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holl_ands | Home > Bi-Quad Antennas

Bi-Quad Antennas Bi-Quad Antennas analyzed using 4nec2. Note that the outer tips of a Bi-Quad connect to each other.  Chireix antennas are similar, but with a GAP at the tips. Date(s): 19 Aug 2011. 1 - 4 of 4 Total. Shared

1. UHF Bi-Quad NO Refl - khaye   (13 Mar 2011) UHF Bi-Quad with NO Reflector (per khaye post) analyzed using 4nec2. Element Diameter = 1/8-inch (AWG8), All Diamond Sides = 17 cm (6.7-in), Feedpoint Gap Size = 2 cm (0.78-in) [4nec2 model used 0.75-in] Outer Angles = 45.0-deg, Inner Angles = 54.5-deg (would be 45-deg for zero Gap Size).  [AWG10 would slightly degrade SWR.] Not quite optimum for New UHF Band (Ch14-51), with high SWR on Ch14.  Improve by using about 10-percent longer side lengths: 18.7-cm (7.4-in). Optimum size for Old UHF Band (Ch14-69) would be 16.3-cm (6.4-in) per side, shifting indicated performance at 770 up to 806 MHz. 253 Visits 12 Images Shared Album 2. Hi-VHF Bi-Quad 4ReflRods - nikiml  (20 Aug 2011) Hi-VHF Bi-Quad with 4 Reflector Rods analyzed using 4nec2. Optimized for entire Hi-VHF Band, see model "BQ4V" on nikml website: http://clients.teksavvy.com/~nickm/biquads/bq4V.html Raw Gain is 10.2-9.5 dBi with SWR under 2.2. Overall Size = 57"H x 46.7"W 440 Visits 11 Images Shared Album 3. UHF Bi-Quad 9ReflRods - khaye  (13 Mar 2011) UHF Bi-Quad with 9 Reflector Rods (per khaye post) analyzed using 4nec2. Element Diameter = 1/8-inch (AWG8), All Diamond Sides = 17 cm (6.7-in), Feedpoint Gap Size = 2 cm (0.78-in) [4nec2 model used 0.75-in] Outer Angles = 45.0-deg, Inner Angles = 54.5-deg (would be 45-deg for zero Gap Size).  [AWG10 would slightly degrade SWR.] 9 Reflector Rods, 3/8-in Diameter, 40-cm (15.75-in) Long with 6-cm (2.36-in) Spacing, 14-cm (5.5-in) behind Bi-Quad. Optimized for New UHF Band (Ch14-51), with Raw Gain & SWR degradation on highest channels. Optimum size for Old UHF Band (Ch14-69) would be 16.3-cm (6.4-in) per side, shifting indicated performance at 770 up to 806 MHz. 288 Visits 12 Images Shared Album 4. Hi-VHF Bi-Quad 8RodRefl (nikiml)  (19 Aug 2011) Hi-VHF Bi-Quad with 8 Rod Reflectors (optimized for Ch11-13 by nikiml) analyzed using 4nec2. For best (compromise) performance across entire Hi-VHF Band, increase all dimensions by ratio 213/198=1.076. 246 Visits 11 Images Shared Album