At 02:26 AM 2007-01-29, Kari SM0HRP wrote:
>I have a 135 feet L-antenna (70 feet vertical, 65 feet horizontal) for 160
>meters with about 20 ¼ wave radials to it. It works well on 160 m and is
>also resonant with low SWR on 24 Mhz and 28 Mhz. I now wonder how does the
>elevation and azimutal pattern look like on the latter two bands? Is there
>any low angle take offs or is it a ?cloud warmer? on the 24, 28 Mhz band?
>Can anyone help me with the modelling since I am not an expert on this and
>do not have EZNEC 3 or 4. I do happen to have the EZNEC wire model file for
>the L-antenna from ARRL Compendium if that helps.
This antenna will have many lobes in all
directions on 20m and higher bands. Some of them
are at low angles and may be useful. Other lobes will warm the clouds.
(For Kari, I attached .jpgs of the low angle
pattern at 14.2, 24.9 and 28.3 MHz which won't go through the reflector).
BTW, this antenna is simple enough that the free
demo version of EZNEC, which is limited to 20
total segments, will produce a fairly
representative pattern (although the feed
impedance will be somewhat inaccurate on 20m and up).
73, Terry N6RY
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