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I will be checking whether I can null out the 106.3 translator well enough to still be able to receive KLOO. This happens just as I thought that there were no more vacant spots on the FM dial.
The antenna pattern plot for K292HH shows an incredible null in the direction of KLOO.
How would such a null be achieved?
I suspect that westside KLOO listeners will complain.Many single null patterns look just like that. You put in the deepest null possible (max 2 db attenuation per 10ยบ azimuth allowed by FCC) in order to get the highest ERP for your class. A softer null often means that you’re bumping up against protected contours somewhere else in the pattern, and a little less ERP is a lot cheaper than adding additional nulls to an antenna design.
But that doesn’t answer your question as to how.
FM DAs use several methods to achieve a directional pattern. It’s not an easy concept to visualize, but it has mostly to do with the phasing of multiple dipoles. The use of directors (metal plates and dowels) is also common.
Here’s KMUZ’s directional antenna. This creates a funky sausage shape pattern and uneven power distribution. I originally specified an even narrower sausage pattern but Mike Brown was able to loosen up the protection parameters by using alternate Globe data.
Antenna:
Pattern:
http://bit.ly/2MKA33THere’s WLVR’s directional antenna. This antenna has multiple complexities because not only are there multiple protections in opposite directions but also nearby Philadelphia, PA still uses Channel 6 for TV which necessitates a power split to limit horizontal power to 0.040 kW whereas vertical power is 0.200 kW.
Antenna:
Pattern:
http://bit.ly/2MI2BekAlso, keep in mind that patterns you see on applications and licenses at the FCC are theoretical patterns. The general rule is that you must fill the theoretical pattern no less then 85% to be compliant. So in reality, the actual antenna pattern isn’t going to have sharp jagged points or hairpin curves that show on the FCC theoretical pattern. Ultimately, it’s the manufacturer that will say if its doable or not. Both of the above examples are Shively antennae, using their Model 6810 as the starting point. Remember, when using multiple elements (bays) (not the case in the examples above) for higher gain, the spacing between them, the size and shape of the tower that they are mounted on, the mounting style (leg mount vs face mount) and azimuth of the bays all factor in the resulting pattern. That’s why the manufacturers all model them on their testing range. Some manufacturers use a scaled down model, however Jampro does full size testing. I deployed a Jampro omni JLLP-1 at KSXM. The main antenna on Stonehenge is an omni Jampro turnstile.
http://www.jampro.com/uploads/tech_docs_pdf/DAprocedure.pdf
DA rules: http://bit.ly/2MKwOJy Note that when installing a DA, the FCC requires not only for an engineer to provide a signed statement on the installation but also a licensed surveyor to sign off on it to make sure it’s pointed exactly as per the CP.
Please smack me with a wet noodle if this is a somewhat obvious question–are KPDQ and KKPZ hoping that they can charge more for airtime, since they will be simulcasting on FM? KKPZ’s FM translator directs its signal into the countryside, away from most of Portland, making it not that useful.
Correct manufacturer, Andy. Incorrect antenna.
Posted photo is Shively 6100 Series. Perhaps the best FM antenna on the market a broadcaster can buy and priced accordingly.
Actual antennae are Shively 6025 Series. Log – periodics. Anybody can make one in a garage.
Moot now as FCC grants Salem Modification and License to Cover.Sorry baravelli. Not according to their filings that show on the FCC pages linked and not according to picture comparison. Those pictures are not generic, they are the actual in use antennae at KMUZ and WLVR. They look exactly like a 6810 and nothing like a log periodic.
First antenna listed at FCC as 6810.
Second antenna listed at FCC as SHIVELY 6810-1D-V/H SPECIAL DA, 1 SECTION
A Shively 6025 doesn’t look at all like those pictures.
Shively 6810 lends itself to DA implementation and is available for all power levels.
Whatever. Guess we can ignore the ACTUAL FCC GRANTED MODIFICATION APPLICATION. https://licensing.fcc.gov/cgi-bin/ws.exe/prod/cdbs/pubacc/prod/eng_fm.pl?Application_id=1785791
You are right about one thing. Posted photo is the 6800 Series and not as I mid-identified as the 6100. My bad memory. But I query; why would Salem pay $25,000 for two 250 lbs 6810 medium to high power behemoths for 99 Watts ERP?
