Yes, I was indeed bored enough to visually trace the thing out from these images. http://www.vonwentzel.net/ABS/ExtendedSnow/AEBS_NoModemAntennaBoard-Big.jpg http://www.vonwentzel.net/ABS/Dissection-Extreme/DSCN1324-pp.jpg
The components found in the signal path are either one of two things: one, of course, would be MMIC amplfiers. These would require only a DC bias for power. However, I have yet to see any that are bidirectional, which would be needed for a WLAN application. The second possibility would be that they are simply PIN diodes used to switch that input/output on or off. PIN diodes work by only allowing an RF signal to pass when a certain DC bias is applied. The fact that they are labelled D1 and D2 seems to back this theory up... my guess is, you apply a positive DC bias to set one, and a negative DC bias to set it to the other.
The board from the version with modem looks like it operates the same way... or does it? The same PIN diodes (I'm only 95% sure... honest!) are there, but U1 and U2 are a mystery. U1 seems to handle switching the antenna set in use between external and internal.
I have a couple more theories on that (assuming this board is dual layer, with the back layer being just a ground plane, and all vias tied to ground)...
First, I'm guessing that U1 is a dual PIN diode module.
A DC bias applied to the "Radio" lead would be blocked from entering U1 by C7. However, it can pass through L3 (which in combination with C9 appear to be a lowpass filter, to allow the DC voltage through) and reach pin 5 on U2. The two outer pins on U1 (at the bottom, as seen in the image) are DC only inputs. One takes a voltage straight off the lowermost black wire to the right, and one takes it off U2. U2 also provides the DC bias to the PIN diodes D1 and D2 through L1...
When the base station is using the external antenna, a DC voltage applied to the lowermost black wire applies a bias to the left diode in U1, and U2 provides no bias voltage to the right diode or the internal antenna select diodes. When the base station is using the internal antennas, bias voltage is disabled to the left diode in U1, and the right diode is activated by U2, which can also select the antenna currently in use by applying a positive or negative voltage at pin 1 (leading up to the antenna select diodes).
Exactly what U2 is remains a mystery. My guess is it's some kind of H-bridge line driver, flip flop, or something equally similar - in short, just a switch for logic levels. Pin 7's ground, 14 is VCC... and R3 is a pull-up resistor. My theory of it being a SMD version of the 7400 quad NAND gate wouldn't all work out due to the pinout configuration of the outputs (darn.)
As for the black wires, the top one's ground, next one down's +5 or +3.3 volts, the next two carry logic levels to control the outputs of U2, and the bottom is just a direct input to switch on the external antenna jack.
So... the bottom line... onboard amplification? Unlikely. And, if you're putting some DC grounded antenna (such as a ring Yagi, Yagi with folded dipole element, biquad, etc.) on without going through the existing antenna board (which does have DC blocking already), you'll probably want to put a DC blocking capacitor inline to prevent whatever drivers down on the radio card provide it from getting shorted to ground.
And this is what I happily do when I'm bored.
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