From: Rick Wakatori <7l1rll@dp.u-netsurf.ne.jp>
To: rsgb_lf_group@blacksheep.org
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Organization: RLL
Date: Thu, 12 Aug 2010 21:26:56 +0900
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Subject: Re: LF: Earth antenna
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HI Tony,
  I will try to change my simple question now.
Did you connect two wires and two earth rods [here after electrodes]
such one electrode to antenna terminal and one electrode for receiver
earth terminal ?  
  Was it 80 meter between two earth rods ?
7L1RLL Rick

On Thu, 2010-08-12 at 12:40 +0100, Tony wrote:
> Hi Rik and Rik,
> 
> Sorry, I too got confused by two Riks, should have looked at the callsigns.
> 
> OK, my set up when I did the signal strength tests were, station earth 
> (mat and radials) for both tests plus first an inverted L, followed by 
> an 80 metre length of wire, mostly laying on the ground but also over 
> small bushes no higher than 1 metre, terminated at the far end directly 
> to an earth stake.
> 
> Thanks for the explanation (other) Rik on Beverages, as my wire is 80m 
> long and doesn't work at all well on 40m band, it seems something else 
> is happening. This weekend I will try to repeat the tests being a bit 
> more technical, for instance comparing the two when connected through my 
> ATU on 160m, 80m & 40m.
> 
> 73, Tony, EI8JK.
> 
> 
> On 12/08/2010 11:38, Rick Wakatori wrote:
> > HI Rik and Tony,
> >    It was no problem.
> > I am simply confusing whether two electrodes (earth )antenna or one
> > electrode as AC line antenna was experimeted.
> > 7L1RLL Rick
> >
> > On Thu, 2010-08-12 at 12:09 +0200, Rik Strobbe wrote:
> >> Tony, Rick,
> >>
> >> oops, it seems I responded to the wrong mail.
> >> My appologies for that, but I got confused by two Ri(c)k's on the reflector.
> >>
> >> 73, Rik  ON7YD - OR7T
> >>
> >> ________________________________________
> >> Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Rik Strobbe [Rik.Strobbe@fys.kuleuven.be]
> >> Verzonden: donderdag 12 augustus 2010 12:02
> >> Aan: rsgb_lf_group@blacksheep.org
> >> Onderwerp: RE: LF: Earth antenna
> >>
> >> Tony,
> >>
> >> my remarks were not meant as critisism, just as a "warning" that the measured values should be interpreted with caution.
> >> About beverages:
> >> Typical length is 1 to 2 lambda, it seems that directivity is optimal at these lenghts.
> >> Short beverages (<<  1 lambda) loose directivity (and directivity is the main reason beverages are used).
> >> Most beverages are terminated at the far end to make the pattern unidirectional, but this is no must (leaving out the termination will get you a bidirectional pattern).
> >> So at first sight the 2 main difference between a earth antenna and beverage is:
> >> - beverage is>= lambda, earth antenna<<<  lambda
> >> - beverage is terminated to ground at the far end (resistor to ground), earth antenna is just connected to ground at the far end
> >>
> >> 73, Rik  ON7YD - OR7T
> >>
> >> ________________________________________
> >> Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Tony [ei8jk@o2.ie]
> >> Verzonden: donderdag 12 augustus 2010 11:30
> >> Aan: rsgb_lf_group@blacksheep.org
> >> Onderwerp: Re: LF: Earth antenna
> >>
> >>    Hi Rik.
> >>
> >> I take your point, but I did say that it was "non-technical"
> >> The earth was the main station earth which is a short (1.5m) length of
> >> 22mm copper pipe to an earth mat and radials and was the same earth used
> >> for both antennas.
> >> The receiver was AC powered but there was no trace of a signal at all
> >> between connecting the different antenna wires
> >>
> >> But a question for the techs, when does a long "earth" antenna become a
> >> Beverage antenna ?
> >> Or, how short can a Beverage antenna be before it ceases to be any
> >> practical use ?
> >>
> >> 73, Tony, EI8JK
> >>
> >>
> >> On 12/08/2010 01:34, Rick Wakatori wrote:
> >>> Hello Tony,
> >>>     Show us your RX earth terminal side and whether AC voltage supply or
> >>> DC battery did you use for the experiment. AC line can be a good long
> >>> antenna for receiving.
> >>> 7L1RLL Rick
> >>>
> >>> On Wed, 2010-08-11 at 16:16 +0200, Rik Strobbe wrote:
> >>>> Hello Tony,
> >>>>
> >>>> measuring voltages on untuned antennas is "tricky", in particular with
> >>>> small electrical antennas (compared to the wavelength) as these tend
> >>>> to have large reactive components.
> >>>> On 60kHz the L-antenna you described has a reactive component of about
> >>>> 10000 Ohm while the resistive part will be some 10's to some 100's Ohm
> >>>> (mostly loss resistance). So properly tuning the antenna will increase
> >>>> the RX voltage by several S-points.
> >>>> Ground loop antennas on the other hand seem more broadband.
> >>>> Maybe that explains why they perform better at lower frequencies
> >>>> ( compared to the untuned L-antenna).
