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How to build a UHF antenna... - Page 3

post #61 of 4787
Reflectors have a specific function. Their value depends on your need for that function.

These dipole antenna arrays have known gain patterns that are symmetric about the plane of the array - front and back have the same pattern, so we call it bidirectional.

Adding a reflector changes the pattern. Like a partially silvered mirror, it blocks most all the signal from the back side, and reflects the signal from the front so it arrives in phase with the next wave hitting the front. This greatly reduces back-side gain and increases the front-side gain - it's now a directional antenna.

Reflectors are highly advantageous in long-distance, LOS applications due to their substantial gain increase in a specific direction. They are also very useful in crowded signal fields where there's interference from a strong station; you can aim the nulls (low gain directions) at the interfering station. But these are all characteristics of any directional antenna; Yagi's do the same things.

DTV gets interesting due to multipath and the crowding of the spectrum - adjacent channels are allowed in a DMA. All the ATSC tuner needs is a lock and the picture's perfect, and that can come from any direction; sometimes a reflection gives the best lock. In other cases, signals are strong, but coming from too many directions and too much phase variation (multipath). I get multipath interference effects in my family room! Yes, 2 feet, left-right, will cause or kill a lock if I pull off the reflector.

The point of this thread is to try things and see what works. Some reflector designs will work better than others. Commercial designs may be optimized, but perhaps not for your application. As long as the reflector is metal, has lots of horizontal runs in the grid, and covers the entire element area, it will "work" quite well to enhance directional gain.

Whether that "works" for you depends on your specific needs.
post #62 of 4787
In most locations, your strongest multipath components will be coming from the BACK
of the antenna. Objects behind you are like a mirror that reflects back toward your antenna.
Objects off to the side also contribute to multipath, but with weaker, glancing angles.
These "objects" can be nearby buildings, tall skyscrapers and terrain.

Hence Front-to-Back (F/B) ratios are important in suppressing multipath.
When you remove reflector to form a bi-directional antenna, you let in more multipath.
post #63 of 4787
Quote:
Originally Posted by fbov View Post

Did you build the exact antenna shown, or one that's close?

What channels are you receiving?

The reason I ask is that the blogspot antenna is a 7" design, which shifts the gain response of a commercial CM-4221 (an 8" design) so it peaks at channel 88 with significant loss of gain below Ch 25. A few posts up, I talk about the effect of this basis dimension on channel gain, predicting response based on 4221 curve scaling and then making and testing the series.

It works; you can shift the channel gain.

Thus the 2-part question, what did you build and what's its channel response?

Frank,
Sorry that I haven't responded, been too busy working.

It's been a while since I looked at my antenna, so I measured it.
I made a hybrid, so here it what I built:
7" whiskers
8.5" Spacing btwn whiskers
5.5" spread width at the end of the whiskers (not sure this matters?)

I only have 1 UHF digital below ch29, so I lucked out on the whisker length .

I receive 6 of the 7 Baltimore stations at 75.2 miles.
2.1 (52)
11.1 (59)
13.1 (38)
45.1 (46)
54.1 (40)
67.1 (29)

Without moving the antenna, I rec stations (at 61~ 63 miles) 49.1 (30), 8.1 (58), & 43.1 (47) up to 40 degrees left from the Baltimore stations. I can't receive any stations to the right of Baltimore though , 144 degrees thru 340 degrees due to a hill and also the mountain (less than a mile behind me). So essentially, I can only receive stations from 75 degrees thru 140 degrees regardless of the antenna.

The Baltimore stations probably get some help by being opposite of the mountain.
post #64 of 4787
Has anyone attempted to increase/decrease the distance between the dipole and the reflector to improve gain on a specific channel? I am thinking about trying just that.
post #65 of 4787
Antenna basics (holl_ands, feel free to comment)

The feedline length between elements determines the wavelength(s) that will add constructively. In a CM4221, that distance is 8", same as the wisker length. The top and bottom feedlines are crossed, causing a 1/2 wave phase change. When that 8" feedline length is also 1/2 wave, the two elements add in phase - constructive interference.

The downlead connection is in the middle so top and bottom pairs arrive in phase as well. With good impedence matching to the downlead, signal voltage to the downlead is maximized.

Changing the element separation changes the wavelength of best signal transfer to the downlead. Since the amount of signal present is determined by the array elements, failure to gang them properly only reduces total gain. You may propagate a shorter/longer wavelength better, but there's less to propagate in the first place. Better to start with an element design that's tuned to the desired wavelength and design feedlines to maximize propagation of that wavelength, as I believe CM did.

