Re: [IRCA] Fwd: [mwcircle] SuperKaz broadside array ...

[neilkaz <neilkaz@xxxxxxxxxxxxx>]

Thx, interesting reading.

You may forward this to MWC.

I'm familiar with Mark's site and was going to suggest that he try a Double KAZ and am glad to see that he did.
How large was Mark's Double KAZ? DXers in quiet coastal locations are continually telling me that they want more signal out of the Double KAZ at the low end. We enlarged it to 20 ft x 140 ft for the recent Yachats OR DXped and even when amped with the wonderful FLG100LN more signal would have been useful on the extreme low end, like 540 and 531. 

At home in the RF jungle of IL, 21 ft x 112 ft unamped gave me all the signal I needed except for the low end, and the addition of a FLG100LN improved even the weak TIS on 530 to fine readability. 

According to EZNEC, if one gets much larger than 21 ft x 112 ft, extreme high end (X-band) F/B can start to suffer when trying to use the same Rt (termination resistance) across the band. However, this is less than an issue for those in Europe who won't have much back end QRM above 1600. I've enlarged to 21 ft x 120 ft here in Illinois and back end nulls are still great even on 1680 and 1700. In Oregon there weren't any X-banded directly off the back to really test the 140 fter's back nulls. DXers in Europe wanting to test a Double KAZ for TA DX may wish to try a base dimension between 120 and 140 ft. I'll do some tests of larger ones myself as I can easily tell effects here in the RF jungle. I also now have the capability to vary Rt from back at the shack, making testing easier.

The Double KAZ is essentially an endfire array of two closely spaced KAZ antennas fed nearly 180 degrees apart. The phase difference from 180 degrees is clearly less at the low end than at the high end, and if we phase two antennas with a phase difference quite close to 180 degrees, we get large losses. This being said, I can understand why DXers in quiet areas near the edges of our continents want even more low end signal to chase stations from across the ponds. Perhaps something larger than a 140 ft base is needed and some high end F/B degradation must be accepted. 

KAZ antenna beamwidths (15 deg above ground) are about 138 deg and F/S (front to side ratio) is about 5.5 dB. Double KAZ beamwidths are about 99 deg and F/S about 10.5 dB and I find that the more narrow beamwidth is extremely useful here in the US midwest. While the KAZ antenna and similar single loop antennas are very broadbanded with a single fixed Rt, it took me some design work and experimentation to cover the entire BCB's 3:1 bandwidth with a fixed Rt when using a Double KAZ or similar Double Loop cousin.

It seems like Mark's new baluns are superior to his former ones and also that he's hit on a sweet spot for great F/B with that Rt for 1377 and that he has an improved antenna for the coming season.

As the KAZ antenna has a wide main lobe to begin with, even a slight narrowing of that main beam from a broadside array is useful. However, it would be much better to be able to space them about 300 ft apart since bemawidths would be significantly narrowed and there'd be deep high band side nulls.

73 KAZ


-----Original Message-----
>From: Nick Hall-Patch <nhp@xxxxxxxx>
>Sent: Aug 5, 2013 12:28 PM
>To: Mailing list for the International Radio Club of America <irca@xxxxxxxxxxxxxxxx>
>Subject: [IRCA] Fwd: [mwcircle] SuperKaz broadside array ...
>
>Especially for those who heard Neil Kazaross' talk at the convention:
>
>(from MW Circle)
>
>
>>..and results.
>>
>>Mark Borthwick in Hawick (Scottish Borders) has installed a broadside array.
>>
>>Description
>>http://scottish-dxing.yolasite.com/blog/super-kaz
>>
>>Results
>>http://www.youtube.com/watch?v=RHmeahDBtEs
>>
>>I think I need a bigger garden.
>>
>>Paul
>>
>>
>>
>>
>>
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