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Re: [TowerTalk] Hi-Z Antenna Stuff

Subject: Re: [TowerTalk] Hi-Z Antenna Stuff
From: Jim Lux <>
Date: Tue, 07 Feb 2012 18:30:07 -0800
List-post: <">>
On 2/7/12 3:04 PM, Dan Schaaf wrote:
> As I understand, the patent is on the buffer.
> Best Regards
> Dan Schaaf

>> There are quite a few of us interested in the answer.

US Patent 7,423,588, applied for in 2005, revised in 2006, granted in 2008
I'm not too impressed by his references, but then, picking references is 
sort of an art.. you want something that looks convincing to the 
examiner, but isn't too close to your invention so it looks like prior art.

Bear in mind that the disclosure part of the patent, which can be quite 
detailed, as it is in Tom's patent, doesn't define the scope of the 
patent.  It just discloses the invention (and by extension, prevents 
someone else from patenting it, because the disclosure itself becomes 
"prior art").

You have to read the specific claims.

You also have to look at what the objective of getting the patent is.. 
In this case, I suspect it's to prevent someone from making schematic 
level knockoff copies, because, as many have pointed out, there's 
nothing special about amplifiers and phased arrays.

First off, the invention is really the combination of a clever low IMD 
limiter + buffer + clever isolation scheme so the feed lines don't 
become part of the antenna. And all designed for reasonably wide bandwidth.

There are 19 claims.

Some of the claims, if litigated, would probably fail as non-novel. 
Claim 19 is basically a generalized phased array.

However, quite a few of the claims are for the specific, detailed design 
that Tom has, which is, in my opinion, fairly novel, at least in his 
combination of the building blocks.

That said, it would be pretty easy to design around the claims that are 
specific enough to stand up in a re-exam.  For instance, claim 9 says:

9. The phased array antenna system of claim 2, wherein said limiting 
circuit comprises: a capacitor; a zener diode coupled in parallel with 
said capacitor; and a first diode arranged in series with said parallely 
arranged zener diode and said capacitor.

This is a pretty specific description. You could design around this by 
maybe adding another component to the limiter, so it's not a zener 
across a cap in series with another diode.  You probably couldn't get 
away with a trivial mod ("a 0.0001 ohm resistor in series with") 
although maybe you could.  If I were writing the claim, I might have 
said something like:

A capacitive element; a zener diode

and generalized it to saying "capacitive element comprised of a single 
capacitor or plurality of capacitors in a series or parallel 
arrangement, etc."

Of course, maybe it won't work as well.  Tom spends a fair number of 
paragraphs in the disclosure section describing why this works and why 
you need to do it.

But more claims cost more money, and I think what Tom is really going 
for is to prevent knockoffs at the schematic level, and the claims work 
just fine for that.


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