Parasitic Antenna Array Load Circuit for High-Frequency Impedance Control
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Solution Overview
Problem
Current parasitic antenna arrays fail to produce requisite impedances for high efficiency operation at higher microwave frequencies, particularly above 3 GHz, due to neglecting interconnect impedance effects in their designs.
Innovation Solution
A parasitic antenna array design that includes a substrate, a monopole element, a ground plane, and a plurality of parasitic elements connected through load circuits with a DC bias current source, resistors, capacitors, and diodes, which provide adjustable impedance to the parasitic elements, allowing for efficient radiation patterns even at high frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a standard DC bias network with large resistance or inductance is used for RF choke, then the parasitic antenna array can be implemented with simple biasing, but the interconnect impedance effects become significant at higher frequencies causing failure to produce requisite impedances
Solution Approach 1:
The patent extracts and eliminates the problematic large inductance component from the bias network. Instead of using a traditional RF choke with large inductance, the invention uses a compact bias network with small inductance values (e.g., 1-10 nH) combined with capacitive coupling to achieve the same biasing function without the harmful high-frequency impedance effects
Solution Approach 2:
The patent changes the electrical parameters of the bias network by using small inductance values and specific capacitance values (e.g., 0.5-2 pF) that are optimized for high-frequency operation. This parameter optimization allows the network to maintain proper impedance characteristics at microwave frequencies while still providing effective DC biasing
2Ease of operation
If quarter wavelength lines are used for biasing, then DC bias can be provided to parasitic elements, but the interconnect impedance effects become increasingly significant at frequencies greater than 3 GHz
Solution Approach 1:
The patent transitions from using quarter-wavelength transmission lines (one-dimensional approach) to a multi-dimensional biasing solution that combines small inductors, capacitors, and direct ground connections. This creates a three-dimensional bias network structure that is not constrained by the wavelength-dependent limitations of planar transmission lines
Solution Approach 2:
The patent creates a dynamic bias network that adapts to different frequency conditions by using components with frequency-independent characteristics. The small inductance and capacitance values are chosen to maintain proper impedance matching across a wide frequency range, allowing the system to operate efficiently from L-band through Ku-band frequencies
3Device complexity
If currently available parasitic antenna array implementations are used, then variable reactance can be achieved via single component, but the requisite impedances for proper high efficiency operation at higher microwave frequencies cannot be produced
Solution Approach 1:
The patent segments the single-component reactance control into a multi-component bias network that includes small inductors, capacitors, and diode-based variable reactance elements. This segmentation allows independent optimization of each component's function, enabling precise impedance control that maintains high radiation efficiency at microwave frequencies while still providing variable reactance control
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
The design achieves improved RF and DC performance, enabling efficient operation up to Ku band frequencies (15 GHz) with increased directional gain and power handling capabilities, while reducing size, weight, and cost compared to existing antennas.
Implementation Method 1
a monopole element, the monopole element being connected to the substrate, the monopole element configured for radiating electromagnetic energy in an omni-directional radiation pattern
Implementation Method 2
a plurality of diodes, the plurality of diodes being connected to the parasitic elements, each diode in the plurality of diodes configured for controlling a respective current flow to and from the parasitic elements
Implementation Method 3
a plurality of capacitors, the plurality of capacitors being connected to the parasitic elements, each capacitor in the plurality of capacitors configured for storing electrical energy
Implementation Method 4
a DC bias current source configured for providing a direct current to the plurality of diodes and the plurality of capacitors
Data Source
AI summary
The present invention is load circuit for a parasitic antenna element of a parasitic antenna array. The load circuit may include a DC bias current source, a resistor connected to the DC bias current source, one or more capacitors connected to the resistor, and multiple (ex. —two) diodes connected to the parasitic antenna element. The first diode may be configured for directly connecting the parasitic element to a ground plane of the parasitic antenna array. The second diode may be configured for connecting the parasitic element to the ground plane via the one or more capacitors. The load circuit may be configured for providing a variable (ex. —adjustable) impedance to the parasitic antenna array.