The station transponder is private by default.
Just look at the stations tab and check your station - you should see all persons you have given access (and their rights) as well as 4 options for Company, Friends, Group and All. These are the transponder settings and are by default off (so only you can see them).
To activate them (I know, not what you ask) you click on the signal symbol and it should now be purple instead of grey. To deactivate an option just do the same.
And access to stations is done by whitelisting, so sadly you have to add every single person you want to have access.