GNSS uses PIFA antennas to achieve broadband linear polarization radiation and broadband circular polarization

Normally, in order to better receive GNSS signals, the navigation and positioning antenna needs to be designed as a circularly polarized antenna. To realize the circular polarization radiation characteristics of the antenna, there are many strict requirements in terms of radiating element, antenna base material, and feeding method. This is also the reason why it is difficult to make the size of the navigation and positioning antenna small.

Common methods to achieve circular polarization of antennas:

Single feed point microstrip antenna (such as ordinary car navigation ceramic antenna)

Dual-feed point microstrip antenna (such as sub-meter handheld navigation antenna)

Four-fed microstrip antenna (such as high-precision surveying and mapping antenna)

Single-arm, double-arm or four-arm helical antenna (such as drone positioning antenna)

Converted oscillator (such as Beidou short message command receiver S-band receiving antenna)

Helical antenna (broadband navigation and positioning antenna)

...

The above-mentioned antennas all have one thing in common-the symmetry of the structure, and the requirement of symmetry directly determines that the antenna can only be square, circular, cylindrical, conical, etc. This feature also greatly limits the application of antennas in terminal equipment, resulting in large terminal equipment or limited ID design.

A wideband PIFA circular polarization antenna implementation method:

Here is an article published by Beijing University of Posts and Telecommunications Xing Wang and other authors at the Asia Pacific Microwave Forum. They proposed a PIFA antenna structure that can achieve broadband circular polarization, which provides a new way for the formulation of antenna solutions in engineering practice. Ideas. The antenna is a flat structure, the radiating element is coplanar with the metal ground. The design of the inverted F antenna at the edge of the metal floor and the cross structure at the edge of the floor have achieved a wide frequency band circularly polarized radiation covering 1.1GHz to 1.7GHz.

(1) Antenna structure design drawing

(2) Antenna broadband return loss

(3) Antenna broadband axial ratio

(4) Broadband antenna gain

Inspiration from antenna design:

The principle of this antenna is to use the PIFA antenna to achieve broadband linear polarization radiation, and then change the distribution of the radiation current through the cross groove on the edge of the metal ground. After precise adjustment of each size, the broadband circular polarization is finally realized. In the same way, in the future plate-level antenna design, in addition to the traditional use of the radiating unit itself to achieve circular polarization, circular polarization can also be achieved through radiation superposition of other auxiliary structures and the main radiator.