Practical_Antenna_Handbook_0071639586

210 P a r t I I I : H i g h - F r e q u e n c y B u i l d i n g - B l o c k A n t e n n a s
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Figure 7.3 One-wavelength square loop (single-element quad).
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element driven array, whereby the l/2 section opposite the dipole connected to the feedline
is driven at its high-impedance ends, rather than at its center, from voltages set up
by the fed dipole.
The 1l loop of Fig. 7.3 produces a
bidirectional gain of about +2 dB
over a dipole in directions perpendicular
to the plane of the loop—that
is, into and out of the page. The elevation
pattern formed by this loop is
somewhat “squashed” because the
top and bottom horizontal sections
are in quadrature phasing straight up
and down.
The loop of Figure 7.4 also contains
one wavelength of wire, but the
square has been put into a diamond
orientation so that only one tall support
is needed. In effect, we have replaced
two bent dipoles with two
inverted-vees facing each other, one
above the other. Note that the con-
X 1 X 2 Figure 7.4 Bottom-fed diamond loop.