Hi-VHF Raw Gain = 4.7 to 5.5 dBi and SWR (300-ohms) under 2.7. UHF Raw Gain = -8.0 to 0.0 dBi is Low but usable Gain for Strong Signals. Even better 45-deg off-axis on many freqs. SWR (300-ohms) under 2.7 [Excellent].
######################################################## Suppose you had a metal picture frame that was 36-in H x 24-in W and desired to turn it into a Hi-VHF Rectangular Loop Antenna. Fortunately, it isn't necessary to compromise the structural integrity by cutting into the bottom rail to insert a Balun...because that results in poor Gain & SWR (see Charts at bottom).
######################################################## It is much better if an Element is added from Left to Right in the middle of the Picture Frame, with a 3/4-in Feedpoint Gap in it's middle. The same size material (Half-Inch Diameter) as in the outer Rectangle was assumed in the 4nec2 Model, since NEC2 has a problem handling intersections with large Wire Size differences...and hence we can't determine effect of smaller wires......[sorry]
A Parametric Sweep (using 4nec2) determined the "best" location of the Shorted Feedpoint Element was halfway between the Top & Bottom, forming a TWIN Rectangular Loop, similar to Twin Circular Loop and Hourglass-Loop.
Date(s): 12 Nov 2013. Album by holl_ands. 1 - 21 of 21 Total. 1991 Visits.
enlarge 42KB, 640x1024 1 Hi-VHF Twin Rectangular Loops 3D View
enlarge 214KB, 695x1024 2 Hi-VHF Twin Rectangular Loops Front View - 36-in H x 24-in W [1 large square = 2.5 inches]
enlarge 169KB, 1152x691 13 Hi-VHF Twin Rectangular Loops UHF Raw Gain = -8.0 to 0.0 dBi Low but usable Gain for Strong Signals Even better 45-deg off-axis on many freqs.
enlarge 220KB, 1152x691 14 Hi-VHF Twin Rectangular Loops UHF SWR (300-ohms) Under 2.7 is Excellent
