Difference between GPS Patch antenna and Helix antenna

The function of the GPS receiving antenna is to convert the electromagnetic wave energy of the satellite radio signal into the current that can be absorbed and applied by the electronic equipment of the receiver. The size and shape of the antenna are very important because these characteristics determine the ability of the antenna to acquire weak GPS signals. The antenna can be designed with single L1 frequency, L1 frequency and L2 frequency as required. Because the GPS signal is circularly polarized, all receiving antennas are circularly polarized. Despite various conditions, there are still many different types of antennas, such as monopole, bipolar, quadrifilar helix antenna and microstrip antennas.

What is patch antenna

Patch antenna has become the most widely used antenna because of its durability and relatively easy manufacturing. Its shape can be round, square or long, just like a printed circuit board coated with copper. It is composed of one or more pieces of metal, so the most common shape of GPS antenna is blocky knot, like a pancake. Because the antenna can be made very small, it is suitable for aviation and personal handheld.

Another main characteristic of antenna is its gain pattern, namely directivity. Using the directionality of the antenna can improve its ability to resist drying and multipath effects. In precise positioning, the stability of antenna phase center is a very important index. However, in common navigation applications, people want to use omnidirectional antennas, which can receive at least all satellite signals visible in the sky in the five degree field of view above the antenna horizon. However, when the flat antenna is directly above the antenna, the signal gain is the largest, which has two problems:

1. The reception range of the flat panel is above the flat panel, and the flat panel faces the sky, which will cause trouble for handheld and vehicle. We can see that there are more and more adjustable angle CF receivers (folding SDGPS Ritai 9551). It is precisely because of the characteristics of the flat antenna that the manufacturer has come up with a way to improve the reception effect of the receiver.

2. We know that although the satellite signal above our head is better and easier to lock, in fact, the satellite above our head is the most useless. If there is no low-angle satellite, the error will be relatively high and the accuracy will be very poor. Therefore, based on these shortcomings, the quadrifilar helix antenna is also used on the GPS receiver.

What is quadrifilar helix antenna

The quadrifilar helix antenna is composed of four specially curved metal wires. No grounding is required. It has the characteristics of Zapper antenna and vertical antenna. This ingenious structure makes the antenna have the advantage of 3dB in any direction and increases the receiving time of satellite signals. The quadrifilar helix antenna has the ability to receive 360 degrees. Therefore, when combined with PDA, the quadrifilar helix antenna can receive regardless of the position of PDA, which is different from the limitation that the flat GPS antenna needs to be laid flat to receive better. With this antenna, when the satellite appears 10 degrees above the ground plane, the signal transmitted by the satellite can be received.

However, if there are many interference sources near the ground receiving station, it is not suitable for the quadrifilar helix antenna because the quadrifilar helix antenna has horizontal gain, which will amplify the noise together and interfere with the reception of satellite signals. However, with the progress of science and technology, the quadrifilar helix antenna produced can break through the limitations of many traditional antennas. The antenna is made of ceramic. Near-Field is very small, only about 3~5mm, while some traditional antennas have Near-Field as high as 1m. The smaller the Near-Field, the less interference the human body will cause when the user holds the GPS device. At present, the quadrifilar helix antenna also features a complete Barron circuit design, which can isolate the noise around the antenna, so that antennas with various functions can exist in a small space without mutual interference. The importance of this feature is self-evident for handheld electronic products with increasingly diversified integration functions and emphasis on lightweight and short size.

Mide helix antenna 3701A

After reading the above text, you may know the advantages of the quadrifilar helix antenna, but the price is higher than Patch antenna.Therefore, most GPS receivers using this antenna are high-end products in handheld devices, which are suitable for consumers who like handheld devices and users who have strict requirements on positioning time. MIDE has developed the cost reduction scheme to win a more market-oriented price for this antenna. Helix antenna 3701A not only has good price but also has stable performance, which design for high-precision positioning services, with a stable phase center that maintains high gain at lower elevation positions, providing excellent satellite signal tracking.

Patch Antena

quadrifilar helix antenna