Design of leaky-wave antennas with transverse slots for end-fire radiation with optimized radiation efficiency
<p>A substrate integrated waveguide (SIW) with transverse slots on the top plane can be used to design an effective leaky-wave antenna with good frequency beam-scanning and platform integration capability. For a main beam near end-fire, the phase constant of the radiating wave must be near to...
| Main Authors: | , |
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| Format: | Article |
| Language: | deu |
| Published: |
Copernicus Publications
2019-09-01
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| Series: | Advances in Radio Science |
| Online Access: | https://www.adv-radio-sci.net/17/71/2019/ars-17-71-2019.pdf |
| Summary: | <p>A substrate integrated waveguide (SIW) with transverse
slots on the top plane can be used to design an effective leaky-wave antenna
with good frequency beam-scanning and platform integration capability. For a
main beam near end-fire, the phase constant of the radiating wave must be
near to the free space wavenumber or slightly larger. In this context, the
modified Hansen-Woodyard condition gives an optimum phase constant to
maximize the directivity at end-fire. For the analysis of the wave
propagation we have implemented a modal analysis for rectangular waveguides
with transverse slots. Near end-fire, three types of modal solutions exists,
a leaky improper mode, a surface wave mode and a proper waveguide mode. The
leaky mode can reach phase constants larger than the free space wavenumber
to fulfill the Hansen-Woodyard condition, but loses strongly its physical
significance in this slow wave region, thus the excitation of the leaky-wave
becomes negligible there, whereas the proper waveguide mode is dominant but
exhibits only a negligible radiation loss leading to a strong drop of the
antenna efficiency. Therefore, the optimum efficiency of 86 % for
maximizing the gain as proposed in the literature cannot be reached with
this kind of leaky wave antenna.</p>
<p>But it will be shown in this contribution by analyzing antenna structures
with finite aperture lengths, that the efficiency can reach nearly 100 %
if the phase constant of the leaky-wave meets exactly the free space
wavenumber (ordinary end-fire condition) and the aperture length is adjusted
with regard to the attenuation constant of the leaky-wave from the modal
analysis. For a given aperture length, a procedure is outlined to adjust the
attenuation constant in several steps at the desired ordinary end-fire
frequency to reach maximum gain and efficiency.</p> |
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| ISSN: | 1684-9965 1684-9973 |