I had my big VHF yagi for Buffalo in the analog days of 2,4,7 and with the switch to digital UHF, reception was much improved to 100% reliable.I am 87 miles out from Buffalo South towers LOS.

That's due to the high amount of RF emitted by florescent lights and other high efficiency lamps in the AM band plus the poor noise rejection of AM compared to FM. That's yet another example of how real world results differ from lab results or calculations that don't take all variables into account.

It's well known that commonly used radio waves don't penetrate large volumes of water. That is unless they are at extremely low frequencies used by submarines to communicate while submerged. The frequencies are so low that they are not useful for anything else. Try comparing how well 2.4GHz and 5GHz WiFi penetrates walls. 2.4GHz does better. Then there is the claw back of TV frequencies in the UHF bands. Those frequencies are more desirable for communications because 600MHz-800MHz frequencies penetrate buildings better than the higher frequencies currently in use. There are lots of frequencies available above 20GHz but they are not usable for most cellular use because they do not penetrate buildings and other obstacles and must be used line of site.

Heh! Just wait until 5G wireless comes about. Talk about short, limited range! That's going to be the trade-off with the much higher frequencies that 5G is expected to assume.

In the cellular world, think about the relative tower density between 700 MHz operators ATT and VZW as compared with Sprint and T-Mo who operate primarily in the PCS (1700-1800 MHz?) band. T-Mo and Sprint pretty much need four times the number of towers to provide the same level of coverage, if everything else were equal. There's a good reason you don't see many of those PCS-band towers in the rural areas.

Needless to say, REAL WORLD RANGE is COMPLICATED...but for some reason you ONLY asked about LOS Range.

LINE-OF-SIGHT (LOS) SPECIAL CASE:

1) Free Space Propagation Loss is MUCH HIGHER on higher Frequencies, varying as 20*Log(Freq):
Lf (dB) = 36.58 + 20 log(MHz) + 20 log (miles) [Use 32.44 constant if km]

2) Hence the FCC Allocates MUCH LOWER Transmit Power Levels in Lo-VHF Band [Kilowats] than Hi-VHF Band [Tens of KW's] and HIGHEST in UHF Band [100's of KW's, up to 1000 KW Max], where they PRESUME a viewer on the outer fringes will be using a LOW Gain [4 dBd = 6.2 dBi] Antenna for Lo-VHF, Medium Gain [6 dBd = 8.2 dBi] Antenna for Hi-VHF and Higher Gain [10 dBd = 12.2 dBi] Antenna for UHF Band [with Very Poor Assumption of SAME Gain all across each Band] and as a result allocate ORDERS of Magnitude MORE POWER than is required for a LOS connection, since it must have sufficient POWER to overcome various 1-Edge and 2-Edge Propagation Obstacles:
https://transition.fcc.gov/bureaus/o...et69/oet69.pdf [See Table 3 Planning Factors on pg 3]

In practice, Power Allocations are fairly complicated due to same Channel Numbers being reused in nearby DMA's.....a complicated Software Program is now in use to calculate an estimate for the number of viewers reached and NOT reached by various Transmit Power Levels and associated Transmit Antenna Patterns for all affected stations.

Because FCC chose to NOT include Man-Made Noise in the Power Allocation procedures, Stations (and the NAB) complained all along that VHF....and esp. Lo-VHF was NOT being allocated sufficient Power.....so after DTV Transition was well along, FCC finally was convinced that they had made a MISTAKE [just as they were repeatedly warned about] and Allocated slightly HIGHER [no where near enough] Transmit Power for SOME VHF (esp. Lo-VHF) Band Stations. Here is the "latest" data from 1960 CCIR 322 Report, charting "Fa", which is how much higher Man Made Noise is than Thermal Noise Level. FCC still PRESUMES Fa=0 for UHF Band...but even UHF can be affected by Man-Made Noise, esp. on lower UHF Band Channels):
http://photos.imageevent.com/holl_an...20-%201960.jpg [MEDIAN Noise Levels per CCIR 322 (1960)

The difficulty with trying to include Man-Made Noise into the Calculations is the fact that it varies all over the place....and we REALLY have NO IDEA what TODAY's Noise Levels are. Note that on Ch2 the "MEDIAN" can be as much as 30 dB HIGHER than FCC Thermal Noise PRESUMPTION....and at any particular location at any particular time, the ACTUAL Man-made Noise Impulses [which is what causes Audio/Video Glitches] can be a LOT higher than the "MEDIAN". In 1960, primary source of Man-Made Noise [mostly IMPULSE Noise at that time] was probably Fluorescent Light Tube Ballasts (Impulse Spikes at 60 Hz Power Frequency, mostly used THEN in Business Areas rather than Homes], Car Ignitions Systems (Variable Impulse Rates....but Resistor-Suppressor Wires have mostly "fixed" this problem), Brush Type Motors (modern Brushless Type are Much Less of a problem) and Arc Welders [many years ago, Taiwan had a nation-wide RECALL for several manufacturer's equipment to add "better" RFI/EMI Filters...followed up by a Gov't "Seek and Destroy" Mission].

