements in antennas employing them. Solutions present achieve this through provisioning one or more capacitive series reactances discretely or in combination with one or more shunt capacitive reactances.

Inventors

MOVAHEDINIA, Reza
BOTROS, JOSEPH
Hautcoeur, Julien

Assignees

Calian GNSS Ltd.

Dates

Publication Date: 20260513
Application Date: 20230808

Claims (5)

A filar antenna comprising: a ground plane; a feed point proximate the ground plane; a first filar element comprising: a first element having a first end electrically coupled to the feed point and a second distal end; a second element having a first end electrically coupled to the ground plane and a second distal end; and a third element having a first end electrically coupled to the ground plane and a second distal end; and a second filar element comprising: a fourth element having a first end electrically coupled to the ground plane and a second distal end; and a fifth element having a first end electrically coupled to the ground plane and a second distal end; wherein the second distal end of the second element is electrically connected to the second distal end of the first element; the second distal end of the third element is electrically connected to the second distal end of the first element; a first electrical length from the feed point to the ground plane via the first element and the second element is established in dependence upon a multiple of a half wavelength of a first operating frequency of the first filar element; a second electrical length from the feed point to the ground plane via the first element and the second element is established in dependence upon the same multiple of a half wavelength of a first operating frequency as that of the first electrical length; the second distal end of the fourth element is electrically connected to the second distal end of the fifth element; a third electrical length from the ground plane to the ground plane via the fourth element and the fifth element is established in dependence upon a multiple of a half wavelength of a second operating frequency of the second filar element; wherein the second filar element is radiatively coupled to the first filar element.
The filar antenna according to claim 1, wherein an electrical length of each of the fourth element and the fifth element are established in dependence upon an odd multiple of a quarter wavelength of the second operating frequency of the second filar element.
The filar antenna according to claim 1, wherein the first filar element and the second filar element are either attached to a carrier or supported by the carrier; the carrier is shaped to a predetermined geometry; the first element, the second element, and the third element are shaped appropriately such that each trace a helical path from its first end to its second distal end across the carrier; the fourth element and the fifth element are shaped appropriately such that each trace a helical path from its first end to its second distal end across the carrier; the first element and the second element are separated by a first spacing; the first element and the third element are separated by a second spacing; the fourth element and the fifth element are separated by a third spacing; and the second filar element is disposed at a fourth spacing from the first filar element.
The filar antenna according to claim 1, further comprising: a feeding network on a circuit board comprising the ground plane and a combining network with a plurality of feed points; and a filar antenna with an equal plurality of filar nodes, wherein said combining network comprised of circuit elements effective to constructively sum microwave electrical signals present at each of said feed points, each of said electrical signals having a predetermined relative phase relationship, each of said feed points connected to a corresponding one of said filar nodes; said filar antenna comprising a plurality of the first filar elements arranged around and above the circuit board and a plurality of the second filar elements arranged around and above the circuit board.
The filar antenna according to claim 4, wherein the plurality of first filar elements and the plurality of second filar elements are either attached to a carrier or supported by the carrier; the carrier is shaped to a predetermined geometry; the first element, the second element, and the third element are shaped appropriately such that each trace a helical path from its first end to its second distal end across the carrier; the fourth element and the fifth element are shaped appropriately such that each trace a helical path from its first end to its second distal end across the carrier; the first element and the second element are separated by a first spacing; the first element and the third element are separated by a second spacing; the fourth element and the fifth element are separated by a third spacing; each second filar element of the plurality of second filar elements is disposed at a fourth spacing from a preceding first filar element of the plurality of first filar elements in the alternate arrangement; and each second filar element of the plurality of second filar elements is disposed at a fifth spacing from a succeeding first filar element of the plurality of first filar elements in the alternate arrangement.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This patent application claims the benefit of priority from U.S. Provisional Patent Application 63/370,774 filed August 8, 2022; the contents of which are incorporated herein by reference. FIELD OF THE INVENTION This patent application relates to global navigation satellite systems and more particularly to antennas, antenna elements and antenna assemblies employing compact multi-element single band and multiband antenna filar elements. BACKGROUND OF THE INVENTION A global satellite navigation system (satnav) or global navigation satellite system (GNSS) is a system that exploits a network of autonomous geo-spatially positioned satellites to provide geolocation and time information to a suitable receiver anywhere on or near the Earth where there is an unobstructed line of sight. In applications where relatively low precision is required low complexity surface mount patch antennas are generally employed accessing a single GNSS signal. However, other applications requiring high precision of timing and/or location require accurately tuned, wider bandwidth, antennas which, ideally, support multiple frequency operation providing higher fidelity reception and thereby improved multipath rejection and better output phase linearity. Even within these applications there is a constant drive for compact multiband antennas that can be easily integrated into portable devices or more generally into mobile platforms and equipment. These antennas should provide a controlled radiation pattern, namely a uniform coverage of the upper hemisphere of their radiation pattern and circular polarization purity to improve cross-polarization rejection and hence multipath rejection. Further, low profile, low weight and smaller footprint are of particular importance for applications such as Unmanned Aerial Vehicles (UAVs) and for personal tracking, etc. Accordingly, it would be beneficial to provide antenna elements that support these requirements whilst enabling operation across multiple GNSS. However, these GNSS specifications when combined define a wider operating frequency range at the lower band between approximately 1.160GHz to 1.300GHz (140MHz) than at the upper band between approximately 1.559GHz and 1.610GHz (51MHz). Within the prior art designs typically provided wider bandwidth operation at the upper band relative to the lower band. It would therefore be beneficial to provide GNSS equipment designers with GNSS antenna designs that provided improved performance in the lower band enabling operational compatibility with multiple GNSS systems. Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures. SUMMARY OF THE INVENTION It is an object of the present invention to mitigate limitations within the prior art relating to global navigation satellite systems and more particularly to antennas, antenna elements and antenna assemblies employing compact multi-element single band and multiband antenna filar elements. In accordance with an embodiment of the invention there is provided a filar antenna comprising: a ground plane;a feed point proximate the ground plane; anda first filar element comprising: a first element having a first end electrically coupled to the feed point and a second distal end;a second element having a first end electrically coupled to the ground plane and a second distal end; anda third element having a first end electrically coupled to the ground plane and a second distal end; whereinthe second distal end of the second element is electrically connected to the second distal end of the first element;the second distal end of the third element is electrically connected to the second distal end of the first element;a first electrical length from the feed point to the ground plane via the first element and the second element is established in dependence upon a multiple of a half wavelength of a first operating frequency of the first filar element; anda second electrical length from the feed point to the ground plane via the first element and the second element is established in dependence upon the same multiple of a half wavelength of a first operating frequency as that of the first electrical length. In accordance with an embodiment of the invention there is provided a filar antenna comprising: a feeding network on a circuit board comprising a ground plane and a combining network with a plurality of feed points; anda filar antenna with an equal plurality of filar nodes, whereinsaid combining network comprised of circuit elements effective to constructively sum microwave electrical signals present at each of said feed points, each of said electrical signals having a predetermined relative phase relationship, each of said feed points connected to a corresponding one of said filar nodes;said filar antenna