Why not cut to the chase? Antennas are based on Fields and
Wavres and not geometryas many seem to imply.The poster
stated "waves" since it is his starting point. he question he then asks
is in reference to element length relative to reflection and direction
which obviously eminates from those who are self taught around a
specific antenna ( yagi ) i.e vectors, rectection, defection,
reradiates e.t.c which some call semantics and is not how fiels and
waves are handled in general education. And their is good reason for
this, an element creats a field not a missile
that is reflected , deflected or independently deflected by individual
elements or sequentialy. What you really looking at is a reactionary
energy field formed by other elements that are impinged upon by the
initial energy field generated at the initial source.Thus the reaction
field generated by one or more elements to the impinging electrical
field is not based on element length but the field generated in
reaction by whatever is
in the field of reference which could be anything of any number, length
or material.IF the antenna is specifically a yagi you can ascribe to it
certain details as a subset to antenna education
and in general get away with it since the Yagi is in voque. In this
particular case the poster rightly starts off with the field aproach
but is confused by antenna education which revolves around a specific
antenna (yagi) whose design specifically
rebvolves around a singular design which allowed Tom to safely say
"that is how it is" thus avoiding reffering to true radiation
academics that revolve around fields and waves and where actual element
lengths can be viewed as academic. Would it not be better to respond
with an array example that could provide a shorter element by
reitterating what is taught in
accepted text books rather than concentrating what can be termed a
caveate in radiation in a similar way capacitance
is based on the premise of homoginous field e.t.c
This question is often asked and it is not thru ignorance but by
confusion generated by so called gurus who trot out an answer
that is close enough to the question askedand evading a corrective
response toi a question with thought that is not to be satisfied with
that is the way it is, a comment that is good for passing tests only
and not for furthering aducation.. Cherry pick all you want or give
answers to a question that you think should have been asked but that is
not how to perpetuate a title of a true guru
Nothing personal but the books that I have on antennas begin with field
and wave generation which individual arrays such as a yagi are descibed
as a subset and not the other way around.
Art