> >>>>
> >>>> Anyway, your L-antenna should perform well on 500kHz.
> >>>>
> >>>> 73, Rik  ON7YD
> >>>>
> >>>>
> >>>> ______________________________________________________________________
> >>>> Van: owner-rsgb_lf_group@blacksheep.org
> >>>> [owner-rsgb_lf_group@blacksheep.org] namens Tony [ei8jk@o2.ie]
> >>>> Verzonden: woensdag 11 augustus 2010 14:05
> >>>> Aan: rsgb_lf_group@blacksheep.org
> >>>> Onderwerp: Re: LF: Earth antenna
> >>>>
> >>>>
> >>>>
> >>>> Hi Roger.
> >>>>
> >>>> The soil here is well drained peaty topsoil about 400mm - 500mm deep
> >>>> on a mixture of slate and shale and although I am 500m from the sea, I
> >>>> am 75m above the water.
> >>>> I have no idea what the electrical conductivity is but I imagine it's
> >>>> probably lower in the winter when my windows get a covering of salt
> >>>> during storms. It would be interesting to pick on one reliable ground
> >>>> wave transmission and monitor it through various weather conditions.
> >>>> It would also be interesting to see how it works lower in frequency
> >>>> (sub 50 KHz), which is something that I will definitely look into.
> >>>>
> >>>> 73,
> >>>> Tony, EI8JK
> >>>>
> >>>>
> >>>> On 11/08/2010 11:32, Roger Lapthorn wrote:
> >>>>> Thanks for this Tony.
> >>>>>
> >>>>> Do you know what sort of soil/rock you have beneath you there? Here
> >>>>> I am on relatively low conductivity chalk/clunch with clay a few
> >>>>> miles to the north west under fenland peat.
> >>>>>
> >>>>> If the earth electrode antenna is behaving as a loop (a debated
> >>>>> theory) then it is most effective is the "loop in the ground" is as
> >>>>> large as possible, which would be the case with low conductivity
> >>>>> soil/rocks underneath: the return path between electrodes would be
> >>>>> forced to take a longer route deeper into the ground. If the soil
> >>>>> between the electrodes has good conductivity then the return current
> >>>>> would flow directly making the effective loop size small.
> >>>>>
> >>>>> In the last few days we've had a lot of rain here and the results on
> >>>>> 500kHz last night with the earth electrode antenna suggest the rain
> >>>>> made little difference to performance with reception several times
> >>>>> by PA0A. This is counter-intuitive to me, as I would have expected
> >>>>> levels to be weaker if the soil was wet (loop formed being smaller
> >>>>> etc.). Of course it could have been that the contact resistance of
> >>>>> the earth probes was lower and overall the two effects cancelled?
> >>>>>
> >>>>> Whatever the theory says, the earth electrode "antenna" has some
> >>>>> mileage especially when, like me, there is little space for large
> >>>>> "in the air" antennas. Sure, a big vertical or large loop in the air
> >>>>> would be better (I think), but this is about experimenting and
> >>>>> discovering the limits of possibilities.
> >>>>>
> >>>>> Good luck and keep everyone posted if you do further tests.
> >>>>>
> >>>>> 73s
> >>>>> Roger G3XBM
> >>>>>
> >>>>>
> >>>>>
> >>>>> On 11 August 2010 10:34, Tony<ei8jk@o2.ie>   wrote:
> >>>>>            I have finally found the time to get some (radio) work done
> >>>>>           here and got my 2nd tower finished and I erected an inverted
> >>>>>           L, 10m vertical and 30m top rising to 15m at the far end. I
> >>>>>           still have the "earth antenna" which is just a length of
> >>>>>           wire laying on the ground 80m long and terminated directly
> >>>>>           to an earth stake and laying roughly in the same direction
> >>>>>           as the top wire of the L .
> >>>>>           Comparing the two gave some very interesting results.
> >>>>>
> >>>>>           10 MHz  CW                L = S7    earth = S1
> >>>>>           7 MHz CW                    L = S9    earth = S3
> >>>>>           R. Bristol 1566 KHz    L = 0    earth = S2
> >>>>>           Donebach 153 KHz    L = S6    earth = S8
> >>>>>           DCF77 77.5 KHz        L = S3    earth = S5
> >>>>>           MSF 60 KHz                L = S4    earth = S8
> >>>>>
> >>>>>           All very non-technical I know, neither antenna was matched
> >>>>>           or tuned in any way and was all done about 13:00z.
> >>>>>           There was no noticeable difference in the noise level but
> >>>>>           when I tried it before the earth antenna was very much
> >>>>>           quieter after dark. I will try and repeat this tonight and
> >>>>>           see what the difference is then.
> >>>>>
> >>>>>           Tony, EI8JK.
> >>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>> --
> >>>>> http://g3xbm-qrp.blogspot.com/
> >>>>> http://www.g3xbm.co.uk
> >>>>> http://www.youtube.com/user/g3xbm
> >>>>> G3XBM   GQRP 1678    ISWL G11088
> >>>
> >
> >
> 
>