[Antennas] Diminishing Returns

[Loren Moline WA7SKT]

Hello,

Just my 2 cents.

When you modify the radial system you also modify the lobes of the antenna pattern.

Just gaining more signal at a certain location may not indicate anything more than modification of the lobe in that direction. This may be at the expense of lessening the lobe in a different direction meaning not really more gain for the overall antenna.

 

Loren   WA7SKT


 
Member: ARRL and Pacific Northwest VHF Society

Member: Hearsat Satellite Monitoring Group

Location: CN86cx                                                                                        
                          
                                 








> Date: Thu, 4 Jun 2009 10:46:10 -0700
> From: richard at karlquist.com
> To: Cboone at earthlink.net
> CC: antennas at mailman.qth.net
> Subject: Re: [Antennas] Diminishing Returns
> 
> > meter fed from the same transmitter, steady carrier) and the signal was
> > received over a
> > thousand feet away and relayed back on the 440 band by a linear translator
> > and measured on
> > a spectrum analyzer.  (everything was pre-tested)
> >     Ron  KA4INM - I'm proud to be Chuck's pop!
> > ______________________________________________________________
> >
> > I'd LIKE to see THAT "Linear translator"....sorry but that was a waste of
> > time and not very accurate in signal strength...just have a spectrum
> > analyzer with a live human 1000ft away taking readings. Would have been
> > more
> > accurate.
> 
> I own several spectrum analyzers, but I don't drag them out
> for antenna testing.
> 
> What I do is turn down the RF gain on the HF radio until the
> AGC is inactive.  Then I connect the audio from the headphone
> jack to an HP Multimeter that displays AC volts in decibels.
> This is actually quite accurate, as long as you keep the AGC
> out of the act, and don't let the audio clip.  Use a sensitive
> range on the meter.  If you can't get a multimeter with
> decibels, you can just display AC volts and use a calculator
> to convert to decibels.
> 
> The audio could be sent over wires or over UHF rig.  In the
> latter case, it is important to use only a few kHz of deviation
> to avoid any effects from the speech clipper.  The nonlinearity
> of the speech clipper could ruin the accuracy.
> 
> I chuckled at your comment about no one using 16 radials.  I
> have 120 radials under one of my verticals.
> 
> Rick N6RK
> 
> 
> 
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