You can now help support WorldwideDX when you shop on Amazon at no additional cost to you! Simply follow this Shop on Amazon link first and a portion of any purchase is sent to WorldwideDX to help with site costs.
The Feb 2025 Radioddity Giveaway Results are In! Click Here to see who won!

Reply to thread

Message

[ATTACH=full]31743[/ATTACH] While I've tried many different matching networks on Yagi antenna's, I can honestly say I've never been able to measure even a db of change from one working design to the next. That's simply not where the noticeable differences are. Expect to note differences in Common Mode Currents present on the transmission line and skewing of the pattern. Not extra db's in signal.

The best way to prevent CMC and pattern skewing is to use a matching network that threats both sides of the driven element exactly the same. The currents on both halves of the driven element must be perfectly equal with the exact center of the element at ground potential for best results here.

Unfortunately, the only matching network I'm aware of that performs this function, is also the most difficult to construct and properly tune. That would be the "T" match using two solid bars with no insulators, where both sides are feed equally with the proper 180 degree phase inversion. It's virtually indestructible too since there are no insulators involved other than inside the RF connector being used.

<blockquote data-quote="Shockwave" data-source="post: 691254" data-attributes="member: 10882">[ATTACH=full]31743[/ATTACH] While I&#039;ve tried many different matching networks on Yagi antenna&#039;s, I can honestly say I&#039;ve never been able to measure even a db of change from one working design to the next. That&#039;s simply not where the noticeable differences are. Expect to note differences in Common Mode Currents present on the transmission line and skewing of the pattern. Not extra db&#039;s in signal.The best way to prevent CMC and pattern skewing is to use a matching network that threats both sides of the driven element exactly the same. The currents on both halves of the driven element must be perfectly equal with the exact center of the element at ground potential for best results here.Unfortunately, the only matching network I&#039;m aware of that performs this function, is also the most difficult to construct and properly tune. That would be the &quot;T&quot; match using two solid bars with no insulators, where both sides are feed equally with the proper 180 degree phase inversion. It&#039;s virtually indestructible too since there are no insulators involved other than inside the RF connector being used.</blockquote>

[QUOTE="Shockwave, post: 691254, member: 10882"] [ATTACH=full]31743[/ATTACH] While I've tried many different matching networks on Yagi antenna's, I can honestly say I've never been able to measure even a db of change from one working design to the next. That's simply not where the noticeable differences are. Expect to note differences in Common Mode Currents present on the transmission line and skewing of the pattern. Not extra db's in signal. The best way to prevent CMC and pattern skewing is to use a matching network that threats both sides of the driven element exactly the same. The currents on both halves of the driven element must be perfectly equal with the exact center of the element at ground potential for best results here. Unfortunately, the only matching network I'm aware of that performs this function, is also the most difficult to construct and properly tune. That would be the "T" match using two solid bars with no insulators, where both sides are feed equally with the proper 180 degree phase inversion. It's virtually indestructible too since there are no insulators involved other than inside the RF connector being used. [/QUOTE]

Top Bottom