[amsat-bb] Dual band "cheap yagi" question ( interlacing elements?)

[Michael Tondee]

I'm in the process of putting together a portable FM satellite station 
and I intend to homebrew the antenna using the WA5VJB "cheap yagi" 
design. In looking at a picture in the May/June 2007 AMSAT Journal I've 
noticed that the  so called "AMSAT demonstration antenna"
  that is composed of two elements on two meters and five elements on 
70cm has the 70cm antenna built completely ahead of the  two meter 
antenna on the boom. In other words, the elements for the two bands are 
not interlaced with each other.
  I'm planning to build a larger antenna with more elements as I will 
use it on a tripod rather than holding it by hand and I'm wondering if I 
can interlace the elements of the two antennas on the boom without 
adversely affecting performance. To build the antenna I envision in the 
fashion shown in the picture with one antenna built completely ahead of 
the other on the boom would result in an unruly boom length.
  Also, if I do interlace the elements, should I place them at 90 
degrees orientation to each other as is done in the Arrow design? I 
doubt it makes any difference but just to be clear, I will be using two 
separate radios for TX and RX so no diplexer will be used.
Yagi antennas, especially dual band designs, are not exactly my forte so 
I thought I'd ask this question just to be sure.
Tnx and 73,
Michael, W4HIJ