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Apple’s iPhone 4 antenna troubles dominated the news this week, and Jeff Carlson did yeoman’s duty in covering both the iOS 4.0.1 update that fixes the iPhone’s signal strength algorithm and Apple’s press conference about the issue. Also, Rich Mogull delves into his past in the rescue and emergency services community to explain why the iPhone 4 antenna has two separate problems, one common to all mobile phones and the other unique to the iPhone. Changing gears, Adam warns about how the iOS caches iTunes account passwords, which could result in inadvertent purchases, and also relays news of the upcoming MacTech Conference for IT professionals and developers – register soon while there’s still space! Lastly, we’re giving away copies of Apago’s PDF Shrink in DealBITS this week, so be sure to enter if you need to compress PDFs for more efficient transmission. Notable software releases this week include ChronoSync 4.1 and ChronoAgent 1.1, Panorama 6.0.0 build 92277, and AppleJack 1.6.

Jeff Carlson 7 comments

iOS Updates Adjust iPhone Bars, Apply iPad Fixes

Apple released updates to the two branches of its mobile operating system, addressing the way signal bars are displayed on the iPhone and fixing bugs on the iPad. iOS 4.0.1 for iPhone, and iOS 3.2.1 for iPad are both available now.

iOS 4.0.1 for iPhone — iOS 4.0.1 primarily modifies the formula used to determine cellular signal strength. Apple promised this update at the beginning of the month in response to reception problems caused by bridging the iPhone 4’s external antennas when holding the phone (see “iPhone Signal Strength Sets Bars Too High,” 2 July 2010). The change doesn’t address the signal issue; instead, it allegedly reports the signal strength more accurately. Apple did, however, increase the size of the first three bars to make them more prominent (and, no doubt, to make people feel better about the reduced reception).


The update also quietly addresses sync issues with Exchange ActiveSync Mail, Contacts, or Calendars that may cause syncing to fail or go slowly. Some Exchange Server administrators may also notice their systems running more slowly due to this problem. The update resolves these issues by installing a new configuration file that increases the amount of time an iOS 4 device will wait for a sync request response from the Exchange Server.

Apple has released a beta of iOS 4.1 to developers, and held a special iPhone 4 press conference to address the signal concerns that have gained significant media attention (see “Apple Responds to iPhone 4 Antenna Issue,” 16 July 2010). Even a United States Senator, Charles Schumer (D-NY), weighed in.

The update works with the iPhone 4, iPhone 3GS, and iPhone 3G. The original iPhone is not capable of running iOS 4, and the iPod touch remains at version 4.0.

iOS 3.2.1 Software Update for iPad — Both models of the iPad (Wi-Fi and 3G) gain a handful of fixes in iOS 3.2.1, which Apple calls out as follows:

  • Improved Wi-Fi connectivity
  • Fixed an issue that could prevent copy and paste of single-page PDF attachments in Mail
  • Addressed an issue that could cause video playback to freeze
  • Improved reliability of video-out when using iPad Dock Connector to VGA Adapter
  • Added Bing as an option for Safari’s search field

Both updates are available from within iTunes: connect your device, select it in the sidebar, and click the Check for Update button. iOS 4.0.1 is a 579.3 MB download; iOS 3.2.1 is a 456.9 MB download. (The updates are full images of the iOS, not just patches needed to update the operating system, which explains their large sizes. This approach enables easy restoration of the software within iTunes in case something goes wrong with the device.)

Adam Engst 3 comments

New MacTech Conference for IT Pros and Developers

With the loss of MacHack/ADHOC and, more recently, both C4 and the IT track at WWDC, the Apple world is at a bit of a loss for highly technical conferences aimed at IT professionals and developers. Sure, Macworld Expo has the useful MacIT Conference track, but Macworld doesn’t put all the conference attendees together in a single hotel and provide an immersive experience for networking and further discussion, as did MacHack and C4.

That then, is the goal of the MacTech Conference 2010 in Los Angeles – to create an immersive technical conference at which developers and IT professionals can learn more about key tools, technologies, and techniques related to the Apple product ecosystem. And, despite Apple’s emphasis on the iOS these days, the MacTech Conference won’t be ignoring the Macintosh.

