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Recently, I have received an antenna from one of the Chinese manufacturer and they haven't disclosed the detailed specification with us.

Below is the picture of my antenna (please ignore the specification in the picture):

enter image description here

The specification that are provided by the vendor are over here.

  • Frequency: 865-867 MHz
  • Gain: 3dBi
  • VSWR < 3.0 : 1
  • Radiation Pattern: Omnidirectional
  • Impedance: 50 ohm
  • Length (From connector to Antenna End): 500mm

I want to know from it's size and gain, Can we predict it's antenna type (e.g. Collinear antenna), it's design (dipole or mono-pole), internal construction, polarization and various other parameters?

These kinds of antennas look to be standard and I think others who have used them in the past can help me in identifying my own antennas. I am waiting for my manufacturer to share detailed specification but I am not sure how long will they take.

EDIT:

According to my calculations, the wavelength for 865 MHz signal would be 0.346580 meters. So, for half-wave dipole, the length should be 0.17329 meter. However, length of my antennas is bigger than that. I think that's why it is collinear dipole array antenna. Please correct me if I am wrong.

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It's most likely some kind of co-linear array of dipoles.

The lack of a ground plane means it's not a monopole. And as you've calculated, it's substantially physically longer than a half-wave dipole would be. Further supporting the notion of some kind of array, the indicated gain of 3dBi is greater than the gain of a simple half-wave dipole (2.15 dBi).

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  • $\begingroup$ Since it takes single ended RF signal. Does it have internal balun? $\endgroup$
    – abhiarora
    Oct 30 '18 at 19:45
  • $\begingroup$ if you will, yes, it does, in the shape of a defined length of outer conductor "folded inside out". $\endgroup$
    – Marcus Müller
    Oct 30 '18 at 20:02
  • $\begingroup$ indeed, quite likely of the "bazooka" balun variety: antenna-theory.com/definitions/bazooka.php $\endgroup$
    – Phil Frost - W8II
    Oct 30 '18 at 21:07

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