Conformal Surface Wave Feed Tapered Microstrip Impedance Matching
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Solution Overview
Problem
Conventional low-profile waveguide surface-wave couplers are non-conformal, suffer from high insertion loss, radiate power into free space, and have limited bandwidth, making them inefficient for launching surface waves onto conformal artificial impedance surface antennas.
Innovation Solution
A conformal surface wave feed that transitions energy from a coaxial line to a tapered microstrip line, matching wave speeds between the microstrip and surface-wave media substrates to minimize insertion loss and maximize bandwidth, using a dielectric substrate with electrically conductive patches and a Klopfenstein impedance taper to ensure efficient energy transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a low-profile waveguide surface-wave coupler is used, then the device can feed surface-wave antennas, but the insertion loss is much higher
Solution Approach 1:
The patent applies parameter changes by carefully selecting and varying the permittivity values of dielectric substrates in the transition section. The microstrip substrate has a first permittivity and the surface wave medium substrate has a second permittivity, with an intermediate permittivity value in the transition region to gradually match impedances and minimize insertion loss.
Solution Approach 2:
The patent introduces an intermediate transition structure with specific permittivity values between the microstrip line and the surface wave medium. This intermediary substrate acts as a mediator to facilitate smooth impedance transformation and reduce reflection losses.
2Adaptability or versatility
If a low-profile waveguide surface-wave coupler is used, then the device can feed surface-wave antennas, but the bandwidth is lower
Solution Approach 1:
The patent achieves broadband performance through parameter changes by optimizing the permittivity values and geometric dimensions of the transition structure. The gradual variation in permittivity and the tapered geometry enable wideband impedance matching across frequency bands.
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 conformal surface wave feed achieves insertion losses of less than -25 dB and broad phase front distribution, enabling efficient energy transfer and power/data transmission in conformal artificial impedance surface antennas with improved bandwidth and reduced power radiation.
Implementation Method 1
A conformal surface wave feed (CSWF) provides a transition from a coaxial line or other transmission line to surface wave transmission that can be used to launch a surface wave onto surface-wave media
Implementation Method 2
The permittivity of the MS substrate is lower than the permittivity of the SWM substrate in order to match the wave speeds between the MS and the surface wave, thus minimizing insertion loss from the MS to the SWM
Data Source
AI summary
A transmission line feed for a surface wave medium having a dielectric substrate with an array of electrically conductive patches formed thereon. The transmission line feed includes a microstrip substrate, the microstrip substrate having a first permittivity which is lower than a second permittivity of the dielectric substrate of the surface wave medium, the microstrip substrate abutting against the dielectric substrate of the surface wave medium; a tapered microstrip disposed on the microstrip substrate, the tapered microstrip tapering from a relatively narrow end to a relatively wide end, the relative wide end terminating where the microstrip substrate abuts against the surface wave substrate; and an adapter for coupling a transmission line to the relatively narrow end of the tapered microstrip.