U.S. Military Special Forces Buy Unique Satellite Receive Suite From Nashua-Based Windmill International, Inc.

Windmill International, Inc. announced that it has received a $9 million order for their KA-10 Suitcase Portable Receive Suite (SPRS) for Central Command Special Forces in Afghanistan.  The order included KA-10s, training, and product support. Windmill's KA-10 SPRS is a highly-portable, rugged satellite receiver system developed to support Special Operations forces deployed overseas.  The battle-ready KA-10 conveniently brings crucial command center information and data to the in-field warfighter, substantially improving mission success probabilities and saving lives. [...more]

In September of 2004, Mr. David Martin (Windmill International, Inc.) and I, along with our AFRL sponsor Mr. John Turtle briefed the Special Operations Command on the results of our SBIR Phase I and Phase II program.  The briefing was entitled "AFRL SBIR contract to develop lightweight GBS Rx antenna for Special Forces".  The press release above is the culmination of that briefing and the result of hard work by a fantastic engineering team that simply did not understand that it couldn't be done.

Dave Martin (R) and myself (L) at Wahiawa, HI demonstrating the "Iron Maiden" in July 2004

In the picture above, our prototype weighed 65 lbs., but replaced about 400 lbs. of equipment, and ran on batteries.  The then-current system is shown in the background; it is a 1-meter dish antenna.  The "Iron Maiden" was the precursor of the new KA-10 system which weighs about 40 lbs. 

The working prototype KA-10, with Dave and I on our way to a demo in Washington DC, December 2005

The original goal of the system was to be sized for airline carry-on.  It struck us that we had achieved our goal when we were on a commuter jet bound for DC from Manchester NH.  (Photo by Dave Martin)

Upon arriving at Dulles, we were reminded by the Arrivals Board that while the hardware may be working perfectly, there were things that could still go wrong.  One challenge was that it was FREEZING in DC when we got there, and had to go to the mall to buy thermal underwear for the demo.  We demonstrated the unit on Pearl Harbor Day, December 7th, 2006.

The system worked perfectly, though the demo gremlins were quite active.  We had overcome magnetic anomolies, loose hardware, and a temperature-related sensor failure.  All these things were taken back to the engineering team as lessons learned and made the ultimate product better.  And, yes, we blamed some problems on software... unfairly.  Sorry, Dan.

There are many, many people to thank for having worked on this project, and I have not asked any of them permission to use their names.  But to them I say THANK YOU!!  It's been a wild ride.

At MILCOM 2006

(U.S. Patent 7,889,144 and other U.S. and International Patents both issued and pending.)

And playing the game is not optional.

-with apologies to C. P. Snow

Breaking the laws of physics is a popular pastime. Who would not want to get a thousand miles per gallon, lose weight by taking a pill, or receive a fortune in cash from a Nigerian prince by email? But, most of us understand it just ain't going to happen. And so it is with antennas. Previously, I wrote about the tradeoffs associated with antennas. The most contentious corner of our tradeoff triangle seems to be size; it's the easiest to measure, and the one in most visible conflict with other aspects of wireless product design.

You want your antenna small, admit it.

Small antennas have been around a long time. Remember pagers? They most often operated in the VHF band, where wavelengths were on the order of two meters. Yet, they were tiny (although the volume of cell phones is approaching what later model pagers were) and the antennas they contained were even tinier. The facts that enabled their good performance were: narrow frequency range and receive-only operation. You can have small size if you give up bandwidth and efficiency. No problem. For many years, AM radios operated from 510-1800 KHz (with wavelengths in the hundreds of meters) using a ferrite loopstick at the core of their antenna; narrow bandwidth, low efficiency, and completely successful.

But, these days who wants to give up bandwidth? If size is the easiest thing to measure, then impedance bandwidth is a close second. An RF network analyzer can measure impedance bandwidth in a few milliseconds, and generate a curve which can be put in a data sheet, or used to compare to an existing data sheet. So, let's make a small antenna with wide bandwidth!! If we're lucky, nobody will ask about the efficiency (which is pretty hard to measure, but easy to experience).

And so, some companies manufacture Antennuators. These are a cross between antennas and attenuators. Between good and evil. Between protein and carbohydrates. Between Apple and Microsoft. Let's radiate some energy and burn some energy as heat. That way, it's kind of usable, and the measured impedance bandwidth is glorious!

