Archive for July, 2010

Introducing the new !Phone

Wednesday, July 21st, 2010

You?re probably aware of the iPhone4 antenna saga that?s been in the news the last couple of days. I find all the responses from different bloggers, news reporters and Apple quite amusing.? Something in particular that caught my attention is that most smartphone designers position the antennas at the bottom of the phone. My immediate response is, ?Why do they keep on putting the antenna at the bottom?? Why don?t they simply move it to the top of the phone where users? hands would least likely interfere with the signal??

I think Spencer Webb hit the nail on the head with his explanation in his blog entitled. Apple ?iPhone 4 Antennas…?. He explains why in spite of the fact that it?s the most impractical position, 99% of modern cell phones are manufactured with the antenna placed at the bottom, back of the phone. The FCC (Federal Communications Commission) puts strict limits on the amount of energy from a handheld device that may be absorbed by the body. The absorbed power is determined by measuring something called SAR (Specific Absorption Rate). All new phone models have to pass SAR tests which, surprisingly, are done in the vicinity if a human head model (or phantom) but without a model of a hand holding the device! Cell phone manufacturers are required to print the maximum SAR in the phones user manual and the test results have to be less than 1.6 or 2 watts/kg (in the US and Europe respectively). So in order push down measured SAR, the antennas are moved as far away from the head as possible – the bottom, back of the phone.

It seems to me like the issue that needs to be addressed isn?t the fact that Apple slipped up or how to improve mobile phone reception when the antenna is shielded off by a human hand.? Obviously SAR needs to be regulated but it seems like there?s a lot of hype generated by uninformed individuals who claim that RF radiation from mobile phones is a massive health risk. It seems that this is more of a marketing issue. The SAR value that is printed in a device?s user manual needs to be minimized to keep the public happy in spite of the fact that SAR in the hand is ignored during measurements. In practical situations more power needs to be radiated to compensate for signal loss due to the vicinity of the hand – increasing the actual SAR and reducing the phone?s battery life.

I wonder what would happen if the FCC includes a mandatory hand model in SAR tests – how many smartphones would pass these tests?? Or if they decide to double the allowable maximum SAR limit what would the response be??

Another solution for the iPhone 4 would have been to make the phone work when flipping it upside down (so the screen automatically rotates 180 ?) while on loud speaker or browsing the internet. This would in effect reposition the antenna in its most logical position ? at the top of the phone. Maybe they could then call it the ?!phone? : )

"Hold it like this."                                                   ????????????  by Cartoonist, Konrad Brand

"Hold it like this."                                                    by cartoonist, Konrad Brand

Author: Robert Kellerman

Version 2.2 released!

Wednesday, July 21st, 2010

To all our blog subscribers and those of you who might not be aware, we recently launched Antenna Magus 2.2.0. Version 2.2 includes 6 exciting new antennas and in addition to new FEKO and CST MICROWAVE STUDIO? antenna models that have been added to the database, improved memory management and performance really makes it worthwhile updating to Version 2.2. You can read more about?this release?in the latest Newsletter 2.2

Preview of newsletter 2.2

Preview of newsletter 2.2

Author: Robert Kellerman

Pringles Cantenna measured in an anechoic chamber

Friday, July 9th, 2010
Pringles Cantenna in anechoic chamber

Pringles Cantenna in anechoic chamber

We recently did some antenna pattern measurements and included the Pringles cantenna (which I blogged about a few weeks ago) amongst a couple of other great antennas. I doubt if this has ever been done before! The Pringles cantenna performed surprisingly well seeing that we did nothing to improve the conductivity of the can.

We also built a replica of the Pringle version out of copper as show in the image below. The graphs below compare measured S11 and gain patterns between these two antennas.

Pringles and copper cantennas

Pringles and copper cantennas

S11 simulation vs measurements

S11 simulation vs measurements

Pringles vs copper cantenna pattern comparisons

Pringles vs copper cantenna pattern comparisons

Author: Robert Kellerman