This is further complicated TODAY by Microwave Ovens, Dimmer Switches, LED/LCD Lights, Fluorescent Tube Ballasts (newer ones are MUCH better) and a Plethora of other Electronic Devices taking over everyone's Home & Office [and some counterfeits NOT conforming to FCC Class B RFI/EMI Requirements]....and even EMI from Street Lights that are smack within the Roof Mounted Antenna Pattern, rather than being in the Null UNDER it. [PS: ZERO consideration has yet been given to users trying to use INDOOR Antennas...other than more robust, probably lower-rez ATSC 3.0 Sub-Channels.] And our Antennas are now picking up hundreds if not thousands of individual Cell Phone Transmissions that interfere with the UPPER UHF Channels that CAN NOT be cost effectively Filtered out. Recognizing the ever growing problem, FCC has initiated NEW Noise Level Tests.

Despite the higher VHF Power Allocations, Stations in Lo-VHF Band still feel that they are being short-changed, esp. when compared to their old ANALOG Power Allocations which intentionally assumed VERY LONG RANGE Coverage from PROTECTED Lo-VHF Channel Assignments.....and NO Adjacent Channel Interference to worry about.

If ANY TV Channel Frequency is "better" than another, I would guess that it would be mid UHF Band, where ACTUAL Receive Antenna Gain is usually MORE than on the Lower UHF Channels....and Upper UHF Channels would FREQUENTLY benefit from EVEN HIGHER Gain than Mid UHF Band [depends on the Antenna], but would also have HIGHER Cable Attenuation than Mid-Band unless using Preamp....so viewer results would be MIXED.

3) TERRAIN, rather than POWER is the ACTUAL Limit on Line-Of-Sight Range (ignoring 1-Edge and 2-Edge Propagation), which is primarily driven by how HIGH the Transmit Antennas are above the various Receive Antennas. Under the [Very Good] presumption that there is MORE then sufficient POWER to actually make a good connection, fol. provides the Equation and an On-Line Calculator for determining LOS Range. Note that LOS Range is ONLY determined by Geometry, being INDEPENDENT of Frequency:
https://www.easycalculation.com/phys...ansmission.php
http://www.rfcafe.com/references/ele...-nomograph.gif [NOMOGRAPH]
Unfortunately I could only find LOS RANGE NOMOGRAPH in Nautical Miles [Statute Miles = 1.151 * Nautical Miles].

i do understand higher freq needs more LOS (going back to 1999 when I switched from 900mhz for 2.4 wireless itnernet bridges)

but example:
if a station had 1kw vfh mhz station
and a 1kw uhf station, besides LOS
what are the differences..



"power limit regulations" and other regulatory data is irreverent here as we are generally speaking


Now in North America (where regulatory laws apply)
if you were to buy a home use TV modulator (analog or ATSC Digital) for home use (lets say you lived on a 20 acre farm) but connect it to an antenna so TVs can get the signal wirelessly, which frequency would you use (i do understand every market, environment is different, but where would you start so you are within legal limits) besides the ones in use by stations.
Which amplifiers would you use, , type, linear, etc. which antenna would use you, ( i would assume bow tie)

What is being proposed is illegal in North America. Using a high powered transmitter will land you in legal trouble if someone complains of interference. Interference is quite likely with cheap equipment and will be noticed in rural areas due to the number of OTA TV viewers. Interference on the wrong frequencies could also involve the military or scientific communities.

If you want point to point communications, it would be much better to use devices that operate on public low power frequencies. That could be a pair WiFi routers configured as a bridge. Instead of an amplifier (which is illegal for WiFi) use high gain, highly directional WiFi antennas to create the radio link. Note also that in Canada it is illegal to use some WiFi frequencies outside. Something like a Slingbox or a PC with freely available media software such as KODI can be used to manage the programming.

For this, UHF would be better. Last time I looked, ATSC modulators were not available. However, an ATSC repeater that uses WiFi bands is better.

Illegal.

Illegal.

