thetimadator
Member
.....some of the antennas you see on cars have coils on them. not loading coils like in a k-40, the big black plastic bulb(lol), but when the antenna wire has been coiled, like a spring, a few inches from the base. what is the purpose of these coils? do more coils and the size affect the performance? do they allow multiple frequncies from one antenna? from what i've been reading an antenna can relatively speaking be only one length, whether it's 1/4,1/2, 5/8 or full wavelength. i see commercial antennas that are all diferent sizes and most have these"coils" in them. does the coil create a "dead" to allow for additional wavelength? for example can a 800 mhz tx/rx antenna have multiple wavelengths if i were to go 1/2 WL then a coil then 5/8? i've only been learning antennas for a bout a week on my own so i've got alot to learn. i want to build an antenna for a mobile data card is my end goal. i understand i can do a straight whip at 1/4,1/2, etc but i would like a better understanding how it works. a 5/8 WL for 800 mhz isn't very big at all and that's what confuses me. some you see in the store or online are longer. will a longer antenna work better. when the coils are put in at different WL's is that refered to as stacking? sorry for all the questions but i just haven't really found answer that i'm satified with yet just by doing searches on the net. thanks to anyone that helps!!!
