K7ITM wrote in news:9b6a34a7-9578-4660-b4f0-5cf02e3ee862
@z14g2000yqa.googlegroups.com:

The other thing that the free-space length of the elements will affect
is the feedpoint impedance. I'd suggest, again, that you model it to
make sure the net impedance of the paralleled feedpoints is something
you don't mind matching to.


An interesting point. I cannot recall any of the online articles
discussing feedpoint Z, and by assumption it is 50+j0... but that doesn't
happen by accident.

Here is a deck for 8 halfwaves at 435MHz with a single stub tuner.

CM 8 half waves coaxial collinear on 435MHz
CM Assumes lossline TL, VF=0.667, effective choke at bottom of array.
CM Matched to 50 ohms with single stub tuner.
CM Owen Duffy 2009/04/05
CE
GW 2 20 0 0 -0.23383 0 0 0 0.0045
GW 3 20 0 0 -0.46766 0 0 -0.23383 0.0045
GW 4 20 0 0 -0.70149 0 0 -0.46766 0.0045
GW 5 20 0 0 -0.93532 0 0 -0.70149 0.0045
GW 6 20 0 0 -1.16915 0 0 -0.93532 0.0045
GW 7 20 0 0 -1.40298 0 0 -1.16915 0.0045
GW 8 20 0 0 -1.63681 0 0 -1.40298 0.0045
GW 9 10 0 0 -1.87064 0 0 -1.63681 0.0045
GW 200 1 -0.01 0 -2.25634 0.01 0 -2.25634 0.001
GW 201 1 -0.01 0 -2.35634 0.01 0 -2.35634 0.001
GE 0
GN -1
EK
EX 0 200 1 1 0
TL 3 1 2 1 -50 0.350745 0 0 0 0
TL 4 1 3 1 -50 0.350745 0 0 0 0
TL 5 1 4 1 -50 0.350745 0 0 0 0
TL 6 1 5 1 -50 0.350745 0 0 0 0
TL 7 1 6 1 -50 0.350745 0 0 0 0
TL 8 1 7 1 -50 0.350745 0 0 0 0
TL 200 1 8 1 50 0.42855 0 0 0 0
TL 200 1 201 1 50 0.0837 0 0 1e99 0
FR 0 0 0 0 435 0
XQ
EN

The antenna bandwidth is quite narrow as might be expected from so many
resonant lengths.

It reaches about 7.8dBi gain, well short of the much touted 9dBd or
11.2dBi.

Owen