I’ll be driving on Cornell Road from downtown to Hillsboro tomorrow and will be shaking my head. Meanwhile, you grab good field glasses and take a look.
Keep making XLR -TRS adapters.If you want, License to Cover Application non-directional circle has a dot in it. GO for it.
Gawd are you lost or what.
The License to cover for K292HH? I was answering jr tech’s question about directional antennae in general.
The K292HH antenna, as I said, has one null and is pretty much standard fare. If you would bother to read other people’s posts completely instead of flying off into space, your confusion might be minimized. I was clearly talking about DA’s in general. jr had asked how it was achieved, taking a swipe at the rules or asking a good question about how the hardware works. I chose to answer the latter. KMUZ, Turner and WLVR-FM Bethlehem are not K292HH, but are good examples of more complex patterns that can be achieved without using a bunch of stacked log periodics or yogis.Your replies have nothing to do with what I mentioned.
Gotta say your credibility keeps taking hits here on the board as a result of your own inability to read what others write. No biggie. I have no problem constantly correcting you.
“The antenna pattern plot for K292HH shows an incredible null in the direction of KLOO. … How would such a null be achieved?”
Shively 6800 Series is not directional. Log period and Yagi-Uda are. I answer jr tech’s question more clearly with facts. Try it sometime.
nothing personal“Shively 6800 series is not directional”
Guess again, cell boy.
Read Shively’s own write up and then come and talk about it.
“Model: 6810
This ring stub antenna is higher power than the 6815 and has more directional capabilities.”
“Model 6810 is a directional antenna. Custom Directional Pattern work is available.”
“Directional system with custom mounts”
A. Let’s keep the name shame game on the Politics board where it belongs.
2. I can make two coat hangers into directional antennae with “offset mounts”but no one doesexcept for your cited exception.
III. White/Blue pair to pins 5 and 4, …Guess who else uses a Shively 6810 to achieve a directional pattern. The answer is here: http://www.fccinfo.com/CMDProEngine.php?sCurrentService=FM&tabSearchType=Appl&sAppIDNumber=621795
I think that the key is that the 6810 will produce a circularly polarized signal that is directional. The log-periodic produces linear polarization. Shively’s log-periodic can be placed at an angle to make the signal compatible with both vertical and horizontal receive antennas, but that is a compromise compared to having real circular polarization.
“but no one does except for your cited exception.”
Wrong again.
You clearly do not know wtf you are writing about. All the major antenna manufacturers offer similar solutions.
ERI does it with their Rototiller model and Jampro with their Penetrator (formerly called Double-V). Stacked log periodic or yagi style elements must be deployed in 1/4 wave spaced horizontal and vertical pairs to achieve circular polarization, so you have to buy 4, 6, 8 etc. elements to achieve the pattern. If you stack only horizontally or only vertically, as Alfredo points out, that’s the polarization you get. That’s popular in the reserved band due to Ch. 6 interference requirements, but it chews up a lot of tower real estate.Tell us, how many FM DA applications have you written Mr. Baravelli?
Have you ever discussed DAs with the brainiacs at ERI, Jampro or Shively? Have you ever sent them patterns that you software modeled by stacking with log periodics or yagi style elements and asked them if they can build a circular polarized version with one element due to limited tower space?
I have.
Seven FM. 12 AM. Dozens cellular.
Alfredo T: URL does not link in private browsing.
A [single] Shively 6800 Series antenna is not directional, is H/V and not “circular”. Takes two or more for directional radiation patterns when elements are spaced or “offset” (let’s say) 1/2 lambda on the vertical and horizontal planes for horizontal ‘figure eight’ 90 /270 degree patterns. Or, ‘back to back’ 1/2 lambda spacing on the horizontal plane for 0 / 180 degree patterns. For 106.3 mHz, 1.38 – 1.41 meter spacing between elements. Please remember the center ‘stub’ is adjustable for VWSR which also affects radiation power and pattern.
Physics. It’s a bitch.
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