Default [Q] Does protective case hamper reception and browsing speed?

Hi All,

Does using a protective case like a flip-case or a notebook type case, cover up the antenna or hamper reception and browsing speed in any way?
Also, does it increase heating of the phone?

I recently purchased a Sony Xperia Z1. I have also bought a flip-case for protection. (Image attached)

The case covers the phone edges for protection. I am not sure where the antenna/receptor is situated in Z1. I am worried if covering up the edges might hinder radio reception?

Does anyone know if there is any such issue or any other issues like heating with using protective cases?

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Sony Xperia Z1 (C6902)
Sony Xperia ZR
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