[TowerTalk] SteppIR DB36/42 80m option

[Joe Subich, W4TV]

On 10/14/2015 9:20 PM, K2CB wrote:
 >
 > While we are discussing 80m antennas, can someone shed some light on
 > the radiation pattern of the SteppIR dipole option for the larger
 > DB36 and DB42 models?

The SteppIR is a shortened dipole (end loaded).  Radiation pattern
would typically be within 0.5 to 1 dB of a "flat" full size dipole
at the same height.

 > Is the maximum radiation towards the front and back of the antenna
 > elements, or off the left and right sides of the boom?

Maximum radiation is broadside to the boom - at right angles to the
beam on the other bands.

 > I also have legs for 160m fed off the same feed point, which sit/hang
 > 2 or 3 feet above the 80m legs.  They are tied to the same end posts
 > as the 80m legs. I just leave the ropes for the 80 m legs a little
 > bit looser so they sag down below the 160 m legs by a few feet on the
 > way down from the tower.

The 80m legs are redundant and most certainly couple with the SteppIR
when the SteppIR boom is parallel to the inverted V.  I would get rid
of the 80m legs and make the inverted V a 160 meter only antenna or
consider shunt feeding the tower for 160 and get rid of the wire all
together.

> As a non-scientific comparison, my buddy (N2II) up the road a few
> miles with only a two element 24ft boom linear loaded 40m yagi at the
> same 89ft height seems to do equally as good, if not slightly better,
> as I do with the three element 36ft boom SteppIR on 40 m.

The difference between a two and three element yagi is only a couple
dB.  If your buddy has a slightly better ground elevation (think HFTA)
in some directions, he will most likely make up a dB or two very
easily.


73,

   ... Joe, W4TV


On 10/14/2015 9:20 PM, K2CB wrote:
>
> While we are discussing 80m antennas, can someone shed some light on
> the radiation pattern of the SteppIR dipole option for the larger
> DB36 and DB42 models?
>
> Is the maximum radiation towards the front and back of the antenna
> elements, or off the left and right sides of the boom?
>
> Also, what would you consider this design? Some sort of "H" dipole?
>
> Anyone know of any good write ups on this sort of "H" antenna design
> (the 80m portion, obviously) on the web?
>
> Finally, has anyone compared this to an 80m inverted V at similar
> heights?
>
> I have the DB36 with the dipole option at 91 ft, and an inverted V
> 80m dipole with the feed point/ apex just below it at 89 feet. The
> end of the two legs of the inverted v are at approximately 45ft above
> ground.
>
> I also have legs for 160m fed off the same feed point, which sit/hang
> 2 or 3 feet above the 80m legs.  They are tied to the same end posts
> as the 80m legs. I just leave the ropes for the 80 m legs a little
> bit looser so they sag down below the 160 m legs by a few feet on the
> way down from the tower.  Unfortunately I have no trees on the
> property, so the only tie offs are two posts in the far corners of my
> property.
>
> I am sure there is some severe interaction, so it really is hard for
> me to tell which one works better sometimes.
>
> My experience with both seems to show that the StrppIR "H" dipole is
> a little better for the long haul stuff into Europe, while the
> inverted V is much better (by 10db) for the close in (200-300 mile)
> and rag chew type contacts on 80 m.
>
> On a related note, I believe I am having some noticeable interaction
> with these inverted V's when I have the SteppIR on 40 m. As a
> non-scientific comparison, my buddy (N2II) up the road a few miles
> with only a two element 24ft boom linear loaded 40m yagi at the same
> 89ft height seems to do equally as good, if not slightly better, as I
> do with the three element 36ft boom SteppIR on 40 m.
>
> I have no experience with modeling, unfortunately. My area of
> expertise in the hobby is radio and amplifier repair. FWIW, I am
> willing to trade repair services for modeling services if anyone is
> ever interested in modeling my antenna set up.
>
> Eric K2CB
>
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