Andy aka Andy aka 1. Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password. Post as a guest Name. Email Required, but never shown. The Overflow Blog. Does ES6 make JavaScript frameworks obsolete? Podcast Do polyglots have an edge when it comes to mastering programming For more information Google: "speed of light in gigahertz inches".
Last edited by rjstone. Tags: antenna 2 meter math arrl chapter 4 arrl module 9. But the easiest way to solve this problem is to remember that a meter is a little longer than a yard, or approximately 39 inches.
To calculate this, half of the 6 meter wavelength would be 3 meters. To convert that to inches, multiply by 39 inches per meter:. Quarter wavelength dipole is the same, but divide by the frequency in megahertz. This is easier to remember since 's digits are sequential , so just remember that one and convert up when needed! We are looking for a half wavelength antenna length, so we can begin by dividing the 6 meter wavelength by 2, which gives us a 3 meter wavelength.
Now that you have converted to GHz, you can divide the speed of light expressed as Last edited by saalberg. Tags: antenna 6 meter math arrl chapter 4 arrl module 9. The radio waves emit out along the length of the dipole outward, and is strongest at the middle.
There is little to no RF energy coming out the ends of the antenna. So Broadside is the correct answer. The feed line has no effect in the emission of a dipole antenna if properly chocked off by a baluns. Last edited by qgolden. Tags: antenna polorization antenna propagation arrl chapter 4 arrl module 9. By the geometry of the antenna we can change how the antenna emits radio waves, or RF energy. We can focus it like a spot light by using a yagi antenna, or we can let it flood out more evenly like a room shop light, by using a dipole antenna.
The higher the gain, the more focused the beam of RF energy, which results in an increased signal strength in a particular direction. Last edited by bdengle32 yahoo. Tags: antenna transmit power arrl chapter 4 arrl module 8. Makes it easy to remember the correct answer.
What about the distractors? Last edited by mitchellday. Subelement T9. Here is some basic information for a staring point per your questions. Theory tells us resonance is when the capacitive reactance and inductive reactance are equal. Yes, mostly. Again, it is when the capacitive reactance and inductive reactance are equal. If the physical length is such that the capacitive and inductive reactance are not equal if the antenna is too short it is more capacitive and if it is too long it is more inductive such as a just a random length antenna, capacitance or inductance can be added to the antenna as needed.
Yes it does, There are losses associated with the coil inductor and antenna capture area larger is better in general terms. The loading can make reduce the bandwidth of the antenna. If the physical length is such that the capacitive and inductive reactance are not equal if the antenna is too short it is more capacitive and if is is too long it is more inductive such as a just a random length antenna, capacitance or inductance can be added to the antenna as needed.
For example a physically short CB antenna will have added inductance somewhere base loaded, center loaded or top loaded. There are losses associated with the coil inductor and antenna capture area larger is better in general terms. If the antenna is really short, these losses will add up and the antenna may not perform well.
As others' have posted, start with ONLY the simple theory of antennas. Here's why: Antennas are very complicated. Take for example a transmitter. There are many different components in that radio; resistors, capacitors, ICs, coils, etc. And those parts all have very short theory to them. Now the antenna is part of that system so that you can transmit. But it has the largest amount of theory per part of a transmitting station!!! There are many, many books on antennas; but there's only one small pamphlet detailing resistors.
Do as others've posted, start at the part that you feel comfortable with and study that first, then expand your knowledge later. Who knows, maybe you could design a better antenna as time moves on. I like the analogy of a pebble dropped in a pond and the ripples it made going out in circles. That's very similar to an antenna sending signals.
So the quantity of how the wave is propagating is important in the design of an antenna. The current distribution over the dipole plays an important role e. Python Javascript Linux Cheat sheet Contact. Why is "wavelength" used as a unit for the length of an antenna? Consider a monopole and look at the impedance it presents to the circuit it attached to: - A typical quarter wave monopole has zero reactance magenta line and has a radiation resistance of about 37 ohms although it's a tad difficult to get a precise value from the graph above.
A fast car isn't necessarily a Ferrari or a Lamborghini Actually this is a very basic question about high frequency HF applications.
0コメント