Coaxial Cable: How to Choose The Right Kind For You
Understanding Coaxial Cables
There are many different kinds of coaxial cables and they are an integral part of many electronic systems. But with all these options it can be hard to decide which are best for you. There are a few important factors that can help you decide. First, the quality of the materials and secondly the impedance of the cable.
There are three materials that most coaxial cables are made of; copper, aluminum, and silver.
Copper is the most common of these and is the second highest quality. It is the second best conductor and is fairly cheap. Copper can be difficult to use even when soldered because using most common fluxes will leave behind corrosive residues.Despite this, it has become the standard metal used for electrical conductors.
Aluminum is the cheapest metal used and it was extremely common decades ago when copper was in short supply. While aluminum is not as conductive as copper or silver it actually conducts better than copper on a per pound basis making it an ideal choice for wiring in weight constrained situations such as aircraft. Aluminum is also very susceptible to corrosion especially in the presence of moisture. Many older residences with aluminum wiring and connections often need to be switched over to copper because of this corrosion.
Silver is the third metal that you often encounter in wiring. While silver is the best conductor of the three it is the least common. This is for purely economic reasons as it is significantly more expensive than both copper and aluminum. Despite this, if you can find silver wiring it will provide superior conductivity and is easily soldered.
Cable impedance is directly related to the materials that the cable uses. This is measured in Ohms (Ω) and it can be described as the resistance that electricity or signals experiences as it travels through the wire. This means that the lower the impedance the higher quality the cable is. For coaxial cable there are two common impedances used in household electronics, 50 Ohm and 75 Ohm.
75 Ohm cable is the most common coaxial cable. It is the cheaper option and is commonly used for televisions and internet routers.This kind of wiring is often built into homes and electronics unless customers specify they need the higher grade connections. While 75 Ohm is not as fast as the 50 Ohm cables it is still perfectly capable of transmitting information across small distances (50 feet or less) before any serious loss occurs. So if you’re in a small use scenario you can easily save some money using the cheaper cable.
50 Ohm cable is not as common as it’s 75 Ohm counterpart however it offers considerable benefits. It is able to run over a hundred feet before it starts to experience data loss which makes it ideal for larger scale commercial applications. This does come with the drawback of having to install thicker cables and larger connectors to accommodate the superior data transfer. This can be a difficult constraint to overcome especially if the building was not originally designed to have these thicker wires running through it.
To provide a concrete example for you a 75 Ohm cable will lose about 1.6 times the amount of signal every 10 feet. This ends up being about -2 dB at 50 feet and this is where the affect can start to become visible.
A Brief Summary
The quality of metal used in cables can make a big difference in the end result of not just your cell phone signal booster system, but in any electronics. When price is not an issue it is best to get cables that have silver or copper in them and to only get aluminum cables when you are constrained by budget.
When comparing impedances of cables it is important to remember that as a rule of thumb lower is better. That being said common cables such as 75 Ohm cabling will not provide much benefits in situations where you are running cable less than 50 feet. After that distance though you will notice that the higher quality cables will begin to make big impacts in the end result of your projects.