What is the difference between wifi device with and without antenna? Which one is better?

All wifi devices have antennas. That is how they are able to transmit wifi signals. Without antenna there can be no wifi.

Portable devices like mobile phone, chip based wifi adapters, laptop and computers have PIFA (planar inverted-F antenna). They are used because:-

“PIFAs can be printed using the microstrip format, a widely used technology that allows printed RF components to be manufactured as part of the same printed circuit board used to mount other components. ” [1] [2]

“A: printed inverted-F antenna, B: meandered printed inverted-F antenna: C: patch antenna: D: Planar inverted-F antenna (PIFA) ”

In case there is no visible antenna in a Wifi device it is most probably using PIFA.

Visible antennas are of various types [3] depending upon the requirement. Most commonly, though you’ll find dipole antennas on wifi device that are omni directional. That is they can radiate signals in all directions.

An external antenna is better in the sense that it does allow you to have better transmission and reception capabilities. So it will most likely outperform a device that has no external antennas.

The newer wifi devices these days,with external antennas, come with MU-MIMO support (do check the specifications though before buying!) which allow them to introduce parallelism in data transfer. That is transmitting and receiving data from multiple devices at once.

So yes, an adapter with an external antenna is an indication of a better performance (in terms of transmission and reception quality) than a similar device with no external antenna.

[1] https://en.wikipedia.org/wiki/In...

[2]https://en.wikipedia.org/wiki/Pa...

[3]https://www.accessagility.com/bl...

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