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detuning and decay

Apple is not wrong, to understand that things can be proven to what is wrong. This thing is two questions, first is the antenna design is wrong, the second is that Apple's own display algorithm signal problems.
again requested the antenna engineer Spencer Webb:
According to tests,[link widoczny dla zalogowanych], will firmly hold the iPhone 4 24dB signal attenuation, which is the worst situation. In this case, there will be two very different results. 1, the mobile phone base station nearby, assuming that the original signal strength is-60dBm, pay close attention to mobile phones, after attenuation 24dB, the signal strength of the rest of-84dBm, but still the fifth grid (-51dBm to-91dBm) the scope and therefore still display iPhone 4 full signal. 2, a signal is worse for the place, the assumption is-80dBm, attenuation of 24dB, the signal intensity of left-104dBm, you will find, iPhone 4 of the signal format quickly dropped from over 2 grid cells - with a 24dB attenuation However, the behavior of the signal indicator and its linear graphical features of disorders.
This is the AnandTech test results on the iPhone 4. Signal format of linear increase, but the fifth frame (the highest cell) represent the signal range extends from the maximum value of-51dBm to-91dBm, and the minimum grid covers only-107dBm to-113dBm range. Apple deliberately increases the signal coverage of the full grid, causing users to have a \less dramatic changes in the signal indicator.

design is not wrong

unknown why the details of the report of the effectiveness of the test is so strong? Even with the authority of the magazine and reliable person, but as a laboratory report, no written test environment, test equipment, measurement methods and steps, hastily concluding paragraphs to make up a bit too hasty?

July 2 Apple said in a statement:
is a compromise, not a mistake

added attenuation (Attenuation), or known loss. Because the staff is dielectric, so it is easier than gathering the air field. This is called the permittivity (Dielectric Constant), staff of the dielectric constant is high, about 12 or 20, depending on diet and vary the degree of obesity. However, the hand is also a conductor, though not a good conductor, but enough to make you taste the taste of a shock: p.

get smart always pay the price. Also, since using a more sensitive baseband chip, so why should be better and \

so to understand the detuning (Detuning). Imagine an empty wine glass with a fork to beat, and then sent to a frequency of the sound of glass. If you pour some wine into the cup and then knocked, the frequency of the sound will change and become higher.
modern media may amplify the severity of a problem, but as long as the look of \Than a certainty of the conclusions, people need to understand the testing process is scientific.
things do not quite understand the process of the readers look at the following figure:
This antenna is the same. Antenna resonant frequency of its work, when people put his hand on the antenna, the equivalent load a lot of salty dielectric (Dielectric), which reduces the antenna's resonant frequency, and affect the ability of a specific frequency transmitted signal. If the antenna is very narrow, then it may even paralyze the ability to work. Typically, small antennas for the band said, a large antenna for broadband, you can use to understand the concept of wavelength. So this is why the hand touch the antenna mismatch is the first resulting from adverse consequences. This is true for all of the antenna.

we have returned to the laboratory for repeated testing of all issues, the results no different ─ ─ iPhone 4 in All of our mobile wireless performance is the best product.

FCC's testing process, but there is a problem, which requires the subjects close to the head phone, but do not take into account the impact of hand-held antenna (it assumes that manpower is an insulator), AT & T is true, the phone needs and the FCC after a similar test before allowing network access, the same effect regardless of hand-held. Therefore, the essence of the antenna design become more and more to meet the test results, than to consider the efficiency of sending and receiving signals and staffing impact. Care of this and he lost, this is the first compromise - Apple is to meet the FCC requirements, but also do not want to lose the characteristics of products.

iPhone 4 is a great phone!

second party is the AT & T. Wireless communication system composed of many base stations, test signal strength,[link widoczny dla zalogowanych], you need to determine the phone is connected to a single base station, or switch between different base stations. Base station location, the surrounding terrain and will affect cell respiration signal reception. As stated above, the signal are both full frame state, but in different test sites lose after iPhone 4, some at 5 cells, and some down to 2 squares. Thus, although AT & T can not prove how much the impact of factors, but obviously can not be falsified.

he wrote: \tests done exactly the same. \Hold the antenna will be subject to any mobile phone signal attenuation, iPhone 4 will be moved to the side of the antenna increased attenuation, coupled with the wrong signal display algorithm, enlarged the extent of the problem.
iPhone past the bottom of the antenna in the fuselage, outside the plastic case with insulated, while the bow hand into the antenna to a working space, so \the performance is not obvious, but the grip will attenuate the signal of any cell phone to say, there is no wrong. If Apple do not start the algorithm, or on the iPhone 4 iOS 4 in the use of the \In addition, iOS take an average of 10 seconds, the signal is intended to signal a sudden change in the appearance of weakening, it is self-denial.
We call this non-good conductor as a \When the RF energy through the manpower or the head, some will be converted into heat, which is the origin of the SAR, the antenna when the hand after the injection this effect will reduce the signal energy. This is the second of touching the antenna.
third-party design team and Steve Jobs of Apple. For new designs and beauty, and make functional compromise.
Webb friend's iPhone 4 was done with the test, the results support his prediction - strip no effect.

