Antenna properties:

• Height x Diameter = 3.3 inches x 1.4 inches
• Test Frequency: 900 MHz (Wavelength = 33 cm or 13 inches)

I see some conflicting formulas to calculate the near field distance for an antenna w.r.t. the frequency of interest.

Method 1: (multiple sources)

Reactive Field <= 0.63 x sqrt(Height^3/Wavelength) ===> 2.6 cm or 1.02 inches

Method 2:

Reactive Field <= Wavelength ===> 33 cm or 13 inches

Which one applies here accurately.

Antenna properties:

• Height x Diameter = 3.3 inches x 1.4 inches
• Test Frequency: 900 MHz (Wavelength = 33 cm or 13 inches)

I see some conflicting formulas to calculate the near field distance for an antenna w.r.t. the frequency of interest.

Method 1: (multiple sources)

Reactive Field <= 0.63 x sqrt(Height^3/Wavelength) ===> 2.6 cm or 1.02 inches

Method 2:

Reactive Field <= Wavelength ===> 33 cm or 13 inches

Which one applies here accurately?