AIS Antenna?

[CaptnBry]

A regular marine VHF antenna is the right length for AIS. If you are using a telescopic antenna, extend it to 17 inches. I use an active splitter on my regular VHF marine antenna and it works well. Don't put a passive splitter on, as you will destroy your AIS receiver the first time you transmit on your VHF.

Sent from my P027 using Tapatalk

OK, I'm confused:
If people are using VHF antennas for AIS, the 1/4 wavelengths cannot be optimal?
VHF 30-300MHZ
AIS 161.975-162.025 Mhz

Not VHF - MARINE Vhf. 156 - 162Mhz.  You could argue slightly out centered a little low but for receive you won't notice the difference.

Thank you , that makes sense
So the SDR-RTL Calibration routine that tunes to GSM-850 (USA, California AIS ) and finds a Channel around 889MHz can be ignored in terms of antenna frequency?