antenna-theory.com

[JDB3]

Hi All,

Please help me with a brainstorm thread... I have a simple question that can be answered in many ways and I am hoping for a wide range of answers - off the cuff, well-thought-out, whatever works for you!

What antenna applications do you think can benefit the most from an increase in antenna efficiency?

In other words, assume that you could make any current antenna more efficient in a given application, what application would you choose?

There is certainly no wrong answer here, but I am trying to discern if antenna efficiency is a significant issue in practice and, if so, in what practical applications it is most significant.

Thanks in advance. I look forward to a good dialogue. I'm happy to respond to questions.

- JDB

[bigSteve]

Well satellite dishes, horn antennas, and spirals (commonly used in defense programs) are all highly efficient (>50%) so there's not a whole lot of possible gain there.

Antenna efficiency is most limited when volume is limited - this is most common in hand-held personal electronics. Often GPS, WIFI or cell antennas can have potential improvement of 6 dB or so, and that's a big gain.

Now, for transmit antennas on personal electronics, you don't necessarily want more efficiency, because of SAR limits:
http://www.antenna-theory.com/definitions/sar.php

So I guess the biggest gains may come in GPS and diversity cell antennas (which don't transmit). Or whenever antennas are volume constrained, or packed in a region with a lot of lossy materials.

What specific applications are you considering?

[JDB3]

bigSteve,

Thanks for the thoughtful reply! Your comments make a lot of sense.

We agree that volume constrained/lossy materials are good indicators of places where a more efficient antenna could benefit a system. Aside from the consumer electronics that you pointed out (rightfully so), do any ideas come to mind?

A few other areas we have discussed are implanted medical devices (recharging, transmitting power, monitoring systems, etc.) and RFID tags/readers. Any specific thoughts on those areas?

Thanks, again!

Hopefully some other people will post as well to continue the conversation...

[Bobby Digital]

For implantable medical devices (ICD's pacemakers) with rf radios in them, they would fall in line with what bigSteve said about size constrained hand held devices in that the tantamount need for as small a volume as possible leads to highly inefficient antennas that may even be electrically small at the frequency of operation. The Medical Implantable Communication System band is 402-405 MHz, and thus the antenna will be severely size limited, even after taking into consideration the permeability of the body.

[JDB3]

Thanks Bobby D.! I appreciate the input on med devices.