Along with a keynote from the inimitable Andy Ihnatko and two separate tracks of sessions from well-known members of the IT and developer communities, the conference will include all meals to maximize the informal networking opportunities that are often as valuable as the formal presentations.

Plus, the first evening will feature an exclusive group visit to Griffith Observatory, complete with a behind-the-scenes talk on how planetarium animation is created and a chance to look through the observatory’s 12-inch Zeiss telescope. The second evening will include food and entertainment at Jillian’s, along with bowling as part of the MacTech Bowl fund-raiser to help 5th graders take field trips to Griffith Observatory.

The three-day conference will kick off at 10 AM on Wednesday, 3 November 2010, and will run through Friday afternoon, 5 November 2010. Attendee spots and hotel rooms are limited and will likely sell out, if the quick sellouts of recent C4 and WWDC conferences are any indication. Conference registration costs $899 and includes food, a MacTech Magazine subscription, and all the sessions, but through 22 July 2010, a limited number of early bird passes bring the cost down to $699. A limited number of partial and full student scholarships are also available. Travel and hotel
cost extra, of course, and a limited number of rooms at the Sheraton Universal (where the conference will be held) are available to attendees at the conference price of $169 per night, plus taxes.

Although I don’t believe I’ll be able to make it this year, our own Matt Neuburg is scheduled to be one of the presenters, and speaking as someone who took classes from Matt during college, he always puts on a good show.

Adam Engst 2 comments

DealBITS Drawing: Win a Copy of PDF Shrink 4.5

One of the aspects of PDF production to which we pay careful attention when creating Take Control ebooks is the size of our PDF files. It may not seem as though a few megabytes matter in today’s Internet, but you’d be surprised how many people still work on limited bandwidth connections, and, in fact, the increased use of cellular data connections for iPhones and iPads has made the problem of unnecessarily large files even worse. Plus, email servers often reject attachments over 5 MB, providing yet another reason to compress PDFs. Image-heavy PDFs generated from programs like Keynote and PowerPoint tend to be especially massive, but it’s nearly impossible to predict when a PDF might balloon in size. Some of our Take Control ebooks have
hit 100 MB before we shrink them to between 1 and 5 MB.

We compress our ebook PDFs using Apago’s industrial-strength PDF Enhancer, which also performs other tasks for us. But if you just want to reduce the size of PDFs quickly and easily, Apago’s $35 PDF Shrink is all you need. Drop your PDF file on PDF Shrink, and it quickly compresses images in the PDF, and performs various other manipulations that save space while still producing a fully functional and compatible PDF (something that’s not true of all tools that can reduce PDF file sizes). You don’t need to understand the inner workings of PDF to choose appropriate settings; PDF Shrink takes advantage of multi-core CPUs to process multiple files at once; and you can even feed it an entire folder
to process a large number of files in one action.

So if you want to win one of two copies of PDF Shrink 4.5, worth $35, enter at the DealBITS page. All information gathered is covered by our comprehensive privacy policy. Remember too, that if someone you refer to this drawing wins, you’ll receive the same prize as a reward for spreading the word.


Adam Engst 15 comments

Be Aware of iTunes Password Caching

A brief tempest of recent blog posts highlights a design compromise that Apple made with App Store and in-app purchases from iOS devices.

To summarize, designer Mike Rohde bought an app on his iPad and, while waiting for it to download, his 7-year-old son played a free aquarium app called Fishies that offers additional items for sale via in-app purchases. Without realizing what he was doing, Mike’s son purchased a number of items within Fishies, including a chest of pearls priced at $149.99 – he racked up almost $200 for the day. Reasonably enough, Mike went ballistic when he saw the bill from iTunes. Luckily, despite the iTunes
terms stating that all sales are final, he was able to call Apple Support and have the largest charge refunded.

