GPS antennas

What are the Pros and Cons of a Yagi Antenna?

Yagi antennas, which also go by the name of Yagi-Uda antennas, are named in honor of the 2 Japanese (engineers by profession) who invented them. We can find practical applications for these antennas in amateur radio, television reception, and as a bridge antenna that will help connect a site to a Wi-Fi base station.

The key radiating element of the Yagi type of antenna, otherwise known as the “oriented” part, is referred to as its “dipole”. In most situations, a “reflector” is positioned behind the driven part. The reflector usually adds 4 to 5 decibels to the signal.

Yagi  and Their Advantages

We qualify Yagis as a directional type of antenna. Most of these antennas have a 50° to 70° beam diameter. Compared to omnidirectional antennas, they usually have a higher gain since they focus their data in just one direction only. This renders them very ideal for receiving weaker signals.

They also have a good range due to their high gain. Contrary to how antennas like log-periodic are built, Yagi antennas have the most gain with respect to their physical size.

Almost all signal noise from the opposite direction is filtered out by the antenna’s design. This explains the reason why Yagis make an excellent substitute for high-demand technologies such as telecommunications.

A Yagi type of antenna is easier to aim at than those of other arrays. But because of their design, they’re simple to mount even on vertical towers or any other form of structure.

signal tower

Since Yagis are less challenging when placed alongside log-periodic antennas, they are generally less expensive. Even if printed circuit board Yagis are available, others can be produced with just a few well-placed rods.

Possible Disadvantages of Yagis

  • The frequency range, or bandwidth, is somewhat restricted.
  • The antenna would need to be very long if you are seriously aiming for a high gain level. Even then, if you have more than one Yagi in an array, the gain is reduced to only about 6-9 dB.
  • By stepping further away from the frequency, the electrical properties of these types of antennas tend to wither away (feed point impedance, gain, front-to-back ratios).
  • The main disadvantage of this type of antenna is that they are difficult to feed and match signals at higher frequencies.

Further Observations

Yagi antennas are designed for balance, but if a balun is used at the feed joint line where it links to the drive part, it runs the risk of becoming what it should not become, unbalanced. 

They can be balanced or unbalanced, depending on the style of the driven feature. Remember that if relatively inexpensive Yagis are balanced, it takes away the need for a balun.

Adding elements to this type of antenna enhances its directionality. It broadens its attention, but since the signal-to-noise ratio is increased, it receives the signals from that direction way better than before. In summary, the levels of interference are significantly reduced, most notably from the sides. 

 

Should I Install a GPS Antenna in My Car?

GPS stands for global positioning systems. They work by receiving signals direct from orbiting satellites, and that functionality will not work well in the absence of a good working GPS antenna. If you have been wondering why you are not seeing any visible sign or indication of an antenna whenever you look at your GPS unit, it is because most of the time they are built right into it. 

There are also GPS devices that offer greater flexibility of use in terms of providing users an option to install an external antenna to it. While the installation and the use of an external antenna are not prerequisites, there are instances that they can be of great help.  

If you had your GPS unit for some time now, and you have not encountered any pressing concerns about it in terms of accuracy issues or loss of signal, then you may abandon the idea of having an external antenna. Such may not be necessary anymore. Perhaps one good exemption we need to cite here is if you have intentions of driving your car somewhere uncharted. Somewhere you are not very much familiar with it. In such cases, you will make good use of an external antenna.  

But, if on the contrary, you have been having issues with your GPS unit, if you keep losing your signal, then you can amplify this and strengthen your signal with the use or help of a GPS external antenna. Two possible things can bring this about, there are obstructions that you need to deal with. Second is the quality of the antenna that your GPS device comes in.  

Internal vs. External GPS Antennas

So what is the difference between internal vs external GPS antennas? The vast majority of GPS navigation units on the market today have internal antennas built internally. Under normal circumstances, they should work okay and good. What do we mean by saying under normal circumstances? We are referring to a clear view of the sky, there are no obstructions that can get in the way of receiving GPS signals from satellites above.  

These internal antennas are less capable compared to their larger external antenna counterparts. They are either passive or amplified. 

For external antennas, they can have double GPS strength versus an unpowered antenna. If you are realizing that there are occasions that your GPS devices signal is failing you, or that you are finding that it is sometimes inaccurate, the best course of action to remedy this is to take advantage of an external antenna. Most of the time, this action alone will help resolve the issue. 

You may think that the practical way to get around this problem is by trying to move your GPS device around your vehicle first, thinking that it would allay the interference or obstruction issues that your unit is having. However, you will eventually realize that there is only one viable solution for this, and that is to install an external, amplified antenna instead.

car GPS antennas

Amplified vs Passive Antennas

GPS external antennas are either amplified or passive. An antenna is qualified as a passive type if they are just on the receiving end of a GPS signal and relay it to a proper GPS navigation device. As for the active/amplified type, they usually come about with amplified power whose main purpose is just to boost the power of the signal. 

The active or amplified antenna comes a little more expensive when compared to the passive antenna. It is also more challenging to install. Perhaps what makes it distinct from a passive antenna is the fact that you have the liberty of installing it at a safer distance away from your GPS device as opposed to what a passive antenna can handle. Usually, you need to install a passive antenna with a coaxial cable that is not more than three feet, between it and your GPS device. 

Active antennas are pretty much better option to use for larger vehicles since you can install them much further away.