About Us

December 5th 05, 05:53 PM posted to rec.radio.shortwave

wrote:
I've always wondered how this antenna would have performed if the
feedpoint had been in the center as a classic dipole and the xfmr
Z-ratio was different than 1:1. Would this allow some semblance of a
"multiband" antenna as opposed to the direct feed or 1:1 situation
where the antenna essentially is optimum on the primary freq and the
3rd harmonic? Why did I choose the Windom? Because the radio room is
directly across from the 35% length point on the antenna. Even though
it works well I'm not convinced that there is anything "magic" or
unique about the 33 to 35% point on a wire antenna unless there is a
true overall impedance averaging effect when fed at this point. (???)

Frank
----------------------------------
About 10 years ago I experimented 9again) with dipoles for HF.
I tried several different ratios in an attempt to improve recpetion.

I tried a dipole cut for 10MHz and then one cut for 18MHz.
I tried 1:1, 2:1, 3:1, and 9:1.

A 70' "long" wire out performed the dipoles on every frequency, with
every
ratio even on the design frequency with a 1:1.

Of the dipoles, the 2:1 transformer with the 5MHz dipole worked best.
I suspect it worked best because of it's greater length.

The transformers seemed to mainly decouple the coax from the antenna.
If I ever get the time I would like to retry these experiments with
triax or
twinax.

I tried a direct connection with several ferritte cores, but after
reading John
Brynt's excellant article on "Is your Feedline acting like an antenna"
I accept
that I did not have anywehre near enough inductance to supress common
mode effects. I had a LOT of RFI from household devices.

Terry

Thread Tools	Search this Thread
Show Printable Version	Search this Thread: Advanced Search
Display Modes
Switch to Linear Mode Switch to Hybrid Mode Threaded Mode

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Even more on antenna feedlines and matching to an antenna.	Telamon	Shortwave	2	December 5th 05 07:35 PM
tech. Q. about balun	Nicolae Santean	Shortwave	8	June 5th 04 05:55 AM
which J-Pole?	Dave Platt	Antenna	3	March 5th 04 09:13 PM
Balun Grounding Question ?	John Doty	Shortwave	4	November 25th 03 01:29 PM
Need Hamstick ZL-Special (or similar phased array) help	NQ4S - Delbert	Antenna	1	November 4th 03 03:03 AM

Menu

About Us