[thomasr]

Looking to build a unidirectional antenna to receive WBBZ channel 7 from about 150km away. I know this is fringe, but I've got good line-of-sight in that direction, and I'm successfully pulling in several UHF channels from these distances already.

I want to isolate channel 7, and the steeper the rolloff on either side of 177mhz the better IMO as I don't want this antenna "polluting" the other channels.

I'm having a surprisingly hard time finding the design and formulas I need to make this DIY happen.

edit: whatever the design of the antenna, does it matter much if it's oriented horizontally or vertically? Are the transmitter signals polarized?

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[BOUVAL]

Simply Google this: yagi antenna design channel 7
.

 

[rabbit73]

Looking to build a unidirectional antenna to receive WBBZ channel 7 from about 150km away. I know this is fringe, but I've got good line-of-sight in that direction, and I'm successfully pulling in several UHF channels from these distances already.

Hello, thomasr.

That will be difficult. Here is your report from a previous thread:
RabbitEars.Info

I want to isolate channel 7, and the steeper the rolloff on either side of 177mhz the better IMO as I don't want this antenna "polluting" the other channels.

A Yagi has a much narrower bandwidth than a bowtie antenna, especially if it has been designed for a single channel. If you need it narrower than that, you would have to add a single channel bandpass filter for channel 7, like an interdigital bandpass filter which would have a small insertion loss for channel 7.

I'm having a surprisingly hard time finding the design and formulas I need to make this DIY happen.

Here is a design I found on Google as suggested by BOUVAL:
thread:
Design for a channel 7 yagi for -14NM (dB)
post with link:
Design for a channel 7 yagi for -14NM (dB)
design:
A 12 element long yagi for WWNY Channel 7

edit: whatever the design of the antenna, does it matter much if it's oriented horizontally or vertically? Are the transmitter signals polarized?

Yes, it matters; WBBZ is using a transmitting antenna with circular polarization, so your receiving antenna can have either horizontal or vertical polarization. However, I suggest you try both as a test. I think horizontal polarization would be better because it would tend to reject ambient electrical noise interference that has primarily vertical polarization.
RabbitEars.Info

 

[ExDilbert]

I want to isolate channel 7, and the steeper the rolloff on either side of 177mhz the better IMO as I don't want this antenna "polluting" the other channels.

Use a UVSJ to combine VHF and UHF antennas.

 

[thomasr]

Thanks rabbit, that's helpful. Based on the design you posted it looks like the boom is five meters long! As cool as it would be to put something like that on the roof, my wife would shoot me.

I can live without WBBZ.

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[ExDilbert]

A yagi is the best bet for VHF. They can be anywhere from 2 to 12 elements (or more.) A 6 element yagi will be about half the length of the 12 but would not perform as well. They can also be stacked easily. There are some threads on yagi antennas on this forum. Even though UHF stations are receivable it does not mean that VHF will be. That's due to lower power for VHF transmitters and higher local noise levels. Distant VHF stations are also more susceptible to tropo interference than UHF.

 

[rabbit73]

.....it looks like the boom is five meters long! As cool as it would be to put something like that on the roof, my wife would shoot me.I can live without WBBZ.

Just remove some directors from the front.

This is shorter, but has less gain than an antenna of the same length designed for 7; it's for 7-13:
https://www.newark.com/stellar-labs/30-2476/deep-fringe-directional-antenna/dp/71Y5462#

You are well outside the area of coverage:

and the signal path is difficult, but not impossible:

using different terrain profile software for the same signal path:

 

[audioguy_on_ca]

I’m not that far from WBBZ or CTV and have recently found a significant length of 300-ohm twin lead in a wall I had to run some UTP cable through to get internet to where it wasn’t. Kaching! Now if I can only find that post on how to make custom-tuned VHF antennæ using 300-ohm twin lead, I’ll be golden!


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[rob50312]

WBBZ reception will be hopeless in Markam.WBBZ has only 66 metre relay tower vs WKBW with 433 metres from same area.2 edge VHF signal in a city is hopeless.

 

[audioguy_on_ca]

Lucky for me, I’m basically equidistant from the 2 of them...30 miles across the lake, 30 miles to Buffalo...


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