observing the phase pattern of a corrugated horn antenna in HFSS , the phase gap between -20 deg and 20 deg is a little big, not reach the requirement ,who knows What can influence the phase characteristics of a corrugated horn antenna ? Thanks!
Hi,
As I understood, corrugated antenna is something like a slow wave structure. May be, i am wrong, but if you use periodic boundary condition, then you will get correct results.
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Thanks,
Please can you clarify what you mean by the phase gap - do you mean the phase change, or the movement of the phase centre, or something else?
Malcolm White Sorry,my English is poor. In HFSS ,setting like this: rE------rEY-------ang_deg ,There will be a group of curves ,the gap of these curves between -20 deg and 20 deg. And do you know how to find the phase centre ,how to set in HFSS? Thanks!
I do not recognise what you are describing. It may be that you are talking about the phase curvature across the aperture, by which I mean the difference in phase between a flat phase front and the roughly spherical phase front that is at the aperture of most corrugated horns. This can be plotted against radius or against angle, although I am more used to plotting it against radius. The curvature of the phase front is determined by the length of the taper and by the radius. The only way to reduce it is to make the taper longer or to put a lens in the horn, usually in the aperture. Because the size of the gap between curved phase front and the aperture plane doesn't change with frequency, the phase across it increases with increasing frequency. If you want a minimum-beamwidth antenna, the phase should not be more than about 1/8 wavelength at the top frequency you want it to work at.
In case you are measuring in 'Fresnel Region', it can happen as in this region you won't find phase stability, in turn, pattern stability. If so, use Fronhoffer rgion for the measurement. Also, Corrugation will create more irregularity in fresnel region.
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