Any info on the LPDA wide band balun ? - Canadian TV, Computing and Home Theatre Forums

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post #1 of 8 (permalink) Old 2018-02-10, 01:37 AM Thread Starter
 
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Question Any info on the LPDA wide band balun ?

Does anyone have any links to information on the LPDA wide band balun.
And how would it be calculated ?
Can we home brew it ?
Wondering if it's calulated the same way as the LPDA antenna .
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post #2 of 8 (permalink) Old 2018-02-10, 03:37 AM
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How "Wide Band" of a 1:1 Balun are you looking for????

I haven't seen anything, but I DID find fol. via Google Search for "wideband lpda balun":
https://www.google.com/search?q=wide...nt=firefox-b-1

Research Gate Articles only require FREE Website Registration, so start there.

IEEE Article Download MAY require fairly expensive IEEE Membership and Current Subscriptions to each Journal you want to see OLD Articles in [If I remember that correctly....]. [Reminds me....I need to renew my "Senior Discount" Membership....and somehow make room for storing more Hardcopy Journals.]

OR w/o IEEE membership, you can simply spend $$$'s to download MOST individual articles....or make a copy at a well equipped (i.e. University) Library. But I nearly always have problems locating Articles in "Conference Proceedings".

BTW: Sometimes, you can find a FREE Download by searching by Author & Title....esp. if you find their HOME Website [frequently a University]....

I looked at the extended summary for Mirzapour's IEEE Article....the "Balun" is described as a "mode converter balun" [Google it], which is more commonly implemented as the well known [and easy to implement in Substrate for SHF] "TAPERED TRANSMISSION LINE" that transistions from one impedance to another (so, what about Balanced to Unbalanced?):
Radio Antenna Engineering - Tapered Transmission-line
https://www.google.com/url?sa=t&rct=...96NpaFSVsNRlqB

BTW: I used a LINEAR TAPERED TRANSMISSION LINE [aka "Triangular", rather than the more "accurate" (i.e. Idealized) Exponential Taper] in the fol. Hi-VHF Zig-Zag LPDA (with Center Booms)....note the unusually LONG pair of wires at the FRONT that were tweaked until SWR was acceptable [this was before nikiml's Optimizer]:
https://imageevent.com/holl_ands/zig...igzagboomwedge

PS: I ACTUALLY implemented and unsuccessfully tried to squeeze the WAY TOO BIG Hi-VHF Zig-Zag LPDA (NO BOOM, both Stacked and Wedge versions) into my son's Attic, trying to NULL OUT nearby Ch12. NO Boom version did NOT require the Tapered Transmission Line:
https://imageevent.com/holl_ands/zigzaglpa/zigzagnoboom

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

Last edited by holl_ands; 2018-02-10 at 04:00 AM.
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post #3 of 8 (permalink) Old 2018-02-10, 04:10 AM
 
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The simplest, used by numerous manufacturers of UHF TV antenna - is to design 75 Ohm LPDA and lay coax cable through boom (inside). Coax shield is connected to this boom at both ends.
To match arbitrary impedance to 50 or 75 Ohm - military designs used tapered coaxial transformator inside boom. That's expensive design, not for TV.

Toroid balun with bifilar wiring (non-bifilar wiring work poor >50 MHz) are 2:1 and 4:1. 2:1 can be used with LPDA designed for 150 Ohm impedance.
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post #4 of 8 (permalink) Old 2018-02-10, 05:41 PM Thread Starter
 
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I just found the LPDA antenna a very good antenna , and want to test building a LPDA balun design on 9.5 X 9 bow tie antenna .

I have located the calcutions now.

And will be testing using bow tie or GH
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post #5 of 8 (permalink) Old 2018-02-10, 07:34 PM
 
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What impedance of antenna itself do you plan? 75, 150 or 300 Ohm?
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post #6 of 8 (permalink) Old 2018-02-10, 09:24 PM Thread Starter
 
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post #7 of 8 (permalink) Old 2018-02-10, 09:26 PM Thread Starter
 
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Holl_ands and Yurii may I send you a pm with a link to some info ?
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post #8 of 8 (permalink) Old 2018-02-10, 11:02 PM Thread Starter
 
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First UHF test. Was not to bad for ruff mock up
Made for 585 MHz
First test with the balun in H
Test sweep on my hisense tv meter signal strength .
All stations from 482mhz to 628 MHz were coming in at 29 % to 40 %
Second test with balun in V
All stations from 482mhz to 628 MHz improved 40% to 53 %

Next test is to reverse the baluns 3 connection pionts
Wife just loves me lmao
Test antenna mockup of a 4 bay bow tie
11 inch whiskers. With 11 inch spacing . Phase lines spaced 1 1/2 inches. Spread of whiskers 5.5 inches
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