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EP-4362218-B1 - ADAPTIVE TUNABLE ANTENNA

EP4362218B1EP 4362218 B1EP4362218 B1EP 4362218B1EP-4362218-B1

Inventors

  • MAJKOWSKI, Joseph
  • Packer, Malcom
  • LOPEZ ARAGONES, Luismael

Dates

Publication Date
20260506
Application Date
20230926

Claims (10)

  1. An adaptive tunable antenna system (100), comprising an antenna feed (112), a first radiating element (104) having an elongated length extending from a first proximal end (108), adjacent to the antenna feed (112), to a first distal end (110); a second radiating element (106) extending from the first distal end (110) and comprising a helical member (118) extending along a central axis (124) from a second proximal end (114) to a second distal end (116) and defining a plurality of turns (122); a diplexer (204) configured to frequency multiplex high-band RF energy between the antenna feed (112) and the first radiating element (104), and low-band RF energy, having a lower RF frequency than the high-band RF energy, between the antenna feed (112) and the second radiating element (106); a low-band circuit (216) disposed in an internal lumen defined by the helical member (118) and configured to selectively bypass one or more of the plurality of turns (122) in response to a control signal by coupling low-band RF energy from an end feed point of the second radiating element (106) adjacent the second proximal end (114), to one or more of the plurality of turns (122) intermediate of the second proximal end (114) and the second distal end (116).
  2. The antenna system (100) of claim 1, wherein the first radiating element (104) is comprised of a tubular member (302) having a central bore extending along the elongated length.
  3. The antenna system (100) of claim 2, wherein the tubular member (302) is a gooseneck structure.
  4. The antenna system (100) of claim 2, wherein the diplexer has a high-band antenna port and a low-band antenna port and wherein the antenna system (100) further comprises a high-band matching circuit (206) coupled to the high-band port of the diplexer (204) and to the first radiating element (104), the high-band matching circuit (206) configured to facilitate an impedance match between the first radiating element (104) and a transceiver (102) when connected to the antenna feed (112).
  5. The antenna system (100) of claim 4, wherein the diplexer (204) and the high-band matching circuit (206) are both disposed in a base housing (109) disposed at the first proximal end (108).
  6. The antenna system (100) of claim 2, further comprising a shielded transmission line (208) coupled to the low-band port of the diplexer (204), the shielded transmission line (208) extending through the central bore and connected to the low-band circuit (216), wherein a shield of the shielded transmission line (208) is connected directly to the distal end (110) of the first radiating element (106).
  7. The antenna system (100) of claim 6, further comprising a boundary control unit (214) disposed along a portion of the shielded transmission line (208) configured to selectively allow RF energy to be coupled to the low-band circuit (216) through the shielded transmission line (208) when in a first condition and prevent coupling of RF energy to the low-band circuit (216) in the second condition, and/or wherein the control unit (214) comprises a ferrite choke (220), the ferrite choke (220) surrounding a part of the shielded transmission line (208), and an electronically controlled switch (222), the electronically controlled switch (222) comprising a first and a second terminal, wherein the first and the second terminal are connected to the shield of the shielded transmission line (208) on opposing sides of the ferrite choke (220).
  8. The antenna system (100) of claim 7, wherein the low-band circuit (216) is comprised of a low-band control unit and a plurality of switches (218) which are responsive to the low-band control unit to bypass one or more of the plurality of turns (122).
  9. The antenna system (100) of claim 8, wherein the low-band circuit (218) includes an RF choke (502) connected to a shielded conductor (518) of the shielded transmission line (208) to couple a DC supply voltage (516), when present on the shielded conductor (518), to the low-band circuit (216).
  10. The antenna system (100) of claim 1, wherein the helical member (118) is disposed within a low-band housing (113) comprising a radome.

Description

BACKGROUND Statement of the Technical Field The technical field of this disclosure concerns wireless communications, and more particularly methods and systems for antennas which are operable over a wide range of frequencies. Description of the Related Art The related art concerns methods and systems for antennas that are used in radio communications. Antennas used in portable operations often need to support operations over a wide range of frequencies in the VHF and/or UHF bands. In order to maximize operational effectiveness and minimize power consumption it is important that such antennas efficiently radiate RF energy . However, simple antenna structures such as monopole antennas will usually provide efficient performance over only a relatively narrow frequency range. This frequency range is sometimes referred to as the operational bandwidth of the antenna. Antenna efficiency can be affected by several factors. For example, the physical dimensions of an antenna will usually have a material effect on its efficiency. The physical size or length of an antenna will affect its resonant frequency and it is recognized that antennas often perform more efficiently when operating at or near their resonant frequency. Another antenna design consideration is impedance match. A transceiver transfers RF power to and from an antenna most efficiently when the input impedance of the antenna is properly matched to the output impedance of the transceiver. However, the input impedance of the antenna will naturally vary as a function of frequency. Accordingly, it can be challenging to achieve impedance matching with an antenna over a wide range of operating frequencies. This can lead to a high voltage standing wave ratio (VSWR) in the antenna feed line at certain frequencies. Adjustable antenna matching circuits disposed between a transceiver and an antenna can provide a mechanism to match the impedance of the antenna to the transceiver. Examples for tunable antennas and antenna systems are disclosed in the documents US 2013 / 009 832 A1, US 2019 / 173 179 A1, US 3 852 759 A, US 6 169 523 B1 and US 4 924 238 A. SUMMARY The invention is defined by independent claim 1. Further embodiments are defined by the dependent claims. This document concerns an adaptive tunable antenna system. The system is comprised of first and second radiating elements. The first radiating element has an elongated length extending from a first proximal end, adjacent to an antenna feed, to a first distal end. The first radiating element can be a tubular member having a central bore extending along the elongated length. In some scenarios, the tubular member is comprised of a gooseneck structure. The second radiating element extends from the first distal end and is a helical member. The helical member extends along a central axis from a second proximal end of the helical member to a second distal end of the helical member and includes a plurality of spiral turns. In some scenarios, the helical member is disposed within a low-band housing comprising a radome. The system also includes a diplexer configured to frequency multiplex high-band RF energy between the antenna feed and the first radiating element, and low-band RF energy, having a lower RF frequency than the high-band RF energy, between the antenna feed and the second radiating element A low-band circuit of the antenna system is disposed in an internal lumen defined by the helical member. However, in an embodiment not encompassed by the appended claims, the low-band circuit can be at least partially disposed in the internal lumen defined by the helical member. The low-band circuit is configured to selectively bypass one or more of the plurality of turns in response to a control signal. The bypassing operation involves coupling low-band RF energy from an end feed point of the second radiating element adjacent the second proximal end, to one or more of the plurality of turns intermediate of the proximal end and the distal end. A high-band matching circuit can be coupled to a high-band port of the diplexer and to the first radiating element. As such, the high-band matching circuit can facilitate an impedance match between the first radiating element and a transceiver which may be connected to the feed point. In some scenarios, the diplexer and the high-band matching circuit are both disposed in a base housing disposed at the first proximal end of the antenna system. A shielded transmission line is coupled to a low-band port of the diplexer. The shielded transmission line (e.g., a coaxial transmission line) can extend from the base housing through the central bore of the first radiating element. The shielded transmission line is connected to the low-band circuit. Further, a shield of the shielded transmission line is connected directly to the distal end of the first radiating element. The antenna system also includes a boundary control unit. The boundary control unit is advantageously disposed along a por