There are several ways to build an Antennuator. The easiest method is to build it with lossy materials in the parts that carry RF current. One example of such a material is stainless steel. Stainless steel is a rather poor conductor, but its nice to look at and resists corrosion. There are many whip antenna made from stainless steel, and often the environmental considerations outweigh the loss from the material selection. And in certain antenna types, which are inherently high impedance (such as the Kraus Helical) the difference in material losses will be insubstantial. But, when antennas are made physically small the currents can get rather high, and this is where lossy materials will rear their ugly head.

A few years ago I was working for a company that manufactured various specialized receivers and transmitters operating in the VHF, UHF and low-microwave range. I was the in-house antenna engineer as well as a product designer. A good friend of mine, John D., came to my office with a question. He ran the test department which had the responsibility of tuning and testing all the equipment before shipment. A group of "tactical repeaters" were being tested, and one was on his bench transmitting a few watts of RF at VHF into a six- or eight-inch "rubber duck" antenna (a helically wound short monopole).

"Spence, should the antennas get warm?"

I turned and looked at him incredulously. After careful consideration I answered with a incisive question of my own, "HUH?!!?"

"After about five minutes the antenna is warm, and I don't remember this happening before. Is it normal?" John asked.

"Hell, no!" was my measured response which began a careful investigation into this Antennuator.

I verified that, indeed, the antenna was warming up substantially, and that it was not some other portion of the system making heat and warming up the antenna. After some digging, John and I determined that there was a recent vendor change from vendor "C" to vendor "A". I grabbed some examples of the parts from each vendor and started cutting them open (this is a recurring theme, as you will see, Dear Reader). The helical conductor from vendor "C" was copper-colored, and that from vendor "A" was stainless-steel colored. Hmmmm.

Then I took scraps of the plastic that encased each antenna and carefully tested the dielectric loss using an UHF RF Thermal Conversion Exposure Cavity. Yep. . . a microwave oven. The difference in thermal dissapation between the two plastics was very significant: after about 15-20 seconds of exposure (with a cup of water at the opposite corner of the microwave for loading) the plastic from vendor "A" got hot whereas that from vendor "C" was not noticably warmer -- lossy dielectric confirmed. (While this test was conducted at about 2450 MHz, it is still indicative of losses at VHF.)

The Antennuator from vendor "A" looked great on the RF network analyzer, and even better in the purchasing department's scorecard. But, it was burning precious (battery powered) RF in the process. I immediately wrote an ECO (Engineering Change Order) eliminating vendor "A" as a supplier, and specifically naming vendor "C" as the supplier for this particular part. Problem solved. Purchasing had been credited for saving money on cheaper antennas, and Engineering looks evil throwing out inventory. The Earth continued turning on its axis.

More recently, one of my clients brought me a product from a Serious Defense Contractor, which was labelled "Antenna, Broadband, 50-2000 MHz". It was about twelve inches long, about 5/8-inch in diameter, with a BNC male connector on one end. It was flexible, black, and no doubt expensive. Since my client was taking a training class, I immediately used it as an example of an Antennuator. I started a discussion with the class as to how a twelve-inch long antenna can be rated for operation from 50-2000 MHz. After a healthy amount of discussion, one of the students put the antenna on an RF network analyzer and swept it from 50-2000 MHz, measuring the input impedance.

"It looks good to me!" he said, showing a respectable "knot" in the middle of the Smith Chart, indicating a VSWR of less than about 2:1 (ref. 50-ohms) over the range.

I said, "You'd think so, but remember the engineering rule: if you can't fix it, at least you can break it!". I extended the low end of the measurement down to 2 MHz. And do you know what we saw? It still had a VSWR of about 2:1. . . . but, it shouldn't have. It SHOULD have looked lousy at 2 MHz. Now think, what has a VSWR of 2:1 at 2-, 50- and 2000-MHz? That's right -- a RESISTOR!

I made a bold (and risky) statement to the class: "There's a 100-ohm resistor in parallel with the connector.", I confidently proclaimed, hoping like hell nobody would call me on it. Well, I was with a group that did not see any impediment to cutting open the antenna and finding out Right Now. And so, they did.

