On Sat, 1 Mar 2014 13:27:53 -0800, Liam O'Connor
wrote:

In a recent thread, there was speculation on the WiFi specs of
the Apple iPad with respect to similar non-Apple tablets; but,
no proof was provided.

Recent thread where? Article ID please.

This thread is intended to nail down the 3 key WiFi specs of
the Apple iPad.

To start, I ask of all ...

Do you know where we can find the 3 key WiFi specs for the iPad?
1. WiFi radio transmit power (usually specified in milliwatts or dBm)

In the FCC type certification test results. The tx power is somewhat
different for each end of the band and for different modulation nodes
(b/g/n/a). There is no single value for tx power.

For USA:
Model A1219 FCC ID: BCG E2381A
Model A1337 FCC ID: BCG E2328A
Model A1395 FCC ID: BCG A1395
Model A1396 FCC ID: BCG A1396
For the iPad 3:
Wi-Fi Only FCC ID: BCG A1416
Verizon LTE FCC ID: BCG A1403
AT&T LTE FCC ID: BCG A1430
etc...

When the FCC ID web pile stops crashing, plug the FCC ID number into:
http://transition.fcc.gov/oet/ea/fccid/
and you should eventually find the xmit power. I would post some
examples, but as is normal on weekends, the FCC ID site has crashed.

For the iPad 3, nominal 2.4GHz tx output is about 16dBm. For 5GHz,
it's about 17dBm, except in the UNI-1 band, where it's 13.5dBm.

2. WiFi radio sensitivity (usually specified in dBm)

That's not easily measured. The best that can be done is to assume
that it's the same as the sensitivity of the chipset. Most iPads use
a Broadcom BCM43291HKUBC chip, which requires that you request the
data sheet from Broadcom and possibly sign and NDA. Good luck:
https://www.broadcom.com/products/Bluetooth/Bluetooth-RF-Silicon-and-Software-Solutions/BCM4329
Please note that the receive sensitivity is different of each mode
(b/g/n/a) and for each connection speed. Like transmit power, there
is no single value for sensitivity. Sensitivity is usually measured
with a BER (bit error rate tester) and a pile of test equipment. Check
out the various Wi-Fi test equipment vendors for app notes.

Just to make things interesting, the usable sensitivity can be reduced
by external influences, such as your hand on the antenna as in the
iPhone 4. There can also be RFI generated by the processor and
display drivers inside the iPad. Treat the specs as best case.

3. WiFi antenna gain (usually specified in dBi)

The antennas in the various iPad mutations vary in location and type
with model number. For example, the iPad 1 has it behind the Apple
logo, which methinks is a great location.
http://www.cultofmac.com/156848/ipad-3-wi-fi-issues-tested-worst-performance-yet-but-does-it-really-matter/
The iPad 2 has it just to the (rear view) right of the power
connector.
http://cdn.imore.com/sites/imore.com/files/field/image/2012/07/iPad-2-wifi-antenna-caution-area.jpg
On the iPad 3 antenna, the wi-fi antenna is glued to the speaker,
which is not a great idea. It also looks kinda minimal:
http://www.ifixit.com/Guide/iPad+3+4G+Wi-Fi+Antenna+Replacement/8750
See steps 41 thru 43.
On the iPad Air, there are two antennas glued to the inside lower
back. They're the black rectangles with the coax cables in the photo:
http://d3nevzfk7ii3be.cloudfront.net/igi/j1bWSkU3hGUAmpcU.huge

The dual band (2.4/5GHz) antennas are possibly a PIFA (Planar Inverted
F Antenna) type. I haven't torn one apart yet to see what's inside.
It's difficult to determine the gain for such antennas without an NEC
model. This might help
https://discussions.apple.com/thread/4866269
Kinda looks like these numbers came from an NEC modelling program, and
not from field tests.

So, what problem are you trying to solve? Lousy sensitivity perhaps:
https://discussions.apple.com/message/17887360#17887360
(1400 messages). It's apparently a common problem.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558