New to this but have a question, on 50kw signals does the number of bays matter on coverage area. I'm talking about signals with same tower height or close to the same height with 50kw, WPST has a 3 bay antenna whereas WSTW when they were 50kw had 10, WJBR 6, WMGM 6, WAYV 3, WFPG 6 and so on, was just wondering why do some stations use less, some more.
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bays
- Thread starter wibgradio99
- Start date
In simple terms, what increasing the number of bays does is reduce the transmitter power needed to get the same coverage at ground level.
If you put approximately 10 kw into a single circularly polarized antenna element, you will get about 5 kw horizontal and 5 kw vertical, radiated like a light bulb... up, down, sideways. If you put 10 kw into a 4 bay antenna, you get 10 kw horizontal and 10 kw vertical, but less power goes up towards the sky and less towards the ground and more towards "straight out" to the horizon.
Add move bays and you get the greater power towards the horizon, less going up to the sky and right to the ground at or near the site.
At some point, the addition of bays creates a bunch of lobes of power that cause variations at different straight-out distances, so once you get to 8 to 10 bays, it starts being less useful if you want to reduce the costly electricity consuming transmitter power to get the same coverage.
However, in theory, if a station is licensed for 50 kw ERP at 500 feet, they can get that with a 50 kw transmitter and two bays or with a 25 kw rig and 4 bays and so on. It's an engineering and cost decision. Each of us will have slightly different opinions on this, as well as things like the spacing of the elements mounted on the tower and even the maker of the elements.
I tried to stay away from db's and math, so this is very approximate but I think I covered your question.
If you put approximately 10 kw into a single circularly polarized antenna element, you will get about 5 kw horizontal and 5 kw vertical, radiated like a light bulb... up, down, sideways. If you put 10 kw into a 4 bay antenna, you get 10 kw horizontal and 10 kw vertical, but less power goes up towards the sky and less towards the ground and more towards "straight out" to the horizon.
Add move bays and you get the greater power towards the horizon, less going up to the sky and right to the ground at or near the site.
At some point, the addition of bays creates a bunch of lobes of power that cause variations at different straight-out distances, so once you get to 8 to 10 bays, it starts being less useful if you want to reduce the costly electricity consuming transmitter power to get the same coverage.
However, in theory, if a station is licensed for 50 kw ERP at 500 feet, they can get that with a 50 kw transmitter and two bays or with a 25 kw rig and 4 bays and so on. It's an engineering and cost decision. Each of us will have slightly different opinions on this, as well as things like the spacing of the elements mounted on the tower and even the maker of the elements.
I tried to stay away from db's and math, so this is very approximate but I think I covered your question.
thanks, one more thing, why do some signal outputs show 50kw horizontal and 45kw vertical, I believe WPST shows this but most stations only list one form of power.
Some stations added vertical radiation after they had the original horizontal system installed... to save money, they added a separate vertical polarization antenna, and the gain may have been different.
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