By: Dr. Carl O. Jelinek N6VNG

The frequency scaling formulas for Cubical Quad antennas are shown in Figure 1. Note that frequency is measured in Megahertz {MHz} and the total length of each element is measured in feet {ft}. The spacing of each element is the same and all directors are the same size. The gamma match uses a small air variable capacitor approximately the value given and an adjustable shorting bar at the end connected to the element. The antenna is tuned by adjusting the length of the shorting bar on the gamma match for minimum VSWR with the variable capacitor half engaged. Then adjust the capacitor for minimum VSWR at the mid band frequency. The enclosed EXCEL program can be used to determine the element lengths and the gamma match values for different frequencies. In general the design is robust and may be optimized for gain or front to back by adjusting the spacing of the elements. This antenna design has been built for both the ten and two meter versions and I have used them for T-Hunting and in two CVARC Field Day events with good results. Figures 2 and 3 show the calculated antenna patterns and performance. Table 1 shows an example output from the EXCEL Scaling program. Figure 4. Shows VSWR vs. Frequency for three different 2 meter antennas, a 4 element Quad, a 6 and a 12 element Yagi.

 Figure 1. Cubical Quad Frequency Scaling Equations.

 Figure 2. Elevation Pattern for the 4 element Cubical Quad 36" above a perfect ground

 Figure 3. Azimuth Pattern for the 4 element Cubical Quad 36" above a perfect ground

 CUBICAL QUAD Scaling Formulas 3/19/97 22:24 Dr. Carl O. Jelinek Total Length All the same All the same N6VNG Lr Ldrv Ldir S G W C f=Frequency {MHz} Reflector {ft} Driven {ft} Directors {ft} Spacing {ft} Gama {ft} Width {ft} Cap {pfd} 146.565 7.028 6.857 6.652 1.584 0.292 0.094 20.0 222 4.640 4.527 4.392 1.045 0.193 0.062 13.2 445 2.315 2.258 2.191 0.522 0.096 0.031 6.6 52 19.808 19.327 18.750 4.463 0.822 0.264 56.3 28.5 36.140 35.263 34.211 8.144 1.500 0.482 102.8 Notes: Scaling Lr = 1030/f Ldrv = 1005/f Ldir = 975/f S = 232.1/f G = 42.75/f W = 13.74/f C = 2930/f File Quad.zip 73 de Carl N6VNG. [See Quad.zip to scale to another frequency and retrive this Power Point Presentation] Table 1. Cubical Quad Scaling Relationships

 Figure 4. VSWR vs. Frequency for Three 2 Meter Antenna Designs.

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