I'm living at the 6th's and top floor of an apartment building. I have a balcony with a metal balustrade. Above the balcony there is a metal roof rail. I need an antenna which won't be noticed by the house owner or which can be put away easily while not being used.
One thought I had was talking to my neighbor, who has a balcony roughly 6m away, whether I could throw a cable over. If this is done close to the wall it might be hardly noticeable from the ground. The issue I see is that both ends will end close to the metal balustrades and be close to the house wall which I fear will be causing trouble with emitting and receiving radio waves in good quality.