Now that the Antennacraft FM6 is discontinued, what's my best bet for an antenna?

ChopperChas

Super Member
Looking to mount a bigass antenna on the roof. 90% interested in FM, 10% in HDTV reception. I have a coax distribution amp already. I'm trying to pick up a low-powered college station (WKNC) about 18 miles from my house. My Jeep can pick it up just fine in my driveway, but my tuners struggle with indoor wire antennas. There are also a couple of great stations out of greensboro I'd like to listen to... and would love to get something out of Charlotte on a good night.

Thoughts?

Charles.
 
Some general information.

A full sized purpose built antenna is will usually give the best performance whether it is a 3 element or 10 element antenna.

How much of an antenna will be needed will vary location to location. What works well for one person may not work all the well for someone else in a different location, even within the same town or sometimes even with in a few city blocks. It depends on how much signal is hitting the antenna.

I have read a number of positive reviews of the Stellar Labs antenna. It is a basic 4 element FM broadcast band antenna and it is not rocket science to get this correct. However the same caveat applies. I understand that this may not fit you definition of a big antenna and may not be enough gain for your particular situation.

To be clear, when you say that you all ready have a distributions system, does that mean that you also already have an over the air TV antenna? My take is that you do not, but that may not be correct.

Using an over the air TV antenna for the FM broadcast band can be hit and miss, trial and error. Not all over the air TV antennas are created equal when it comes to FM broadcast band reception. If a combination antenna is to be used, are all of your stations of interest in the same direction from your house? If not a rotor may be in your future.

Using an FM broadcast band only antenna for over the air TV reception can be an even bigger hit and miss situation.

Check you existing distribution amplifier to be sure that it does not have an FM broadcast band trap, if it does be sure that it is turned off. Not all do, but it is not unusual, and some may have unswitchable FM traps.

It all boils down to how much signal is in the air, from what directions, for the stations of interest right where the antenna is located.

Eickmewg beat me to the reference to the Stellar Labs antenna.
http://www.audiokarma.org/forums/index.php?members/eickmewg.191034/
http://www.audiokarma.org/forums/index.php?members/eickmewg.191034/
 
I have a distribution amp that was in the house when I bought it, and was hooked up to Time Warner Cable. I don't know if it has an FM trap. I just assumed a CATV distribution amp would work fine, is that true? I don't currently have any kind of real antenna. I put a simple dipole in my attic, but it's not enough. My attic is small (crawl-height) and there are metal rafter supports within inches of the antenna, and a whole house fan about a foot and a half away. But I've already wired the attic down to the distribution amp in the basement, which is where all of the coax in the house terminates. So all I need to do is feed some coax out of the attic onto the roof. I'm getting a gable-mount antenna bracket and I'm going to put the antenna 10' above my roof line.

I also already have an HDTV UHF antenna that I was considering I might mount lower on the same mast, and then use a combiner to merge the signals. But really my primary focus is FM radio.

Charles.
 
attached is an link from the old "Electronics World" from December 1967 . It describes how to make a FM antenna using a wood frame and wire(also a VHF/FM version). I built one back in 1968 and wow did it work fantastic. http://www.introni.it/pdf/Electronics World 1967_12.pdf

In general LPDAs function by having specific groups of elements operate over a given range of frequencies. Over a given range of frequencies they tend to operate as 3 or 4 element beams regardless of the total number of elements. For example if the frequency of interest is slightly lower that what is shown below, then elements 3, 4, and 5 would be the elements in operation and if the frequency is higher then it is elements 1, 2, and 3.

If a LPDA antenna is used to cover a very wide range of frequencies such as an antenna used to cover the FM broadcast band and the over the air TV frequencies, it would function as above. The elements that have electrical lengths corresponding to the frequencies of the various TV channels frequencies would not contribute a lot (if any) to the reception of the FM broadcast band frequencies.


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Here is some addition information.

You can take look at your distribution amplifier and check for a switchable FM trap, most that have an FM trap are switchable.

Not all distribution amplifiers are created equal in terms of their performance for FM band reception. What is needed for good operation is not necessarily the same as for FM broadcast band reception for several reasons. Some distribution amplifiers have higher noise figures than one would want for weak signal FM broadcast reception. These amplifiers are very broad banded, can have very high levels of amplification and may supply your FM tuner or receiver with high levels of out of the FM broadcast band signals. This may or may not be an issue.

Best design practices indicates that the amplification should be placed at the antenna. That can improve the noise figure by several dB (that is noise generated in the antenna system that will be competing with your weak FM broadcast band signal). This is done by using an RF preamp at the antenna, and in the case of the FM broadcast band a low noise figure FM broadcast band preamp.

If you use a basic signal combiner at the antennas you will loose about half the signal (3dB) from each antenna.

CATV amplifiers work as designed because the cable company gives them a relatively large signal from the outside.

Having said the above, many people just plug and play and it works fine. Chances are, all though it is not certain, what you want to do will work fine.

To be clear I am not trying to discourage what you want to do. I am just sharing general information.
 
FM6? Can't have mine ... neener neener ... <G>

fm-antenna-stack.jpg


Wonder why they'd discontinue it? It's not like FM is dead ... yet anyway. Hopefully, they'll decide to either put it back on the market OR let someone else make them OR someone else builds a clone that works as well but gets by the little litigators. Not sure there'd even be any legal issues as it's a pretty basic yagi with no fancy electronics. Length, spread, number of elements ... that's all pretty much dictated by the target frequency.
 
