Adding in
the center of the shunt wire an inductor allows adjust antenna
resonance frequency that makes the antenna very universal. Input
impedance of the antenna is 200- Ohm so it is possible match the
antenna with 50- Ohm coaxial cable with help of 4:1 transformer. Gain almost the same as at shunt BiQuad
antenna. SWR is lower compare to the shunt BiQuad
antenna.
Figure 9 shows design of the Shunt BiQuad
antenna with center inductor. Figure 10 shows Z of the Shunt BiQuad antenna with center inductor. Figure 11 shows SWR of the Shunt
BiQuad antenna with Center Inductor. Figure 12 shows DD of the Shunt
BiQuad antenna with center inductor.
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Another
modification of the antenna is 3-D BiQuad
Antenna. Input impedance of the antenna is 200- Ohm so it is possible match the
antenna with 50- Ohm coaxial cable with help of 4:1 transformer.
Gain almost the same as at shunt BiQuad
antenna. SWR is lower compare to the shunt BiQuad
antenna.
Figure 13 shows design of the 3-D BiQuad
antenna. Figure
14 shows Z of the 3-D BiQuad
antenna. Figure 15
shows SWR of the 3-D BiQuad antenna.
Figure 16
shows DD of the 3-D BiQuad antenna.
73! de RW4HFN
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