I was wrong. There were two, 200-ohm resistors (each rated 3-watts) in parallel across the connector. As I see it, when RF current flows in a conductor the only thing it can make is radiation, but when RF current flows in a resistor the only thing it can make is heat. So, the ONLY possible reasons those resistors were there were to make the transmitter happy over that frequecy range (no spurious oscillation, no VSWR alarms), to make the datasheet look magnificent (and meet procurement requirements), or to prevent the buildup of ice. Unfortunately, my clients are professional communicators and in need of their equipment actually... you know... communicating, and they were already acutely aware of the inefficiency of this product. Putting "50-2000 MHz" on the body of an antenna does not make it so. Notice the efficiency was not stated on the same placard. Pity.

Once I designed an antenna for a small surveillance product that had a resistor in it. The product was battery operated, and had a very high efficiency transmitter. Sometimes, however, if the antenna came too close to a conductor, it presented the transmitter with a very low impedance that caused a spurious oscillation. This was Very Bad in the intended application. I ended up using a small series resistor in the feed loop of the electrically small loop antenna. The cost of this resistor was a fraction of a dB of transmitted signal in normal operation, but it prevented the spurious oscillation completely and the associated loss of signal. This was a carefully weighed decision, it solved the problem, and the efficiency cost was calculated and acceptable. The problem could have been solved further upstream in the power amplifier, and there would have been an efficiency cost there, too.

Resistors turn current into heat. That's what they're supposed to do, and thank goodness they do it so well. But, when you find 'em in antennas, it's worth asking why they're there.

Sometimes, it's useful to burn undesired energy of the wrong polarization as in a Terminated Bifilar Antenna or a Log Spiral Antenna, for example. In that case, polarization purity (axial ratio) is more valuable than efficiency. That is an engineering decision, and a good one.

Sometimes, it's critical to keep the transmitter happy and invest in a bit of heat to do so.

Sometimes, it's to make the datasheet look miraculous and score a big order from the government.

Perhaps someone should ask the professional communicators if the solution to their very real problems is an Antennuator. I think not.

You can have it:

    Fast
    Accurate
    Cheap

Pick any two.

Every professional pursuit has its tradeoffs which must be managed.  In fact, I believe that it is the principal function of the engineer to manage tradeoffs.  We want airplanes to be strong, but light and affordable.  We want our favorite restaurant to be inexpensive, tasty and prompt.  We want our politicians to be honest, responsive and effective (OK... it's just theoretical). These competing desires are what we call the Tradeoff Triangle.  Sometimes the number of parameters we need to balance exceeds three, but for the purposes of our discussion today, the number shall be three... no more, no less.  Three shall be the number of thine tradeoffs, and the number of the tradeoffs shall be three. Four shalt thou not consider, neither ponder thou two, excepting that thou then proceed to three. Five is right out.

But, I digress.

Let's explore what the job of an antenna is, and where its tradeoffs can be found and thence managed.  And we are going to assume that antennas are reciprocal.  That means they can make radiation from RF current (transmitting), and they can make RF current from radiation (receiving).  In any wireless device, there is a receiver section, a transmitter section or both (transceiver).  These functional blocks are designed by a clever and talented RF guy, and generally interface to the antenna via a transmission line of a certain characteristic impedance; the most familiar values for this impedance are 50- and 75-ohms.  (The reason for the existance of these two values is a good subject for a future blog entry.  Anyone know the history of these choices?)

Usually, I hate it when someone tells me the punchline before I hear the joke.  Sorry, but here it is: Your antenna can be wideband, small or efficient.  BANDWIDTH, SIZE, EFFICIENCY.  Pick any two.  It is a sure sign of Antenna Snake Oil when you see tiny, wideband antennas boasting ultra-high efficiency.  Run the other way.  OK, let's take a closer look...

Antennas operate over limited bands of frequencies.  Sometimes these bands are smaller than we wish they were.  A useful way to think about bandwidths is called "fractional bandwidth" (FBW); for our purposes we'll define fractional bandwidth as the high frequency divided by the low frequency.

