On Tue, 13 Jul 2010 10:05:54 -0800, Bruce in alaska
wrote:

Issue One. Apple has already admitted that the Signal Level algorithm,
used in the IPhone4 was seriously flawed in how it displayed Signal
Level. (Bars) When the Phone displayed 4 or 5 Bars, it may actually only
be receiving at a 1-2 Bar Level. This they have corrected with a
Software Patch.

Hi Bruce,

Jim's second link (which I quoted in my response to him) gives very
specific signal levels. Aside from that, and as is obvious by the
numbers, the "bars" are merely window (with apologies to M$) dressing
in any phone (except as a RF exposure risk indicator).

Issue Two. The Multi-Band Antenna design in the iPhone4 is a Kludge
Compromise at best, and burying it in the Metal Frame where Left Hand
users put the flesh against it, seriously detunes it. Apple is in the
process of hiring a small group of Engineers, with expertise in this
area.

A bumper would seem to mitigate the risk. Conformal coating would to
some lesser extent. All-in-all, the amount of metal seems to be
consistent with best engineering practices (but, perhaps, not best
consumer packaging practices).

73's
Richard Clark, KB7QHC

If the phone is disturbed by touching with dry skin, a thin insulating
layer won't help. At cell phone frequencies, the capacitive coupling
will have less impedance than skin.

Roy Lewallen, W7EL

On 7/13/2010 3:12 PM, Baron wrote:

Aren't cell stations vertically polarised. The one near me is, and one
of the IF's is smack on 144.005 Mhz.


EME'r?

tom
K0TAR

On Jul 13, 3:51*pm, Jim Lux wrote:
Baron wrote:
Richard Clark Inscribed thus:

On Mon, 12 Jul 2010 21:54:17 -0500, tom wrote:

On 7/12/2010 9:46 PM, Richard Clark wrote:
The only thing that remains a mystery, for me if for no one else
here,
is the literal specification of the antenna. *Google (gasp) fails
me.

73's
Richard Clark, KB7QHC
And that does seem to be the crux of the matter. *What is the antenna?
And what does it interact with that's not, be it part of the phone or
part of the user?
Hi Tom,

The antenna is reported as being the metal trim that surrounds the
perimeter of the phone. *As that is much too large for the frequencies
involved to be taken literally, there is more to the story that
remains clouded. *Maybe I'm wrong....

I think you're right. *"Design Flaw" Someone messed up testing big time.

If the loop (or dipole) is suitably matched, it doesn't give much
polarization diversity. *Perhaps no phone does anyway.

Aren't cell stations vertically polarised. *The one near me is, and one
of the IF's is smack on 144.005 Mhz.

Insofar as being "part of the user," we well know the EM of HTs and
the hand/body contribution. *If such were the case, then this would be
an agnostic problem that users of all mobile phones would complain of
(which mildly refutes what the gadget blogs dismissed). *On the other
hand, the über-hip, whose complaints are more vocal for their "pain,"
would be outraged at the notion of their simply enjoying the identical
experience of techno-trash. *Amazing what a 10 fold cost differential
brings to your perception of quality of service.

73's
Richard Clark, KB7QHC

From a casual look at the phone the metal band seems to be a continuous
loop. Its unlikely that there is a physical coupling between it and the
RX/TX, so any tuner or coupling is going to be affected by the hand
grasping it. *Since suggestions have been made to hold the phone in a
different place, I would guess that the coupling method is suseptible
to adsorbtion effects and that the hot parts are near the base of the
phone.

FWIW Every mobile phone I've played with has the antenna and coupling
circuitry near the top behind the display.

Not any more.. recent phones (last several years) put the antenna at the
bottom to reduce the SAR number, since the top of the phone is next to
your head, and the bottom isn't. *There's a really good explanation from
a guy who does, oddly, wireless device antenna design consulting..http://www.antennasys.com/
specificallyhttp://www.antennasys.com/antennasys-blog/2010/6/24/apple-iphone-4-an...

http://www.anandtech.com/show/3794/t...-4-review/2has some
information

My new antenna can easily handle this job.
You make it for the lowest frequency and it will handle all the
frequencies above at a constant impedance..... and with more gain and
the radiater smaller in size!

On Jul 13, 8:27*pm, Art Unwin wrote:

My new antenna can easily handle this job.
You make it for the lowest frequency and it will handle all the
frequencies above at a constant impedance..... and with more gain and
the radiater smaller in size!

Is it fractal?

On Jul 13, 9:10*pm, Bill wrote:
On Jul 13, 8:27*pm, Art Unwin wrote:

My new antenna can easily handle this job.
You make it for the lowest frequency and it will handle all the
frequencies above at a constant impedance..... and with more gain and
the radiater smaller in size!

Is it fractal?

No!
Total resistance = R1+ R2 The trick is to reduce
R2 in value so more current is being applied to radiation. Very simple
my dear Watson.

On 7/13/2010 9:42 PM, Art Unwin wrote:
On Jul 13, 9:10 pm, wrote:
On Jul 13, 8:27 pm, Art wrote:

My new antenna can easily handle this job.
You make it for the lowest frequency and it will handle all the
frequencies above at a constant impedance..... and with more gain and
the radiater smaller in size!

