2023 TV Antennas & Equipment

[WHJ]

I have added some new TV antennas and associated equipment. All of the new antennas have been mounted but some custom antenna selection equipment needs to have its construction completed. The equipment is summarized below:

The combination of filters and selective combiners is used to prevent mixing of unwanted local signals from off-frequency antennas hurting reception of DX from the more directive antenna. The selectivity of the HD HomeRun tuner seems to be worst of the low VHF channels. The filters there help prevent overload and IMD from FM stations hurting low VHF reception. The installation to the 10A3F120 tuner has been completed. Its reception can be observed at https://rabbitears.info/tvdx/one_tun...0A3F120/tuner0

I will include some pictures of my new antennas. I have long had a 9-element custom antenna for channels 2 and 3 and a 10-element custom antenna for channel 6 and the lower FM frequencies but nothing specifically for channels 4 and 5. Using some surplus tubing that I have a 7-element antennas channel 4 and 5 was recently installed.

The top antenna is a Winegard HD7698P with the new channel 4 & 5 antenna just below that. A fixed direction Stellar 30-2440 is side mounted on the tower.

I redesigned the Televes 149783 UHF antenna. Twelve elements were added, and the length of all directors was extended.

My 10-element channel 6 antenna is on top.

I thought that I would try something different and install my first vertically polarized TV antenna. It is just a side-mounted vertical dipole tuned best for channels 2 and 3. It is spaced from the tower to produce the following pattern:


It is shown below with my 9-element channel 2 & 3 antenna just above it.


There has not been much tropo or Es opening recently (or expected in the next week) hurting evaluation of the new antennas.

[WHJ]

Today I got my second HD HomeRun tuner converted as close as possible to my new connections shown on the chart. I will need to have my fourth tuner added to BandScan and complete my construction of the Agilent 8765F RF switch control circuit to go further. This circuit will allow the continual connection of a selected antenna or have either of the two antennas alternated every two minutes. The second tuner receptions can be viewed at https://rabbitears.info/tvdx/one_tun...0A0E179/tuner0 I need to get revised names for those tuners.

I better tested my new channel 4 and 5 antenna today. The receive strength of semi-local KNHL (channel 5) 74 miles away was 100% / -44 dBm when beaming towards it. With the antenna pointed in its normal SSE heading the station could not be received at all. The difference is shown below.

So, if KNHL or other local stations are not shown as being received, it probably is because the best antenna is not pointed towards it.

[WHJ]

Until my TV Band Scan tuner names have been changed and my new tuner is added, I think that I have found a better way of connecting my antennas. Two of my three tuners shown on TV Band Scan will just have one VHF/UHF antenna connected (Winegard HD7698P's) along with either my 9-element channels 2 & 3 Yagi or my new 7-element Channels 4 & 5 Yagi. The two Winegard antennas are at different heights on different towers controlled by different rotators. Additional details are shown below.

The third 4K tuner will have a new custom circuit to automatically cycle between up to six different UHF antennas, or a Stellar 30-2476 VHF antenna or my custom 10-element channel 6 antenna. The UHF antennas will be changed every two minutes. For now, just 4 antennas will be connected, concentrating on the first two.

A chart of my interim connections is shown below. The no longer appropriate TV Band Scan names for my Garland, NE receptions are shown in red.

With some TV band combiners having around just 30 dB of isolation, I often have filters added to prevent the directivity of a band's antenna from being compromised by other connected antennas.

I am not sure why the reception of the Kansas City stations has changed this year. Originally KCTV-24 was the first KC station received. Local KSNB moving to channel ended that. Then, KPXE-30, WDAF-34 and KSHB-36 were all pretty close in being the first KC stations received. KMCI-25 and KSMO-32 were a little bit behind those three. Both of those two stations going to ATSC 3.0 did not seem to change things much. For about the last three months however, KMCI has been the clear winner as the first KC station being received.

[WHJ]

I figured out why KMCI has jumped to the easiest Kansas City station to detect. They have changed their ATSC 3.0 core layer from the same 256QAM 9/15 as their programing has to QPSK 4/15. Below shows the difference between their original signal in late 2021 to their current one.

That makes their signal 21.5 dB easier to detect. The video will still take a stronger signal to view, but it should speed recapture of a weak signal.

When reception is marginal, it is more commonly received as follows.

