Stereo Tool

Most station in the U.S. use the circularly polarized antenna for FM broadcast, but I'm aware that a number of countries use the Vertical polarized antenna,VP. What seems to be the preference where you live .

We're circularly polarized as are a lot of other major capital city stations, most of whom share the same antenna stack.

A lower power station close by use vertical as they don't have much tower space and can't mount stacked arrays of circularly polarised radiators. They still deliver a good signal.

C.

Most ( pirate )stations in NL use vertical stacked dipoles.

Here is a nice ( old ) video of some pirates from the NL that used 10KW+ / 110 meter tower and 8 stacked dipoles

http://www.youtube.com/watch?v=nx8q3GAsURg

I'm using a dominator myselve, because my crack up pole that is just 25 meters high, and am living in an suburban area.

So no high power for me, just 500W...

In Germany, most commercial FM-Stations using horizontal polarized antenna arrays. Small (low power) broadcast stations like us have to use vertical polarized antennas to minimize interfere with the "big guys".

interesting..On mobile receivers I think the CP would get the nod, but on fixed receivers(home,offices) I think the VP is better. Haven't seen too many higher power fms using horizontal.You can ask 10 different engs which is the best and get 15 different answers.lol keep the comment coming.

I think that the biggest disadvantage of the CP is antenna gain.
You have stack 4pcs to get gain
CP's are really needed in crowded areas with a lot of tall buildings, or with hills.
Because of combinded horizontal and vertical radiation, the signal will penetrate better.


NL is as flat as a pancake, and only the bigger cities have a lot of tall buildings.
There fore the officials are using panel antennas: a steel panel with two vertical v shaped dipoles in front of it, openings angle 90 degrees.
They stack 4 pcs in a circle for 360 degrees radiation, and that setup times 10 or 15 above each other.
Most of the time with combiners so more than one station can use the same antenna system.

The pirate stations are mostly located in the country side, and think that cp antennas are a waste of gain.
They prefer 2,4 or 8 pcs verticals.
Most of the time they have their 1,5,10 or 20kw transmitter on studio location.

The "city" pirates mostly place their transmitter on a high building, ( with 10ghz stl, hacked wifi or a prepaid dongle ) 1 or 2 verticals and a 150~500 watt transmitter

Most antenna here in the U>S> seem to be CP and brands like ERI,Shively,Jampro,etc. ERI seems to have the most in service and their antennas are expensive, but they really perform.I noticed you mentioned using the Dominator which some engs here say is junk. How is it working for you and have you compared it to other antennas?

My experience with this antenna is outstanding!

Donald from fmbroadcastantennas is not selling 'air' thats for sure!

I have the "original" one, but this antenna is copied many times and is very popular among the low power pirates over here

Since i am a low power broadcaster, and my antenna tower is just 25 meter, this antenna with low radiation angle is perfect for my needs.

I compared it with 2 verticals at this height, and i'm very satisfied with the results.
It has a wider spread of the signal, due the true omnidirectional pattern.

Also very lightweight, and no HF interference like humming audio equipment at my place or at the neighbours.
Compared to the 2 verticals: not true omni, and lots of HF interference at my place and in the neighbourhood.

Just for fun i now have 2 stacked 2 elements verticals that im testing.

From what i know CP is more resistant to reflection than VP. When a linear polarized signal (vertical - horizontal) is reflected by some kind of object it changes polarization resulting in a 20bd loss in the receiving antenna. The same applies for a vertical to horizontal antenna transition. When a Circular polarized antenna is used there is always a 3db loss (its the circular to linear loss) but when a circular polarized signal is reflected of an object it remains circular and so you can get 3db loss and not 20db.

The problem with CP is directionality. The usual CPs are omnidirectional but there are directional ones (x-yagis/cross-yagis)
The problem is that they have to be fed with a phase difference and making phase sift networks capable of handling alot of KW is dificult.

That is my opinion. Thank you very much for your time.Waiting for response

(disclaimer : i am not an rf engineer (yet) so there is a big possibility that i am totally wrong.)

THANKS

_________________
Very proud user of Stereo Tool since 2010. Thanks Hans.

My radio station
http://amradio.ddns.net

i don't think it does well. I have a guy about 8 miles that has a job box radio in his shop. he had to flip and flop play with antenna to get a signal, but i have an LPFM with a single bay shively that he could pick up just fine...conversely, in his car with a mast antenna, mine smoked the other one


Response of Dominator antenna user when asked how it performed on radios with horizontal receive antennas. But it seems to do very good on mast antennas that some but not many vehicles have.