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Found different types of antenns on FM, see this:-

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Willen

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I visited a place of taller hill last time. There are lots of towers of cell phones, AM radios, FM Radios and Televisions. There are two photos of FM's:-
I think "A" antenna is a type of yagi for one side powerful transmission. There are 3 rods to which i marked with red circle. Which is the antenna rod? I think- front is director, middle dipole and last is reflector, isn't it? I hope this dipole length is similar as single dipole!

I've never seen "B" type of antenna. I found it on 10,000 watt FM station. Cannot understand the theory of it, even cannot reconized the rod of the antenna!

Anybody, do you have internal diagram of these antennas and working theory in simple?
 

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Antenna A is very directional. It is pointing in one direction.
Antenna B is not directional. It sends out power in all directions. North, south, east west. It does not send power up or down.
 
Antenna A is very directional. It is pointing in one direction.
Antenna B is not directional. It sends out power in all directions. North, south, east west. It does not send power up or down.


Yes, but the dimensions of the Yagi look interesting, as there seems to be a very big difference between the element lengths, almost like a log periodic, but you cant see the feed on the boom . This may be to broaden the bandwidth, but it would reduce the gain. It is also vertically polarised, which could suggest it is used as a gap filler possibly meant for car reception, if it is used for FM broadcast. (that of course would depend if the normal broadcast was horizontal)

The second one I don't think is omnidirectional, the "swept back" angle of the elements is partly for impedance matching, and partly to send most of the signal away from the tower (aided by the spacing from the tower). They are phased as said to prevent the signal going up or down, mainly to avoid strong fields at ground level and to get most of the signal going straight out in the vertical plane. The omnidirectional version has another dipole mounted "back to back" so that each antenna looks more like a square. Any single dipole has two major lobes.
There also doesn't appear to be another element in the vertical plane which would indicate circular polarisation.


Now we need a broadcast engineer to tell us exactly!!!!

What country are they in?
 
As ronsimpson says, it's EXTREMELY simple:

A = vertically polarised directional yagi (probably just a receive aerial).

B = horizontally polarised stacked dipoles, omnidirectional.
 
What country are they in?

I found Both transmitter antenna on Nepal (Asia). Station of antenna A is called "Image FM 97.9MHz" and station of antenna B is called "Kantipur FM 96.1MHz". Station B has higher transmission power of 10KW.
 
I built broadcast stations for 6 years.
Antenna A is not for transmitting a ratio station. I had several stations with both antenna A and antenna B on the same tower.
Antenna B is very likely used in a 10kw station.
Antenna A is likely used to connect two buildings together. I used this type of antenna to transmit from the studio to the transmitter shack. We used directional antennas because the intent was for one transmitter to talk to one receiver and no where else. In some cases we had more than one studio and they needed to be connected together. In several cases one studio talks to many transmitters.
 
I built broadcast stations for 6 years.

Wow great experience!


then asking most important questions please

- I think all antennas are not manufactured for particular frequency. Will you adjust them during station stablishment by cutting manually according to the frequency of station? :)
I think we should have to make order to manufacturer to design antenna suitable for our station's frequency, isn't it?

- Here are 32 different amplifiers to produce 10KW. One amplifier makes almost 320 (?) watt. How they connected between each other and how these various small powered (320 Watt per amp) amplifiers produces 10KW in combination? Any diagram?
Can I make four amplifiers of 5 watt to produce total 20 watt like this way?
 
I think all antennas are not manufactured for particular frequency. Will you adjust them during station stablishment by cutting manually according to the frequency of station?
Broad cast antennas are made for a certain frequency. I have move a station 3 channels but I would never go from one end of the band to center with out replacing the antenna. Some antennas have a end that screws on and can be adjusted a little.
Here are 32 different amplifiers to produce 10KW.
I have seen solid state amplifiers parallel to get more power. I have never used one. My transmitters use tubes. Some times multiple tubes. Tubs come larger than a basked ball.
 
If I have 500mW exceiter and i added 2 amplifier of 5 watt. Then if I connected the output of both amp with coaxial cable (Like in attach),in this way Is it possible to connect 2 amplifier in parallel to produce double power like 5+5=10? Wow!
 

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You have to use a device called a "combiner". It presents a 50Ω impedance to each transmitter, and a 50Ω source impedance to the antenna.
 
You have to use a device called a "combiner". It presents a 50Ω impedance to each transmitter, and a 50Ω source impedance to the antenna.

Any simple diagram and theory?
 
The transmitters are built for 50 or 75 ohms and must drive that load. The antenna is built for a certain load. And the coax is 50 ohms. All need to run at the impedance they are designed for. No choice.
 
Hi Willen,
I hope your powerful FM transmitter does not cause interference to the radio station I listen to in Canada.:rolleyes:
 
Hi Willen,
I hope your powerful FM transmitter does not cause interference to the radio station I listen to in Canada.:rolleyes:

When he doesn't even recognise simple aerial types I'm dubious that he will ever get anything working - and if it does it will soon self destruct :D

'Presumably' he's trying to build a commercial station? - so you simply buy the gear and the aerials, and the suppliers sort out what's needed.
 
Not going to make!!!
This 10KW Amplifier system amazes me actually! I used to thought there are serial chain of amplifiers to produce more power! But got different!
I wanted to see just a from a near by using schematic thinking that most of electronics device can be shown in basic form! :p
It is not need to build professional station to interference. 2SC1971 is quite enough :)
 
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