About the Bandwidth Extension option
R&S
®
SMW-K555
10
User Manual 1179.5776.02 ─ 01
Figure 2-1: Bandwidth extension without phase corrections
A
= Band A
B
= Band B
f
BW A
= Bandwidth band A
f
BW B
= Bandwidth band B
f
BW
= Extended bandwidth of band A and band B
f
c A
= Center frequency band A
f
c B
= Center frequency band B
f
c
= Center frequency of band A and band B
f
OL
= Bandwidth overlap between band A and band B
Ideally, the resulting baseband signal has an extended bandwidth f
BW
=
f
BW A
+
f
BW B
at
center frequency f
c
. In reality, destructive interference effects occur at the bandwidth
overlap f
OL
and result in a signal level drop at f
c
. To compensate the signal level drop,
phase corrections are added so that signal level of the resulting band A+B is constant
over the whole bandwidth range f
BW
.
Figure 2-2: Bandwidth extension with phase corrections
A+B = Extended band A+B with corrected overlap
f
BW
= Extended bandwidth of band A and band B
f
c A
= Center frequency band A
f
c B
= Center frequency band B
f
c
= Center frequency of band A and band B
You can obtain phase correction data, for example, from a coupled alignment source
after combining the baseband signals. The alignment source can be a power sensor or
a spectrum analyzer. Also, this alignment source has direct feedback (LAN) to base-
About Bandwidth Extension