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I opened two different GSM antenna housings as shown on the images.

The first image shows the RF SOLUTIONS ANT-GHEL2R-SMA antenna, which is an helical 1/4 wave monopole antenna.

The second image is the SIRETTA DELTA2C/X/SMAM/S/RA/25, which is, according to its datasheet, a dipole antenna.

My question is why do they look so similar except for the shape of the copper? I would expect a dipole antenna to actually show two poles. Does the connector housing act as the other pole? If so then why is the monopole not a dipole as well?

enter image description here enter image description here

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  • \$\begingroup\$ "My question is why do they look so similar except for the shape of the copper?" What other difference IS there? \$\endgroup\$
    – Trevor_G
    Commented May 3, 2017 at 13:29
  • \$\begingroup\$ Well, as far as I'm concerned, they're both quarter wave monopoles. Provide links to the sources of the information please. Oops you did! \$\endgroup\$
    – Andy aka
    Commented May 3, 2017 at 13:37
  • \$\begingroup\$ they are both monopoles of some kind \$\endgroup\$
    – Edwin van Mierlo
    Commented May 3, 2017 at 13:37
  • \$\begingroup\$ One is top-loaded, the other bottom-loaded. \$\endgroup\$
    – analogsystemsrf
    Commented May 3, 2017 at 14:03

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Whenever you see +2dBi gain, and the manufacturer has fairly measured gain to be 2dB above an isotropic radiator, then the antenna is more complex than a simple quarter-wave monopole. I would hesitate to guess exactly how the pig-tail top of the upper photo monopole attains its gain.
A simple half-wave dipole might have intrinsic gain near +2dBi. The one pictured in the bottom photo appears to be end-fed half-wavelength antenna with a low-Z to high-Z matching section buried in the connector shell. Arranged as shown, it would be vertically polarized...an end-fed dipole, rather than a centre-fed dipole.

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  • \$\begingroup\$ You wrote both comments so that even I can follow their logic! Thanks! \$\endgroup\$
    – jonk
    Commented May 3, 2017 at 15:24
  • \$\begingroup\$ Sounds good +1 for the info. \$\endgroup\$
    – Andy aka
    Commented May 3, 2017 at 17:04

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