Aaaacck - I just re-read your note: reflector spacing. Same advice as for feedlines ...

Again, think constructive wave interference, but this time with 1/2 wave coming from the "reflection" process (actually absorbtion and re-transmission) and the other 1/2 from propagation distance. However, the prop. distance is traversed 2x, so you want a 1/4 wave spacing. CM uses about 4" ...

To tune a reflector, you need a channel-frequency table, or knowledge of one channel since they're all 6 MHz apart. All you need to know then is:
Ch Frequency Range
2 54-60
7 174-180
14 470-476
post #66 of 4787
Thanks Frank. I guess I won't tinker with the reflector spacing. I held a reflector up to my YouTube & I thought I noticed difference in gain from RF23 & RF56 depending on spacing. That experiment was rudimentary and I thought, "There's something else going on."
I have been frustrated today because of strong winds. I rechecked my antennas today & I'm getting erractic readings and some dropouts.
Has anyone experimented with this design lately? I tried it with limited success.

LOL. This is RF 58 at 28 miles.
post #67 of 4787
post #68 of 4787
Reviving this thread again.. before I splurge on a CM-4221/4228 or Hi-VHF/UHF directional antenna, I want to try the DIY bowtie antenna myself. I need to see whether it excels my present HDTVa for channel 61 (it's at -75dbm) and I face problems in reciving this (WNET-DT, PBS). Also 3-4 channels are moving to Hi-VHF post transition, so need to evaluate the VHF performance too for the anetenna.

Problem is, I stay in an apartment, and I don't have all these raw materials, which you guys do.. obviously because you guys own house. I have managed to get a 2x4 from Home Depot for $0.51. However, I am facing problems in resourcing the >, < and the wire connectors. It sounds silly to me to beg for coat hangers in my local dry cleaners (but if no option, I guess I have to do that). Some of you mentioned #18 ceiling wires, is it readily available in Home Depot/Lowes? I searched their website, I couldn't come up with anything. Any idea on the price for the ceiling wire.
With lot of searches, I found these pipe hooks (#12) made out of copper/aluminum.
http://www.homedepot.com/webapp/wcs/...ctId=100192486
They are already in V-shape so bending them will be little easy, however not sure how will I straighten them. These items are cheap too, considering that these are #12. Also each leg of the V is either 6" or 8". Do you guys have any other suggestion on the whsiker materials and the connectors, preferably available in either Home Depot/Lowes within $10.
post #69 of 4787
Kousikb,
I used ceiling wire for elements and feedlines; any place that sells suspended ceiling systems has this wire used to hang the grid. ~$3 for 100 ft. Look under suspended ceilings. It comes rolled but it's not hard to straighten. You'll also need 10 small screws to build it and unless you're running twin-lead, a balun to connect it. $10 should do.

Your pipe hook link fails for me, but they sound about right.

Remember this is for the bi-directional antenna. To make it directional, add a metal reflector ~4" behind the elements. I used cage wire; $10 for the roll of 1x1" mesh galvanized - my biggest single antenna expense. You may not need it, so start simple and move up as needed.

Stand it behind the TV aimed about like your ZSS and see what you get. To get UHF 61, build it to CM-4221 specs: 8" wiskers and 8" element separation gives peak gain at UHF 63. You won't get much VHF-high and nothing on VHF-low with the 4-bay.

I have a 9" one of these in my attic with reflector and I get UHF 58 very well at -77.5 dBm signal per TVFool. I also got it well without the reflector, but all my stations transmit from the same hill so the reflector has advantages.

HAve fun,
Frank
post #70 of 4787
Thanks fbov !
Yes I already have these scres/washers and a drill lying around. Balun, I will probably buy from RS. I searched in Lowes and Home Depot, walmart. They don't have it. I hate to go to RS, because their prices are usually jacked up. Thanks for the other tips too. I myself have studied antenna theory, design in my EE course, but haven't used it for the last 10 years (am in software from the start of my career).
It indeed is really fun..
post #71 of 4787
Quote:
Originally Posted by kousikb View Post

Thanks fbov !
Yes I already have these scres/washers and a drill lying around. Balun, I will probably buy from RS. I searched in Lowes and Home Depot, walmart. They don't have it. I hate to go to RS, because their prices are usually jacked up. Thanks for the other tips too. I myself have studied antenna theory, design in my EE course, but haven't used it for the last 10 years (am in software from the start of my career).
It indeed is really fun..

