Testing internal vs. external antenna strengths

Due to placement of a Particle Photon I am building (inside a metal box), I needed to buy an external antenna. I was curious what kind of performance difference a full-sized antenna would get me in a bench setting, sitting in a room about 10m from my router.

Refresher: you can force the active antenna using one of the following commands before the setup() function:

STARTUP(WiFi.selectAntenna(ANT_EXTERNAL)); // Use external antenna
STARTUP(WiFi.selectAntenna(ANT_INTERNAL)); // Use internal antenna

Antenna stats: 6dB, Omni-directional. This is your run-of-the-mill wifi antenna.

Internal Antenna metrics: -57dBm, 65mbit tx rate, 52mbit rx rate
External Antenna metrics: -51 dBm, 65mbit tx rate, 65mbit rx rate

I have to say I was very surprised at the relative similarity between the tiny integrated antenna and the giant external antenna. Particle has done a very good job getting solid performance out of their reference design product. It is clear to me from this that the only time you’d need an external antenna would be in the event the photon is put inside something attenuating signal. In other words, consider an external antenna simply as a relocated antenna, not a better antenna.

Pic of the setup. Ignore all of the extra stuff; this Photon is going to live its life as a Pool House automation system.

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@qwerty if I remember correctly, dBm is a log scale such that 3 dB change is a factor of 2. So the external antenna is -6 dB higher is 4x stronger signal. 10 dB difference is 10x difference in the signal.

The internal antenna is great for being in the same room, but can be marginal at the far end of a house or upstairs. Poor reception if located in a metal box.