Buck
If your background is not in science then it is natural that you would
have difficulty with what I stated. If your background was in science
then this stuff would be studied in 101 i.e from first principles.
With a firm understanding of scalar quantities you are then fully armed
to deal with antenna "curl" and other interesting facets of antennas.
It would appear to me that many of this group do not have a science
background but have got by in life because of a good memory and where
knoweledge of first principles is not a requirement.
Ofcourse age can take that advantage away which appears to have happened
with past engineers of this group.........amazing!

Regards
Art



"Buck" wrote in message
news
On Tue, 08 Mar 2005 05:29:03 GMT, "
wrote:


"Buck" wrote in message
. ..
On Fri, 04 Mar 2005 05:41:29 GMT, "
wrote:

I have just come to realise that if one drew a polygon of element phases
in
a array
and all elements were 180 degrees to its companion element and excluding
the
driven element, the max gain and max front to back will occur at the
SAME
frequency!
Until now I was of the understanding that these two max figures could
not
occur at
the same frequency. Is there anything written about this possibility?
Regards
Art



Art,

Your description is too vague for someone who doesn't have some form
of reference (maybe this is a continuation of a discussion from
elsewhere?) Anyway, since a polygon is any shape with more than two
sides in which all sides and angles are equal,


It does! then I have used the incorrect term.

In a yagi type diagram you can calculate the current and phase of each
elemrnt
but what one is interested in is the summation of the whole array and you
can do this
in the same way as you would do a vector diagram of forces.
With the yagi array you would first start with the reflector and draw to
scale a line
reflecting both phase angle and magnitude. You then add lines in
cosecutive
order for all other elements in the array. The end of this 'toe to tail'
some what
erratic line will finish up some distance from the starting point,
but this distance, if drawn, represents the phase and magnitude
of the array as a whole. As a former mechanical engineer

I am not ... You may be using a term familiar to your trade and I am
unfamiliar with. I would be a layman in respect ... that could be
the misunderstanding. I was trying to envision the antenna you were
describing... can you imagine what I was seeing in my mind?




but now nothing ,I was taught the term "polygon of forces" which is a
cumulative
vector array but the shape did not necessarily consist of "equal "sides as
you stated..
But then I am English born and it is known that Americans completely
messed
up the Elizabethan era language which a true cockney still adheres to ,
where as
others in the same country have learned to talk in such a way it sounds as
if they
are trying to retain a marble in their mouth.without swallowing it.

Actually, I like the UK accents. As I believe my misunderstanding has
nothing to do with the queen's English, but rather techno-speak for
your trade, I will pack up my octagon shaped array of dipole antennas
and gracefully move on to another topic.
Good luck and I'll catch you in another thread.

Buck


Regards
Art


--
73 for now
Buck
N4PGW