On Aug 4, 5:19*pm, Jim Lux wrote:
Chris wrote:
I've been looking at a few satcom antennas for a project I'm working
on. *We were originally looking at parabolic dishes but have recently
taken a look at slot arrays. *A low profile solution is desirable
which would lead to a small dish or a low (but very wide) slot array.
Some of the people we've talked to have warned us that slot arrays are
narrow bandwidth. *I thought I understood this issue, but I'm
beginning to doubt myself.

Suppose a slot array could transmit at Ka frequencies from 30 to 32
GHz at a bandwidth of 3%. *If the center frequency of transmission is
31GHz a 3% bandwidth would be equal to 930MHz or 465MHz on each side
of the center freq. *This may be narrow to an antenna designer but
this is more spectrum than we'd ever hope to get on the satellite
anyway. *I'm a little confused over why this is an "issue", which
makes me think I have a misunderstanding of the terminology.

Can anyone clear this up for me?

Well.. a parabolic reflector has exceedingly wide bandwidth, and,
furthermore, its beam direction and or focus doesn't change with frequency.

Arrays of dipoles (which is what a slot array is) are (relatively)
narrow band, and the boresight direction/sidelobes may change with
frequency. *The mechanical tolerances may also be tighter.

That said, lots of people use flat slot arrays or printed dipole arrays..
See, e.g.,http://descanso.jpl.nasa.gov/DPSumma...mp20051028.pdf

So it appears the statement is true and technically accurate but in my
case it simply isn't relevant.