I have very little knowledge about antennas (I just read about simple dipoles and monopoles recently) and I need to buy a directional antenna for my wireless device. I have found a cheap antenna (I know cheap eBay antennas are not what the sellers claim) and I want to know more about the antenna before buying it. The seller listed that it has an 8dbi gain, <2 VSWR and they didn't provide the radiation pattern. I have an image of the antenna elements, can you please tell me the type of the antenna? Then, I can read some more about this specific type.
Inside, it is formed by two plates. The driven element is a 40x50mm plate. The reflector is larger, curved, and grounded. A black plastic is there between the plates but there is a metal bolt in the center causing electrical contact between the plates.
Edit: Is the metal bolt okay in this design? It is sorting the patch and the ground.
Please forgive me if this is a very common antenna. As I have said, I am very new to this.