Array Solutions Four Square Controller
6
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Array Solutions
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Fourth: The L2, C2 -90 to-120 phase shift circuit should be tuned next.
(L-network)
Select the 1
st
default position of your controller switch.
Place scope probes (channel 1) on J4, ANTENNA PORT 1, and trigger the scope on this signal.
Place the channel 2 scope probe on J5, ANTENNA PORT 2.
The probes can be attached to the foil feeding the connector, and the ground leads should be
attached to the same ground point on a ground foil at the connectors or on the connector
mounting screws. Adjust the scope so you get a pattern like that shown in Figure 3 below.
Note that the sine wave on the trigger channel 1 is 8 blocks wide. This is 360 degrees of phase.
To do this use the VARIABLE Time function and stretch the wave so it peaks on 8 blocks. Each
block vertical line is 45 degrees of phase shift and each grid line inside will be 9 degrees of phase
shift. You can see that the lagging sine wave for antenna 2 is adjusted to be about 0.6 X the
amplitude of the 0 degree waveform. Adjust your inductor tap and capacitance to achieve this
approximate waveform. It may change a little as you adjust your next setting, so don’t be too
picky. Mutual coupling will change these patterns as you adjust the system.
Note on your schematic that J5 and J6 are the same phase in the
default direction
position.
Check J6 to verify it is the same phase and magnitude as J5. If it is not your doing something
wrong. Make sure the controller is in the no 1 position and no relays are pulling in.
Going back and forth from these two phase shift networks will result in a good pattern. If you have
a 3
rd
scope channel, you can now connect it to J7. Or move your second channel to J7.
Adjust the L3, C3 network for -118 to -225 degrees and magnitude called for in your model.
Figure 3: 90 to 120 degree phase shift adjustment