So what happened? Developer Manton Reece explained it well in his own blog post. In essence, because Mike had purchased an app on his iPad and then let his son play with Fishies immediately afterward, iTunes cached Mike’s password and used it when his son made purchases within Fishies, instead of requesting it again. Mike’s son was prompted for each purchase, but since the iOS didn’t require a password, it’s easy to see how a 7-year-old could agree to the in-app purchase prompts without realizing what was happening.

This entire situation came about because of a design compromise. By requiring you to enter your iTunes account password for a purchase or free download, Apple ensures that an authorized user is in control of the device. That’s a good thing. And by caching the password for 15 minutes, Apple reduces the significant annoyance of typing passwords (especially strong ones that include numbers and punctuation) on a virtual keyboard. In general, that’s also a good design, although it can obviously have unintended side effects.

To eliminate those side effects, Apple could require a password for every purchase or free app download, but that would hurt the overall user experience. In most instances, there’s no need to prompt multiple times for purchases made in quick succession because it is most likely that they’re being made by the same authorized user.

Arguably, Apple could also cache the password separately for app purchases and in-app purchases, such that purchasing an app wouldn’t enable in-app purchases without requiring a password. However, there’s no telling if such a change would be easy to make or if it would make a significant difference, since any sort of caching will allow inadvertent purchasing.

Another solution would be to add an option in the Store settings panel that would enable users concerned about this possibility to require passwords more frequently, for transactions over a certain amount, or even for every transaction.

In the end, though, the best advice is merely to be aware of the possibility that a cached iTunes password could be used for purchases, which is most likely to happen when an iOS device is shared with young children who might purchase things inadvertently. Older children might become aware of the loophole and exploit it intentionally, but that’s something to be solved via discipline, not technology. It’s much like an automatically locking door – if you’re concerned about security, you wait to see if the door has closed and locked behind you after you enter or exit the building, because if you don’t pay attention, it would be possible for someone to grab the closing door and enter without having a key.

That said, the constant increase in the number of passwords – on multiple devices – that we need to deal with is becoming a significant user experience problem, and one that Apple would do well to think about.

Jeff Carlson 15 comments

Apple Responds to iPhone 4 Antenna Issue

Apple enjoys – and pays for – some of the best public relations in the world, but in last week’s special press conference, Steve Jobs and company focused on science, not spin, to explain the antenna issues that have arisen with the iPhone 4. (Apple has posted a streaming video of the press conference online. The video omits a long and interesting Q&A at the end.)

Addressing the Problem — Although the core of the presentation focused on explaining the problems involved, Apple is offering a few concrete solutions.

As promised when the issue first appeared, Apple released iOS 4.0.1 the day before the press event, an update that changes the iPhone’s algorithm for calculating and displaying signal strength. This doesn’t improve signal reception but makes small changes in signal quality more obvious, and displays worse signal quality more accurately.

The update also increases the size of the first three signal bars, to make the drop-off in signal not seem so severe (see “iOS Updates Adjust iPhone Bars, Apply iPad Fixes,” 15 July 2010).

Apple will also offer free cases (normally $29) to all iPhone 4 purchasers through 30 September 2010, and give refunds to people who bought Apple’s iPhone bumper cases. That includes purchases made outside the United States. The company can’t make bumpers fast enough through the end of the quarter, said Jobs, so Apple will offer a choice of free third-party cases beginning late this week. (Not all third-party cases will be available, and the refund applies only to bumpers, not to third-party cases that were purchased.)

The company will also allow early buyers to return an undamaged iPhone 4 for a full refund within 30 days of purchase; the same applies to AT&T. Apple hedged during the Q&A that followed the presentation as to whether AT&T would waive cancellation fees to release customers from a service contract. AT&T and other carriers typically allow only a 14-day rescission period.

Aside from the antenna issue, Jobs said that Apple is actively investigating a problem causing the proximity sensors of some iPhone 4s to not work properly, suggesting a fix would appear in the next iPhone software update. Also, the white iPhone 4, which was not available at launch, will begin shipping at end of July.

Antenna-gate — The crux of the issue, according to Jobs, is that this antenna problem affects all cellular phones, not just the iPhone 4. Jobs joked that Apple didn’t make it easier on themselves by identifying the area at the lower left edge where two antennas meet, saying, “Here’s where you touch it, everybody!”