I've seen balun's at K-Mart as well. Imagine my surprise when I found that out after spending nearly 10 bucks on the balun from Radio Shack. :P
post #72 of 4787
I've found that a copy of the cm4221 design except using bowtie elements 10" long and element spacing of 9 1/2" seems to work best for the UHF channels 14 - 50 where the bulk of the stations are transmitting currently and in the future. A 36" x 36" reflector spaced 5" behind the elements greatly increases VHF hi reception and slightly increases UHF, if VHF hi isn't a concern than a 26" x 36" reflector will do fine. Slightly more gain and a narrower beamwidth can be had by bending the outer 8 inches the 36" reflector forward 2" at the ends. I've built some of these and they work great on UHF and very well on VHF high. No magic here just a rescaling of the proven design down to the frequencies most used today.
post #73 of 4787
Does bending it decrease the VHF pickup ability? I'm in a bad way in my area. I have stations on 46 and 49, and stations on 11 and 13. I'd like one device to do both (even if only mediocre), instead of two antennas (antennae?).
post #74 of 4787
Quote:
Originally Posted by mclapp View Post

I've found ... No magic here just a rescaling of the proven design down to the frequencies most used today.

Yes, it really is that simple, and my personal antennae are 9" on-center for exactly the reasons you cite, plus the need for UHF 58 and 59 for 10 more months. At 10" I start getting issues up there.
http://www.avsforum.com/avs-vb/showt...8#post13338498

Frank
post #75 of 4787
Quote:
Originally Posted by aethyrmaster View Post

Does bending it decrease the VHF pickup ability? I'm in a bad way in my area. I have stations on 46 and 49, and stations on 11 and 13. I'd like one device to do both (even if only mediocre), instead of two antennas (antennae?).

Antennas will often have both VHF and UHF antenna as one unit. If your VHF and UHF stations are the same direction then you could use a combined antenna, if they are in different directions then have separate UHF and VHF antennas.

Antennas are made for a wide range of channels, a VHF antenna or a VHF high channel antenna would get both 11 and 13 with a VHF high channel antenna being even better. You could make an antenna that was optimized for 11 and 13 and not a compromise to get the lower range of VHF high channels.

Similar you could make a UHF antenna optimized for 46 to 49 instead of a compromise for the UHF band.
post #76 of 4787
Quote:
Originally Posted by aethyrmaster View Post

Does bending it decrease the VHF pickup ability? I'm in a bad way in my area. I have stations on 46 and 49, and stations on 11 and 13. I'd like one device to do both (even if only mediocre), instead of two antennas (antennae?).

What gives mclapp's antenna it's VHF gain is its size. He's made a 4221 4-bay array with a 25% increase in element scale, and a reflector the size of an 8-bay CM4228's! It should not be surprising that he gets VHF-high gain; so does the 4228.

It would be interesting to see what happens with a 4-bay when the reflector is enlarged to VHF-high 1/2 wave dimensions (27.7-33.4").

Gee, looks like mclapp already did!

As a side note, I ran you zip code through TVFool, and your post office is in rabbit ear territory. Unless you're house location is drastically different (mine's ~25dB different), a simple 4-bay should work. I have mine in the attic and I get -77dBm stations very well.

Have fun,
Frank
post #77 of 4787
Quote:
Originally Posted by aethyrmaster View Post

Does bending it decrease the VHF pickup ability? I'm in a bad way in my area. I have stations on 46 and 49, and stations on 11 and 13. I'd like one device to do both (even if only mediocre), instead of two antennas (antennae?).

The reflector element bending doesn't really do much for VHF HI, the size is the key there. The element bending just narrows the UHF beamwidth width and slightly increases forward gain. The one I built seems to work good on 11 & 13, I put one up for a friend of mine and he is getting 2 DTV stations out of Scranton, PA on those 2 channels which are 70 mi away through the hills.
post #78 of 4787
Quote:
Originally Posted by fbov View Post

As a side note, I ran you zip code through TVFool, and your post office is in rabbit ear territory. Unless you're house location is drastically different (mine's ~25dB different), a simple 4-bay should work. I have mine in the attic and I get -77dBm stations very well.

