Le Tue, 8 Aug 2006 20:55:42 +0200,
"noexqs" a écrit :

Hi Dominique,

I doubt that your spreadsheet will give accurate design information for
actual design.
As you already mentioned, it has it's limitations since it will not give
gain, f/b and antenne impedance as
a function of operating frequency.

It is not a broadband antenna, but a channel antenna.
On the central frequency, you will get a resistive impedance in all cases with it (, so it must be very easy to interface it with a transmission line.

I just trust the Balanis. The antenna is optimized for the maximum forward gain, but the calculation of that gain is not in this book. It use other references as some IEEE papers and I don't have them.

A. Shoamanesh and L. Shafai, "Properties of Coaxial Yagi Loop Arrays" and "Design Data for Coaxial Yagi Array of Circular Loops"


I have done quite a lot of loop yagi antenna modelling in NEC2 and MMANA and
I found out
that the loop yagi performance is infuenced quite dramatically by the
physical dimensions of the
individual loops and their relative position. I have not mentioned the
effect of the element diameter.

I have done only a few test with the NEC2 software. I know at the original NEC2 code is quite old now. The theory in the balanis is very recent, and I trust more my own calculation based on the Balanis as the NEC2 calculation.

I don't know MMANA, so I cannot speak about it.

In addition I have built several loop yagi's. Testresult of my 6 element 2m
loop yagi can be
found on the internet (google: loop yagi pe2wdo).

I found a 2005.xls file with a comparison between different antennas, among them a few loop yagi.
What's look strange to me is at you get a gain of 9,2 dB with a 144MHz loop yagi 7 elements, and 10,8 dB with a yagi 7 elements. According to Balanis, it must be the contrary. The loop yagi must have more gain as the dipole or linear yagi. But maybe at you have another optimisation as for the max forward gain.

If you are interested I can send some design details of my loopyagi design.


I will really appreciate it, thank you.
Dominique

Best regards,

Willem
PE2WDO



"Dominique Michel" schreef in bericht
news:20060805171848.3a8f7cf6@localhost...
Hi all,

I have done a spreadsheet for the calculation of Yagi-Uda array of
loops. You can get it on internet at
http://home.citycable.ch/monde-meilleur/index.html

Sorry it is in french, a direct link to the page where the spreadsheet
reside is:
http://home.citycable.ch/monde-meill...antennes1.html

It is 2 versions, the original one for gnumeric at
http://home.citycable.ch/monde-meill...adres.gnumeric
and another one for excel at
http://home.citycable.ch/monde-meill...multicadre.xls

I have tested the excel version only with openoffice (I use linux at home)
and it worked.

I have done a TV RX antenna on 487.25 MHz with just a few wood stick and
some coaxial cable. It took me 2 hours of job, and I was able to receive
with the color a channel I was just able to receive in black and white and
a lot of snow with the biggest Wisi UHF antenna.

Such an antenna can outperform any commercial antenna. It will just become
bigger as you get down in frequency. As example, a five elements 27MHz
will do 9.5 meter length for a diameter of the active element of 3,89
meters.

Any comments are welcome.
I will appreciate very much If someone can take a look on my English and
correct it. Just drop me a word or two.

Dominique