For example, modern cell phones generally require antennas that operate from 806 to 915 MHz (FBW=1.14 or 14%) AND 1710 to 1990 MHz (FBW=1.17 or 17%).  This covers all the GSM bands as well as the PCS bands.  Another familiar band is the 2.4 GHz ISM band which is where WiFi lives; this band is 2.4 to 2.5 GHz (FBW=1.04 or 4%).  Yet another example is the 900 MHz ISM band which is often used for wireless phones and other household and office devices; this band is 902 to 928 MHz (FBW=1.03 or 3%).  And finally, we are all familiar with GPS which needs about 10 MHz of bandwidth centered around 1575 MHz (FBW=1.006 or less than 1%).

So, antennas for each of these applications need to operate over the entirety of these bands.  This property, which is the first of our three tradeoffs is loosely called BANDWIDTH.  In the four examples above, note that the fractional bandwidth is representative of how "hard" it is to meet this requirement in light of our (soon to be illuminated) other tradeoffs.  GPS seems easy, and "Quad Band GSM" seems hard.  And so they are.  

Now, using the term "bandwidth" without any further qualification is Engineering Blasphemy (see also my rants about the use of "dB" without a reference).  The bandwidth of an antenna is completely dependent upon what is relevant to the application.  For cellphone applications, it may be the "efficiency bandwidth" or that bandwidth over which the total radiated power (TRP) or the total isotropic sensitivity (TIS) is north of a required value.  For GPS we may be bandwidth-limited by the axial ratio, or the quality of the circular polarization (RHCP in the case of GPS).

Frequently, the bandwidth of concern is the impedance bandwidth, which is the bandwidth over which the antenna's impedance remains within a certain "distance" (on the Smith Chart) of the ideal impedance.  Often this is expressed as Return Loss (10 dB is the usual minimum value), or VSWR (Voltage Standing Wave Ratio) where 2:1 is the usual limit.  If someone uses the term "antenna bandwidth" without explicity saying which bandwidth they are referring to, it is probably the impedance bandwith.  And thereafter they shall be scolded.

The second tradeoff in our triangle is SIZE.  There's different ways to think about  size.  You care about physical size when you are trying to stuff ten pounds of stuff in a five pound bag: you want your consumer product to be as small as possible and the industrial designer has graciously given you a volume which would not host most DNA molecules.  The antenna designer is thinking in terms of wavelengths.  As the antenna volume starts becoming a smaller and smaller fraction of a wavelength, the impedance bandwidth starts shrinking, and the ability to remain efficient with real-world materials starts disappearing.  

In December 1948, Lan Jen Chu published the paper "Physical Limitations of Omni-Directional Antennas", in which he derived a theoretical formula of the bandwidth of an electrically-small antenna.  In the interest of circumnavigating a soporific vortex, the conclusion is thus: the smaller the antenna, the narrower the bandwidth.  So there.

EFFICIENCY is the measure of how much of your RF power is going to be radiated, and how much is going to be turned into heat.  Assuming your goal is not de-icing, heat is an undesireable byproduct.  With real-world materials, especially as we shrink antennas, this becomes a significant concern.  A side-effect of shrinking the antenna is causing the antenna's RF currents to become large enough to make the radiation happen.  These high currents make the material losses which were previously ignorable a very real concern.  I have designed electrically-small loop antennas which have a radiation resistance (the good "resistance") measured in milliohms.  Suddenly the fact that the conductor is copper as opposed to aluminum becomes really important.  The dielectric materials used in trimmer and fixed capacitors for resonating such antennas become critical.

While it is pretty clear that losses in conductors and dielectrics are undesireable from an efficiency standpoint, there lurks in the shadows a side effect as enticing as it is detrimental.  These efficiency-robbing losses make the impedance bandwidth appear larger.  In fact, the higher the losses the wider the impedance bandwidth until the limit where ALL the energy is dissipated in losses and the bandwidth seems "infinite".  The ultimate example is a 50-ohm terminator: a perfect match over a huge bandwidth... and zero radiation.  The Dummy-Load Antenna.  The lesson is clear: When presented with an antenna with unexpectedly large bandwidth for its size, ask about the efficiency.  Oftentimes, this line of questioning is met with a stunned silence at best, or a complete change of topic at worst.  There is a tiny fraction of antenna companies operating today whose business plans depend upon your failing to inquire about efficiency.  I'll say it again: About the Efficiency -  Ask!

