About two weeks ago, I published a blog piece on the iPhone 18 Pro Max antenna configuration disparities between the Apple C2 modem equipped international model and the Qualcomm X80 modem equipped US model, which is now a notable outlier in the latest Apple iPhone lineup. I had not researched nor written any cellphone regulatory filing analysis in several years, but once the news was confirmed about the iPhone 18 Pro Max variant split between Apple and Qualcomm modems, I had a feeling that there could be some interesting RF differences lurking inside beyond just the two distinct cellular basebands.
Yes, once I started digging into the two separate FCC OET (Office of Engineering and Technology) filings for the international and US models, the antenna design dissimilarities became apparent almost immediately -- most notably the band n41 antenna configuration graph that I generated and used as an example in the previous article and have reproduced for reference below:
In the text of that earlier article, I alluded to similar discrepancies in other bands, such as low band n71, so a numerical and graphical follow up in that regard seems only natural. And as we will see in the conclusion, those two bands were not selectively examined by coincidence.
In that low band n71 realm, the Qualcomm X80 model actually possesses a 0.10 dB (2 percent) greater peak antenna gain, though as the percent conversion shows, this difference is negligible. What truly is notable, however, is the antenna gain consistency (or lack thereof) across the two iPhone 18 Pro Max models. Each model incorporates two low band antennas, and focusing specifically on their lesser antennas, respectively, the Apple C2 model has a 1.80 dB (51 percent) antenna gain advantage. That is significant, and it also is reflected in the average antenna gain figures, favoring the Apple C2 variant by 0.85 dB (22 percent) -- exactly the same average gain disparity displayed in the band n41 analysis. See my n71 antenna graph:
This raises an interesting possibility. Hearkening back to the 2010s period of a 3GPP GSM/W-CDMA and 3GPP2 CDMA2000 technology schism when Apple produced multiple distinct iPhone models for AT&T and T-Mobile versus those for Verizon and Sprint, could Apple at some point in its iPhone 18 Pro Max design and manufacturing phase have intended to supply T-Mobile with the Apple C2 modem equipped variant? After all, mid band n41 and low band n71 are deployed extensively and almost exclusively in the US by T-Mobile.
Honestly, I doubt the theory holds much credibility -- just some circumstantial evidence, correlation not necessarily leading to causation. Nonetheless, it is an interesting thought exercise, since the iPhone 18 Pro Max with Apple C2 modem that ended up as solely an international model appears in some ways to have had its antenna configuration optimized for T-Mobile in the US.
Source: FCC OET
No comments:
Post a Comment