Losses at mast head

[Andrew Thornett]

Nooelec’s docs list the SAWbird+ H1 (no 50 Ω “reference” termination present) at ≈0.8 dB NF and the versions that include the internal 50 Ω reference/termination at ≈1.05 dB NF — so the internal termination/added loss raises the measured noise figure by about 0.25 dB according to Nooelec.

Compare this to effect of coaxial connectors at the masthead.

Typical insertion-loss values per connector (per mated pair), based on standard RF practice. These are not exact numbers for a specific brand but the commonly accepted engineering averages.

SMA ⬄ SMA

• Good-quality stainless SMA pair: 0.05–0.1 dB
• Brass SMA pair: 0.1–0.2 dB
• Cheap/poor-quality SMA: sometimes 0.2–0.3 dB

At L-band (1.4 GHz), the usual real-world figure engineers use is:
➡️ ~0.1 dB per SMA connection

N-type ⬄ N-type

N-type connectors are physically larger and normally have slightly lower loss:

• Precision N-type: 0.02–0.05 dB
• Standard N-type: 0.05–0.1 dB

At L-band (1.4 GHz):
➡️ ~0.05 dB per N-type connection

Comparison

Connector Type	Typical Loss per Mated Pair (1.4 GHz)
SMA–SMA	≈0.1 dB
N–N	≈0.05 dB

Practical guidance for radio astronomy

• Losses add up very quickly in front of your LNA.
• Two SMA connectors + a short cable + one more adapter can easily be 0.3–0.4 dB, which is large compared with an LNA NF of 0.8 dB.

[Alex P]

The Value of intentionally degrading the performance of the System by adding noise from an option not useful to your application Being  ?

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