I'm not quite sure what you mean your location being ~25 dB different, but I think I get you. I have used antennaweb and TV Fool both, and I'd love to pick up everything on the TV Fool list.

Also of note - my house is 300~400 feet from the actual location of the post office in Berwick. My problems stem from the fact that I have a metal roof; I don't think mounting in the crawl-space I have would be much good - it'd be like wearing a foil hat. The building right next to me in the direction of the broadcast towers I care about is slightly taller than my house too.

Right now, I'm using rabbit ears to tune my stations. I have them upstairs by the window, with a segment of RG-6 running down to the TV downstairs. I'm getting 30 to 45% signal strength on all channels, depending on weather and such. I feel I should be getting way better than that for at least ONE channel, but haven't really had time to put in the effort that it would require (either that, or my wife has been watching TV).

Quote:
Originally Posted by mclapp View Post

The reflector element bending doesn't really do much for VHF HI, the size is the key there. The element bending just narrows the UHF beamwidth width and slightly increases forward gain. The one I built seems to work good on 11 & 13, I put one up for a friend of mine and he is getting 2 DTV stations out of Scranton, PA on those 2 channels which are 70 mi away through the hills.

I've attached a picture showing all the stations that I care about getting. I'm thinking the only real option for me is a chimney mount antenna. The delay/dilemma I have is just whether I want to buy, or build. I love projects like this, but sometimes I just want stuff to work. Also, the TV is on one side of the house, and the chimney on the other - If I do chimney mount, it would probably be about 60 feet of cable to make the run to the TV, maybe a little more.
LL
post #79 of 4787
Quote:
Originally Posted by aethyrmaster View Post


Also of note - my house is 300~400 feet from the actual location of the post office in Berwick.

I don't know for sure but I expect that they may use the center of the zip code zone and not the post office as the location based on the zip code.

Quote:


Right now, I'm using rabbit ears to tune my stations. I have them upstairs by the window, with a segment of RG-6 running down to the TV downstairs. I'm getting 30 to 45% signal strength on all channels, depending on weather and such. I feel I should be getting way better than that for at least ONE channel, but haven't really had time to put in the effort that it would require (either that, or my wife has been watching TV).

You could put an improved antenna in the window, especially for the UHF station. I have made single station antennas out of balsa wood and electrical wire, very cheap and quick, good for a test at least.

[/quote]I've attached a picture showing all the stations that I care about getting. I'm thinking the only real option for me is a chimney mount antenna. The delay/dilemma I have is just whether I want to buy, or build. I love projects like this, but sometimes I just want stuff to work. Also, the TV is on one side of the house, and the chimney on the other - If I do chimney mount, it would probably be about 60 feet of cable to make the run to the TV, maybe a little more.[/quote]

If it is an outside antenna then you might consider making an antenna if you use the best materials and construction methods, try to get as good as the consumer grade from the store, otherwise you will need to repair it more then you would like. You are looking for a narrow range of frequencies in each VHF and UHF so a custom antenna would be of value in low signal areas. If you get 30% of signal with rabbit ears then the wider band antennas from the store would probably just fine. You don't need low VHF so look for high VHF and UHF combination, some companies may make as separate antennas that fit together on the same boom.

Could also do a roof mounted tripod to place antenna closer to tv location. Could do a mast (pipe) from the ground braced to the side of the house.

If you were to do an outside antenna you could take the antenna and a short mast (pipe) which you would need for any outside mounting and tie it up to the chimney. If it works well then gets the chimney mounting parts, if it doesn't then consider another mounting location.
post #80 of 4787
Quote:
Originally Posted by aethyrmaster View Post

I'm not quite sure what you mean your location being ~25 dB different, but I think I get you.
...My problems stem from the fact that I have a metal roof; I don't think mounting in the crawl-space I have would be much good - it'd be like wearing a foil hat. The building right next to me in the direction of the broadcast towers I care about is slightly taller than my house too.

Right now, I'm using rabbit ears to tune my stations. I have them upstairs by the window, with a segment of RG-6 running down to the TV downstairs.
...
I've attached a picture showing all the stations that I care about getting. I'm thinking the only real option for me is a chimney mount antenna. The delay/dilemma I have is just whether I want to buy, or build. I love projects like this, but sometimes I just want stuff to work. ...

