Let the games begin!
in [Wireless Internet]
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From: NotMe on 4 Jul 2010 12:04 "John Navas" <spamfilter1(a)navasgroup.com> wrote in message news:d4a1361l0j2j3jrmsk678lcupvgdu1hj1d(a)4ax.com... > On Sun, 04 Jul 2010 15:12:12 +0000, in > <Xns9DAB71F4CB77Enoonehomecom(a)74.209.131.13>, Larry <noone(a)home.com> > wrote: > >>nospam <nospam(a)nospam.invalid> wrote in news:030720102142454132% >>nospam(a)nospam.invalid: >> >>> right, and people are blaming the iphone antenna, without having ruled >>> out other causes. >> >>Ruling out other causes is very easy. Just pick up the cheapest free >>phone >>ATT sells and dial out a call right next to iPhone 4. Does the call work? >>Yes? Not the infrastructure or traffic's fault. That points it quickly >>at >>the real cause of failures.....iPhone 4's defective antenna system. > > Yep. > >>If Apple's gonna be in the radio business, they need to hire some radio >>engineers.... > > They are trying to do just that. > They've been at the game for years and so far have not been able to do so. (MacBook etc has very poor performance wrt wifi antenna)
From: nospam on 4 Jul 2010 12:19 In article <4u6136ha9pm482n6psbk2882cbnlmig4v7(a)4ax.com>, John Navas <spamfilter1(a)navasgroup.com> wrote: > Yep -- HTC makes great phones, which is why Apple has decided it has to > compete in court instead of just in the market. nonsense. how conveniently you forget that htc infringed not only on apple intellectual property, but microsoft too.
From: nospam on 4 Jul 2010 12:21 In article <Xns9DAB71F4CB77Enoonehomecom(a)74.209.131.13>, Larry <noone(a)home.com> wrote: > Ruling out other causes is very easy. Just pick up the cheapest free phone > ATT sells and dial out a call right next to iPhone 4. Does the call work? > Yes? Not the infrastructure or traffic's fault. That points it quickly at > the real cause of failures.....iPhone 4's defective antenna system. that's not a controlled test in the least. there are way too many variables to be able to say it's *only* the antenna. > If Apple's gonna be in the radio business, they need to hire some radio > engineers.... they have plenty.
From: Jeff Liebermann on 4 Jul 2010 14:35 On Sun, 04 Jul 2010 15:07:50 +0000, Larry <noone(a)home.com> wrote: >Jeff Liebermann <jeffl(a)cruzio.com> wrote in >news:ch1036t0runcdu2aik64spu0pn9o268tva(a)4ax.com: > >> Matching >> a wide range of frequencies is not. Hint: I do some antenna design in my spare time: <http://802.11junk.com/jeffl/antennas/> >http://en.wikipedia.org/wiki/Log-periodic_antenna >http://www.radio-electronics.com/info/antennas/log_p/log_periodic.php A log periodic antenna will not fit inside an iPhone. It's also rather directional, which is not what's needed in a cell phone. With small antennas, the efficiency is what usually goes down the drain first. Directionality goes next, as small antennas like to radiate in a spherical pattern, which mangles the SAR test. Most cellular antennas are loaded monopoles, PIFA, fractal, or just plain squashed into a pretzel. If I'm lazy, I just input the target specs into the modeling program, fire off the optimizer, and leave for a short vacation. When I return, I have a weird looking, best effort antenna, which usually works amazingly well. Incidentally, I have built LPDA antennas on e=10 ceramic substrates, which will reduce the size by about a factor of 4. However, for 800-1900MHz, it's still to big for inside a cell phone. >http://www.tpub.com/content/et/14092/css/14092_35.htm Close. That's a conical dipole. Inverting the cones results in a bi-conical, which is an excellent broadband dipole. However, it has the same problem as the LPDA. It won't fit. >http://www.ramseyelectronics.com/downloads/manuals/DA25.pdf That's a discone. It's half a bi-conical, with a capacitive hat. It's one of the worst antennas ever sold, were it not for the advantage of having a huge bandwidth. For a base station, if you don't mind having all of your RF going well above the horizon, it's fine. That's why you see it at airports. >Here's your slot iPhone 4 antenna...nothing new... >http://archive.electronicdesign.com/files/29/9986/figure_01.gif Hmmm.... 5 different antennas. Here's some exploded views of the iPhone that might help you identify which of the 4 antennas is in the iPhone 4: <http://www.ifixit.com/Teardown/iPhone-4-Teardown/3130/> Hint: The stainless frame is not a patch antenna because it's no suspended above a ground plane. It's also not a loop because it's broken into 2 seperate antennas (one for BT and Wi-Fi, the other for cellular). There's no meandering line or slot. However, the iPhone 4 antenna might be a PIFA antenna, which is the "inverted F" in the picture. I can't tell from the photos or the FCC page. When I get my hands on an iPhone, or better photos, I can make a determination. I wouldn't be surprised if the frame antenna is just a piece of wire with a messy matching circuit. >http://ceta.mit.edu/PIER/pier86/10.08090701.pdf >very broadband antennas can be made for microwave frequencies from PC board >material. Yep. UWB antennas are difficult but possible. However interesting, the iPhone 4 is not a UWB device and only needs to operate on 800, 900, 1800, and 1900 MHz. >http://www.sumobrain.com/patents/wipo/Broadband-tem-horn-antenna/WO1997012252A1.pdf That's a horn antenna. I'm trying to visualize how one would use a horn antenna with a cell phone. Certainly they're broadband, but are more suitable for illuminating a dish antenna, than cramming into a cell phone. Same problem as the others... too big and too directional. >Matching a wide range of frequencies isn't much of a challenge in 2010. It is difficult in a cell phone. If you don't care about size, shape, directionality, SAR, gain, and price, it's easy. Hint... do some searching in the IEEE Antennas and Propagation Journal: <http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=74> Type "cellular antenna" into the search box near the top of the page. You won't get the contents, but the abstract should be sufficient for this exercise. 3800 articles. >Placing the antenna where it will have a reasonable chance of radiating >into space is becoming more and more of a political problem as the greenies >take over the political system. That's true for cell sites. I'm somewhat involved locally in the process. However, I don't think that politics had anything to do with the design of the iPhone 4 antenna. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558
From: Jeff Liebermann on 4 Jul 2010 16:04
On Sun, 04 Jul 2010 15:09:52 +0000, Larry <noone(a)home.com> wrote: >Jeff Liebermann <jeffl(a)cruzio.com> wrote in >news:gp2036pkfqgq665djupris1ps6a9msh37q(a)4ax.com: > >> Yep. Worse, when the system is really busy, like during rush hour, >> VZW will drop calls that have been running for over 10-15 minutes to >> make room for new callers. I suspect the other service providers are >> doing something similar. It's really difficult to tell what caused a >> call to drop from the handset end. >Jeff, did you see the news where the Feds are going to give up another 500 >Mhz for more wireless bandwidth? > >It was on Google News midweek. No, I didn't. I couldn't find anything of the sort with various searches. Got a link? All I could find is that Obama is "backing" the release, whatever that means: <http://www.telecoms.com/21309/obama-plans-to-free-up-500mhz-of-spectrum/> Obama said the government would collaborate with the Federal Communications Commission (FCC) to make available a total of 500MHz of federal and non-federal spectrum over the next ten years, suitable for both mobile and fixed wireless broadband use, to be licensed and made available for shared access by commercial and Government users. Note the "federal and non-federal spectrum". That's about as vague as any politician could make it. I would guess that includes all spectrum. Never mind that any change in allocation will require ITC/WRC approval before it can be reallocated. At best, maybe 5 years for minor changes. The last and only release of federal spectrum was the shared release of 3650-3700Mhz in 2007, a paltry 50MHz. <http://wireless.fcc.gov/services/index.htm?job=service_home&id=3650_3700> Unfortunately, it's useless within 50 miles of major metro areas thanks to the need to protect Sprint satellite uplinks. Where the FCC is going to find 500MHz of spectrum of uncontested spectrum needed for mobile and fixed wireless (actually for auction), is anyone's guess. -- Jeff Liebermann jeffl(a)cruzio.com 150 Felker St #D http://www.LearnByDestroying.com Santa Cruz CA 95060 http://802.11junk.com Skype: JeffLiebermann AE6KS 831-336-2558 |