Return-Path: Received: from mtain-dh08.r1000.mx.aol.com (mtain-dh08.r1000.mx.aol.com [172.29.65.28]) by air-dd01.mail.aol.com (v129.4) with ESMTP id MAILINDD013-86574c63f940d1; Thu, 12 Aug 2010 09:38:08 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dh08.r1000.mx.aol.com (Internet Inbound) with ESMTP id 8073A38000105; Thu, 12 Aug 2010 09:38:06 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OjXy6-0007hI-6U for rs_out_1@blacksheep.org; Thu, 12 Aug 2010 14:37:14 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OjXy5-0007h9-J8 for rsgb_lf_group@blacksheep.org; Thu, 12 Aug 2010 14:37:13 +0100 Received: from relay01a.mail.uk1.eechost.net ([217.69.40.75] helo=relay03.mail.uk1.eechost.net) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OjXy4-0000lx-O7 for rsgb_lf_group@blacksheep.org; Thu, 12 Aug 2010 14:37:13 +0100 Received: from [88.151.27.235] (helo=[192.168.1.107]) by relay03.mail.uk1.eechost.net with esmtpa (Exim 4.68) (envelope-from ) id 1OjXxq-0005UB-Al for rsgb_lf_group@blacksheep.org; Thu, 12 Aug 2010 14:36:59 +0100 Message-ID: <4C63F8FB.6090801@o2.ie> Date: Thu, 12 Aug 2010 14:36:59 +0100 From: Tony User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.2.8) Gecko/20100802 Thunderbird/3.1.2 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4C626E89.5020002@o2.ie> <4C629209.8060206@o2.ie> <1281573260.7575.12.camel@vaio3rd> <4C63BF50.8040900@o2.ie> <1281609490.7575.52.camel@vaio3rd> <4C63DDA8.9090405@o2.ie> <1281616016.7575.74.camel@vaio3rd> In-Reply-To: <1281616016.7575.74.camel@vaio3rd> X-Auth-Info: 3810@permanet.ie (plain) X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,RATWARE_GECKO_BUILD=1.426 Subject: Re: LF: Earth antenna Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G x-aol-sid: 3039ac1d411c4c63f93e20ad X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) Hi Rik, Yes ... exactly that. The "earth" that I attached to the "earth" terminal on the receiver was a reasonably good station earth and the wire that I attached to the antenna terminal was an 80m length of wire to a single earth rod. Tony, EI8JK. On 12/08/2010 13:26, Rick Wakatori wrote: > 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 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 >>> >> > >