It seems that padding the element capacitance as needed for equal capacitance would help.
Dave KH6AQ On Thu, Mar 30, 2023 at 4:48 PM Frank W3LPL <donov...@starpower.net> wrote: > 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" <davek...@gmail.com> > To: "Frank W3LPL" <donov...@starpower.net> > Cc: "topband" <Topband@contesting.com>, "PVRC" <p...@mailman.qth.net>, > "Pete N4ZR N4ZR" <pete.n...@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: > donov...@starpower.net | donov...@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.n...@gmail.com | > pete.n...@gmail.com ] > > To: "topband" < [ mailto:Topband@contesting.com | Topband@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 > _________________ > Searchable Archives: [ http://www.contesting.com/_topband | > http://www.contesting.com/_topband ] - Topband Reflector > ______________________________________________________________ > PVRC mailing list > Home: [ http://mailman.qth.net/mailman/listinfo/pvrc | > http://mailman.qth.net/mailman/listinfo/pvrc ] > Help: [ http://mailman.qth.net/mmfaq.htm | > http://mailman.qth.net/mmfaq.htm ] > Post: mailto: [ mailto:p...@mailman.qth.net | p...@mailman.qth.net ] > Message delivered to [ mailto:davek...@gmail.com | davek...@gmail.com ] > > This list hosted by: [ http://www.qsl.net/ | http://www.qsl.net ] > Please help support this email list: [ http://www.qsl.net/donate.html | > http://www.qsl.net/donate.html ] > > > > _________________ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _________________ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector