[Elecraft] 6 meters - need info (OT?)

[Bill W5WVO]

Hi Tony,

Good to hear you are using HFTA. Excellent tool.

It's all about takeoff angle, which is determined by (a) the kind of 
antenna(s) you are using,  (b) their height above ground,  (c) the terrain 
characteristics, and  (d) frequency. What takeoff angle you need is in turn 
dictated by the kind of propagation you are using and the path distance.

A single 6M yagi at 82' will have several deep nulls in its elevation profile, 
as HFTA is undoubtedly telling you. For sporadic-E propagation, you will want 
to be able to cover takeoff angles from 0 up through around 16 or 18 degrees 
elevation, which will cover single-hop path lengths from the theoretical 
maximum single-hop distance (1400-1450 miles) down to around 350-400 miles.

You need those higher takeoff angles mostly for sporadic-E propagation. When 
the F2 comes back in four or five years, it is unlikely that you will need a 
takeoff angle much higher than 0 degrees because the band will be at or just 
below the F2 MUF, placing the critical angle of refraction close to the 
visible horizon. It will be an extremely rare (though not impossible) 
occurrence to have an F2 path on 6M with shorter than the maximum possible 
skip distance. Shorter skip is likely to be sporadic-E, which can and does 
coexist with F2 during solar maxima.

Therefore, if you have no interest in working grid squares over shorter path 
distances of 400-1000 miles or so (plus any multi-hop Es paths that may be 
comprised of these shorter hops), you needn't worry about covering the higher 
takeoff angles. But that's really where most of the fun is on 6M IMHO, and to 
cover all the bases for sporadic-E, you definitely need to have a solution for 
covering those takeoff angles. This can be done either through phasing of 
stacked arrays, as modeled in HFTA, and/or by placing one or more antennas 
closer to ground. Just trust HFTA to give you the best configuration for what 
you want to do.

Bill / W5WVO

N2TK, Tony wrote:
> Interesting info about 6M. I am presently using the XV50 with my K2.
> Had a lot of fun in June working many Europeans and Caribbean
> stations. Can't wait till I get my K3 with a little more power on
> that band. Now I need to get an XV144.
>
> I do have a question for you 6M aficionados. Hopefully this isn't too
> far off the normal intent of this reflector. I have 6 el at 82'.  I
> can also put a 6 el beam at 47'. HFTA says that will help me.
> My questions are:
> - I have heard a rumor that 6M beams don't work too well when
> side-mounted. Is this true?
> - Since I am not yet familiar with all the types of propagation on
> 6M, are there rules of thumb for high and low antennas? Do you think
> I am too high at 47' and 82'? Do I need a lower antenna also like on
> 10M for when the sunspots are high again?
>
> If this is too far off normal topics on this band, please respond
> directly.
>
> Tnx
> N2TK, Tony
> #3481 K2
> Batch #1 K3
>
>
> -----Original Message-----
> From: elecraft-bounces at mailman.qth.net
> [mailto:elecraft-bounces at mailman.qth.net] On Behalf Of Bill W5WVO
> Sent: Thursday, September 27, 2007 12:16 PM
> To: elecraft at mailman.qth.net
> Subject: Re: [Elecraft] 6 meters - need info (OT?)
>
> Ken Kopp wrote:
>
>> Six tends to peak near the Spring and Fall equinox because
>> of the earth's tilting towards the sun at these times.
>
> Probably a typo, but should be corrected.  :-)  6M sporadic-E
> propagation peaks around the SOLSTICES (June and December), not the
> equinoxes. There is rarely ever any sporadic-E propagation around the
> equinoxes.
>
> The summer Es season in North America typically runs from mid-May
> through mid-August, with the southeast US getting some early
> sporadic-E openings by late April. The winter Es season, in which the
> openings are typically less numerous and weaker than during summer,
> extends from roughly late November through mid-January. Sporadic-E
> can occur at any time, but it is extremely rare from mid-February
> through mid-April and from mid-September through mid-November in
> North America.
>
> There is a tremendous amount to be learned about 6 meter propagation.
> It is the only band we have where ALL known radio propagation modes
> (and probably a
> few unknown ones) can be experienced at one point or another. It is
> truly a mix of HF and VHF characteristics.
>
> Bill / W5WVO
> DM65
>
> ______________________________________________2
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com
>
> _______________________________________________
> Elecraft mailing list
> Post to: Elecraft at mailman.qth.net
> You must be a subscriber to post to the list.
> Subscriber Info (Addr. Change, sub, unsub etc.):
> http://mailman.qth.net/mailman/listinfo/elecraft
>
> Help: http://mailman.qth.net/subscribers.htm
> Elecraft web page: http://www.elecraft.com