To demonstrate how widespread the issue is, he played videos of Apple engineers holding a BlackBerry Bold 9700, HTC Droid Eris, Samsung Omnia II, and an iPhone 3GS, all of which lost signal when held such that the bottom antennas were blocked by the hand. (You can watch the videos at a page Apple created on its Web site.)

Refuting the idea that Apple didn’t properly test the iPhone 4 before launch, Jobs explained that the company has spent $100 million to build a state-of-the-art test facility comprising 17 anechoic chambers, run in part by 18 scientists and engineers holding Ph.Ds. Apple also posted a video about these chambers and its testing methods. (This adds to a growing library of Apple high-tech behind-the-scenes peeks, such as the way iPhone 4 screens are manufactured and tested, or how the unibody MacBook Pro is

For a closer look at the antenna problem and why offering a free case will help, see Rich Mogull’s article “Why Using an iPhone 4 Case May Improve Signal Strength” (16 July 2010).

Recalibrating Perceptions — Jobs admitted, “We knew that if you gripped it in a certain way, the bars were going to go down a bit, like every smartphone. And we didn’t think it would be a big problem.”

Apple’s real job with the press conference was to counteract the idea that the iPhone 4 is worse in this respect than others. After all, the reason Apple held the press conference (and apparently pulled Jobs away from a vacation in Hawaii) was to address the high level of attention the issue has received.

To do that, Jobs unveiled numbers that indicated the scope of the problem is much smaller than the reporting and speculation would suggest:

  • Apple has sold more than 3 million iPhone 4s in the product’s first three weeks. These numbers tell the story that buyers haven’t been discouraged by antenna reports, but don’t reveal whether buyers are dissatisfied or not.
  • According to AppleCare call logs, the percentage of all iPhone 4 users who have called about antenna or reception issues has been 0.55 percent. Farhad Manjoo suggests at Salon that Apple’s previous lack of response on this issue may have suppressed such complaints, but that requires the assumption customers expected to be stonewalled and avoided calling as a result.
  • AT&T’s return rates for the iPhone 4 are lower than those for the iPhone 3GS for “early shipments” compared to this time period last year. Returns of the iPhone 3GS were 6 percent, while the iPhone 4 returns are at 1.7 percent.
  • Using data given to Apple by AT&T a few days before the press conference, the frequency of dropped calls using the iPhone 4 is slightly higher than the iPhone 3GS. Jobs wouldn’t reveal AT&T’s exact numbers for competitive reasons, but noted that the number of dropped calls is less than 1 additional per 100 compared to the iPhone 3GS. Slate’s Farhad Manjoo says that AT&T told him in 2009 that the average iPhone call drop rate was 1 in 100, meaning the iPhone 4 rate could be twice as high (nearly 2 percent of calls) unless AT&T and Apple have improved call dropping. In any case, even a 1-percent call drop rate should be unacceptable on any phone.

Jobs offered a “pet theory” about these last numbers. Since the iPhone 3GS had the same form factor as the iPhone 3G, people who upgraded kept their cases. They didn’t experience the antenna issue because they weren’t touching the phone itself.

And a Few Words for the Assembled Press — Jobs repeatedly emphasized that Apple is an engineering company. “We think like engineers,” he said, “we love it. We think it’s the right way to solve real problems.” But he also reiterated, dozens of times, that Apple loves its customers and wants to make them happy, even the small percentage of users who are impacted by the antenna problem.

In the question-and-answer session that followed the presentation, Jobs didn’t hide the fact that he thought the press coverage of the issue has been “blown so far out of proportion.” Jobs, along with Chief Operating Officer Tim Cook and Senior Vice President of Mac Hardware Engineering Bob Mansfield, took jabs at Gizmodo (referencing the iPhone 4 prototype that the site acquired in a dubious fashion) and refuted two specific press reports. A Bloomberg article stating that an Apple engineer warned about the problem during development was “a total crock” and “total B.S.” Also, a New York Times article asserting that a software update could fix the problem was “patently false,” according to Scott Forstall, Senior Vice President, iPhone Software.

“In the search of eyeballs for Web sites, people don’t care what they leave in their wake,” Jobs said. “Haven’t we earned the credibility and trust from some of the press to give us a little bit of the benefit of the doubt, of our motivations, the fact that we’re confident and will solve these problems? I think we have that trust from our users, but I didn’t see that in the press. This thing was blown so far out of proportion. But I’m not going to say we’re not at fault. We didn’t educate enough.”

Despite expectations about free cases (now granted) and iPhone 4 recalls (not ever seriously considered, according to Jobs), the antenna situation is the same today as it was before the event. The real goal of the press conference was to dampen runaway speculation. By the end, Apple did something that is, of late, uncharacteristic of the company: it became more transparent about a real problem, owned up to its mistakes, and promised to improve in the future. How refreshing.

Rich Mogull 28 comments

Why Using an iPhone 4 Case May Improve Signal Strength

Consumer Reports said on 12 July 2010 that it could duplicate iPhone 4 call and data quality drop-off problems in its lab when part of a hand covered the external antenna gap on the phone’s left edge. Based on its testing, holding the phone in your left hand so that you create an electrical bridge over the small plastic gap between the two metal pieces has a dramatic effect on the phone’s connection, large enough to disconnect active calls.

Consumer Reports considers the problem so serious that the organization cannot recommend purchasing an iPhone 4, even though it otherwise topped their smartphone ratings. At the end of the article, Consumer Reports recommends a quick, simple fix that’s been widely reported in other publications. Merely placing a small piece of tape or clear nail polish over the gap on the lower left side of the iPhone 4 can fix the problem, as can putting your phone in a case or using Apple’s own bumper case that wraps around the phone.

The testing organization’s report was followed later in the week by Apple’s press conference, when the company announced it will be providing free bumper cases to all iPhone 4 owners to address the issue (and Apple’s PR woes). Apple will also refund the purchase price of bumpers purchased from its stores. (See “Apple Responds to iPhone 4 Antenna Issue,” 16 July 2010.)

Yet since many people think the main problem is that our hands absorb the radio signal as we hold the phone – an issue a piece of tape can’t possibly fix – the recommended solution can seem a bit confusing.

The reason a case (or some tape) helps is that the iPhone 4 actually suffers from two different antenna issues. One is common to all phones, and the other results from the iPhone’s unusual external antenna design.

Of Radio Waves and Absorption — While I’m not a radio antenna engineer, deep in my past I spent a considerable amount of time in the rescue and emergency services community, including over a decade with Rocky Mountain Rescue. Aside from handling our own radio communications in austere, remote environments, we also spent a fair bit of time practicing how to find emergency rescue beacons used by backcountry skiers and located in aircraft (and boats – not that I went hunting for many of those in the Colorado Rockies).

Much to my surprise at the time, this work required some basic knowledge of radio frequency propagation and even antenna design. It’s awfully hard to find that crashed airplane if you plug the wrong antenna into your receiver.

The first issue with the iPhone 4 is that when you hold it in your left hand, your hand covers the antenna used for cellular voice and data transmission and reception, and attenuates some of the signal. From an antenna’s perspective, the human body is a big bag of water, and water absorbs radio waves superbly. (Attenuation is a fancy term for blocking a signal through absorption, which can be by a body part, a wall, or other materials. Even the air around us attenuates a signal.)

This is a problem for all mobile phones, not just the iPhone, but it has never manifested itself quite so clearly before. During its press conference, Apple showed competing smartphones dropping signals when Apple engineers held those phones in a typical manner that covered the “sour spot” where the worst results from attenuation occurred.

Like other mobile phone manufacturers, Apple positioned the iPhone 4 antenna’s maximum power output as far away from the head as possible. An increasingly large number of studies involving long periods of time and lots of people have failed to demonstrate a relationship between cell phone use and health conditions, such as cancer in the head closest to where a phone is typically used. But there is no dispute that having the least amount of electromagnetic radiation focused on the head to avoid heating effects is the best course of action. It’s also worth noting that the FCC’s absorption rules on emissions are based on proximity to the human head, and ignore the hand.

