Topband: [PVRC] 2-element receiving arrays

[Frank W3LPL]

Hi Dave, 

Anyone who has experimented with a high impedance antenna such 
as an end fed half wave has experienced the extreme environmental 
influence on the feedpoint impedance of a high impedance feed. 

The required spacing to trees and buildings is very difficult to predict 
with any confidence. The impedance of a high impedance element 
-- and hence the amount of voltag if feeds into the preamp -- 
is heavily influenced by its immediate environment. 

If all of the high impedance verticals in an array do not produce the 
same voltages from the signals received by the array, the pattern 
of the array and especially its nulls are significantly degraded. 

73 
Frank 
W3LPL 







From: "K3ZJ David Siddall" <davek3zj at gmail.com> 
To: "Frank W3LPL" <donovanf at starpower.net> 
Cc: "topband" <Topband at contesting.com>, "PVRC" <pvrc at mailman.qth.net>, "Pete N4ZR N4ZR" <pete.n4zr at gmail.com> 
Sent: Friday, March 31, 2023 12:34:28 AM 
Subject: Re: [PVRC] Topband: 2-element receiving arrays 

Frank, 
" wrt to-negative effects of nearby trees and buildings." for high impedance verticals: 

Is there any data measuring how much loss if placed in the woods? Minimum distance from a tree to minimize the loss? Are their other effects too, such as less directionality? 

73, Dave K3ZJ 



On Thu, Mar 30, 2023 at 1:38 PM Frank W3LPL < [ mailto:donovanf at starpower.net | donovanf at starpower.net ] > wrote: 


Hi Pete, 

For a monoband receiving array, you might consider using low impedance 
resonant verticals rather than high impedance verticals. 

The primary advantages of high impedance verticals are 
- very short verticals (but taller verticals produce stronger signals) 
- multi-band operation 
- no radials 

The primary disadvantages are 
- reliability issues with outdoor electronics 
- lightning susceptibility of outdoor electronics 
- higher cost 
- much lower signal levels 
- extreme care required to suppress common mode signals (buried feedlines are highly recommended) 
- negative effects of nearby trees and buildings. 

The primary advantages of low impedance verticals are 
- much stronger signal levels 
- much less criticality of common mode signal suppression, 
- much lower cost 
- much higher reliability 
- immunity to lightning damage 
- much less affected by nearby trees and buildings 

The primary disadvantages are 
- taller verticals (typically about 24 feet) 
- radials (they can be very short if many radials are used) 
- mono band operation (switchable matching networks can be used for multi-band operation). 

I highly recommend the DX Engineering Receiving Antenna Phasing System. 
Its expensive but well worth the investment especially for a small array. 

[ https://www.dxengineering.com/parts/dxe-ncc-2 | https://www.dxengineering.com/parts/dxe-ncc-2 ] 

If you have 120 feet for a three element array, the YCCC array is a great choice 
It can use high impedance or low impedance verticals 
Unfortunately its no longer available from DX Engineering 
The nine element YCCC array uses only three active elements at any time, 
so its really a three element array switchable in many directions. 

[ https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf?_gl=1*1cv0fc9*_ga*MjEyMDA1Nzc3MS4xNjUyMzAyMjc0*_ga_NZB590FMHY*MTY4MDE5NTk1OC40My4xLjE2ODAxOTYwNTYuNTAuMC4w | https://static.dxengineering.com/global/images/instructions/dxe-yccc-switch.pdf?_gl=1*1cv0fc9*_ga*MjEyMDA1Nzc3MS4xNjUyMzAyMjc0*_ga_NZB590FMHY*MTY4MDE5NTk1OC40My4xLjE2ODAxOTYwNTYuNTAuMC4w ] 

[ https://www.youtube.com/watch?v=dl-crM5Kb6A | https://www.youtube.com/watch?v=dl-crM5Kb6A ] 

[ https://www.youtube.com/watch?v=lVW1CmrzP7c | https://www.youtube.com/watch?v=lVW1CmrzP7c ] 

A two element array occupies only 60 feet or even a little less. 

73 
Frank 
W3LPL 


----- Original Message ----- 
From: "Pete N4ZR N4ZR" < [ mailto:pete.n4zr at gmail.com | pete.n4zr at gmail.com ] > 
To: "topband" < [ mailto:Topband at contesting.com | Topband at contesting.com ] > 
Sent: Thursday, March 30, 2023 12:54:30 PM 
Subject: Topband: 2-element receiving arrays 

Thinking ahead to next winter on 160, I'm interested in replacing my 
K9AY Loop with a 2-vertical phased array. I'd like to homebrew the 
antennas and just buy or build the remote control unit for the shack. 
I'm looking for sources of components (antenna-located preamps and an 
in-shack controller), and would prefer not to completely homebrew them, 
but the prices at the usual suspects are awfully high. Any ideas? 

I have pretty reasonably-priced access to 25 and 31-foot fiberglass 
poles (used for wind-socks by model airplane enthusiasts). I'm thinking 
that one relatively low-cost approach might be to attach, say, #14 wire 
to the poles, with preamps at the base, but wonder if there is a 
downside to using such small-diameter antenna elements rather than 1 or 
1.5 inch tubing? Alternatively, are clones of the DX Engineering 8' 
short verticals with preamps a good alternative? 

-- 
73, Pete N4ZR 
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