Hi-VHF+UHF Figure-8 Loop-in-Loop idea? - Canadian TV, Computing and Home Theatre Forums

 
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post #1 of 5 (permalink) Old 2019-05-22, 02:06 PM Thread Starter
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Hi-VHF+UHF Figure-8 Loop-in-Loop idea?

I've been perusing this forum for a while now and I'm guessing that my situation is pretty familiar. I have local stations that cover a broad swath of UHF, but I also have that *one* station still on VHF. I've tried a couple variations of GH, bow-tie, figure-8, and cubical quad with limited success across all channels. Not sure why, but I'm enamored of the loop antennas, and I'm currently using a ~23" dia 4-element cubical quad (actually loops, but electrically they're the same) which seems to work fairly well for both VHF and UHF. But I'd like the signal to be better on those troublesome days (high wind, rain). My antenna is in the attic, but windy days seem to mess with reception just as much as rain.

I've looked through holl_ands collection of antenna analyses and was about to build the 8-el bi-quad yagi, but it will . But then I started wondering what you would get by combining a VHF Figure-8 and UHF Bi-quad (which are both loop antenna variations), and then throw in two separate reflector layers. And maybe some yagi directors.

I guess I could try some of these on 4nec2 myself, but I'm a noob (and also on a mac).

Thanks,
jhelms
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post #2 of 5 (permalink) Old 2019-05-22, 06:09 PM
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In general, locating a UHF Antenna INSIDE a VHF Antenna doesn't work....it's just some randomly placed metal mucking up the works of BOTH Antennas.

A Jointly Optimized UHF/VHF Antenna is NOT EASY....but good luck....

FYI: CocoaNEC is the version that runs on MAC....and is primarily a SpreadSheet Driven Program:
cocoaNEC
Introduction [CocoaNEC can IMPORT & EXPORT 4nec2 Files]
https://hottconsultants.wordpress.co...re-for-the-mac
https://www.youtube.com/watch?v=EzAYu1zU9uw

MiniNEC is also available for the MAC:
MININEC Pro Antenna Analysis Software

PS: Although from time to time I have been "forced" to use various versions of someone else's Mac [like my son, the Mac GURU], I have NO experience with these programs....

PPS: There are also NEC2 versions that run under LINUX, such as described in this thread:
https://www.digitalhome.ca/forum/186...ftware-85.html

FYI: Depository for ALL NEC2 versions for PC, MAC & LINUX....NOT for newbies:
http://nec-archives.pa3kj.com

Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2019-05-22 at 06:24 PM.
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post #3 of 5 (permalink) Old 2019-05-22, 07:32 PM
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Quote:
Originally Posted by jhelms View Post
I have local stations that cover a broad swath of UHF, but I also have that *one* station still on VHF...... I'm enamored of the loop antennas, and I'm currently using a ~23" dia 4-element cubical quad which seems to work fairly well for both VHF and UHF. But I'd like the signal to be better on those troublesome days (high wind, rain). My antenna is in the attic, but windy days seem to mess with reception just as much as rain.
Hello, jhelms; welcome to the forum.

The attic location makes the signals weaker, and worse reception with wind and rain are a symptom of trees in the signal path.
Quote:
I started wondering what you would get by combining a VHF Figure-8 and UHF Bi-quad.....
A UHF antenna and a VHF antenna can be easily combined with a UVSJ (UHF-VHF Separator-Joiner), which is a low loss device.

It would help if you can post a TVFool signal report so that we can see what the signals look like at your location. Please let us know what channels are important to you, by callsign. You can do a report here:
TV Fool

*** WELCOME TO NEW MEMBERS: Read these OTA Forum instructions before posting ***
https://www.digitalhome.ca/forum/81-...%2A%2A%2A.html

If you can not measure it, you can not improve it.
Lord Kelvin, 1883

Last edited by rabbit73; 2019-05-22 at 09:44 PM.
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post #4 of 5 (permalink) Old 2019-05-23, 03:46 AM
 
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1. LPDA
2. VHF/UHF diplexer +
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post #5 of 5 (permalink) Old 2019-05-28, 09:37 PM
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Eznec isn't the be all end all to antenna design so the only REAL way to find out is build one.
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