iPhone 4天线硬件设计无瑕疵？

苹果(Apple)日前针对该公司新款手机iPhone 4的收信不良问题，发出正式声明指出该问题与天线设计无关，而是一个为使用者报告收信程度的程序出了问题。然而仍有业界专家坚称苹果没有为iPhone 4的创新天线设计做出完整解释。

不久前，有iPhone 4的使用者表示，当紧握住该款手机左下角的黑色金属地带时，手机收信会突然变弱；而苹果也证实了此一问题。然而该公司随后却又发布声明指出，他们已重回实验室进行全面测试，发现iPhone 4的无线通信性能仍然是无与伦比，而上述收信不良的问题，是一个计算收信强度并在手机屏幕上以柱状图显示的程序出现错误。

“我们的程序在很多情况下，会错误的显示比实际信号强度多两个以上的柱状图；”苹果的声明指出，因此当用户看到信号掉了四格或五格，其实是因为所处的环境原本就是在信号覆盖度较差的地方，手机信号本来就没有到达满格的程度。但以上的解释似乎无法说明为何是使用者手掌握到手机金属边带时，才会出现信号变弱的情况。

根据拆解分析机构UBM TechInsights分析师的说法，iPhone 4的蜂窝式与GPS天线是置放在手机框架中；而手机的黑色金属带正好位于两个天线之间，当用户的手接触会产生桥接作用，并因此对天线的性能产生影响。但苹果的声明并未对其天线设计做任何评论，仅提到：“有人指称iPhone 4天线设计有瑕疵。”

UBM TechInsights资深分析师David Carey表示，由于缺乏精密的测试，很难确定苹果所声明的软件问题究竟是否属实：“iPhone 4的天线设计很独特，等于是让现在手机的内建天线直接曝露于外并直接与使用者的手接触。在我看来，苹果的设计意味着手产生的效应可能发生，其RF性能衰减的机会也比其他手机来得高。”

不过也有科技网站Anandtech指出，经过测试，iPhone 4的收信在某些状况下比其他竞争手机来得好；但该网站也表示，iPhone 4比其他手机更会因为特定的手握方式而产生信号衰减的问题。该网站建议苹果应该为iPhone 4机壳的不绣钢金属带添加绝缘涂层，或是保护条，而那些都是很简单可行的。

至于程序错误的问题，苹果表示将会采用AT&T所建议的公式于近期进行修正，并在几周后公布免费更新程序；而由于这个软件问题也出现在前一代的iPhone，因此软件更新将适用于iPhone 3GS与iPhone 3G。

第二页：参考原文(Update:ApplesaysiPhone 4problem is a math glitch, by Rick Merritt)

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Update:Apple says iPhone 4 problem is a math glitch

Experts say hardware antenna issues remain unresolved

by Rick Merritt

Perceived problems with cellular reception on the Apple iPhone 4are not due to a poor antenna design, but a faulty formula for reporting reception levels to users, according to a statement issued byAppleInc. Experts, however insist Apple is not telling the full story about the handset's novel antenna design.

"Some users have reported that iPhone 4 can drop four or five bars when tightly held in a way which covers the black strip in the lower left corner of the metal band,"Apple admitted in its statement released Friday (July 2).

However, the company has "gone back to our labs and retested everything, and the results are the same--the iPhone 4's wireless performance is the best we have ever shipped," the statement said.

The problem, according to Apple, is that "the formula we use to calculate how many bars of signal strength to display is totally wrong. Our formula, in many instances, mistakenly displays two more bars than it should for a given signal strength," the statement said.

Thus when users saw signals drop four or five bars, they were likely already in an area of weak coverage, the company claimed. "Their big drop in bars is because their high bars were never real in the first place," the statement said.

The rationale does not seem to address the problem reported in some cases that users had a usable signal but lost it when they covered the black strip in the lower left corner of the metal band.

Analysts at UBM TechInsights, who helped conduct a teardown of the iPhone 4, said the handset placed its cellular and GPS antennas in the case's frame. The black strip marked the space between the two antennas that, when bridged by a user holding his hand over it, changed the length and thus the performance of the antenna.

The Apple statement made no comment on the design of the antenna except to say "some have accused theiPhone 4of having a faulty antenna design."

"Absent sophisticated testing, it is hard to state with certainty whether Apple's claim that it's just a software problem is true or not," said David Carey, a senior UBM TechInsights analyst and founder of the Portelligent teardown service.

"The iPhone 4 antenna design is unique in that the basic internal antenna technology of today's cellphones is now exposed directly to the outside and to direct contact with the hand," Carey said. "Apple's design means it becomes possible for hand effects and degraded RF performance to be more pronounced [than with other handsets] it seems to me," he added.

Separately, the Anandtech Web site said the iPhone 4 in some ways has better cellular reception than competing phones it tested. However, it also said theiPhone 4is subject to greater signal loss than other phones depending on how the handset is held.

"Apple should add an insulative coating to the stainless steel [antenna] band, or subsidize bumper cases. It's that simple," the Anandtech reviewer said.

Apple said it will address the situation by "adopting AT&T's recently recommended formula for calculating how many bars to display for a given signal strength. We are also making bars 1, 2 and 3 a bit taller so they will be easier to see," the statement said.

"We will issue a free software update within a few weeks that incorporates the corrected formula. Since this mistake has been present since the original iPhone, this software update will also be available for the iPhone 3GS and iPhone 3G," the statement added.