The basic PLP0 information is received due it only requiring a -0.3 dB SNR. Since the enhanced PLP1 QAM256 programming requires a 21.2 SNR, the video cannot be viewed. The Flex 4K Development dBm strength and dB SNR data makes easier to see the point of reception. The first two receptions were made on a Flex 4K without the Development enhancement.

An example of KMCI reception in the middle of the afternoon without any significant opening is shown below.


The above was from https://rabbitears.info/tvdx/all_tuners

[WHJ]

It has still been a slow start to the Es season this year. And most of the tropo openings have not been far enough west and/or north to help my location. I changed my 2023 equipment diagram at the top to show what is currently being used rather than my planned changes. I need my fourth HDHomeRun tuner added to TV BandScan before I can go much further. My three active tuners scan channels 2 - 36 rather than the default 2 - 51. My fourth tuner just scans channels 2 - 6.

[Crazy Monkey]

Can you elaborate more on what you're using for the FM filters and tell me exactly what stations are causing overload? How far are these stations from your receive antenna? You seem to be doing rather well with DTV Es while I struggle.

I'm particularly curious because my situation sounds similar. I have broadcast stations of 12 kW and 16 kW with transmit towers 1.5 and 2.0 miles from my receive location, and trying to get a clean low-VHF band seems to be impossible (particularly on channel 6 due to local 88.1).

[WHJ]

I do not have excessive FM overload, but enough to limit things. I have two 100 kW FM stations about 14 miles away and a low power FM 8 miles away. 1.5 to 2 miles away your local FM signals should be beaming over your head (depending on the transmit antenna height and gain). It is the combined strength of all the signals going to your tuner and its filters which matters.

For comparison, I made field strength measurements on a channel 23 DTV station which use an antenna about 450' high. I made measurements along one azimuth radial. Starting close to the tower, its signal strength went up as went further from the tower. Only after I reached ten miles from the tower did the strength start going down with increased distance.

The chart shows the low band filters that I use. I fortunately have four different low band antennas. My channel 2 & 3 antenna uses a Mini-Circuits SCLF-65 filter:

As the graph shows, even 88.1 FM is down by 30 dB.

My channel 4 & 5 antenna uses a Mini-Circuits BPF-A69 filter:

By the time that you get to my first close 100 kW station's frequency (96.9 MHz), it's down 25 dB.

My channel 6 antenna uses a CirQTel FBT filter:

It's down a bit further on that first station.

[Crazy Monkey]

I do not have excessive FM overload, but enough to limit things. I have two 100 kW FM stations about 14 miles away and a low power FM 8 miles away. 1.5 to 2 miles away your local FM signals should be beaming over your head (depending on the transmit antenna height and gain). It is the combined strength of all the signals going to your tuner and its filters which matters.

For comparison, I made field strength measurements on a channel 23 DTV station which use an antenna about 450' high. I made measurements along one azimuth radial. Starting close to the tower, its signal strength went up as went further from the tower. Only after I reached ten miles from the tower did the strength start going down with increased distance.

Ok, thanks.

I've come across some graphs in the past which showed just how much power was reaching the ground at a certain angle beneath the tower, but I haven't been able to find these graphs for FM. From my understanding (and I was told), FM signals don't have this tight pattern like DTVs do. But maybe someone can provide actual graphs for this. It seems from my experience, the FMs here are far worse overload. But I do notice that filtering out the strong 1 to 2 mile DTV transmitters raises the signal quality of some of the weaker DTVs by 10 to 20%.

Here is an old example of what I'm referring to...

[WHJ]

The elevation lobe compression depends on the number of antenna bays (effectively dipoles) which are vertically stacked. It's best if those are one wavelength apart. That distance is the inverse of the frequency ratio. You show the elevation pattern of a 24-bay channel 49 (683 MHz) antenna. A 24-bay 97.5 MHz FM antenna would need to be seven times the size of your UHF example. That's not practical. FM antennas generally have a 12 or 14 bay maximum. Some elevation patterns of FM antennas are below:

Due to power licensing, a 4-bay antenna will require much greater transmitter output power than a 12-bay antenna for 100 kW ERP. Both will produce the same signal at the coverage extreme. The power bill will be much lower when the 12-bay antenna is used. However, everybody inside the coverage extreme will have a stronger signal with the 4-bay antenna.

Yes, filtering the stronger signals from FM and DTV signals can aid reception--that's part of the reason that I am using so many filters. Go to the following web page to see my recent 24-hour low VHF receptions: https://forums.wtfda.org/forum/wtfda...ot-frequencies