• VERTICAL STACKS properly spaced

• Gain of 2.2-3 dB from adding second antenna

• Gain of 1.5-2 dB by adding a third antenna

• Gain of .5 - 1 dB by adding a fourth antenna

• Gain is very good at .75 > .5 Wave Length separation

• Switching allows control of take off angle including BOP

• Angle of lobes can be bad due to poor spacing of yagis

• Stack lobe will always slightly higher than top yagi alone

• 18-20 dB of difference can be seen from peak to null

• This is more important than the raw gain of the array

• BOP useful for gaining high angle lobe from a 2 high stack at the sacrifice of only 3db of max stack gain

• This could be a secret weapon in SS and NAQP contests

• A high stack can be made to act like its close to the ground

   

  SUMMARY - PATTERN

• Stacks can clean up high angle unwanted lobes

• Separation space and boom length are closely related

• Always model the intended stack for lobe anomalies due to spacing

• Rotating an antenna 90 degrees or 180 degrees is an effective way to beam in two or three directions at once.

[ next ]