Re: NEC-LIST: URBAN ANTENNAS

Are we talking reflections in the far field or the near field? Once you're
in the far field, I wouldn't think it makes much difference. In the near
field, sure, but discontinuities in the near field of ANY antenna cause
changes in the pattern.

As for power from one element going out and reflecting off something and
coming back to to another element and reradiating... If you do the bistatic
radar calculation you'll find that the there's not very much power coming
back. I was just doing some calculations for putting something in front of
an 1.5 meter array (at 7 GHz) to deliberately introduce a -20dB reflection,
and I was surprised how big an object it takes.

The usual flat panel array is some sort of slotted radiator or an array of
patches. If flat, there is the whole problem of travelling waves
propagating across the surface, but again, whether it's in a multipath
environment or not probably isn't a big deal.

"zvi frank" <zvi_f_at_mti-group.co.il> writes:
> Hi All,
> I recently received comments from various sources that flat panel
> array antennas are unsuitable for use in an urban environment. The reason
> given was that since these usually constitute a planar array of elements .
> In such a case multiple reflections could result in different phasing
> between the various elements and hence lowering og the resultant gain of
the
> structure.
> Is anyone familiar with this effect? How can one overcome this effect?
> what sort of elements would be suitable?
> Thanks in advance,
> Zvi
>
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