What is 1-1478978-0?
It is a through-hole, right-angle mount part with a gold-plated stainless steel body and gold-over-beryllium copper centre contact. The dielectric is PTFE, and the shield is terminated by solder. This is a single-port connector built for RF signal paths where the SMA interface is the standard — test equipment, instrumentation, and microwave sub-assemblies up to 12.4 GHz.
The 12.4 GHz top-end frequency covers L, S, C, and most of X band; if your application runs above that, you need an 18 GHz or 26.5 GHz SMA variant. The 500 mating cycles mean this connector can handle repeated connect-disconnect in test fixtures or field-service gear without the centre contact wearing out — the gold-over-beryllium copper contact is chosen for spring retention over many cycles. Insertion loss is specified at 0.1 dB, which is tight for a right-angle SMA; the right-angle body does add a small reflection compared to a straight launch, but the loss figure says it is well-compensated.