Decoupled Inner Slot Antenna for Phased Array Grating Lobe Reduction
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Solution Overview
Problem
Current antenna technologies, such as Tightly Coupled Dipole Antennas and Vivaldi arrays, face challenges in reducing grating lobes as frequency increases and require a large number of RF ports, making them unsuitable for conformal and airborne applications.
Innovation Solution
The integration of a Wideband Slot Antenna within a larger electric dipole or cross dipole antenna structure, utilizing a De-Coupling gap to isolate the inner and outer antennas, along with a compact single pole wideband slot antenna design with inverted co-planar waveguide feed, allowing for independent feeds and transmission lines, thereby reducing mutual coupling and increasing frequency bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Tightly Coupled Dipole Antennas are used to reduce antenna spacing and achieve wide bandwidth, then frequency bandwidth is improved (up to 100:1 ratio), but the number of RF ports increases extremely
Solution Approach 1:
The patent implements nested antenna structures where inner slot antennas are positioned within the conductive areas of outer dipole antennas. Multiple frequency bands are achieved by nesting different sized slot antennas (first, second, and third slot antennas) within the same conductive space, allowing wide bandwidth operation without proportionally increasing RF ports.
Solution Approach 2:
The outer dipole antenna structure serves multiple functions: it acts as a radiating element for lower frequencies and simultaneously provides the conductive area within which inner slot antennas operate at higher frequencies. This multi-functionality reduces the total number of separate antenna structures and RF ports needed.
2Shape
If Vivaldi arrays are used to achieve conformal antenna design, then conformality is improved, but grating lobes increase as frequency increases and volume consumption increases
Solution Approach 1:
The patent uses nested slot antennas within dipole structures to achieve frequency interleaving, where inner antennas at higher frequencies are positioned within the conductive areas of outer antennas at lower frequencies. This nesting approach reduces grating lobes by maintaining proper spacing relationships across the frequency spectrum while enabling conformal mounting.
3Volume of moving object
If simple slot structures are placed within antenna elements, then compactness is improved, but mutual coupling between inner and outer antennas increases
Solution Approach 1:
The patent introduces decoupling structures including decoupling slots and decoupling conductors positioned between the inner slot antennas and outer dipole antennas. These intermediary elements act as electromagnetic barriers that reduce mutual coupling while allowing the compact nested configuration to be maintained.
Solution Approach 2:
The patent divides the antenna system into segmented functional regions with decoupling structures that separate the inner and outer antenna elements. The decoupling slots and conductors create electromagnetic isolation zones that segment the coupling paths between nested antennas, reducing harmful interactions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables a compact, conformal antenna design with reduced grating lobes and fewer required RF ports, supporting a wider frequency range while maintaining independent operation of inner and outer antennas.
Implementation Method 1
A de-coupling gap isolates the monopole antenna structure from the inner antenna slot conductor and slot antenna tuning element
Implementation Method 2
The RF Electric Field generated from the inner Slot Antenna is generated between the Inner Antenna Slot Conductor and the Tuning Element
Data Source
AI summary
In the design of phased array antennas, as well as simple use of compact antennas, there is a strong interest to locate higher frequency antennas closer in spacing, and/or on the same surface, as the larger frequency antennas. What is needed is an array antenna technology, which can be conformal, and can interleave elements, as the frequency increases, to reduce array grating lobes. The desired solution would have much fewer required RF antenna ports, than the Tightly Coupled Dipole Antenna solutions. The optimal solution would also enable Dual or Diverse Polarization. This innovation embeds a wideband Slot Antenna, within the physical area of a larger electric dipole Antenna or Cross Dipole Antenna, with a De-Coupling gap around the Slot Ground Plane (or conductor) and isolates the Wideband Slot Antenna (the inner antenna) from the Dipole or Monopole antenna leg(s) (the Outer Antenna). Both (Inner and Outer) antennas have independent feeds and independent transmission line(s). Two key innovations are the use of a De-Coupling gap, and the use of the patent pending innovation “Compact Single Pole Wideband Slot Antenna Design with Inverted Co-Planar Waveguide Feed”. Both the Inner Slot Antenna and its CPW feed are independent and isolated from the Outer Antenna and its feed and transmission line. This structure, which could have a multiplicity of inner Slot Antennas with numerous RF ports, is very different from the slot or parasitic inner structure within a single port antenna system.