I have a 15W transmitter... trying to get the best range I can off that... I have a GP antenna and on the instructions it told me to cut the antenna to be at optimum with certain frequencies (how much I cut depends on what the frequency is)... let me know of any suggestions.. trying to get 5 miles out of this sucker.
More information would be needed to help ya, like what frequency do you plan to use and what kind of transmitter? Cutting the whip will raise the tuned frequency of the antenna. If using a ground plane antenna you should also modify the length of the ground portion aka the 4 whips sticking out horizontally at the base to be the same size as the vertical whip. Start with the vertical portion first. Remember though that you can cut away but it sure isn't easy to put back!
For size of a GP antennas vertical and horizontal parts you use the same calculations you do for a dipole antenna for one half of it. This link is for a 2 meter ham antenna, but the calculations are the same for all frequencies... www.hamuniverse.com/2metergp.html
5 miles from 15 watts? I got three miles from 100mW (2 of them solid stereo) and a 1/4 wave groundplane on the house.
If FM, you can try the URL Darklife gave (which is actually the one I used!) or if you are more advanced and have a SWR meter, a J-Pole is an awesome performer:
CMRADIO is right, you should be able to achieve some kind of signal five miles out with 100 milliwatts. I have a dipole at 30 feet above ground, that can be herd 8 miles out with 100 milliwatts.
The copper dipole on the Radio Brandy part 15 FM page, delivers results, and ultra low SWR. 7 watts into the dipole, delivered a signal 35 miles away, with a mountain range in the middle.
The copper dipole on the Radio Brandy part 15 FM page, delivers results, and ultra low SWR. 7 watts into the dipole, delivered a signal 35 miles away, with a mountain range in the middle.
I think it's funny how a commercial station that forced a pirate off the air in Whistler, BC needs 470 watts on top of a mountain and has crappier coverage than the pirate did with 10 watts with an Isoplole on his apartment balcony
We have a LPFM with 100 watts, that delivers a better signal, than a 6000 watt station. The antennas are about the same height, and only 3 miles apart. The antenna is everything to good coverage, and feeding that antenna with good cable, helps allot too.
Post by HighMountainRadio on May 20, 2018 4:15:51 GMT -6
Greetings !
I just saw your antenna question here. Yes, there are several varieties of FM broadcast antennas, however, overall, you are most likely to find commercial and non-commercial broadcasters alike using one of two varieties of 'Circularly Polarized' FM broadcast antennas. The reason for this is that they emit half of the signal in the vertical plane and the other half of the signal into the horizontal plane, thus maximizing reception quality for both home receivers as well as those listening in vehicles.
Especially for those listening while driving, this type of antenna greatly helps to alleviate a common problem to FM broadcast known as 'pickett fencing' whereas as you drive the signal, in certain areas tends to flutter, just as you experience with sound waves from your car being reflected off of a nearby pickett fence, thus the name..
I hope that you find this information helpful in choosing what type of antenna to use !
73... Spooky...
Attachments:
"Knowledge Is Always Made More Valuable By Sharing It With Others !" Always Remember To Be Kind ! True Greatness Often Has Very Humble Beginnings ! Help A Kid Out Today ! *** High Mountain Radio *** "Broadcasting From Somewhere High In The Remote Appalachian Mountains"
Post by HighMountainRadio on May 20, 2018 4:22:55 GMT -6
Greetings Again Yacek !
Here are a few other FM broadcast antennas that you will encounter although not nearly as often as CP antennas and Folded Dipoles. The first pictured antenna is known as a cross polarized antenna as opposed to circular polarization, the two are different, don't be confused although you can attain circular polarization as well with this type of antenna using the correct, easy to fabricate phasing cables.
Cross Polarized Antenna - Cross Polarized signals eliminate multipathing due to unwanted reflections and refractions, and penetrate more obscure areas in comparison to a single plane antenna. These are more commonly known, mostly in the amateur radio community as an 'eggbeater' or 'turnstile' antenna.
Circularly Polarized Antenna - Mixed Polarized dipoles are an excellent choice for FM radio single transmission frequency local area coverage. Community broadcast groups with a limited budget find these an affordable and effective option.
73... Spooky...
Attachments:
"Knowledge Is Always Made More Valuable By Sharing It With Others !" Always Remember To Be Kind ! True Greatness Often Has Very Humble Beginnings ! Help A Kid Out Today ! *** High Mountain Radio *** "Broadcasting From Somewhere High In The Remote Appalachian Mountains"
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