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abcd567
abcd567
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The antenna in photo below is the 1st antenna of the question.

Wi-Fi 2.4GHz 0.5 Wavelength Dipole

It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if its length is different from 1/2λ. However the impedance/swr of antenna changes as the length changes. When dipole's length is exactly 1/2λ, its impedance is 75 ohms.

Please see sketch below which shows Gain & Radiation pattern for dipoles of lengths from 0.12λ to 1.25λ (total of both limbs):

CLICK ON IMAGEIMAGES BELOW TO SEE LARGER SIZE

Dipole length vs radiation pattern

Dipole SWR vs Length (0.1λ ~ 2.1λ)
dipole swr vs length

Dipole Gain vs Length (0.1λ ~ 2.1λ)
dipole gain vs length

Dipole Impedance vs Length (0.1λ ~ 2.1λ) dipole impedance vs length

The antenna in photo below is the 1st antenna of the question.

Wi-Fi 2.4GHz 0.5 Wavelength Dipole

It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if its length is different from 1/2λ. However the impedance/swr of antenna changes as the length changes. When dipole's length is exactly 1/2λ, its impedance is 75 ohms.

Please see sketch below which shows Gain & Radiation pattern for dipoles of lengths from 0.12λ to 1.25λ (total of both limbs):

CLICK ON IMAGE BELOW TO SEE LARGER SIZE

Dipole length vs radiation pattern

The antenna in photo below is the 1st antenna of the question.

Wi-Fi 2.4GHz 0.5 Wavelength Dipole

It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if its length is different from 1/2λ. However the impedance/swr of antenna changes as the length changes. When dipole's length is exactly 1/2λ, its impedance is 75 ohms.

Please see sketch below which shows Gain & Radiation pattern for dipoles of lengths from 0.12λ to 1.25λ (total of both limbs):

CLICK ON IMAGES BELOW TO SEE LARGER SIZE

Dipole length vs radiation pattern

Dipole SWR vs Length (0.1λ ~ 2.1λ)
dipole swr vs length

Dipole Gain vs Length (0.1λ ~ 2.1λ)
dipole gain vs length

Dipole Impedance vs Length (0.1λ ~ 2.1λ) dipole impedance vs length

added 135 characters in body
Source Link
abcd567
abcd567
  • 389
  • 1
  • 2
  • 7

The antenna in photo below is the 1st antenna of the question.

Wi-Fi 2.4GHz 0.5 Wavelength Dipole

It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if its length is different from 1/2λ. However the impedance/swr of antenna changes as the length changes. When dipole's length is exactly 1/2λ, its impedance is 75 ohms.

Please see sketch below which shows Gain & Radiation pattern for dipoles of lengths from 0.12λ to 1.25λ (total of both limbs):

CLICK ON IMAGE BELOW TO SEE LARGER SIZE

Dipole length vs radiation pattern

The antenna in photo below is the 1st antenna of the question.

Wi-Fi 2.4GHz 0.5 Wavelength Dipole

It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if its length is different from 1/2λ. Please see sketch below which shows Gain & Radiation pattern for dipoles of lengths from 0.12λ to 1.25λ (total of both limbs):

CLICK ON IMAGE BELOW TO SEE LARGER SIZE

Dipole length vs radiation pattern

The antenna in photo below is the 1st antenna of the question.

Wi-Fi 2.4GHz 0.5 Wavelength Dipole

It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if its length is different from 1/2λ. However the impedance/swr of antenna changes as the length changes. When dipole's length is exactly 1/2λ, its impedance is 75 ohms.

Please see sketch below which shows Gain & Radiation pattern for dipoles of lengths from 0.12λ to 1.25λ (total of both limbs):

CLICK ON IMAGE BELOW TO SEE LARGER SIZE

Dipole length vs radiation pattern

Source Link
abcd567
abcd567
  • 389
  • 1
  • 2
  • 7

The antenna in photo below is the 1st antenna of the question.

Wi-Fi 2.4GHz 0.5 Wavelength Dipole

It is supposed to be 1/2λ long (radiator+sleeve). However its length is 2x25 mm instead of 2x30 mm. The antenna will still work even if its length is different from 1/2λ. Please see sketch below which shows Gain & Radiation pattern for dipoles of lengths from 0.12λ to 1.25λ (total of both limbs):

CLICK ON IMAGE BELOW TO SEE LARGER SIZE

Dipole length vs radiation pattern