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## Re: [TowerTalk] Analysis of phase errors for transmit phased arrays

 To: richard@karlquist.com Re: [TowerTalk] Analysis of phase errors for transmit phased arrays Jim Lux Sun, 15 Jan 2006 20:02:26 -0800
 ```At 06:44 PM 1/15/2006, Rick Karlquist wrote: >Jim Lux wrote: > > In numbers, if you control the phase to within 45 > > degrees, in 99.7% percent of the cases, you'll lose less than a half dB. > > > > The writeup and graphs are at: > > http://home.earthlink.net/~w6rmk/antenna/phased/txtol.htm > > > > > Thanks > > Jim, W6RMK > > > >I didn't see in the report details of what the arrays were >other than # of elements, but the 3rd paragraph says it all: >"doesn't necessarily apply to superdirective arrays". >There are enormous differences in phase sensitivity of different >commonly used amateur arrays. I can certainly give you plenty >of examples where you need to control the phase to a lot better >than 45 degrees to lose less than 1/2 dB. Try end fire arrays >with 3/16 wl spacing, binomial amplitudes. Not too bad with cophasal >currents, but as you increase the phase gradient to get more gain, (and >enter the superdirectivity regime) the array gets extremely sensitive >to phase and amplitude errors. The gain you can get is directly >related to accuracy. On the other hand, broadside arrays will still >work even with fairly large phase/amplitude errors, especially >if you don't care about sidelobes. That's the next step.. to look at superdirective arrays. This analysis is only for arrays where you're using phasing that matches spacing (broadside arrays being a straightforward example). A question about the superdirective array is whether the phasing criticality is the excitation, or the actual radiated phase from the element. Superdirective arrays (in general) store a fair amount of energy in the near field, so the trickiness is in the mutual Z, which is highly sensitive to drive phases. As it happens, the non-superdirective case was easy to run (since I had the models from work). The superdirective case will require cranking up some new models. _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
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