The product designer, antenna designer, industrial designer and marketing professional together must all cooperatively grapple with the antenna tradeoff triangle: BANDWIDTH, SIZE, EFFICIENCY.

Like it or not... Pick two.

(*If a non-magical person is a Muggle, then I propose that henceforth a non-nerd is a Nuggle.)

Most significantly, I taught a training course on antennas over the course of two weeks.  Eighty hours of training.  If you've ever done training, that may sound exhausting.  And you'd be right.  But, boy, was it rewarding!

Getting opportunities to teach what I have been learning over the last sixteen years is, for me, a lot of fun.  I have trained groups from the commercial, government and law-enforcement arenas.  The topic of antennas is often intimidating for those that use them, but don't design them.  It's seen as super-technical and borderline black-magic.  Perhaps it's because RF and antennas seem to the uninitiated what Einstein called "spukhafte Fernwirkung" or "spooky action at a distance".  You can't see it, but it works.  As one antenna guy put it, "If RF was visible, we'd be out of business."

So, in order to train people how antennas work, you have to make the RF visible.  And for two weeks, that's what we did.

We started with some physical demonstrations which explain how the dipole antenna works; and we make the claim that the dipole is the simplest resonant antenna you can construct.  We spend some quality time watching water slosh back and forth in carefully constructed clear tubes.  Then, once people have spent time developing a mental model for how the electrons slosh back and forth in a dipole (and have personally done the sloshing), they "get" resonance, radiation, and even impedance.

Next we get out a telescoping dipole antenna.  The very same one we use as a standard in the AntennaSys lab.  Add an RF network analyzer, a video projector and the strategic "laying on of the hands" and you have the next "ah-hah!" moment.   The students start connecting their simplified physical analogy to the actual electrical system they are playing with.  They can't see the electrons "sloshing", but now they believe it's happening based upon the real-time information the network analyzer is giving them.  Now, they start believing they can maybe understand a little of this stuff.

Then we predict what would happen if we.....

    shorten the antenna,

    lengthen the antenna,

    feed the antenna at a point offset from the center...

And then we back up their predictions and observations with computer simulations that introduce color-coded graphics which further confirm their observations.

Finally, we started actually building antennas.  Everyone in the class made their own dipole.  All materials came from the hardware store.  Everyone communicated over radios between their hand-made dipoles.

Suddenly..... magic happens.  The antenna is no longer a wonderful mystery.  Wonderful, yes.  Mystery, no.

We introduce more complex antennas: helicals, Yagis, corner reflectors, parabolic reflectors and more.  Add a healthy dose of decoupling, polarization, directivity, transmission lines, Smith Charts, link budgets, multipath and a slew of client-specific topics and the week goes by pretty fast.

When you take a person from the "antenna as mysterious object" phase to the "it's all about getting the slosh right", you've created a better antenna user, a better product engineer, a better systems engineer, a better communications professional.

And the spukhafte Fernwirkung ain't quite as spooky as it was. 

(Thank you Steve and Corinne for helping AntennaSys deliver a great course.  A special THANK YOU to Agilent and Anritsu for providing the RF Network Analyzers used in my course!)

In their FCC filing, Apple describes the WiFi antenna as a "PIFA".  This stands for Planar Inverted-F Antenna.  I would never describe the "frame" antenna using those terms.  So, this seems to support the theory.  Further, the photos (thanks to Arstechnica) of the new Verizon iPhone show elimination of the frame gap on top (which was the WiFi and GPS antenna) and creation of new gaps on the sides.

Is the new iPhone using antenna diversity (two antennas in the frame with switching between them) to compensate for hand effects?  Possibly. 

Stay tuned.

(thanks to Greg Keizer of Computer World for sending me the link to the photos.)

-SW

Thank you, Apple.

"dude, where's the blogs? are you on vacation?" -David O.

The email, tweets and calls I have been receiving have been voluminous. Both from the extremely positive responses to the previous posts, and those folks anxiously awaiting results of the more detailed tests that we promised. I should say up front that I wish we could have spent more time on these tests, but the reality is that it takes WAY more time to make careful measurements than we care to admit, and more than anyone really believes (including Consumer Reports, apparently). Alas, we will finally report on our foray into quantifying the quagmire.

