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Re: [TowerTalk] Isolated Mode Antenna Technology

To: "Ed Callaway" <>, <>
Subject: Re: [TowerTalk] Isolated Mode Antenna Technology
From: "Bill Aycock" <>
Date: Sun, 20 Dec 2009 09:40:26 -0600
List-post: <">>
Thanks, Ed. It read like something put out just to say they had published, 
perhaps to "be on record".  It was obviously not a "Peer reviewed" thing. I 
wonder how the timing problem will be handled when one antenna is used for 
send and receive?

----- Original Message ----- 
From: "Ed Callaway" <>
To: <>
Sent: Sunday, December 20, 2009 7:22 AM
Subject: [TowerTalk] Isolated Mode Antenna Technology

> Bill,
> I suspect that the article made little sense because the actual design of
> the specific antenna is the "secret sauce" of the authors' company, and 
> the
> article is largely a commercial advertisement, not a true technical paper.
> (Part 2 is available at
> , but doesn't add 
> much
> to the reader's understanding.)
> However, the idea underneath is a sound one, and is well-known in the art:
> Given an arbitrarily-shaped radiator, it's possible to feed it at multiple
> points such that the feedpoints are isolated from each other.  Each feed
> produces (in general) a different radiation pattern.  Having different
> radiation patterns is useful in MIMO applications, which count on the
> uncorrelated multipath propagation between multiple antennas (i.e.,
> independently-fading signals arriving from multiple directions) to 
> increase
> throughput "above" the Shannon Limit for the channel.  In 802.11n
> (Wi-Fi(tm)) and next-generation cellular systems, the developers are
> counting on MIMO for this throughput increase but, as a practical matter,
> having multiple, physically separated antennas on a cell phone is a
> problem -- there's no room.  Having a single radiating structure but with
> multiple feeds is a much more practical solution, so that's where the 
> market
> for this technology likely will be.
> Although it doesn't involve feeding at multiple physical points, a simple
> (perhaps degenerate) example of this concept most relevant to the Tower 
> Talk
> world might be two-wire Beverage receiving antennas, the patterns for 
> which
> move 180 degrees just by changing from differential to common-mode feed.
> Note that for DXing this technique is unlikely to be as effective as true,
> multiple-physical-antenna diversity:  The signal is likely to be coming 
> from
> only one direction, and the multiple-feed antenna will produce a DX signal
> only on one feed (assuming independent patterns).  In a true diversity
> system, both antenna patterns would be pointed in the direction of the DX,
> so the DX signal would appear on both feeds, fading independently due to 
> the
> antennas' physical separation and providing diversity gain.  In the cell
> phone MIMO case, the signals are expected to be scattered and arrive from
> multiple directions, where the different antenna patterns can all be used 
> to
> collect the signal(s).
> Meandering lines, or meanderlines, are runners on a substrate that are
> physically shortened by having them go back and forth, like queues at
> Disneyland.  They often look like little square waves when seen on circuit
> boards, and are the 2-dimensional analogy of 3-dimensional helical
> structures.  Like helices, they can be used as inductors, resonators, and
> radiators.
> Ed Callaway N4II
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