In the old days, the problem of where to place the antenna was solved via a big antenna sticking out the top, but big pop-up antennas are no longer fashionable in civilized society, even though they worked quite well.

If you can position the antenna in such a way as to reduce how much radiation the head absorbs, you can increase the overall power output while keeping the FCC happy. Unfortunately, different locations for the antenna also increase the potential for signal obstruction.

Different Frequencies Have Different Behaviors — Adding to the problem is that current phones use a variety of frequencies, most of which are at much higher ranges than our old analog phones. It used to be quite expensive to make chips that could operate at higher frequencies (in this case, typically between 1700 MHz and 2100 MHz). That’s no longer a bar, and spectrum around the world has been continuously freed up to allow greater use of mobile phones and other devices.

As you might know from looking at a classic sine wave, the higher the frequency, the shorter the distance between two peaks or troughs; that distance is the wavelength. For example, an 850 MHz signal runs through 850 million cycles per second.

The downside to using higher frequencies is that signal strength drops off faster than at lower frequencies. The higher the frequency, the more “energetic” it is, allowing the signal to drop quickly as it bounces off and is absorbed everything from buildings and trees to the air itself.

That’s why 2.4 GHz Wi-Fi, used with 802.11b and g originally, and supported with 802.11n, can cover an entire house, while the 5 GHz band used by 802.11a and supported in n, may cover just a couple of rooms. It’s also one reason why VHF television signals were easier to receive than UHF back in the day – VHF (very high frequency) was lower frequency than UHF (ultra high frequency), and would thus travel further with less signal loss.

Practically speaking, this meant that in my rescue days we preferred lower frequency radio channels since they would travel longer for a given power output (a big factor for battery size and life) and pass through objects better. Higher frequencies required more energy to travel a given distance (outside a vacuum), and were more likely to “bounce” off objects. When you are hanging from a rope a thousand feet off the ground with someone else controlling the brakes, you tend to like a nice, clear signal.

This has direct implications for mobile phones. Higher frequencies effectively require more energy to cover a given distance, and signals struggle more to penetrate objects and buildings. Believe it or not, cell carriers can tell when trees lose their leaves based on the signal changes in the towers near the trees.

It also means phones are designed to minimize the interference with the antenna. That’s why the original iPhone needed a plastic section on its otherwise-metal back. Metal would block the signal, which passes through plastic fairly well. The iPhone 3G and 3GS used an all-plastic back, solving the problem.

The iPhone 4 takes this a step further and sticks the antenna on the outside of the phone. This is one reason for overall improvements in signal strength, but if you block the strip on the left side of the phone with a big bag of water (your hand), some of the signal is lost. There isn’t a phone on the planet that doesn’t lose some signal if you block the antenna with your hand.

It’s why Steve Jobs joked at the antenna press conference that Apple had provided a target for blocking – no other phone has as clear a location where, when covered, you will guarantee higher attenuation than other areas.

While placing the antenna on the outside reduces signal attenuation from the body of the phone, it does cause a second problem.

Bridging the iPhone 4 Antennas — That metal band around the iPhone 4 isn’t just a single antenna for the cell phone. It’s actually two different antennas, which explains those little black bands. One antenna is for the cell phone itself, and the other is for Wi-Fi, GPS, and Bluetooth. The black band on the right is decorative, with the antenna continuing underneath the plastic, but the one on the left side is a physical split.

Crafting external antennas is actually a tough problem. The size and shape of an antenna is dictated by our old friend, the wavelength. Antennas aren’t merely random sticks of metal, but carefully designed components sized to match the frequencies they work with. Lower frequencies have longer wavelengths, and thus require longer antennas.

The antennas used to communicate with submarines in the Very Low Frequency band are a heck of a lot bigger than the little ones in our phones. There are even Ultra Low Frequency communications systems used by the military and in mining that can travel through the Earth itself. For instance, a 60 KHz signal broadcast from Fort Collins, Colorado, sets the time for the entire United States on those radio-set clocks that adjust themselves.