Have you tried anything like what spokeybob is making? His post from 3/29 (can't see post numbers/links) shows a very simple antenna similar to one that I have working in my attic with signals far weaker than yours. The idea would be to put it in the same place as your rabbit ears, or perhaps nearby if aesthetics count. If the bi-directional array isn't enough, add a reflector; your transmitters are well clustered.

You may have a metal roof, but how about the walls? Keep it inside and a lot of the home-built robustness issues are moot.

Yes, I get a -25dBm drop in TVFool signal prediction between entering my zip code and entering my long/lat. I live in a "basin." All stations are -70 to -77.5 dBm at my house and they all give me excellent (90+) signal at the tuner with a 4-bay home-built in the attic. I also get reasonable VHF 10 and 13 analog image quality from it, but I won't know about VHF digital performance until next year.

Frank
post #81 of 4787
Quote:
Originally Posted by n4yqt View Post

I have a couple of those old style indoor 2-bay 'Double Bow Tie' UHF antennas and I decided to see how I can enhance their performance by adding aluminum foil to the rear of the grill. I've attached some images of the antennas. I have tested the antennas before and after the modifications and I have noticed an increase in signal strength on UHF and now I have decent signal strength on VHF-Hi, too. Of course, these are indoor antennas but they seem to do very well in my area.

I'm not surprised the first one improved; reflector elements must be horizontal (like the EM polarization) to actually reflect. The other place to add foil is the bowtie's themselves - scale it up for better results at lower frequency bands as suggested by this modeling analysis:
http://www.hdtvprimer.com/ANTENNAS/DoubleBow.html

And try spacing the reflector back 4-5", so you get an actual 1/4 wave reflection. These should work as well or better than the wiskered versions!

Frank
post #82 of 4787
John said:
I don't know for sure but I expect that they may use the center of the zip code zone and not the post office as the location based on the zip code.
I find that to be true. Thanks for posting that.
Frank: You have mentioned "Rabbit Ear Territory" before. On the TV Fool, it lists
Rx(dBm). Which value puts it in Rabbit Ear Territory?
Thanks for your help.
post #83 of 4787
That's in the TVFool FAQ
http://www.tvfool.com/index.php?opti...d=14&Itemid=50

"The most important value to pay attention to is the "Rx(dBm)" value since that is roughly how much signal you have to work with. Higher values represent stronger signals, but note that the values are negative because of the units being used. There are a lot of factors that affect each situation differently, but in VERY ROUGH TERMS, signals above about -70 dBm should be strong enough to receive with an indoor antenna, signals above about -90 dBm should be strong enough to receive with an attic antenna, and signals above about -110 dBm should be strong enough to receive with a rooftop antenna. These are only estimates and your particular situation may be significantly better or worse than indicated. Your mileage may vary."
post #84 of 4787
Baluns have been evaluated and discussed here, and there are performances differences between them. In general, cheaper ones don't work as well.
post #85 of 4787
Quote:
Originally Posted by Ken H View Post

Baluns have been evaluated and discussed here, and there are performances differences between them. In general, cheaper ones don't work as well.

That makes sense Ken. Although I paid $5 for the first one at Radio Shack, I wonder if it is a cheaper one. On my next YouTube build, I will test that theory against my Ebay baluns.
Frank: Thanks for the FAQ post. I did a CECB/Youtube install this morning at ZIP 61260. As an afterthought, I tried her rabbit ears with the CECB. It would only pickup 38,49,56 with the ears carefully positioned next to the glass slider.The Youtube is now hidden behind the couch and gets 38,49,56,58,23,45,& 25.
LL
post #86 of 4787
That channel reception pattern is interesting, especially in light of TVFool giving worst-case predictions, what's called P(90,90). (90% probablity with 90% confidence, iirc)

P(90,90) is something like 10 to 12 dB lower than P(50,50), so the actual signal received with rabbit ears (38,49 and 56 have signals >-80.7 dBm) was more like -70 dB, right at TVFool's indoor limit. Add an antenna with roughly 10 dB gain and you're getting stations will into the -90dBm range, although I'll bet that KWKB-25 and WQPT-23 are the first to fade when conditions worsen. It'll be interesting to see what happens.

Frank
post #87 of 4787
Well, update for all you folks. I got wire from a buddy I visited on Friday last week (he was running his Tesla Coil - neat stuff!). 14 gauge household electrical wire. I measured it and bent it for use as a Single Gray-Hoverman, as I didn't want to cut anything. Finally bought a Phillips balun from K-Mart today, for 3.99. Took my wires, a wooden yardstick and screwed them down to it. I only put screws in the center point where they were needed for the balun, just to test it out. I check the TV using my DTX-9900, and WOW.

