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#1
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On Sun, 17 Oct 2004 17:01:22 -0400, "G&R" makes a claim and opens
himself up to skewering: |Hi Art, | |While this was the common theory many years ago, there other ways to get |gain from an antenna other than boom length and number of elements. | |ie On 2m we are able to get 11.2 dBd on a 45inch boom with 3 elements |stacked 2 wide. Yes, this is range tested see results at |http://www.csvhfs.org/ant/CSANT04.HTML Uh Oh! The measured data show 11.2 dBd, the advertising shows 13.97 dBd. I thought maybe I went to the Raibeam site by mistake but no, I went he http://www.degendesigns.com/StackedVwave.htm I love that precision BTW. I've done a fair amount of antenna range testing using HP 8510s for measurement receivers and I've never been able to establish gain within 1/100 dB. But you can do it with a ham receiver and "subjective analysis". Congratulations. Since you're using two 45" booms spaced 58" apart, I would argue that you should compare your design to a 148" boom Yagi and see what happens. How about posting your dimensions so we can see what modeling says about them. One further note: The Dataq DI-194 mentioned at: http://www.degendesigns.com/Downloads.htm WILL NOT work with all computers. This device is powered by the serial port and my Toshiba laptops will not drive it. |
#2
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Wes,
You make the point quite well that I was trying to make before I read your post (written simultainiously) and at the present time NEC is seen as judge absolute. Yes there are many ways to increase gain but you cannot use a shackled NEC program to authenticate the results and we often use such as a crutch. On the subject of boom length I was basing things on a single boom length where number, position and physical atributes of additionion elements are brought into play to overcome program idequacies and provide correction of assigned dimensions to achieve maximum gain.(Is this to much to ask now that we have the NEC tool/) To often the accusation comes up that computor input was incorrect or not enough segments provided e.t.c. and a datum curve would prove a valuable tool, not only to those that use computor modelling but also to experimentors who seek real world answers and possibly challenge the authenticicity of either methods Thanks for the links,will read them later, have to get a floooooo shot now Art "Wes Stewart" wrote in message ... On Sun, 17 Oct 2004 17:01:22 -0400, "G&R" makes a claim and opens himself up to skewering: |Hi Art, | |While this was the common theory many years ago, there other ways to get |gain from an antenna other than boom length and number of elements. | |ie On 2m we are able to get 11.2 dBd on a 45inch boom with 3 elements |stacked 2 wide. Yes, this is range tested see results at |http://www.csvhfs.org/ant/CSANT04.HTML Uh Oh! The measured data show 11.2 dBd, the advertising shows 13.97 dBd. I thought maybe I went to the Raibeam site by mistake but no, I went he http://www.degendesigns.com/StackedVwave.htm I love that precision BTW. I've done a fair amount of antenna range testing using HP 8510s for measurement receivers and I've never been able to establish gain within 1/100 dB. But you can do it with a ham receiver and "subjective analysis". Congratulations. Since you're using two 45" booms spaced 58" apart, I would argue that you should compare your design to a 148" boom Yagi and see what happens. How about posting your dimensions so we can see what modeling says about them. One further note: The Dataq DI-194 mentioned at: http://www.degendesigns.com/Downloads.htm WILL NOT work with all computers. This device is powered by the serial port and my Toshiba laptops will not drive it. |
#3
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Hi Wes,
Yes I am aware of the difference between the advertising on the site and the range results. As you are aware antennas do not have even gain across the entire band. We have designed the antenna to cover the entire 2m band and as a result do see a variation in the perfromance across the band, hence max gain. And before you cut down my comments, the precision on the results are from the softare and we are in the process of redesigning the format to more accurately reflect our actual results both modelled and actual. Unfortunately our business is antennas and web design. The results posted on the CSVHF society are valid as the antenna was tested with a gain of 11.2dBd at 144.18MHz Horiz Polarization. Design Freq is 146.0MHz. We are in the business of designing and selling antennas not developing antennas and giving them away for free. However, if your serious about the data for the antenna contact me directly so that we can discuss the details (email listed below). As to the DATAQ, well I have no answer for that one, as we don't build it or sell it. Our software is designed to with run it. Strange though, my Toshiba does and so does my SONY through a USB to SERIAL converter. One final point, the purpose of the posting was that identify that an antenna does not always need boom length and elements for gain and that there are other ways to achieve this. Respectfully, Guenther VE3CVS www.degendesigns.com "Wes Stewart" wrote in message ... On Sun, 17 Oct 2004 17:01:22 -0400, "G&R" makes a claim and opens himself up to skewering: |Hi Art, | |While this was the common theory many years ago, there other ways to get |gain from an antenna other than boom length and number of elements. | |ie On 2m we are able to get 11.2 dBd on a 45inch boom with 3 elements |stacked 2 wide. Yes, this is range tested see results at |http://www.csvhfs.org/ant/CSANT04.HTML Uh Oh! The measured data show 11.2 dBd, the advertising shows 13.97 dBd. I thought maybe I went to the Raibeam site by mistake but no, I went he http://www.degendesigns.com/StackedVwave.htm I love that precision BTW. I've done a fair amount of antenna range testing using HP 8510s for measurement receivers and I've never been able to establish gain within 1/100 dB. But you can do it with a ham receiver and "subjective analysis". Congratulations. Since you're using two 45" booms spaced 58" apart, I would argue that you should compare your design to a 148" boom Yagi and see what happens. How about posting your dimensions so we can see what modeling says about them. One further note: The Dataq DI-194 mentioned at: http://www.degendesigns.com/Downloads.htm WILL NOT work with all computers. This device is powered by the serial port and my Toshiba laptops will not drive it. |
#4
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On Tue, 19 Oct 2004 14:02:18 -0400, "G&R" wrote:
|Hi Wes, | |Yes I am aware of the difference between the advertising on the site and the |range results. So are you going to fix it or not? | |As you are aware antennas do not have even gain across the entire band. We |have designed the antenna to cover the entire 2m band and as a result do see |a variation in the perfromance across the band, hence max gain. Huh? So are you saying that you have nearly 3 dB gain variation in 2 MHz.? | |And before you cut down my comments, the precision on the results are from |the softare and we are in the process of redesigning the format to more |accurately reflect our actual results both modelled and actual. |Unfortunately our business is antennas and web design. In a paper I wrote for the ARRL Antenna Compendium, I said, "Simplified 'antenna analyzers', especially those with digital readouts can lull the user into unjustified confidence in the accuracy of his measurements." Change the words "antenna analyzers" to "computer software" and it describes this situation to a T. | |The results posted on the CSVHF society are valid as the antenna was tested |with a gain of 11.2dBd at 144.18MHz Horiz Polarization. Design Freq is |146.0MHz. | |We are in the business of designing and selling antennas not developing |antennas and giving them away for free. However, if your serious about the |data for the antenna contact me directly so that we can discuss the details |(email listed below). My slightly distorted email is above. If you choose to send me your parameters, I promise to keep it in confidence. I don't not design, or manufacture antennas (or anything else) for a living. | |As to the DATAQ, well I have no answer for that one, as we don't build it or |sell it. Our software is designed to with run it. Strange though, my |Toshiba does and so does my SONY through a USB to SERIAL converter. I know you don't build or sell it, I'm just offering a caution to those who might be tempted to buy one. It works on my desktop but not my laptop, which is a pity because I had a portable use in mind. | |One final point, the purpose of the posting was that identify that an |antenna does not always need boom length and elements for gain and that |there are other ways to achieve this. Absolutely. One driven element at the focus of a 40' parabola is a decent antenna at 2-meters. Regards, Wes N7WS |
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