Reply-To: rsgb_lf_group@blacksheep.org From: "Rik Strobbe" Sender: To: rsgb_lf_group@blacksheep.org References: <003e01c130d4$30973360$7798fea9@host.telepac.pt> <3B8E1787.4FB4EC0D@usa.net> <00a601c1316f$0791a180$d3331997@KOSOVEUALESSANDRO> <3.0.1.16.20010911092252.2c47dcf4@mail.cc.kuleuven.ac.be> Subject: Re: LF: Re: CFA (once more) Date: Tue, 11 Sep 2001 11:15:35 +0100 Message-ID: <3.0.1.16.20010911111535.423f583e@mail.cc.kuleuven.ac.be> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Windows Eudora Pro Version 3.0.1 (16) Importance: Normal X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-Listname: rsgb_lf_group In-reply-to: <3B9DD9EA.67F706DB@usa.net> X-Sender: pb623250@mail.cc.kuleuven.ac.be Hello Alberto, Thanks for your comments. I have also a lot of sceptisism in regard with CFA (and similar) antennas but as they say 'eating is the proof of the pudding' (or something like that), so I have more faith in test results than in theoretical discours. As far as I know radioamateurs have tested CFA / EH-antennas on shortwave. I you scale the relative sizes and mounting heights to 136kHz it often comes to an almost 50m heigh constructions mounted at several 100m above ground, I have no doubt that this would make a wonderfull LF antenna. Constructing a 10m high CFA or EH-antenna mounted at groundlevel would already be a big challenge to most of us, if you size that down to 20m you get a 10cm high antenna that you have to put on the ground. I wonder if any CFA of that size will work. But on the other hand we don't need to go for 80 or 90% efficiency, I would be more than happy to achieve 1% efficiency. Bernd (DF8ZR) has built a 20 EH-antenna and will test it at different heights above ground. If this antenna really works the way the inventors explain then then signalstrength should be relative independent versus the height. If the signal strength raises by 6dB when doubling the mounting height then it might just function as an ordinary vertical with a very funny tophat. 73, Rik ON7YD >On this subject, this last weekend I went to a hamfest in Piacenza, Italy, >where some commercial prototypes of the EH Antenna were presented. >They had a couple of Yaesu FT-1000MP, one connected to a full size >dipole for the 40m band, and the other to an EH antenna for the same band. >I asked if I could play a little with them, they said 'yes, of course'. >Then I tuned a faint CW signal with both receivers. The full size dipole >outperformed the EH but only by a slight edge, which apparently was >remarkable, given the difference in size. But then I went outdoor, to look >at both antennas. The EH was installed just half meter above the center of >the dipole.... hmmm... I suspect a strong coupling between the two... >probably the lines of force of the electromagnetic field were made denser >by the dipole in the proximity of the EH antenna... > >Then I asked for a further test on the 20m band, where no dipoles were >installed, using this time an indoor EH antenna, mounted on a 2-meter tall >support. They agreed, and even connected a microphone to the transceiver. >The 20m band was rather quiet (it was about noon on Saturday), with only >a few signals. I called a Cyprus station who called CQ Contest, but no answer. >Then I found another station, an SV1, also calling CQ. This one answered me, >giving me an S5 report, but then he failed to answer a question I posed him, >showing that my readability was less than perfect... > >All in all, I am quite skeptical about this antenna, theoretical considerations aside. >A friend OM regularly makes QSO with a 1.5m whip, base-loaded, from his car >on the 7, 14 and 21MHz bands, so this new EH antenna seems to perform nothing >more, nothing less than a short loaded dipole, not worth the money they ask for >it, nor the troubles for building it. > >Just my opinions. > >73 Alberto I2PHD > > > >