All of my channels are coming in with a minimum of 45, maximum signal level is 83!

The new G-H antenna is also about 3 feet lower than the rabbit ears sat, as it has no lead cable. For being a quick-and-dirty build, incomplete, and not mounted where I want it, I'm thoroughly impressed!

Now, to work on getting more channels......
post #88 of 4787
Quote:
Originally Posted by fbov View Post

That channel reception pattern is interesting, especially in light of TVFool giving worst-case predictions, what's called P(90,90). (90% probablity with 90% confidence, iirc)

P(90,90) is something like 10 to 12 dB lower than P(50,50), so the actual signal received with rabbit ears (38,49 and 56 have signals >-80.7 dBm) was more like -70 dB, right at TVFool's indoor limit. Add an antenna with roughly 10 dB gain and you're getting stations will into the -90dBm range, although I'll bet that KWKB-25 and WQPT-23 are the first to fade when conditions worsen. It'll be interesting to see what happens.

Frank

I again thank you for sharing your knowledge with us. Yesterday we had strong winds and she said 24.1 and 4.1 were pixelating. (She picks up new words very easily.) LOL. Amazing that 12.1 off to the side still was OK. Her antenna is on the south wall of the house, resting on the floor.
I have reverted back to the original Youtube design with 7" whiskers and 5 3/4 spacing. I conducted a coathanger drive and used these also. At the crossover point, I used black tape & did not raise one wire up.
Testing on my garage CECB and using the DISH 622, the numbers are up all across the band. On the next windy day I will take my latest example down to 61260 to see if this is better than hers. The Insignia does not have numbers on the meter, only bad/good.
Here is Vanna & Youtube on my HDTV. They both look good.
post #89 of 4787
Quote:
Originally Posted by fbov View Post

PS I should mention that a channel-frequency table will tell you the frequencies of the channels you want. Those numbers, in megahertz, divided into 300 (speed of light in m/MHz) yield the wavelength in meters. As an example, 600 MHz, Ch 35, would have a 0.5m wavelength, so 1/2 wave is 9.86", but ch 35 a bit low to be practical.

Thanks for the info ... very interesting and educational (for me anyway). I have a question regarding how to calculate the peak frequency. Running the numbers thru the formula, the 1/2 wave for channel 66 (the peak for a CM4221) is 7.5", not the 8" one would expect. 8" would equate to channel 58. Or am I looking at this the wrong way? I have a CM4228 and I noticed that the whiskers are spread approx. 5-1/2". And if I measure horizontally from the point of the whisker to the outer edge, the horizontal measurement is 7.5".

So my question, does it make sense that the peak corresponds to the horizontal measurement of the whisker out from the bend point?
post #90 of 4787
Quote:
Originally Posted by fbov View Post

That channel reception pattern is interesting, especially in light of TVFool giving worst-case predictions, what's called P(90,90). (90% probablity with 90% confidence, iirc)

P(90,90) is something like 10 to 12 dB lower than P(50,50), so the actual signal received with rabbit ears (38,49 and 56 have signals >-80.7 dBm) was more like -70 dB, right at TVFool's indoor limit. Add an antenna with roughly 10 dB gain and you're getting stations will into the -90dBm range, although I'll bet that KWKB-25 and WQPT-23 are the first to fade when conditions worsen. It'll be interesting to see what happens.

Frank

Here is the F(xx,yy) comparison chart andy.s.lee prepared for an idealized smooth earth:
http://www.avsforum.com/avs-vb/attac...0&d=1195561571
http://www.avsforum.com/avs-vb/showt...&#post12266426

He didn't do F(90,90), but it's probably more than 10-12 dB lower than F(50,50).
The difference is also very dependent on range (and topography...which he did not include).

BTW: TVFool uses F(99,99) for Rx(dBm)....which is perhaps 20-30 dB lower than F(50,50):
http://www.avsforum.com/avs-vb/showt...&#post10661475
http://www.avsforum.com/avs-vb/showt...&#post10661305

There is the also an issue re how much Land Use Clutter Loss needs to be added to L-R results.
[TvFool also does not include foliage loss, building/attic/indoor loss, antenna gain, degradation
due to VSWR mismatch, cable/splitter loss and any improvement due to using Preamp....
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