Most antennas would work. The one used would depend on a variety of technical factors. Commercial broadcasters use antennas designed for their specific needs.

^ i never said anything about high power , how is everything u said illegal above?
https://www.ic.gc.ca/eic/site/smt-gs...g/sf08655.html


TV modulators have existed for home for over 50 years

I am sure many people, accidentally connected their TV OUT AND TV IN backwards and it went outside to the TV antenna and didnt serve jail time.

Actually, if you have an amateur radio licence, those are legal, along with using an external antenna. The 2.4 GHz band used for WiFi overlaps an amateur radio band. You can even legally modify the equipment to be used within that amateur band, but outside of the usual WiFi channels. Also, while WiFi operation is not protected from interference, amateur radio use is. So, if a neighbour's WiFi causes interference to amateur radio operations, they have to do what it takes to stop the interference.

If Program SOURCE is HDMI, a Wireless HDMI Extender TRANSMITTER, plus perhaps Wi-Fi Repeater(s), could distribute to MULTIPLE Wireless Extender Receivers, each of which is connected to DTV's HDMI Input Port. IR Control Signals flow back the other way and can be output via an IR Blaster:
https://www.amazon.com/Actiontec-MyW.../dp/B005L9ZZ32 [And all Perfectly LEGAL]
https://www.amazon.com/Actiontec-Wir.../dp/B00LSS10PM
MWTV2TX, MWTV2RX - Actiontec.com
If you want to distribute OTA Signals, DTV's do not (yet) have HDMI Outputs....so you would need to add an OTA HD-STB/DVR....and perhaps a multi-input HDMI Switch if AVR is not already being used an an HDMI Switch [OTA STB could connect to an available AVR HDMI Input Port].

However you cannot use amateur (ham) radio to rebroadcast commercial services or to circumvent commercial services.

Legal for direct connection to another device using coax, not for broadcast. Thirty years ago were a few analog devices that used UHF or VHF for household use but they are likely now illegal. They also didn't work very well. Even small FM modulators that are used to "broadcast" music to nearby automobile FM radios had their allowed power reduced several years ago.

High power for unlicensed consumer devices these days is basically anything over about 100mW or 1/10 of a watt. That's what unlicensed WiFi and cordless phones are limited to. Even that is severely restricted to a few approved frequencies. Modern cell phones operate at similarly low power levels.

Going on air with a "dirty" consumer grade modulator and 1Kw amplifier will make a lot of people upset. Besides, as I pointed out earlier, there are better solutions.

^

"if a station had 1kw vfh mhz station"
"Going on air with a "dirty" consumer grade modulator and 1Kw amplifier will make a lot of people upset. Besides, as I pointed out earlier, there are better solutions."

i didnt know that stations used consume grade modulators.

I was responding to post #20 where home modulators, amplifiers and 1kw stations were mentioned. Maybe I drew an incorrect ling between the two references but the intent to amplify the output of a home modulator to high power and transmit the signal is definitely there.

FYI: Unlicensed Very Low Power Transmitters are LEGAL in the AM and FM Bands [EXCLUDING Ch6 Audio], with Power Limits as described here:
https://en.wikipedia.org/wiki/Title_...d_broadcasting
https://www.fcc.gov/media/radio/low-...al-information
Note that 100-mW MicroTransmitters are ONLY Legal in the AM Band....with extremely inefficient Antennas.....and allowable FM transmissions must live within a specific FIELD STRENGTH limits.

Unlicensed [even Very Low Power] Transmitters are generally PROHIBITED in TV Band [INCLUDING Ch6 Audio], except for a FEW, Highly Regulated Devices, such as Medical Telemetry, Wireless Microphones and so-called White Space TV Band Devices...which REQUIRE Frequency use Coordination with a Master Database of available Spectrum users [with one exception]...as well as a built-in DETECT & AVOID Active Spectrum Sensor:
https://en.wikipedia.org/wiki/TV-band_device

===========================================
Some of you might be thinking that you could operate within the FCC Class A or B Emissions Limits [technically still illegal other than in AM and FM Bands]:
http://image.slidesharecdn.com/fcc-r...?cb=1447049155
However, if you compare those Emissions Limits to FCC OET-69 Minimum Required DTV Signal Levels, Propagation Loss would ensure it never makes it out of the same room [If my math is correct, Ch2 would only go about 1.7-m, Ch7 only 0.3-m and Ch14 only 4.4-m MORE than 3-ft "spec limit"]:
https://transition.fcc.gov/Bureaus/E...et69/oet69.pdf