a) UHF Circular Loop - NO Reflector: Ken Nist's Loopa.ez (7.5-in diameter, using AWG12) is a good choice for the Old UHF Band. A better choice for the (470-698 MHz) UHF Band is 7.75-in diameter, using AWG12. However, SWR is excessive at lowest and highest frequencies.
SWR can be significantly improved by using QICT (Quarter Inch Copper Tubing), with 8.5-in Diameter being best size for UHF Band. Raw Gain is then 3.6-5.1 dBi, SWR under 2.7.
b) UHF Square Loop - NO Reflector Optimum size for UHF Band is 6.9-in per side (x4). Raw Gain is 3.4-4.1 dBi. SWR is under 2.7. Which is lower Gain than the Circular Loop above.
EDIT (6 Sep 2011): Added UHF Square Loop.
Date(s): 15 July 2009. Album by holl_ands. 1 - 37 of 37 Total. 12807 Visits.
QuarterInchCopperTubing significantly improves SWR. Best size is 8.5-in for New UHF Band.
enlarge 283KB, 1024x696 3 Twin-Hoop Chireix vs "Figure-8" Twin-Loop vs Shorted-Bowtie-Loop (SBL) vs 2-Bay Hentenna vs 6-Whisker Bowtie vs Single Loop. In decreasing UHF Gain order.
enlarge 0KB, 1024x819 4 UHF Circular Loop - Raw Gain 7.5-in Diameter using AWG12