Hardware Projects » M.2 (NGFF) WWAN modem USB breakout board

• the ufl pigtail performs best with a performance of 0.2-0.3dB insertion loss over the whole band.
• umc performs the worst with -13dB insertion loss at around 1.6GHz and -10dB at around 3GHz
• amc slopes down to -5dB at around 1GHz and slowly down to -9dB at 3GHz
• hsc also slopes down to -8dB at 3GHz, similar to amc, but with ~1dB better overall performance (less loss)

if we use mhf4 directly on the pcb - the 'hsc' connector seems the best of the batch. recommendation is using the pigtail due to massively better performance.

The last two pictures show a gain: parts or all of the graph is in 1st quadrant of the graph (not exclusivly in the fourth) which is clearly not possible.

The three product names of different brands all refer to the same mechanical plug solution, they should not expose these wide differences in measurements.

i think this is just a minor calibration error: * i was not redoing calib but loading a saved one * the calib was done on a used sma-sma coupler and sma calib kit, not with ufl or similar connectors

i did some traces on the minipci-e board for comparison (ufl to sma adapter onboard)

one image is uploaded twice - I think you wanted to upload another screencopy?

sorry, this should fix it.

• did you double-check / re-confirm the situation with the improbable high loss of the converter involving the PCB trace? Like using another set of MHF4-to-UFL cables / ULF-to-SMA adapter or the like?
• i still have a hard time guessing what the file name of the graphs actually mean in terms of physical cable/adapter/connector comparison. Please explain the results, possibly by creating a small table with human-readable description of the setup next to every graph filename
• did you compare with the mPCIe breakout board trace as requested yesterday?

laforge wrote:

• did you double-check / re-confirm the situation with the improbable high loss of the converter involving the PCB trace? Like using another set of MHF4-to-UFL cables / ULF-to-SMA adapter or the like?

not yet - i am currently on that.

• i still have a hard time guessing what the file name of the graphs actually mean in terms of physical cable/adapter/connector comparison. Please explain the results, possibly by creating a small table with human-readable description of the setup next to every graph filename

i put a long description in the optional filedescription. but its only displayed on top of the page

ufl-ufl_cable.png          vna - sma-ufl adapter - ufl-ufl cable - ufl-sma adapter - vna  'only the ufl-ufl cable (sma-ufl adaptes both sides)'
sma-ufl-cable-ufl-sma.png  vna - sma-mpcie-board - ufl-ufl cable - mpcie-board-sma - vna  'loop through mpcie-board (connect ufl cable twice, use board as adapter on both ports'
ufl-cable-ufl-sma.png      vna - sma-mpcie-board - ufl-ufl cable - ufl-sma adapter - vna  'one side sma-ufl adapter - other side mpci-e board'

i would expect the first having the best measurement results, the second the worst and the last should be most realistic and somewhere in the middle - which measurements confirm.

• did you compare with the mPCIe breakout board trace as requested yesterday?

thats what the last 3 graphs are all about.

these 3 graphs just show a different mhf4-ufl cable being used

the next test was removing the esd protection diode, and the attenuation went away.
these are the amc3/umc3/hsc3 graphs

still not ideal values, but all were better than -2dB now (see *4 graphs for better y scale)

new testrun with new pcb and new diodes:

D5 = ESDAXLC6-1BT2 - digikey# 497-13413-1-ND
D6 = SESD0402X1BN-0010-098 - digikey# SESD0402X1BN-0010-098CT-ND
D7 = SESD0402X1BN-0015-096 - digikey# SESD0402X1BN-0015-096CT-ND

from the graphs i'd say we use the one selected for D5 in this case.
the mhf4 connector used was the 'cheapest one' of the tested ones. (could not see a proper difference inbetween the amc4/umc4/hsc4 graphs)