[Elecraft] dBd vs dBi

Sun Oct 20 22:23:00 2002

I found it listed on the TIA site (it is now called TIA/EIA-329).  Part
1 is not currently available, as it is missing some information.  Part
2 (vehicular antennas) is $47 for either hard copy or download.  The
site says that Part 1 is for base station antennas used between 25 MHz
and 1 GHz.  Having spent much of my professional career measuring
antennas between 50 MHz and 26 GHz, I was curious as to the methods
specified, but not $47 worth.  I don't know the price of NEC4, but I
understand it is quite a bit (NEC2 source code is free, but EZNEC, etc.
are definitely worth their price.)

Bob, N7XY

On Sun, Oct 20, 2002 at 05:46:02PM -0700, Bob Nielsen wrote:
> This is probably getting a bit off-topic, but does anyone have a link
> for RS-329?  Google got me to a couple of sites which provide copies of
> standards (for $$), but a search for RS-329 yielded nothing.
> 
> Bob, N7XY
> 
> On Sun, Oct 20, 2002 at 01:53:07PM -0500, George, W5YR wrote:
> > While I agree with the first part of Earl's statement quoted below, I
> > believe that under certain circumstances, ARRL will in fact publish gain
> > figures, etc.
> > 
> > The following is taken from the ARRL website:
> > 
> > "Antenna advertisements that specify gain, front-to-back ratio, or
> > beamwidth are acceptable if the antenna has been tested in accordance with
> > EIA Standard RS-329, Part 1,
> > and a statement to this effect appears in the advertisement. Certified test
> > results must be submitted with the ad. 
> > 
> > "In lieu of RS-329-certified results, the advertiser may advertise
> > performance figures derived from specific antenna modeling programs. To do
> > so, the advertiser should first
> > model the antenna, using either YO (Yagi Optimizer, for Yagis only) or the
> > latest version of the NEC (Numerical Electromagnetics Code) program. See
> > the ARRL Guideline
> > for Modeling Antennas for Advertising Acceptance for answers to frequently
> > asked questions and for sample graphs. The data files used must be
> > submitted to ARRL at the
> > time the advertisement is submitted. 
> > 
> > "All advertising performance claims derived from antenna modeling must
> > indicate that they are calculated. As a minimum, we expect to see the peak
> > free-space gain (in dBi
> > referenced to isotropic) at a manufacturer-specified frequency. ARRL
> > encourages advertisers to provide even more information to end-users,
> > showing performance
> > measurements or computations over a specified frequency range, rather that
> > at a single frequency. 
> > 
> > "In addition to free-space performance figures, advertisers may wish to
> > show computed performance over ground. If so, they must use a "typical"
> > ground, with a conductivity
> > of 5 mS/m and a dielectric constant of 13. They must invoke the
> > Sommerfeld/Norton ground model if NEC is used, and the terrain shall be
> > flat ground at antenna heights
> > specified by advertiser. 
> > 
> > "Advertisers may elect to show a computed front-to-back ratio at a
> > frequency they specify. However, ARRL encourages advertisers to show the
> > worst-case front-to-rear ratio,
> > over a frequency range of their choice, preferably a complete amateur band. 
> > 
> > "ARRL also encourages advertisers to grant permission to place modeling
> > files on the ARRL BBS for knowledgeable users to try for themselves, to
> > foster greater public
> > confidence in performance claims. As always, the ARRL Laboratory reserves
> > the right to inspect and test an actual antenna to verify modeling claims."
> > 
> > I am pleased to see ARRL adopt this enlightened policy regarding antenna
> > ads rather than avoiding the issue altogether. 
> > 
> > 73/72, George    
> > Amateur Radio W5YR -  the Yellow Rose of Texas
> > In the 57th year and it just keeps getting better!
> > Fairview, TX 30 mi NE of Dallas in Collin county EM13qe
> > K2 #489      Icom IC-765 #2349     Icom IC-756 PRO  #2121
> > 
> > 
> > 
> > [email protected] wrote:
> > 
> > > Be skeptical of any manufacturer's gain claims they give in their specs.
> > > Unscrupulous claims of antenna gain is why ARRL will not publish gain
> > > figures in QST ads.
> > > 
> > > Some claims are honest, while many are not.
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> 
> -- 
> Bob Nielsen, N7XY                          [email protected]
> Bainbridge Island, WA  
> IOTA NA-065, USI WA-028S 
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-- 
Bob Nielsen, N7XY                          [email protected]
Bainbridge Island, WA  
IOTA NA-065, USI WA-028S 