Is it fractal?

No!
Total resistance = R1+ R2 The trick is to reduce
R2 in value so more current is being applied to radiation. Very simple
my dear Watson.

And he tells you nothing. And he provides no proof.

The master of vaportennas.

tom
K0TAR

On Jul 12, 9:30*pm, Richard Clark wrote:
http://www.nytimes.com/2010/07/13/te...apple.html?hpw

"Consumer Reports, America’s trusted source of product reviews, *said
it would not recommend the iPhone 4 because of a hardware flaw with
its antenna that sometimes resulted in dropped calls.

"... its antenna, which is built into a steel band that encases the
phone.

"After users reported problems with signal strength and dropped calls
when they touched the lower-left portion of the phone, however, Apple
suggested that consumers hold the phone differently or use one of many
bumpers to insulate the antenna. It also said that all phones suffered
from similar problems when they were cradled a certain way.

"These comments were widely laughed at in gadget blogs. "

Just thought I would submit this to the Laughing Academy.

73's
Richard Clark, KB7QHC

The rumor I heard was that they tried to put in a "better" antenna to
cure problems with dropouts. While it does have more gain it is
sensitive to the way it's held. Basically they traded one problem for
another.
Any confirmation or rebutal would be appreciated

Jimmie

JIMMIE wrote:

The rumor I heard was that they tried to put in a "better" antenna to
cure problems with dropouts. While it does have more gain it is
sensitive to the way it's held. Basically they traded one problem for
another.
Any confirmation or rebutal would be appreciated

Jimmie

There's a whole raft of issues..

One is that cellphones aren't analog FM anymore, so they suffer from the
"digital cliff" problem.. If the Eb/No is good enough that the FEC
works, then it works great, but a dB or so worse, and it doesn't work at
all.

This is so different from most people's practical experience with
communications that it is disconcerting. E.g. if you walk away from me
while talking, your voice gets fainter and the SNR gradually drops, but
it's not like you've walked out of the "cone of silence" where it goes
from fully intelligible to not at all intelligible in milliseconds.

And, the fact that this happens on a packet by packet basis means that
at the threshold, it "stutters", which is also non-intuitive and
non-physical.


And then, the cellphone companies have managed to convince us that
really crummy sound is ok, even at the full bit rate of 8kpbs. The
voice codecs are impressive, but face it, it still doesn't sound like
56kbps u-law or 25 kHz NBFM, what used to be called "toll-quality"

Jim Lux Inscribed thus:

Baron wrote:
Richard Clark Inscribed thus:

On Mon, 12 Jul 2010 21:54:17 -0500, tom wrote:

On 7/12/2010 9:46 PM, Richard Clark wrote:
The only thing that remains a mystery, for me if for no one else
here,
is the literal specification of the antenna. Google (gasp) fails
me.

73's
Richard Clark, KB7QHC
And that does seem to be the crux of the matter. What is the
antenna? And what does it interact with that's not, be it part of
the phone or part of the user?
Hi Tom,

The antenna is reported as being the metal trim that surrounds the
perimeter of the phone. As that is much too large for the
frequencies involved to be taken literally, there is more to the
story that
remains clouded. Maybe I'm wrong....

I think you're right. "Design Flaw" Someone messed up testing big
time.

If the loop (or dipole) is suitably matched, it doesn't give much
polarization diversity. Perhaps no phone does anyway.

Aren't cell stations vertically polarised. The one near me is, and
one of the IF's is smack on 144.005 Mhz.

Insofar as being "part of the user," we well know the EM of HTs and
the hand/body contribution. If such were the case, then this would
be an agnostic problem that users of all mobile phones would
complain of
(which mildly refutes what the gadget blogs dismissed). On the
other hand, the über-hip, whose complaints are more vocal for their
"pain," would be outraged at the notion of their simply enjoying the
identical
experience of techno-trash. Amazing what a 10 fold cost
differential brings to your perception of quality of service.

73's
Richard Clark, KB7QHC

From a casual look at the phone the metal band seems to be a
continuous loop. Its unlikely that there is a physical coupling
between it and the RX/TX, so any tuner or coupling is going to be
affected by the hand
grasping it. Since suggestions have been made to hold the phone in a
different place, I would guess that the coupling method is suseptible
to adsorbtion effects and that the hot parts are near the base of the
phone.

FWIW Every mobile phone I've played with has the antenna and coupling
circuitry near the top behind the display.


Not any more.. recent phones (last several years) put the antenna at
the bottom to reduce the SAR number, since the top of the phone is
next to
your head, and the bottom isn't. There's a really good explanation
from a guy who does, oddly, wireless device antenna design
consulting.. http://www.antennasys.com/
specifically

http://www.antennasys.com/antennasys...-antennas.html


http://www.anandtech.com/show/3794/t...one-4-review/2 has some
information

Jim. Thanks for the above links. The Youtube vid was most interesting.
I certainly wasn't aware of the gaps in the metal banding nor of the SAR
requirements.

73s
--
Best Regards:
Baron.