4square.nec

zip contains tool for Antenna Modelling with examples

CM 40-meter four-square array, converted with 4nec2 on 29-Mar-06 22:08
CM 	4Square
CM This popular phased array was invented by Dana Atchley,
CM W1CF. It has several desirable properties. Because of its
CM symmetry, it's easy to switch in four directions. The
CM forward lobe is broad enough that four-direction switching
CM gives good coverage to all directions. Good rejection of
CM signals occurs over a broad region to the rear. The small
CM rear nulls can be eliminated and the forward gain increased
CM slightly by increasing the element spacing. However, this
CM may make the physical spacing too far to conveniently use
CM some feed methods. Feeding of the four-square array is
CM covered in detail in Chapter 8 of the ARRL ANTENNA BOOK,
CM 15th and later editions. One interesting feature of this
CM array is that one element has a negative feedpoint
CM resistance if loss is low enough. This is a valid result;
CM the element is absorbing power from the others by mutual
CM coupling and feeding power back INTO the feed system. There
CM is still some lingering belief that the fields from the
CM elements of an array are proportional to the powers
CM delivered to them. Element 1 of this array has a field
CM equal to that from the other elements, and it's FURNISHING
CM power, showing the error in this belief. Observing the
CM currents in the elements reveals the truth: The element
CM CURRENTS determine the field strength, and they're equal in
CM all four elements.
CM This model is fed simply with current sources, to simulate
CM a correctly-fed array.
CE
sy len=32.75
GW 1 6 0     0     0 0     0     len 0.0625
GW 2 6 0     34.42 0 0     34.42 len 0.0625
GW 3 6 34.42 0     0 34.42 0     len 0.0625
GW 4 6 34.42 34.42 0 34.42 34.42 len 0.0625
GS 0 0 ft
GE 1
EX 6 4 1 0 cos(180) sin(180)	'Phase 180
EX 6 2 1 0 cos(-90) sin(-90)	'Phase -90
EX 6 3 1 0 cos(-90) sin(-90)
EX 6 1 1 0 1 0
GN 3 0 0 0 13 5.e-3
FR 0 1 0 0 7.15 0
EN