First a couple of items of administrivia. I read every email I receive. I generally have not responded individually due to lack of time and the demands of my business. However, I am planning on my next blog entry to be the first in a series of "Mailbag Editions", where I will try to answer the answerable emails. You, Dear Reader, are the best source of ideas for this blog and I truly appreciate your input and insight. If you email me, I may use quotes from your email, but I won't use your personal information. If you send me a "mention" on Twitter, however, I may quote it verbatim since you already broadcast it to the world. Please use email to contact me in lieu of a phone call. I actually had someone call me today to ask me if he should buy an iPhone 4. If you are a member of the press, or a blogger, or a podcaster, I promise to do my best to get back to you and answer your questions; but, check this space first for my thoughts and information.

Steve Golson, the lab notebook and the GripOfDeathInator

On to our testing of the iPhone 4. In order to do this right, I needed some help, and not just any help. I needed another nerd engineer. Steve Golson was that unwitting volunteer. I'm implying that he didn't know what he was getting himself into, but seeing as he and I have been friends for about a third of a century, I'm guessing he knew precisely what he was in for. And he got it. In spades.

A bit about Steve. An accomplished VLSI design engineer and consultant, he was the manager of the MIT Rifle Team when I was the manager of the MIT Pistol Team back in the 80's when fast microprocessors had 1MHz clocks and antennas were obvious. Steve and his wife Terry created Hencam.com, and Terry is a wonderful chef and author. Terry released Steve for the day (and night) to accomplish this bit of engineering hacking, and for that I thank her. Without Steve, the GripOfDeathInator would not have been born.

We needed a way to hold an iPhone 4 (or any hand-held device, for that matter) in a way that did not introduce any significant conductive surfaces into its environment, and at the same time allowed a human hand to grip it in a repeatable way. We chose to work in an "open field" environment, with real cell signals. The absolute position of the device under test had be constant, so the relationship of the phone to the cellsite remained uniform. These requirements gave birth to the GripOfDeathInator, pictured above. And that is Steve beginning testing.

The GripOfDeathInator is built from one-inch thick foam sheet. It's glued together with a foam-friendly adhesive from Liquid Nails; thanks to the smart Home Depot guy for that one. The foam is pretty much RF-invisible, but it is strong enough to securely clamp our test devices. I'd love to tell you all the details of the extensive mechanical engineering that went into the design, but really, we winged it. It works as good as it looks. We also found all-plastic saw-horses to create our work table, and a wooden stool for our bag of salty water...um... Steve.

Once we had a way to repeatably position and grip the iPhone, we needed a way to measure the effect of the different grips. The "bars" are useless; we were stunned to find out that we have no idea what they mean, nor what their time constant was. Truly stunned. So, we decided to use the 3G data download and upload speeds. These measurements were made by using the Speedtest.net app. We had very fine-grained measurements of data rate, and indirectly these were telling us about the bit error rate (BER). The BER in turn tells us about the signal-to-noise ratio in the receiver, and the phone's transmitter power received at the cell site; both of these are affected by antenna performance. After much consideration, we decided this was the best way to accomplish the measurement without ripping an iPhone 4 open and firing up the soldering iron... and the microscope. As a result of separately measuring upload and download rates, we discovered that there was a couple of surprises waiting for us as you will see. Each measurement we report was the average of at least five consecutive runs; we also report the spread of those runs to show some indication of the measurement quality.

We also experimented with the azimuthal position of the phone: which direction it was facing. After making a bunch of test runs we decided it was not a significant improvement to include all the points of the compass. However, had we not explored that, we would not have discovered another interesting aspect of our measurement procedure: data rate throttling. You see, Steve was very smart in suggesting that as we tested at the four points of the compass, we rotate the apparatus back to the original position and do a fifth run. This would verify the consistency of our measurements. It was during one of these repeat runs that we observed a drop in the data rate of the download by a factor of 3-4. It lasted about 15 minutes, and things returned to normal. Additional details of this behavior will be the subject of a future blog entry. Has anyone else observed this behavior?

