NEC-LIST: Bruce, rhombics, and NEC

Dear Alexandre Kampouris, Alan Boswell, Dr. Ed Sayre, and others:

 Many thanks for the assistance that I have received. This is THE
group.

 As it turns out, I stopped searching for the US issued, pioneering
patent to Bruce (US2,285,565) about two patents earlier than '565's June
9, 1942 issue date. I should have pressed on. Eleven years and four
months is a very long time for a patent application to be in
prosecution, though hardly a record.
 How very fortunate that I did not press on or we might not have
received Alexandre's contribution!
 Alexandre's analysis of the '565 patent is excellent. The '565 patent
makes clear that Bruce considered his "diamond" to be his earlier
invented, terminated V rotated 90 degrees and worked against a second
horizontal V as a counterpoise. Only in the last independent claim (13)
does "rhombic" appear. I speculate that that claim was added during
prosecution. The UK patent (GB392,201) contains no such language. It
is common for a pioneering patent not to contain the name by which the
invented article is later known. (As an exercise for the vigorous
student, find the pioneering patent for the compound bow.)
 Now to some of the interesting issues:
 It is important to realize that in the early development period (let us
say from WW1 through WW2) relatively few individuals were involved and
only a tiny number of organizations. Most of those few organizations
were interlocked. Beverage, in an interview, talks of being moved
between organizations that we are inclined to think of as being
autonomous. Thus, the fact that so many antenna patents were prosecuted
by the same small set of patent attorneys is not the
conflict-of-interest that it would be today. (It is often observed that
the size of patent law firms is limited today by conflict-of-interest
rules.)
 Another difference in those days is that so many patents have only one
inventor's name. Today's requirement is that all inventors be named.
This suggests that egos were under better control than often seems to be
the case today. While all of the histories that I have found indicate
that Bruce invented the rhombic, most include other persons as
contributors. (They do not agree about who the contributors are.)

 On patent searches:
 Unfortunately, the publically available search engine (from the US PTO)
for early US patents only allows searches on patent number and current
classification. It is very labor intensive to do a proper search. When
using the US PTO's data to find early references, I have found utility
in searching recent patents for such references. If the early patent
was important, it is likely to be referred to again.
 I am indebted to Alexandre for drawing my attention to European data
bases. The last time that I tried to use their system, which was some
few years ago, I found it other than useful. Even now, its locking of
print capability makes use most uncomfortable. However, I shall
continue to endeavor to find a way to make its use effective.
 I think that I have now looked at about all of the relevant US patents,
have printed most of them, and have read with care many of them. I have
been writing short abstracts as I go along as abstracts were not
included in those days. It has been most instructive!

 Alan's observation that the technical aspects of the rhombic were
sorted out in the 1987 ICAP is helpful. I will put our librarians on
track to find a copy. Probably much of what I was interested in doing
has been done. Should page numbers be known, they would help in the
retrieval. The use of an assumption of constant current (or of some
other distribution that was easy to deal with with the tools then at
hand) was a hallmark of early analysis. We must always keep in mind
that what we do is constricted by the tools we have. I well remember
when the height of affordable computation for a student was a book of
seven place log tables and an abacus.

 What is unlikely to have been done is to sort out the derivatives of
the rhombic and V that, for one reason or another, were not viable.
They can be as instructive as the understanding of the successful
design. In my response to Dr. Sayre, I mentioned one such example.
That example is particularly instructive, in part because of its
simplicity. A clear example of the progress made in the antenna art
comes from my orally describing that antenna to my esteemed, younger
colleague (the description used modern terms). He thought about what I
said for a few seconds and speculated about the results. His
speculation was spot on.

 I continue to encourage comments. References, such as Alan's, to
modern papers are particularly helpful to the task of avoiding what has
been done. Many of the early radio people wrote memoirs. They are
particularly tricky to find. I found one just browsing through a
library stack.

 Reading Antennas by Kraus was a turning point in my life, as I expect
it was for many of you. That my father bought me the book on the
recommendation of one of his colleagues who was a classmate of Kraus
heightens its value. Having him as my mentor was the highlight of my
earlier education. Now, I would start today's student (who has
different expectations and background than was once the case - few, for
instance, are radio amateurs) on the path towards understanding with the
analysis of a V or rhombic, and then bring in the more traditional
analysis. -- to close the loop: the existence of NEC should, as new
tools have for uncounted generations, change the way we look at things.

 Many thanks again for your assistance and encouragement. I do not know
what, if any work may come of all of this. However, having the time to
look afresh with the aid of a "new" tool has been most invigorating.
Warm regards, Mac

J. Mc Laughlin - Michigan USA
Home: JCM_at_Power-Net.Net

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