Antennas have sweet spots which are different factors (multiples) of their wavelength. Thus the antenna on a cell tower is bigger than the one in your phone, but they both operate on the same frequency. There are many more factors involved, but this is the important bit for the iPhone 4 problems. Bigger antennas do a much better job for any given frequency, but only if they are the right size and shape for the wavelength they are handling.

Technically, our phone antennas are fractions of the optimum size for the given wavelengths. As one commenter noted, at 850 MHz (one of the GSM bands supported by the iPhone) the wavelength is 35.27 cm (13.89 inches), and antenna of that size wouldn’t fit even in an iPad, much less in an iPhone. Thus we use fractions of the optimum length antennas, and higher frequencies, with their shorter wavelengths, allow us to use more-effective, yet smaller, antennas.

The second problem with the iPhone 4 isn’t your hand absorbing the signal, but instead your hand, as an electrical conductor, acting as a bridge between the antenna on the bottom of the phone and the one on the left side. This not only creates potential interference by allowing the signals to interfere with each other (probably not a huge issue since they are independent frequencies), but it also changes the “size” of the antenna and thus its capability to function properly.

Although each antenna handles multiple services on different frequencies, they are all within the design constraints of the antenna. Consumer GPS receivers listen in at 1500 MHz and Bluetooth and Wi-Fi (all on the right-side antenna) employ 2400 MHz, but because 2400 is not far from 1500, it works out well enough. (The iPhone doesn’t support 5 GHz 802.11a/n.) However, bridging the GPS/Bluetooth/Wi-Fi antenna with the cellular antenna (mostly on the left side), which handles 850, 900, 1800, 1900, and 2100 MHz, doesn’t fall within the engineers’ plans.

That’s why placing tape over that spot on the left side of the iPhone 4 can resolve the problem. It insulates the antenna from your hand, preventing it from bridging the two antennas and messing up the signal propagation/reception. When you insulate the antenna with tape or a case, your bag-of-water hand is still absorbing some of the signal, but it doesn’t interfere with the antenna’s operation by changing its physical characteristics. You probably need to cover only the break point since your hand isn’t that good of a conductor, and bridging from the far ends of the antennas doesn’t have as pronounced an effect. (AnandTech has some good
coverage of this as well.)

Testing the Theory — Again, I’m no radio engineer, but I performed a simple test at home to see if this theory holds water. Placing my phone on my desk, I first bridged the two antennas with my finger and noted a signal drop of one bar in less than 10 seconds. When I licked my finger (to increase conductivity) and bridged the gap, I saw a drop of two bars instead of one. The signal bars show an average of the last 10 seconds, which is why you won’t notice the change immediately.

I then tried bridging the gap with a small piece of electrical wire. I still lost about a bar on average, but it seemed to take longer than when using my finger, and I could never get it to drop two bars.

Finally, if I placed my finger right next to the gap, on either side, I didn’t see any signal loss at all.

Using my finger, which both absorbs radiation and bridges the gap, resulted in the greatest loss. But since I also lost some signal using a piece of wire, that seems to support my theory that bridging the antennas with a conductor is also a factor. Especially since placing my finger right next to the gap has no effect unless I bridge it.

Thus a bumper or case helps with both parts of the problem. It prevents your hand from bridging the antennas, and creates a small gap that lets a little more signal hit the antenna instead of being absorbed by your hand. This contradicts some of Apple’s explanation, which focused on your hand absorbing the signal.

In one sense, the iPhone 4’s design is an advantage over competing approaches, since the external antenna enables Apple to use a larger antenna that’s blocked less by the phone’s case and innards. But the drawback is that the iPhone 4 has a single, small spot where any signal loss effects are magnified.

I don’t have the equipment or software for a scientific test, but my informal results are very consistent and are something you can try yourself (though if you’re in a good coverage area it’s unlikely any of this will matter; for once my terrible AT&T coverage is an advantage).

That may be more than you wanted to know about radio waves and antenna design, but hopefully it gives you a little insight into the seemingly strange recommendations coming from Apple and others.