The VIP

The Half-GripWe developed four grip conditions: None, The Vulcan iPhone Pinch (VIP), The Half-Grip, and The Full-Grip. When the phone was not gripped, the operator (Steve) stayed in position and rested the gripping hand on the lower "C" cut in the foam. This insured that the local environment around the phone remained the same. We also kept any metal about 20 feet away or more, and kept it constant through the data runs.

As we were testing, the VIP appeared to be about the same as no grip at all. But, after crunching the data we were surprised to learn that it seemed to have a slight benefit. This could be explained several ways, and was less shocking than it was amusing.

The Half-Grip and the Full-Grip had negative impacts on the data rate that were sensible: the Half-Grip was bad and the Full-Grip was worse.

The Full-Grip

Overview of our test range showing the control phone to the left

After the data-throttling observation, we decided to set up a control phone to observe the network performance as a whole. We reasoned that should the network slow down (as had been observed) we could normalize the data using the control unit's rate measurement. We were wrong. The data throttling was IP address specific. When we had the control phone set up, we observed normal data rates on it when the other phone dropped by 3-4X. Fortunately, the drop in data rate during those periods was so precipitous, that we were able to remove any affected data points easily. More on that in a future post.

Before we get into the data, I should discuss one major limitation of our technique. We could not control the signal strength of the cell tower. We had to take what we got. The good news is that is was a "moderately good" signal; we did not have a cell tower looming over us. Nor did we have a very weak signal that would be easy to completely obliterate. We were illuminated by one cell site only, eliminating the possibility of switching between sites.

This limitation meant that once we observed a condition with good performance, it was hard to differentiate it from another condition with good performance; in other words, the data rates hit their upper limits. We could have used RF absorber material, or moved locations to reduce the signal level, but we really do have wives and kids and like to see them every now and then.

In graphical form, here are our results, below. We are reporting the average (the little box), and the spread (the little "T" bars) of the data rate measurements for both download (red) and upload (blue). Note that the vertical scale is logarithmic, which means that a change in height of the data represents a constant factor (or percentage) regardless of where it is on the graph. The shape of the "curves" is the most important thing to observe since the absolute data rates may still be broadly dependent on network loads.

We can make several interesting observations.

1) Gripping the Naked iPhone 4 certainly had a strong negative effect on the data rates, both upload and download.

2) The effect of the grips on the iPhone 3G is much smaller. But, the Full-Grip still reduces the data rate on upload.

3) Use of the Apple "Bumpers" has a very positive effect on performance. It mitigates much of the effect of the grips at our signal strength level.

4) The iPhone 4 data rates still beat the iPhone 3G data rates under all grip conditions.

5) There was a large spread in the data during the Full-Grip, in both upload and download. This highlights the sensitivity of the antenna design to direct contact by the hand.

In plain terms, the iPhone 4 SmartModule becomes a SmartPhone with the Bumpers.

What about the Consumer Reports "Duct Tape" fix? Yep, it will help. Any insulator over the "gap" area of the antenna is going to help in direct proportion to its thickness. I think Consumer Reports was going for style points in the selection of Duct Tape. Nice move - they sure dominated the news cycle.

But, hey, Consumer Reports guys: you don't do radiated tests in a shield room. That's like measuring the light output of a desk lamp in a house of mirrors. It's amateur hour. Either you didn't really explain your experimental technique fully in your video and text on your website, or perhaps you did and it really stinks. In either case, we end up agreeing with each other, so let's not dwell on that too much.

I have had the Apple Bumpers on my iPhone 4 now for about a week, and have been putting it through its paces. It does fine. I will probably get an Otter Box case when they come out (provided there are no gotchas). I cannot imagine owning this phone with no case. And I can't imagine not owning an iPhone; it's a great device.

However.... Apple: you really need to give every iPhone 4 owner a free bumper. We've proven it really helps reduce the hand sensitivity problem. And it became a problem the minute one of your employees said to a user, "You're holding it wrong." Instantly, you established that there was a right way and a wrong way to hold it. Surely, if we review our manual for the iPhone 4 we'll discover that .... oh wait .... there is no manual. And the pamphlet that comes with it says absolutely NOTHING about how to hold it. Despite its ironic title: "Finger Tips".

Apple, give everyone a bumper. And give me my twenty nine bucks back for the one I bought.

Or, just buy me sushi and we'll call it even.

