Intermodulation product analysis
Which third, fifth and seventh order intermodulation products of a multi-band repeater or DAS design land inside an uplink band, and what that costs on the uplink.
Carriers
Pick the bands the system carries simultaneously. Downlink edge frequencies are used, which is the conservative case for in-band intermodulation.
FDD bands show both the downlink and uplink range. Only FDD bands have an uplink that intermodulation can fall into.
How this is calculated
IM3 = 2f1−f2 and 2f2−f1 · IM5 = 3f1−2f2 and 3f2−2f1 · IM7 = 4f1−3f2 and 4f2−3f1, plus the three-carrier combinations f1+f2−f3 and 2f1+f2−f3. Lower order means more energy, so IM3 is the primary concern; even orders fall far from the carriers and are filtered out. A product within ±1 MHz of a band edge counts as in-band. Noise-floor impact follows ΔNF ≈ PIM + 174 − NF − 10·log10(BW). The PIM level is an input you set, not a prediction — measure it with a PIM tester (IEC 62037-1). This analysis covers frequencies and risk; it does not replace measurement.