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That is even better than the the military can do.

RF HORIZON.JPG

H1 is the height of the FM broadcast antenna and H2 is the height of the FM broadcast band receiving antenna. If the height of the FM broadcast antenna is 1500 feet then the signal makes it past the horizon by just a little bit.


While the Stellar Labs antenna is a good antenna, I do not see it, on a regular repeatable basis, receiving low power stations with antennas at lower elevations at this distance.

Like I say, that amount of signal at any given location is specific to that location and can not necessarily be used to make a blanket statement about the performance of any given antenna at other locations.
 
You may want to consider two antennas on one mount. Most OTA TV broadcasts have been moved into the old UHF band, which is well away from the frequency band of FM. Two dedicated antennas are going to give you a better response than one "do neither particularly well" antenna.

Even in the old days before most everyone had cable or satellite, a lot of TV Yagis had two separate antenna elements to deal with VHF/FM and UHF.
 
That is even better than the the military can do.

While the Stellar Labs antenna is a good antenna, I do not see it, on a regular repeatable basis, receiving low power stations with antennas at lower elevations at this distance.
Okay, I could have been more specific. I have occasionally matched that (sub-100 watt stations at 100 miles).
What I can consistently receive are 50kw stations.
 
attached is an link from the old "Electronics World" from December 1967 . It describes how to make a FM antenna using a wood frame and wire(also a VHF/FM version). I built one back in 1968 and wow did it work fantastic. http://www.introni.it/pdf/Electronics World 1967_12.pdf

My own huge Yagi on the 40 foot tower has seen better days (we've got some damned fat birds around here!),and I've been contemplating a replacement. I might just give this one a try for the heck of it,seeing as I have suitable materials on hand.
 
Charles The FM-6 was OK but if you want really good performance on the lower end of the FM band put together this three element design at this sit I posted here.
http://www.audiokarma.org/forums/index.php?threads/very-good-fm-antennas.734152/ I live east of Charlotte and get all the stations you are talking about. The three element design walks all over the FM-6. It does not cover the entire band at high gain. It covers 87-96 mhz but picks up all strong stations on the entire band. It is only 41" long and has a very high Front to back Ratio. The article says the numbers are critical but they are not as I have built several for friends and used whatever I had laying around. I did use old TV 3/8" diameter elements to build then. I also have the larger eight element LPDA but I no longer want that large antenna on my roof. There is a four element that is only 3" longer. The article has several full band antennas but they are large. I had the large 14 element LPDA up for a year but it was a very,very large antenna. I had a new roof put on the house and I took down the old tripod and do not want to put antennas on the roof so I have a tall pole up the side of the house and it will not take the wind like the old tripod did. That is the reason for the smaller antennas. I hear stations with this antenna that the FM-6 could barely get.
Ed
 
I really want a full band antenna. I need 100.7, 102.9, and 103.5 as well, and they barely come in at all right now. I don't mind a gigantic monstrosity on my roof. I'm looking at that inexpensive stellar labs 4-element Yagi, a round VT-FM10 omni-directional FM antenna, and also an RCA ANT3036WR FM/VHF/UHF antenna, which would do double duty and pull in HDTV stations as well, I'm hoping.

One of the big problems with my area is that I'm getting signals from all directions. Raleigh, Chapel Hill, Durham, and Greensboro all send signals my way, so I'm not sure how good a directional antenna is going to be to pick up all the stations I like. Only really one way to find out though. I'll probably play with the cheaper antennas first and if they don't do it for me, upgrade to the big 'un.

Charles.
 
An outdoore omni-directional antenna, while working better than than an indoor antenna, is not a gain type antenna, It will not deliver as much signal as a gain type antenna. They deliver about the same amount of signal as the average dipole.

In general TV antennas are a compromise for FM broadcast band performance. Many of the newer TV antennas are cut for the TV VHF high band channels (starting at 174 MHz) and TV UHF channels (starting a 470 MHz). Both of these frequency ranges are far removed from the FM broadcast band. Manufactures include FM broadcast band reception in their descriptions because these antennas will pick up FM signals, just like any piece of wire put up in the air.

An omni-directional antenna will pick up a signal, a directional antenna with 15 dB of gain will pick up a signal and a manufacturer can claim that both will receive FM broadcast band signals, but there is a big difference in the amount of signal that is delivered by each antenna.

I took a quick look at the RCA antenna on line and did not find any actual specifications for it and I found three different pictures all claiming to be this antenna.

And do not believe everything that you read about antennas on the net,

One site that I took a quick look at claims that the VT-FM10 is an omni-directional antenna with 4 dB of gain and and a front to back ratio of 15 dB. Putting the gain figure aside for the moment, by definition an omni-directional antenna will have a front to back ratio of zero dB.

The Stellar Labs antenna and the TV antennas are cheap enough to give them a try. Again it is all about the amount of signal that is in the air right where you put the antenna.

Web site such as TV Fool and FM Fool can give general information about expected RF signal strength, station coverage area and may be of some help in selecting antennas.

I am not trying to be discouraging, I am just sharing information.


 
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