Let me explain.

I enjoy photography, and have had a professional-grade Nikon SLR in my hands since I was about 13. When you buy a camera like that, you really aren't buying a camera. You seperately purchase the body, the lens, a more comfortable strap, perhaps a corrective eyepiece or even a different focussing screen. Then, you have a nice "camera", and are ready for serious photographic action.

Apple has introduced the same philosophy with the new iPhone 4 SmartModule. Don't be fooled, it's not a phone, its a module. Because, you need to add a case, and perhaps an earpiece to make it a phone. But, then it's really a crazy-good product.

After living with the iPhone 4 for a little while, I cannot imagine what the heck Apple was thinking about when they placed the antennas where they are. It's a bold, risky move. However, if you had come to AntennaSys and said, "We'd like to put the antennas in the place with the highest probability of being covered with a hand!", I would have sat you down and calmly explored exactly why it is you felt you must do this. The fact is I would have tried to talk you out of it and find a better solution. Either it is genius or just plain dumb. Time will tell.

When I first thought about and later played with the iPhone 4, I didn't see where the problem was hiding. In fact, I wrote about how I held the Primordial iPhone for years with the Vulcan iPhone Pinch in order to avoid blocking the antenna at the bottom of the case. I tried the same techniques with the iPhone 4 and it worked fine. What was the fuss about? Then, I tried the Grip of Death, and could not kill a call in my office; though I recognize we could have killed that call if we were in a marginal area. And, I have ignored data transfer while concentrating on voice calls.

Then, I received my very own iPhone 4. And lived with it. And finally saw the light.

It was a small light, on a dark background. At first it was fuzzy and distant. It grew closer and brighter and....... I finally found my glasses on the nightstand. Oh, yeah, I saw the light. It said, "No Service."

With the iPhone 4, a true VIG (Vulcan iPhone Gripper) won't drop a call due to the antenna placement. But, anyone who uses the phone for... say.... email, or texting, or Googling, will isolate themselves from the cellular world while doing so. This is because it seems impossible to hold the phone vertically in one's left hand (Lefties, please forgive me), while typing with the right index finger, without putting that fat fleshy part of our palm, right below our hyper-evolved opposable thumb, smack dab over the "hot spot" of the stainless-steel-rim-interruption-fed cellular antenna.

No worries, we're adaptable, right? Just rotate the phone to horizontal mode. Hold the phone in your left hand from the top. Not so fast! While calendar, email, texting and contacts will rotate in text-entry mode, some apps won't. Use the Vulcan iPhone Grip while trying to do text entry? That's a sure path to physical therapy.The Data Interaction Grip

The Primordial iPhone did not have this problem. Previously, I alluded to the fact that Apple moved the "antenna action" from the back of the case to the sides of the case. This is the root of the problem. Grab your iPhone. If you don't have one, grab a deck of cards. Now, place a call on your CardDeck5 SmartPhone. Freeze! Where was your hand while dialing, or looking up the number? C'mon, take a look. Was your hand gripping the sides of the case or the back of the case? I am betting that you were gripping the sides of the case, and the back of the case had a little semi-circular air space between it and your palm and fingers. Am I right?

The Semi-Circular AirspaceThis little space is what gave the previous generation iPhones, and many other cell phone designs, a fighting chance to work. The antenna's got to breathe! That little, natural, air space greatly reduced detuning the antenna, but won't do much for attenuating the radiation heading for your hand. But, it is the prevention of detuning the antenna that allows the RF energy to transfer into and out of the antenna in the first place! And with the iPhone 4 antenna placement, especially without a case, we're detuning the antenna every time.

Sure, once a call is established, we switch to the Vulcan iPhone Grip and all is well. But, during a "data interaction" with the iPhone 4, we may be killing the cell antenna. That lower-left break in the band (as we are looking at the screen) is its feedpoint. And we are smothering it in lean, trim, sinewy muscle as strong as steel bands. Or so.

In preparation for testing (the results of which will be reported here), I am off to the Apple Store to pick up an Apple Bumper case for my iPhone 4 SmartModule. Perhaps it will then become a SmartPhone.

As Leo Laporte told me when I appeared on TWiT #255, "You shouldn't need a freaking manual to learn how to hold a phone!"