iPhone 4 a signal reception problems, but this problem has been exaggerated.
other words
start talking about the Federal Communications Commission FCC, FCC strictly limit the transmission power of handheld devices, it uses the \Early mobile phone antenna is located outside the fuselage, was growing in short, eventually disappear into the enclosure. To meet the FCC's testing requirements, almost all modern mobile phone antenna design at the bottom, away from skull position. The position of the hand under the head, people who naturally hold the bottom of the phone unit, rather than the top.
AnandTech's iPhone 4 evaluation in this sentence: \results. It's eccentric, the so-called optimal only relative, for example, actually increased grip iPhone 4 5dB to 10dB the WiFi signal strength, extraordinary understanding.

tests show iPhone 4 signal reception of the iPhone more than ever, many users have the same experience, because the iPhone 4 baseband chip is more sensitive.
tape can not solve the problem
the basic structure of the capacitor is two conductive plates separated by a layer of insulator. When capacity is high enough when the (conductive plate area is larger, or when the insulator thinner), will be like a short circuit.
not intend to release another iPhone 4 Geohot jailbreak software, but Apple has removed the iOS 4 Field test (Field Test, the engineering mode) of the relevant documents, then, Consumer Reports is how to accurately measure iPhone 4 of the signal reception strength of it? (Test accompanying video showed a GSM test equipment, the equipment and there is no connection between the iPhone 4. At present, the video seems to have no access.) Looking forward to electronic engineering experts can answer this question.
But first free Apple iPhone 4 users to send each plastic sleeve.

antenna engineer Spencer Webb (Spencer Webb) wrote in a blog, hold the phone antenna will have two distinct consequences: detuning and decay.
valuable information in this test only: \> testers iPhone 4 press with your fingertips the bottom left of the \AnandTech Holding the simulated 5 - Normal support machine, force grip, palms flat and so on. Consumer Reports testing process is like? AnandTech test as many times as there are averaging it? Under simulated base station is the number of weak signals,-113dBm or other values nearby? More importantly, what position dominated by the iPhone 3GS comparison test, and Palm Pre? This two test machines located in the fuselage at the bottom of the antenna, the antenna is insulated outer shell, and therefore there is no \. Since there is no dead, if the test machine using a normal grip position, why the iPhone 4 does not use the same pose? And they made no mention of testing methods compared with the machine, so this conclusion is questionable.
summary detuning sent to the antenna circuit to reduce the energy (or vice versa); attenuation of the RF signal is converted into heat.

in this matter, it is important to understand what we discuss is the antenna of the radio frequency current (RF Currents ) rather than direct current (DC). If some insulation tape and cover the iPhone 4 thin black bars to the left, there will not be significantly improved. This is because, although this tape an effective deadening the DC (0 Hz), but the high frequency oscillation of the RF signal (1GHz, or 1 billion cycles per second) could make it a large capacitor.

must be separated to see: antenna design is not wrong, this will be explained below. Apple's planted in the signal display algorithms. Typically, the mobile phone manufacturers balanced by the strength of the signal indicator, it is very easy for the user that the linear relationship between the size of the signal. See next figure:
this picture from Google Trends the horizontal axis is time, vertical axis is the search volume index, the keyword is \IPhone 4 people know the first question is a signal to accept the official sale in the past, some users got the phone early, that is, June 23. After the topic of search volume index soared, but the second day of the formal sale fell back after the index began, and then a few days, the number remained at a stable and Apple July 2 official statement released after the software fix to continue to decline ( site compiled interpretation of this statement of John Gruber.). This, at least in part, explain one thing: If the signal problems iPhone 4 media that really so serious, with the iPhone 4 sold more and more why the search index has been down?
One interesting thing is that both electrical tape, transparent plastic or any other, \problems. This alone can prove that \

Do not stare in weak signal conditions, connection problems, see IPS retinal display, to see many new features iOS 4, double the memory to see larger, back-illuminated camera three-axis gyroscope, a faster GPS positioning speed, iMovie for iPhone, iBooks, Facetime, A4 processors, larger capacity battery,[link widoczny dla zalogowanych], the speakers sound better to the noise microphone, and, even more sensitive baseband chip, HSDPA-enhanced nearly 1-fold increase download speed, HSUPA upload speed increased by 10 times, about the user experience of 3G network delay time is reduced a lot. Really amazing!

iPhone 4 multi-antenna design is suboptimal compromise the results.
Some iPhone 4 users, including readers of this site also said, iPhone 4 signal better. No mistake, Apple iPhone 4 used in the higher sensitivity of the baseband chip. For the UTMS (3G) equipment, cell phone signal strength of the feedback is the best-51dBm, near the base station can be the figure, before the connection in the phone can accept losing the weakest signal strength is-113Bm. In AnandTech's tests, under the weak signal (-113dBm) iPhone 4 performance better than the iPhone 3GS.