And if I’m wrong? Well, you still got to learn some interesting trivia for dinner party conversation.

TidBITS Staff No comments

TidBITS Watchlist: Notable Software Updates for 19 July 2010

ChronoSync 4.1 and ChronoAgent 1.1 — Econ Technologies has released updates to its data management and backup utility, ChronoSync, and its associated remote access utility ChronoAgent, which enables ChronoSync to gain full root access to a Mac that’s been mounted via file sharing.

ChronoSync 4.1 adds new scheduling behaviors and options, email notifications of missed syncs, the capability to wake sleeping ChronoAgent systems, new preference settings for the background scheduler, and new “sync when available” and “when specific volume mounts” scheduling options. The update also improves sync performance, tweaks the user interface, adds agent performance optimization features, and fixes a short list of bugs that includes two crashing bugs. Full release notes are available on Econ Technologies’ Web site.

ChronoAgent 1.1 improves performance, automatically detects changes in network configuration and ensures its availability on the new network, adds the capability to limit volumes that are accessible over a connection, adds support for wake-on-LAN, and enhances the installer. Full release notes for ChronoAgent are also available. ($40/$10 new, free updates, 20.7/3.1 MB)

Read/post comments about ChronoSync 4.1 and ChronoAgent 1.1.

Panorama 6.0.0 build 92277 — ProVUE Development has released a relatively minor update to the powerful database package Panorama, making few code changes but including a whopping 4,750 pages of PDF-based documentation. The updated documentation covers everything in Panorama, including major new features of the Intel-native 6.0 release, such as crash recovery, the capability to revert to earlier versions of a database, live preview for searches, selective hiding of data columns, contextual selection of data, drag-and-drop import of data, and much more. Changes in build 92277 include automatic check for new versions,
new date search options, the capability to change saved favorites in various dialogs, and more. ($299 new, free update for 6.0, upgrades from previous versions range from $179 to $249, downloads range from 23.6 MB to 176 MB depending on documentation and examples)

Read/post comments about Panorama 6.0.0 build 92277.

AppleJack 1.6 — The latest version of the open-source troubleshooting tool AppleJack offers a handful of new features and bug fixes, most notably compatibility with Mac OS X 10.6 Snow Leopard. AppleJack is unique in that you can use it to identify and fix problems on your disk even if you don’t have a separate startup disk or your Mac can’t boot all the way to the Finder. It can repair disks, repair permissions, clean up cache files, validate preference files, and remove swap files. Along with Snow Leopard compatibility, AppleJack 1.6 simplifies the startup process in both Leopard and Snow Leopard, enhances the SMART status verification process, and adds
blessing capabilities for system folders on attached volumes. The update also fixes an unspecified bug that affected user account lists. (Free, 372 KB)

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ExtraBITS for 19 July 2010

The iPhone 4 antenna problems dominated the news this week, and along with a number of articles in this week’s issue, we wanted to point you to an engineer’s dismissal of the Consumer Reports testing methodology and Jason Snell’s tour of Apple’s previously secret wireless testing lab. Also, if you’re thinking of going to Macworld Expo next January, you can get a free show floor pass through next week.

Macworld Tours Apple’s Secret Wireless Lab — As part of the campaign to reverse the damaging discussions of iPhone 4 antenna problems, Apple took 11 journalists on a tour of the company’s previously secret wireless-testing facilities. The tour was designed to show just how seriously Apple takes wireless design and testing, and Macworld’s Jason Snell provided a fascinating description of the experience.

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Engineer Dismisses Consumer Reports iPhone Tests — Consumer Reports has often taken flack for their coverage of the Macintosh, and that trend may be continuing into the iPhone world. On his blog, electromagnetic engineer Bob Egan claims that the RF testing that Consumer Reports did with regard to the iPhone 4 antenna issue was seriously flawed.

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More Free Registration for Macworld Expo 2011 — If you missed the two-week window for free Macworld Expo 2011 registration earlier this year, you have another chance. Through 25 July 2010, you can sign up for a free Expo Only pass at the Macworld Expo Web site. The show floor will be open from 27 January 2011 through 29 January 2011.

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