Wideband Active Antenna Feedpoint Buffers for Compact 0.5-18 GHz Operation
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Solution Overview
Problem
Traditional wideband antennas require larger sizes to operate effectively over extended frequency bands, leading to increased size and potential sensitivity degradation when attempting to cover bandwidths like 0.5 - 18 GHz without compromising receive sensitivity.
Innovation Solution
Integration of buffer amplifiers directly at the feedpoint of the antenna, with each amplifier having a signal input terminal positioned adjacent to the antenna arms, allowing for a shorter transmission line and enabling operation over a wider bandwidth without increasing antenna size, including a low-frequency extension band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the antenna size is increased to operate over extended frequency bands, then the bandwidth is improved, but the size becomes larger
Solution Approach 1:
The patent combines the antenna elements with buffer amplifier circuits into an integrated active antenna system. The buffer amplifiers are directly coupled to the antenna outputs, merging the passive antenna structure with active electronic components to extend bandwidth without increasing physical size. This integration allows the antenna to operate over 0.5-18 GHz while maintaining a compact 2.4-inch form factor.
2Adaptability or versatility
If the bandwidth is extended to lower frequencies, then the frequency range is improved, but the receive sensitivity degrades
Solution Approach 1:
The buffer amplifiers are positioned directly at the antenna feedpoint, performing signal amplification immediately upon reception. This preliminary amplification action occurs before signals traverse long transmission lines or undergo multiple processing stages, thereby minimizing signal loss and maintaining high receive sensitivity across the extended frequency range including lower frequencies.
Solution Approach 2:
The buffer amplifier circuits incorporate feedback mechanisms that stabilize gain and improve impedance matching across the wide frequency band. This feedback control ensures consistent receive sensitivity from 0.5 to 18 GHz by dynamically adjusting amplifier characteristics to compensate for frequency-dependent variations in antenna impedance and signal strength.
3Device complexity
If traditional passive antennas are used without buffer amplifiers, then the structure is simpler, but the bandwidth is limited to ~10:1
Solution Approach 1:
The buffer amplifiers serve as intermediary active components between the passive antenna elements and the receiver system. These intermediaries provide impedance transformation and signal conditioning that enable wideband operation, bridging the gap between the simple passive antenna structure and the requirements for 0.5-18 GHz bandwidth without requiring complex matching networks or multiple antenna elements.
Data Source
Figure 1(a)~1(d)
Figure 2(a)~2(b)
Figure 2(c)~2(e)
AI summary
A wideband active antenna system comprising an antenna having N outputs and a nominal bandwidth, each of the N outputs being directly coupled to an associated buffer amplifier, with a distance between the N outputs and a first active stage of each associated buffer amplifier preferably being maintained as short as reasonably possible and preferably no greater than 1/4 wavelength of any transmission and/or receiving frequency of the wideband active antenna system and/or preferably no greater than 0.1 wavelength of any transmission and/or receiving frequency in an extension band of frequencies lower than a lowest frequency in the nominal bandwidth of the antenna.