Well, I’ll take a crack at this since no one else has. You’ll have to translate my post back to French though. Here’s a Google Translation of your post:
>>hello, I'm new ... I'm trying to understand why my portable rsdioamateur is limited to frequencies 140 to 170 and 400 to 465.. is it because of the settings in the menu or my antenna?
all i want is to be able to listen to the police, ambulance, alert and regional news frequencies from the laurentians, montreal and Quebec.
Can you help me please?
thank you<<
I‘m going to make a guess here, based on the frequencies you listed, that your radio is a Baofeng or similar Chinese radio. Is that correct? If so, most of those radios are intended for the amateur radio and/or business communications markets. Most are analog only. They are limited to the frequencies you listed not by the antenna, but by the internal electronics. They work on the radio bands they are intended to be used on. No more, no less. They are not scanners.
I’m not 100% certain of your location, but it seems Montreal is of interest. It looks like much of the public safety in Montreal is on this radio system:
SERAM - Systeme evolue de radiocommunications de l'Agglomeration de Montreal Trunking System Profile
www.radioreference.com
Since your radio is not capable of decoding digital signals, and does not receive those frequency bands anyway, you are not going to be able to monitor that radio system with your radio. You would need a digital scanner. Since that system appears to be simulcast I would recommend a Uniden SDS100 or SDS200. It would allow you to monitor the Montreal fire & medical radio calls, but the Montreal police are encrypted, so you will not be able to receive the police with any radio.
There is a Quebec forum here at Radioreference. You might ask a moderator to have this thread moved there so people in your area can help you. I’m sure plenty of French speakers will be there as well.
Hope that helps.
Bonne chance !
.