With outdoor applications and runs over 4 feet long, use low-loss cable such as: LMR-400. What cables should I use for my WiFi antenna?
If you have cable loss of 2 dBi (based on your cable length and diameter), but a gain of 7.5 dBi from your antenna, the net effect is +5 dBi regardless of the power level. In short, 1 watt (or 1000mW) is equal to 30dBm. The conversion of watts to dBm uses a complex formula that goes beyond the scope of this section. Since it uses a reference point of exactly one milliwatt, it is an absolute unit of measure. The referenced unit is exactly one milliwatt. So, it doesn’t really matter what level of power is in question, the dBi remains the same.ĭBm refers to the ratio of decibels (dB) to milliwatts. That’s just a fancy way of saying that dBi is a relative measurement. Cable loss is associated with anything that decreases the antenna’s gain, such as the length and/or diameter of the antenna cable.ĭBi is an “isotropic measurement”. Antenna gain is affected by “cable loss”. Just remember, the general idea is to reduce the amount of loss and retain as much gain as possible.Īntenna Gain and Cable Loss are values that are constant no matter what power level you are referring to. This can make your head spin when shopping for antenna’s. On the receiving end, it’s a measurement of how well the antenna receives the radio wave and then converts that to electrical power. It’s called “gain” and it’s measured in a relative unit known as “dBi”.įor the transmitting antenna, gain is the measurement of how well the antenna converts the transmit power into a radio wave that can be sent. Unlike the actual radio transmitter itself, antenna power is not measured in output power. Some people say “power” but what they really mean is “gain”. The range and strength at which an antenna can connect depends on the antenna’s gain. But if you turn the antenna so that the elements are sideways, the antenna is then polarized horizontally. A Yagi antenna with vertical elements is also vertical polarized. Omni-directional antenna’s are vertical polarized. In fact, if you had two antenna’s pointing directly at each other, one with perfect vertical polarization, and the other with perfect horizontal polarization, the antenna’s would not hear each other at all.
Polarization is determined by the physical position of the antenna. Radio wave “polarization” plays a huge part in signal quality. Good performance is all about a strong signal. The broadcasting and receiving antenna must use the same polarity. Regardless of the type of antenna that you use, there is one thing that absolutely must be correct and that is the polarity. They’re made from everything you can imagine: coffee cans, Pringles cans, trash can lids, etc. Many of them post images and plans of their homemade antenna’s. There are a lot of DIY enthusiasts these days. They can help you reach Wi-Fi hotspots that might otherwise be out of reach. Cantenna’s are a great addition to your travel case. Most people use them to replace the rubber ducky antenna’s on their wireless USB adapters connected to a laptop. Omnidirectional antennas are designed for 360 degree operation whereby a vertical dipole radiates and receives equally well on the azimuth plane (in all horizontal directions).Ĭantenna’s are mostly used as a receiving antenna for client computers. What is an omnidirectional antenna?įor starters, Wi-Fi antenna’s are either omnidirectional or directional. Gain is the amount of energy increased by the RF signal. Polarity is the orientation of the electric field (the transmission itself) from the antenna. An antenna provides three things to a radio transmitter:ĭirection refers to the shape or angle of the transmission, which ultimately describes the coverage area. So, whether you are buying an antenna or building your own, make sure it’s designed for the correct frequency band. If it does work, it will not work properly and the range will be terrible. But other factors such as channel width, frequency, and spectrum are equally important.Ī 2.4GHz antenna will not work with a 5GHz signal and vise versa. How do WiFi antennas work?įirst and foremost, frequency wavelength plays a key role in the construction of the antenna. And with some basic knowledge about antennas, you will be better prepared to troubleshoot problems and plan your deployment. But for those of you planning to boost your range, using the right WiFi antenna can save you a lot of time and frustration. Most of you will be using the default antennas that come with your router. We’ll discuss various antenna types, how they work, cable lengths, and coupling requirements.
In this section, we’re going to discuss how to increase WiFi range using the right antenna for the job.
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