[HCARC] 10 meter Loop

[Gary and Arlene Johnson]

I too am not prone to accepting the Whoop Dee Dee claims of magic.  I just 
keep throwing these things out and/or against the wall, as a possible 
antenna that might work, since as far as I can see, no one else has come up 
with a solution for communicating locally on 10 meters.  Bill T indicated 
high height and high power.  Both something probably not found by the 
intended target population that restricts the Meter band to 10 meters - 
Technician Class Operators.  If they were not the intended target then the 
target meter band would be one of the bands where NVIS is possible, would it 
not??.

Gary J
N5"BAA"
----- Original Message ----- 
From: "Dale Gaudier" <dale.gaudier at windstream.net>
To: "'Gary and Arlene Johnson'" <qltfnish at omniglobal.net>
Cc: <hcarc at mailman.qth.net>
Sent: Sunday, August 12, 2012 6:29 PM
Subject: RE: [HCARC] 10 meter Loop


> Gary:
>
> I believe you said you had a copy of the ARRL Antenna Book. There are 
> plenty
> of well-tested designs for 10 meter gain antennas you can try out. The
> software that comes with the ARRL Antenna Book will let you play with 
> these
> designs. One of the fun aspects of ham radio is trying out these different
> antenna designs.
>
> I've a few observations concerning the claims of gain for many antenna
> designs you find on the internet.
>
> All antennas operate according to laws of physics. Antenna gain is
> essentially a result of directivity, i.e. more power is being concentrated
> in one direction than another. The overall power stays the same. The 
> higher
> the gain of the antenna in one direction, the lower in another direction.
> That's why the Yagi (beam) antenna is so popular at HF and VHF 
> frequencies.
> It has good gain in the forward direction and lower gain in the rearward
> direction - what is called the front-to-back ratio.
>
> The actual gain of an antenna is the result of a number of factors: the
> efficiency of the antenna (i.e. how much of the input signal is actually
> output), the electrical gain of the antenna (discussed above), height of 
> the
> antenna above ground (primarily for horizontal antennas), and the type of
> ground in the near field (ground conductivity). All of these can be 
> modeled
> using relatively inexpensive software, such as EZNEC.
>
> I've found that the exorbitant claims for gain from antenna designs 
> commonly
> found on the internet are the product of wishful thinking. At HF it is not
> easy to get more than 6-9dB of gain from a reasonably sized antenna 
> compared
> to a simple dipole at the same height. High gain Yagis based on National
> Bureau of Standards models, top out at about 14.2dB gain compared to a
> dipole. However, this requires 15 elements on a boom 4.2 wavelengths long
> (see http://tf.nist.gov/general/pdf/451.pdf)! A more reasonably sized
> antenna (5 elements on a 0.8 wavelength boom) will give you 9.2dB gain 
> over
> a dipole, based on the NBS models.
>
> Just because Jim Bob puts up a new antenna and starts making lots of
> contacts with 20dB over S9 signal reports from other hams, doesn't mean 
> that
> his new antenna is really good. A lot will depend on the band and
> propagation. It will also depend on the antenna system the other ham is
> using. If the other ham has a really good antenna system, of course Jim 
> Bob
> is going to sound loud. And without a calibrated receiver, a signal report
> is really just a good-faith estimate, not a scientific statement of fact.
>
> Unless an antenna has actually been tested on an antenna range with
> calibrated equipment, a claim for the gain of an antenna is exactly that: 
> a
> claim. The only exception are designs that have been computer modeled 
> where
> the modeled antenna's characteristics have been validated by range 
> testing.
> The National Bureau of Standards has several of these models; a few
> commercial manufacturers have also done such validation.
>
> The other factor you need to be concerned about is mechanical design. A
> design that is too complicated, difficult to erect, or is fragile in the
> wind, is not of much use. Here the KISS principle comes into play.
>
> Finally, no one design will be optimum for all situations. If you want to
> communicate locally and not in a preferred direction, e.g. for a local 
> net,
> an omnidirectional antenna, such as a vertical, will be a better choice. 
> If
> you want to communicate in a preferred direction a directional antenna, 
> such
> as a dipole or simple Yagi, will be a better choice. For close-in
> communications you also need to consider the polarization of the antennas 
> of
> the other parties and have your antenna be similarly polarized (e.g.
> vertically or horizontally).  For DXing you want a low angle of radiation
