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The Quasi Yagi antenna using Bowtie (5-elements BQY) obtained the bandwidth of 560
MHz (2.12 - 2.68 GHz) for S11 < -10 dB, the gain about 6.00 -7.00 dB, and VSWR < 2 for
the entire frequency band. Additionally, it has a front-to-back ratio > 10 dB and cross-
polarization level of < -25 dB at 2.4 GHz. The overall dimension of 5-elements BQY
antenna is 65 mm × 70 mm × 1.6 mm (0.52λ × 0.56λ × 0.0128λ). The BQY (3- elements, 4-
elements and 5-elements) obtained the gain of 5.47 dB, 5.678 dB and 6.20 dB, and 29%,
28% and 23.3% the bandwidth respectively.

The Quasi Yagi antenna using Bowtie driven with curved shape Directors (5-elements
BDQY) obtained the bandwidth of 400 MHz (2.25 - 2.65GHz) for S11< -10 dB, the gain
about 6.25 - 7.01 dB, and VSWR < 2 for the entire frequency band. Additionally, it has
front-to-back ratio > 11 dB and cross-polarization level of < -26 dB at 2.4 GHz. The overall
dimension of 5-elements BDQY antenna is 75mm × 66mm × 1.6mm (0.6λ × 0.528λ ×
0.0128 λ). The BDQY (3-elements, 4-elements and 5-elements) obtained the gain of 5.60
dB, 6.25 dB and 6.67 dB, and 22.12%, 18.50% and 16.30% the bandwidth respectively.

From the results, it has been observed that as directors are added in front of the driven
element, the gain is increased and the radiation pattern of the main lobe becomes
narrower with the cost of the bandwidth of the antenna. The DQY antenna provides high
gain, good front-to-back ratio and low cross-polarization level with low bandwidth as
compared to other designed Quasi Yagi antennas. It obtained a directional radiation
pattern with a flat gain in the range of 6 - 7.52 dB over the bandwidth. This antenna is
suitable for point-to-point communication, and portable direction finding, where a
directional radiation pattern, high gain with moderate bandwidth is the primary
requirement. The BQY antenna obtained almost double the bandwidth as compared to
DQY antenna at the cost of slight reduction in gain. This antenna is suitable for ISM band
applications, and broadband applications, where high bandwidth with moderate gain is
the primary requirement. The BDQY antenna obtained higher bandwidth as compared to
the DQY and lower compared to BQY and it obtained higher gain as compared to BQY
antenna and lower than DQY antenna. This antenna is suitable for ISM band point-to-
point communication, RFID, and portable direction finding, where moderate bandwidth
with moderate gain is the primary requirement.

Key words: Quasi Yagi antenna, Dipole, Bowtie, Curved shaped director, Gain, VSWR, and
Bandwidth.

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