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MULTIBAND VHF/UHF TUNED SHORTING-PIN ANTENNA EMBEDED IN AERODYNAMIC SURFACES

IP.com Disclosure Number: IPCOM000244884D
Publication Date: 2016-Jan-26
Document File: 18 page(s) / 4M

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The IP.com Prior Art Database

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701142: IP.COM

Abstract

The present invention refers to an electrically small antenna for communications at very high frequency (VHF) and ultra-high frequency (UHF) bands, featuring both a wideband behavior at each regime and the ability of integration into electrically small prominent substructures (skins) typically employed in unmanned aerial vehicles (UAVs). The antenna assembly comprises: - a monopole radiating element (1), - a coaxial fed point (2) with an electrical ground (3), - a shorting pin-loaded one-port network (4) operatively connected to the radiating element (1) and the electrical ground (3), and - a input loaded two-port network (5) operatively connected to the radiating element (1) and the fed point (2), characterized in that it further comprises (see Fig. 2): -a metallic plane (9) conformal to the supporting structure of the aircraft (fin/stabilizer) (10) and container of the monopole radiating element (1), -a metallic element (11), which includes the coaxial fed point (2) and the electrical ground (3), -a two-port box (12) containing passive circuit elements and electrical switches (14), and located in electrical contact with the metallic plane (9) and the electrical ground (3) of the metallic element (11), and -a one-port box (13) containing passive circuit elements and electrical switches (15), located in electrical contact with the metallic plane (9) and the coaxial fed point (2) of the metallic element (11), being the metallic plane (9), the metallic element (11), the two-port box (12) and the one-port box (13) forming an electrical circuit such that in use a closed loop is described by a current path flowing from the coaxial fed point (1) to the electrical ground (3) through the passive circuit elements and electrical switches (14), the radiating element (1) and the passive circuit elements and electrical switches (15).

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    MULTIBAND VHF/UHF TUNED SHORTING-PIN ANTENNA EMBEDED IN AERODYNAMIC SURFACES

5 FIELD OF THE INVENTION

        The present invention is related to antenna architecture design. More specifically it presents a multiband electrically small antenna for communications at very high frequency (VHF) and ultra-high frequency (UHF) bands, featuring 10 both a wideband behavior at each regime and the ability of integration into electrically small prominent substructures (fiber reinforced plastic parts) typically employed in aircrafts. Therefore, this invention solves the problem arisen in the design of VHF/UHF wideband antennas for aircrafts (specially for UAVs, due to their smaller size and lower loads they bear). More specifically, it achieves 15 simultaneously: a) a solution for the problem of the reduced size available in comparison with the operating wavelength (usually named as electrically small space); b) a wideband capability of the antenna in the VHF/UHF bands (required for integrating UAVs into non-segregated airspace); c) a conformal element embedded on the aeronautical structure (extending in this way the aerodynamic 20 and structural functionality of the skins of the UAVs, now acting also as electrical substrates of antennas); and d) an accessible integration of the sensitive components for maintenance, diagnostics and repairing (enabling the interchangeability requirement, applicable to traditional VHF/UHF antennas, on those modules, avoiding to apply this requirement to the whole structural part).

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BACKGROUND OF THE INVENTION

        Development of UAVs demands for electronic equipment able to operate in such structures. Communication systems at UAVs are challenging because of 30 the reduced available space in UAVs platforms, the high density of electrical subsystems which can eventually interfere, and the aerodynamic/environmental issues which require for both robustness and reliability. Electrical requirements for the antennas used by those communication systems are varying depending


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on the intended purpose of the UAV. However, the capability of an on-flight VHF/UHF communication is a requirement for certification, enabling the UAV to fly in non-segregated air space. Independently of the size of the UAV VHF/UHF antennas shall be integrated in the air vehicle.

        Antenna integration in aircrafts introduces structural penalty due to the holes that must be performed into the skins, and the additional weight ef the antenna introduced. Moreover, additional requirements such as maintainability or ground plane for the antenna result on a complex integration. In this context, the 10 available locations for the antennas are limited, which in small aircrafts with many communications systems, such as UAVs, antenna coupling, interference or compatibility requirements become challenging issues.

        Multitude of the designs composes the background of antennas able to 15 operate at VHF/UHF regimes at aircrafts. Wire antennas, monopoles, load...