> and probably some gain so either a Yagi type antenna (for 40m/30m and 
> above)
> or a vertical or inverted-L (for 160m, 80m, and possibly 40m) will be the
> usual choices.
>
> I've built a number of antennas over the years - some of my design and 
> some
> by others - and I keep coming back to the basic, tried-and-true, antenna
> designs: dipole, Yagi and 1/4 wave vertical/inverted-L. They are simple 
> and
> they work.
>
> I apologize for the length of this response to your question. My purpose 
> is
> to help you have a better idea of which antenna designs have real merit so
> you don't spend your time chasing after designs that won't live up to 
> their
> hype.
>
> 73,
>
> Dale - K4DG
>
>
>
> -----Original Message-----
> From: hcarc-bounces at mailman.qth.net [mailto:hcarc-bounces at mailman.qth.net]
> On Behalf Of Gary and Arlene Johnson
> Sent: Sunday, August 12, 2012 4:27 PM
> To: Bob Richie
> Cc: hcarc at mailman.qth.net
> Subject: Re: [HCARC] 10 meter Loop
>
> This one is sized for 6 meters, but I suspect it could be upsized for 10
> meters too.  I thought of making these out of excells 1/2 inch copper 
> water
> pipe, or possibly with the soft copper line that they use for refrigerator
> water lines or the stuff they use for copper refrigerant water lines.  So
> many things to think of - so much frustration not to be able to try them
> out.  Someday I will though.
>
> Gary J
> N5"BAA"
>  ----- Original Message ----- 
>  From: Bob Richie
>  To: Gary and Arlene Johnson
>  Sent: Sunday, August 12, 2012 3:15 PM
>  Subject: Re: [HCARC] 10 meter Loop
>
>
>  This antenna has been around for a while.  The problem is finding a place
> high enough to hang it around here. Some of the tall trees in the
> southeastern pine forests would make this a natural, along with some other
> loops.  If you have not been to this site
> http://www.hamuniverse.com/antennas.html it has a bunch of antennas and
> other interesting articles.
>
>  Bob
>  K5YB
>  Kerrville, TX 78028
>
>
> ----------------------------------------------------------------------------
> --
>  From: Gary and Arlene Johnson <qltfnish at omniglobal.net>
>  To: hcarc at mailman.qth.net
>  Sent: Sunday, August 12, 2012 1:54 PM
>  Subject: [HCARC] 10 meter Loop
>
>
>  I found the following while looking at antennas on the net.  It's called
> the "20db over 9 10 Meter Loop Antenna".  Diagram is on the link.
>
>
> http://9m2mgl.blogspot.com/2008/10/with-large-number-of-operators-and-wide.h
> tml
>
>  "With the large number of operators and wide availability of
> inexpensive,singleband
>  radios,the 10-m band could well become the hangout for local ragchewers
> that it was before the advent of 2-m FM,even at a low point in the solar
> cycle.This simple antenna provides gain over a dipole or inverted V.It is 
> a
> resonant loop with a particular shape.It provides 2.1 dB gain over a 
> dipole
> at low radiation angles when
>  mounted well above ground. The antenna is simple to feed-no matching
> network is necessary.
>
>  When fed with 50-? coax,the SWR is close to 1:1 at the design
> frequency,and is less than 2:1 from 28.0-28.8 MHz for an antenna resonant 
> at
> 28.4 MHz.The antenna is made from #12 AWG wire (see Fig 22.80) and is fed 
> at
> the center of the bottom wire.Coil the coax into a few turns near the
> feedpoint to provide a simple balun.A coil diameter of about a foot will
> work fine. You can support the antenna on a mast with spreaders made of
> bamboo,fiberglass, wood,PVC or other nonconducting material.You can also 
> use
> aluminum tubing both for support and conductors,but you may have to 
> readjust
> the antenna dimensions for resonance.
>
>  This rectangular loop has two advantages over a resonant square loop.
> First,a square loop has just 1.1 dB gain over a dipole.This is a power
> increase of only 29%. Second,the input impedance of a square loop is about
> 125 ?.You must use a matching network to feed a square loop with 50-?
> coax.The rectangular loop achieves gain by compressing its radiation 
> pattern
> in the elevation plane.The azimuth plane pattern is slightly wider than 
> that
> of a dipole (it's about the same as that of an inverted V).A broad pattern
> is an advantage for a general-purpose,fixed antenna.Then rectangular loop
> provides a bidirectional gain over a broad azimuth region.
>
>  Mount the loop as high as possible. To provide 1.7 dB gain at low angles
> over an
>  inverted V,the top wire must be at least 30 ft high.The loop will work at
> lower
>  heights,but its gain advantage disappears.For example, at 20 ft the loop
> provides
>  the same gain at low angles as an inverted V.
>
>  Sumber daripada ARRL
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