Ham and CB Radio Myth - Low SWR Indicates a Good Antenna.

the myth is that if you have a low SWR you have a good antenna one that radiates well High s SWR bad antenna now if that's the case I'd like to show you the very best antenna you can get this is called a dummy mod antenna this antenna is all band 160 through 10 m very compact with an S SWR of one on all bands I think I'm going to sell them as a miracle antenna now take a lamp a lamp like here there's a lamp saying the measurement of St in waves in your feed line determines antenna efficiency is like saying the efficiency of the bulb in that lamp is determined by the lamp cord cord has nothing to do with how well the light bulb works that's determined by the nature of the bulb how much light it puts out and how hot it gets which is wasted power now like a lamp cord your coax cable only only connects your transmitter to the antenna it really has nothing to do with the antenna itself s SWR standing wave ratio tells you how your coax cables performing not your antenna s SWR is not really determined by the cable at all it's only determined by the match at the feed point where the cable connects to the antenna a proper diapole has an impedance of about 70 ohms so if your coax is 50 ohms your SWR is 70 divided by 50 or 1.4 hey did you notice that with a proper diapole you don't have an SWR of one if you do something's not quite right like too close to the ground which makes it a worse performer unless you want your radiation to go straight up nothing wrong with that that's what you want now it's true a lwr means more transmitter power is delivered to the antenna but the antenna itself might be really bad like an antenna that's too short for the frequency it's being fed now I can understand CB operators not knowing these things they don't even have to have a license much less pass an exam but ham should know better shouldn't there be a question on the exam about stuff like this maybe there is I don't know it's been so long since I got licens I have no idea you know I watched a YouTube video by a ham who was reviewing this SWR meter now here where it says efficiency he said that's your antenna efficiency completely wrong this only means that all the power from the transmitter is being delivered to the load doesn't mean the antenna's radiating it the load in this case could be my dummy load which I showed you earlier would that mean that my dummy load is a 100% efficient antenna you know I'm discovering that if you'd like to learn all the ham radio myths just watch YouTube fact you know I'm running a little short of myths so if you guys could watch YouTube ham radio videos for me and let me know what all the myths are so uh I can do a video on them so how is an antenna's radiation efficiency determined well let's look at the a L antenna book radiation efficiency the ratio of power radiated to power fed to an antenna determines the radiation efficiency it's given by this simple formula here E equals the radiation efficiency in percent PR power radiated P power fed to the antenna at the feed point you if we just read books like this we might learn something one way to determine an antenna's efficiency is to use field strength meters and compare those readings to a dipole antenna which is a very efficient antenna that should let you know whether that antenna is any good often makers of commercial antennas brag about how efficient their antenna is without providing such measurements they'll publish charts of the SWR curve of a particular antenna which is supposed to mean it's a good antenna well might actually be a poor antenna but ham radio operators will spend a lot of money buy these things and then say Oh it's a great antenna my first Contact was Europe well with good propagation you can work Europe with a 50ft piece of wire 10 ft off the ground doesn't make that an especially good antenna I had a ham radio friend who said the best 80 M antenna he ever had was a wire quarterwave ground plane vertical suspended from his Tower with an SWR of 3 to1 a 3:1 SWR in 80 m is really insignificant so if you really want an efficient antenna just put up a diapole it's cheap and if properly deployed nearly 100% efficient consider subscribing to this Channel and 73