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Looking for antenna advice

The technical side of broadcasting. Think IBOC is a sham? Talk about it here! How about HDTV? Post DX reports here as well.
n8fnr
Posts: 2
Joined: Sat Jan 26, 2019 11:38 am

Looking for antenna advice

Post by n8fnr » Wed Jan 30, 2019 7:01 am

I live in Royal Oak just north of Detroit and am looking for some antenna advice. I want to put up a fixed antenna mainly to get CBET CH 9 and CICO CH3 2. Both are 27 miles away at 157 degrees and are 27 dB NM. Also want to get WDIV CH 45 (3.4 miles away, 76 dB NM), WTVS CH 43 (4.8 miles 72dB NM), WWJ CH 41 (4.8 miles 71 dB NM; I think that this is wrong and it is further away BTW) and WXYZ CH 41 (5.7 miles 70dB NM). All of these are between 191 and 237 degrees. These are the only channels I am interested in and would like to avoid putting up a rotor or using a preamp.

Do you think that a fixed 4 bay bowtie antenna at 20 feet would be enough to get 9 and 32? Are the other channels strong enough that I would get good reception off of the side lobes? Or do you think that I need an 8 bay bowtie?

I am only running this to one TV and will not be putting a splitter on it.

We have a lot of trees in the direction of CH 9 and 32.

If you want to see the Antenna Fool chart go to https://www.tvfool.com/index.php?option ... &Itemid=29 and put in Zipcode 48073.

Any advice on this will be greatly appreciated.

Zack
N8FNR



Arthur Mometer
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Location: Radar Room

Re: Looking for antenna advice

Post by Arthur Mometer » Wed Jan 30, 2019 9:12 am

If you can find one with a full half wave VHF High Element, maybe. I wouldn't count on CBET 9 coming in on a 4 Bay UHF Bow Tie. I think they are on low power now. They were coming in well for a while, now barely at the edge of the cliff and pixelated and off the cliff. That's with a VHF 7 element V log pointed at physical 7/PSIP 2 in the attic.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

innate-in-you
Posts: 205
Joined: Wed Oct 31, 2018 8:54 am

Re: Looking for antenna advice

Post by innate-in-you » Wed Jan 30, 2019 9:27 am

Agree with Arthur that the bowtie won't work well for CBET. A Hoveman type bowtie would have negative gain, and a traditional four bay would fail miserably (the top and bottom elements are fed out-of-phase, but actually work on UHF because the signal travelling on the vertical wires compensate for the phase inversion - on channel 9 there will be less phase shift and the upper and lower elements will partially cancel out the center elements).

Get a small all-channel antenna or High-VHF/UHF antenna and aim it at 157°, then fashion a 6" wire attached to an element at the feedpoint, parallel with the boom, only bent upward or downward about 30°, so it wouldn't be too close to the boom* (it will add the Detroit stations, which are so strong in Royal Oak that they'll decode).

*if the antenna has a built-in balun, use a combiner (splitter in reverse) and put a 6" whip in it.



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craig11152
Posts: 1582
Joined: Tue Nov 06, 2007 8:15 am
Location: Ann Arbor

Re: Looking for antenna advice

Post by craig11152 » Wed Jan 30, 2019 9:58 am

I will leave the technical stuff to the experts.
But when I put up my very modest $30 antenna I already had a tripod on my roof. Since the antenna didn't include a mast I used electrical conduit to raise it another 10 feet at a very reasonable price.


testing...testing...1...2...3...4

n8fnr
Posts: 2
Joined: Sat Jan 26, 2019 11:38 am

Re: Looking for antenna advice

Post by n8fnr » Wed Jan 30, 2019 2:11 pm

Thanks all for the info!

Zack
N8FNR



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ZenithCKLW
Posts: 481
Joined: Sat Nov 13, 2004 11:21 am
Location: Livonia, MI
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Re: Looking for antenna advice

Post by ZenithCKLW » Wed Jan 30, 2019 2:25 pm

I live in Livonia and I typically have lots of TV reception issues. I have one of those flat RCA "HDTV" antenna squares. It worked like crap when I used it as directed (sitting upright on the table), but when I laid it down flat, I receive much more stations like WADl, CBET, CICO, WHNE.



Arthur Mometer
Posts: 742
Joined: Wed Oct 22, 2008 9:52 am
Location: Radar Room

Re: Looking for antenna advice

Post by Arthur Mometer » Wed Jan 30, 2019 6:01 pm

I wonder if it would be possible to just hook up a VHF High folded dipole to a 4 Bay UHF Bow Tie without a combiner without compromising performance. Or maybe just a VHF UHF Splitter/Combiner, that would work for certain. It would have to be a 300 ohm VHF/UHF splitter/combiner.

You do want to get any antenna away from the set to avoid interference.

Another thing, if you have a splitter and aren't using one or more of the outputs, try using terminating resistors.
Last edited by Arthur Mometer on Wed Jan 30, 2019 7:38 pm, edited 2 times in total.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

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ZenithCKLW
Posts: 481
Joined: Sat Nov 13, 2004 11:21 am
Location: Livonia, MI
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Re: Looking for antenna advice

Post by ZenithCKLW » Wed Jan 30, 2019 6:05 pm

Is it true that 75 ohm coax splitters degrade over time?



