WWWB? WBNA Decades

[tripelo]

Hi Trip,

The equipment listed at RabbitEars for WWWB-LD, Clarkrange, TN seems a bit unusual:

1. Seems the same tower height (170' AGL) is to be transplanted to a higher ASL location.

2. The original (nondirectional) antenna is listed as 0.79 dB gain, however the replacement *directional* antenna (different manufacturer) is listed as exactly 0.79 dB gain.

It is possible that a directional and nondirectional antenna could have the exact same gain, but not likely.

3. The newer directional antenna is listed as a Kathrein HDCA-5.

If one looks at the specifications of a Scala HDCA-5 antenna; it is a Yagi type with more gain and a unidirectional pattern, whereas the new WWWB pattern is cardioid (heart shaped pattern).

Since the website doesnt like a link; search "HDCA-5_TV.pdf"

Any comments?

==============================

WBNA-8 Louisville was carrying 'Decades' on 21.5. This was personally viewed this back in
May/June.

 

[Trip]

Hi Trip,

The equipment listed at RabbitEars for WWWB-LD, Clarkrange, TN seems a bit unusual:

1. Seems the same tower height (170' AGL) is to be transplanted to a higher ASL location.

2. The original (nondirectional) antenna is listed as 0.79 dB gain, however the replacement *directional* antenna (different manufacturer) is listed as exactly 0.79 dB gain.

It is possible that a directional and nondirectional antenna could have the exact same gain, but not likely.

3. The newer directional antenna is listed as a Kathrein HDCA-5.

If one looks at the specifications of a Scala HDCA-5 antenna; it is a Yagi type with more gain and a unidirectional pattern, whereas the new WWWB pattern is cardioid (heart shaped pattern).

Since the website doesnt like a link; search "HDCA-5_TV.pdf"

Any comments?

1) This isn't entirely unreasonable. If both towers are of similar height, then that could be correct. In any case, it's the ASL height that's filed with the FCC and what is used for determinations on height. AGL is for informational purposes only.

2) That isn't antenna gain, it's total system gain. But more importantly, what you're seeing is a fluke in how LMS sends data back to CDBS. Check the original filing:

https://enterpriseefiling.fcc.gov/d...Key=25076f9155269a950155932fb34c7f23&goBack=N

You'll note there isn't even a field for TPO. LMS, for whatever reason, copies the value from the previous license's TPO into that field in CDBS. I've noticed it elsewhere, but getting things in LMS fixed can be a hassle, so I've avoided discussing that one and focused on bigger issues. That actually reminds me, there are some stations getting sent back to CDBS without coordinates and I need to see about those...

3) Could be an array of them. Here's the link:

https://www.kathreinusa.com/wp-content/uploads/2015/10/HDCA-5_TV.pdf

If they're using four or five of them in an array, that could certainly make a pattern like the one they've filed.

WBNA-8 Louisville was carrying 'Decades' on 21.5. This was personally viewed this back in
May/June.

Corrected. Thanks.

- Trip

 

[tripelo]

Thanks for your response.

.. That isn't antenna gain, it's total system gain...

Yes, and as you know, the antenna is what contributes positive gain, the other contributors are losses.

... Could be an array of them...

...If they're using four or five of them in an array, that could certainly make a pattern like the one they've filed.

True.

Coaxial cable, matching, and filter losses are usually the main losses to such a system. At channel 3 frequencies, these losses can be fairly low.

That HDCA-5 antenna is listed with a gain of 6.75 dB. An array to spread the energy in azimuth, as indicated by the WWWB pattern, could reduce the gain (depends on the number of units in the array and the method of stacking, horizontal and/or vertical).

So it is conceivable that system gain could be engineered to come up at exactly 0.79 dB.

Guess it may just be a question of why.

-------------------------------------------------

No worry, I realize you have many other things to think about.

Thanks again for your thoughtful response.

 

[Trip]

Guess it may just be a question of why.

Er, it's actually a site code issue, kind of. If the gain is not available in the database, but the TPO is, then the website code calculates the system gain. Since the gain is not available for that application, but the probably-erroneous TPO is and is the same as the old license, and the ERP is the same as the old license, the calculated gain is also the same.

- Trip

 

[tripelo]

... a site code issue... the calculated gain is also the same.

OK, yes, it's a bit clearer now.

You referred to that earlier, I didn't catch it then.

Thanks.