GPS antenna type and characteristics

GPS antenna effect:
The electromagnetic waves emitted by the satellite into a current, because the GPS signal is circularly polarized waves, all antennas are circularly polarized work.
GPS antenna by location into internal and external antennas, including built-in antenna is divided into passive antenna and active antenna.
1.passive antenna

Such as flat-panel antenna, mainly ceramic media, mostly square design, size 25 * 25 to 12 * 12MM, the larger the area, the higher the frequency of resonance, due not to the power supply, So called passive antenna. Figure:

Silver layer:
Surface silver layer ceramic antenna can affect the resonant frequency of the antenna, the ideal frequency is 1574.42MHZ, in time to make the silver surface shape can be adjusted to FM points.
Ceramic sheet:
The quality of ceramic powder and sintering process directly affects its performance, the market size of the ceramic sheet 25 * 25, 18 * There are 18,15 * 15 12 * 12 and so on. The larger the area of ceramics, resonance

The higher the frequency.
CHIP antenna, as shown:

2. active antenna
As the name suggests is to supply antenna module is made of a ceramic antenna, LNA (low-noise signal modules), cables, connectors composition, plus a waterproof seal ring, as shown:

LNA:
The signal is amplified and filtered, pre-LNA gain must cooperate stage LNA gain, GSC3F (SIRF Corporation) requirements before the total gain of the input signal must not exceed 29DB

Otherwise, self-excitation signal generating supersaturation.
Cables:
Impedance matching requirements of choice, typically 50 ohm impedance.
Active antenna characteristics: high gain, strong anti-interference, how to choose to use active antenna or passive antenna it?
A, if there LNA chip, it is recommended to use a passive, if not, will have an active antenna, the key is the chip's antenna input pins can feed
B, active antenna big, you can do an external antenna.
3. the helical antenna
Is given by the four curved metal strips, without any ground, it has the characteristics of a microwave antenna and vertical antenna, so that any gain directional antenna has 3DB, having

Ability to receive 360 degrees. Figure:

Ability to receive 360 degrees. Figure:
Features are as follows:
A, if the ground interference sources are more suited to use, because there are omnidirectional antenna reception, signal interference sources will also enlarge, they interfere with the satellite signal.
B, and now the introduction of helical antenna balun circuit, enhanced immunity, but the price is high.
GPS antenna parameters (active antenna)
A, the operating frequency: 1575.42MHZ (deflectable 2M)
B, enter the group of anti: 50 Ohm
C, VSWR less than or equal to 1.5
D, Bandwidth: positive and negative 5MHZ
E, Gain: 26DBM
F, impatient sound value: 1.5DB

Interface GPS antenna
SMA, also known as reverse polarity male, is an internal thread, are the contacts for the needle in the middle, which is the most commonly used, standard SMA interfaces are used in combination with two devices, one male and one female, as

Public interface is internal thread + needle, then the mother should interface external thread + bore
GPS antenna types and characteristics of soldered on the motherboard (female socket) GPS antenna type and characteristics of the antenna connection (male antenna)
There is another called RP-SMA, is contrary to the above, it is an external thread + needle, thread + bore.