Arthur Mometer
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Joined: Wed Oct 22, 2008 9:52 am
Location: Radar Room

Re: Looking for antenna advice

Post by Arthur Mometer » Wed Jan 30, 2019 6:41 pm

If you remove corrosion from the terminals, they should be OK. I guess technically the capacitors could go bad, but they are not electrolytics, so it is not likely to be that bad. Some kind of ceramic dielectric I think.

Talk about every video under the sun. Here's a video of a guy blowing up ceramic capacitors.

https://www.youtube.com/watch?v=7V9g8w_8gbY

I guess that could happen with static discharge or lightning.


"I'm meteorologist Arthur Mometer."

"Those of you who think you know everything are very annoying to those of us who do."

"Lies have to be repeated and repeated to be believed. Truth stands on its own merit."

djb
Posts: 7
Joined: Tue Feb 15, 2005 11:20 am

Re: Looking for antenna advice

Post by djb » Thu Jan 31, 2019 6:03 am

This...

http://bobbyromeo.com/wp/wp-content/upl ... 00x242.png

I've built many home-brew antennas in the past for DTV; and this one (for me) has been the easiest and most effective. I did the 4-bay bowtie previously, and while it worked well on a calm day; a bit of wind would cause digital artifacts and dropouts of local channels. (Think the beamwidth is quite narrow on a 4-bay bow array).

I'm in the Bay City area, and have this design up in a tree alongside the house; about 15-20ft off the ground. I can easily pick up all of the locals, and occasionally channel 9 from Cadillac on VHF, channel 14 from Mt. Pleasant, and the LP station out in west Midland county.



Mike Oxlong
Posts: 104
Joined: Wed Jan 09, 2019 11:56 am
Location: Nankin Township

Re: Looking for antenna advice

Post by Mike Oxlong » Thu Jan 31, 2019 1:17 pm

So where's the feedpoint, and what's the orientation?



djb
Posts: 7
Joined: Tue Feb 15, 2005 11:20 am

Re: Looking for antenna advice

Post by djb » Sun Feb 03, 2019 8:45 am

Apologies; here's the main link:
http://bobbyromeo.com/diy/make-your-own ... v-antenna/

Feedpoint is at the first bend from the bottom, where the distance between is 2"; you connect a 75/300ohm balun there.

I have the "face" of mine pointing south (so, if looking at the pic, the left side element is west, the right side element is east (if that makes any sense)), though it seems pretty omnidirectional in nature.



Mike Oxlong
Posts: 104
Joined: Wed Jan 09, 2019 11:56 am
Location: Nankin Township

Re: Looking for antenna advice

Post by Mike Oxlong » Mon Feb 04, 2019 9:32 am

djb wrote:
Sun Feb 03, 2019 8:45 am
Apologies; here's the main link:
http://bobbyromeo.com/diy/make-your-own ... v-antenna/

Feedpoint is at the first bend from the bottom, where the distance between is 2"; you connect a 75/300ohm balun there.

I have the "face" of mine pointing south (so, if looking at the pic, the left side element is west, the right side element is east (if that makes any sense)), though it seems pretty omnidirectional in nature.
Thanks. Looks like this is meant to be a vertical antenna. Have you ever tried it horizontal?



jimh
Posts: 2
Joined: Thu Sep 22, 2011 12:02 am

Re: Looking for antenna advice

Post by jimh » Mon Feb 04, 2019 5:12 pm

To receive CICO 32 in Royal Oak on a modest UHF antenna will be no problem. They have a very good signal. I am located in the 14-Mile and Greenfield area. I get great reception of CICO 32 on a small UHF-only Yagi with a rear element corner reflector, mounted on a 1-storey garage on a 2-foot tripod. CICO is very consistent and usually has 24 dB or better SNR, well above threshold of reception (which is about 16 db SNR).

The only problem could be some shadowing from tall buildings in downtown Detroit and Windsor, as the path to their tower from the general Royal Oak area goes right through downtown Detroit. Use GOOGLE EARTH to visualize the path.

On the other hand, I will be surprised if CBET 9 shows up very well on a dipole. They are on VHF Channel 9, on the same tower as CICO, but their signal is not as good. At best it lags CICO by a couple dB, and at worst it drops below threshold of reception. That is using a 9-element Hi-VHF Yagi with some filtering to knock out Ch-7 WJBK.

Here is a view of the antennas. The three-element VHF vertically-polarized Yagi was for the VHF Marine Band, but it is not there now:

http://continuouswave.com/whaler/refere ... 31x612.jpg

A concern in receiving CBET on VHF-9 is the presence of WJBK FOX-2 on VHF-7. They will have an enormous signal compared to CBET. Your tuner might not be able to cope with the close-by signal strength on 7 while tuned to 9.

According to the predictive coverage from the website mentioned in the first post, the expected signal levels will be:
CBET = -52 dBm
WJBK = -25 dBm

This gives WJBK a 27 dB advantage--a power ratio of about 500:1. Your TV tuner will need to be up to the task.

de K8SS



djb
Posts: 7
Joined: Tue Feb 15, 2005 11:20 am

Re: Looking for antenna advice

Post by djb » Wed Feb 06, 2019 8:28 am

Mike Oxlong wrote:
Mon Feb 04, 2019 9:32 am

Thanks. Looks like this is meant to be a vertical antenna. Have you ever tried it horizontal?
I've not.



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