[K3PZN-List] Subject antennas on RV's

[Ray Wright]

Thanks Curt and John

The hope was to have the eagle one vertical on the ladder rack set up for
40m and either another vertical eagle one set up on the ground for 20m or
maybe an inverted diapole for 20m set up as the second antenna to the
vertical on the ladder rack?  Thoughts?

ray and kerri

On Thu, Jan 28, 2016 at 8:13 AM, Curt Milton via K3PZN-List <
k3pzn-list at mailman.qth.net> wrote:

> Possibly what you all are alluding to is sometimes called 'mutual
> coupling.'  Two closely mounted antennas 'experience each other.'  There
> are two effects -- change in the terminal impedance and distortion of the
> antenna behavior.
>
> I didn't get the picture if these verticals are used on different bands or
> the same one?
>
> The other question to ask is whether the radios will be okay with one
> antenna transmitting and the other receiving.  I would very much worry if
> they are used on the same band -- there is possibility for damage if they
> are too close, and too close may not be easily to calculate at the
> extreme.  If these are HF radios used on different bands, the band pass
> filters in the radio contribute some rejection -- and allows coexistence.
> Remember for example when we operated an inverted V below your tribandder
> at field day.  We didn't have issues because they were on different bands
> -- and it helped also to have several feet of separation.
> I do think you can operate on different bands using verticals on an RV --
> but best to separate them as much as possible.
>
> As for winter field day -- sounds like cabin fever after 2.5 feet of
> snow.  And burning some fuel just to stay warm.  I don't know how popular
> it is in the northern reaches, even here.  A QRP group does FYBO this time
> of year, but they are based in Arizona.  I don't know, plenty of other
> activities one can do with radios indoors this time of year.  Outdoors it
> just might be better to be moving, maybe on some cross-country skis or snow
> shoes that sitting using a radio.
>
> CUL 73 Curt
>
>
>     On Thursday, January 28, 2016 7:19 AM, John Stephens <kc3fdl at gmail.com>
> wrote:
>
>
>  Kerri,
>
> I had the same question a a couple of months back.  So to answer the
> question, I contacted Dr. Ed Fong who had recently given a skype
> presentation to the CARA club on his Dual Band J-Pole Antennas.  (By the
> way, it was VERY interesting and CCARC should do the same!).  He actually
> has a patent on his J-Pole design.  His website is
> http://edsantennas.weebly.com.
>
> His response was that it isn't the coax you need to be concerned with, it's
> the antennas.  They will resonate between themselves.  In order to prevent
> the antennas from resonating, 'in theory' (his words) they should be placed
> at least 1 wavelength apart from each other.  For example, if you were
> setting up 2M antennas they should be placed no closer than 2 meters
> apart.  There are some things you can do to mount them closer, like offset
> the height, but the physics and math are not trivial. Antenna for differing
> bands can be placed closer together, say a couple of feet, without any
> significant interference.
>
> Hope this helps.
>
> 73 de KC3FDL / John
>
>
> --------------------------------------------------------
> John L. Stephens // KC3FDL
> KC3FDL at gmail.com
> Latitude: 39.4927 Longitude: -76.8894
> MHGL: FM19nm
>
> On Wed, Jan 27, 2016 at 10:50 PM, Kerri Wright <kb3vwk at gmail.com> wrote:
>
> > Is possible to run two vertical antennas at the same time and location
> > with out harmful feedback on coaxial line.  If so how defeat that
> problem?
> > ______________________________________________________________
> >
> > 73 de K3PZN Westminster, MD
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