[TowerTalk] Fwd: Bandwidth of a 1/4wl 80m vertical

[Mirko S57AD]

Well, how about approach, emtioned even in ON4UN's book - make vertical 
resonant in CW part of band, short it with series capacitor to be 
resonant in SSB portion of the band. Relay, switching in shortening 
capacitor may (at CW portion of band) add piece of phasing line to keep 
correct phasing at both portions of the band.

73  Mirko, S57AD

jimlux pravi:
> Richard (Rick) Karlquist wrote:
>   
>> HansLG at aol.com wrote:
>>     
>>> Hi there,
>>>  
>>> Wasn't there a way with "bazooka" antenna to get a wider bandwidth of any  
>>> antenna? I will remember that you could use a parallel resonator to extend the  
>>> bandwidth on any antenna. An other way was to have a "return" parallel with 
>>>       
>> There were some articles in QST 20 or 30 years ago about using lumped
>> element networks to broadband a dipole.  You can get a mediocre match
>> from 3.5 to 4 MHz using these.  I think it stays under 2:1, but never 
>> gets better than 1.5:1.  That may very well work OK for many users.  The 
>> same technique could be used for a vertical of course.  Much more 
>> effective that making the diameter larger.  Probably isn't going to work
>> for a 4 square, because it will screw up the phasing.
>>     
>
>
>
> You might (might be the operative word here) be able to come up with a 
> multisection matching network that has reasonably low loss to cover the 
> 3.5 to 4 (think of having two masts of the required length a couple feet 
> apart.. you get a sort of W shaped SWR curve)
>
> And once you have that, you might be able to come up with a phasing 
> network that is also broadband and matches whatever weird impedances 
> you'll see on the elements. It will almost certainly have multiple 
> sections too.
>
> Getting low loss would be a challenge with all those inductors and 
> capacitors.
>
>
> A lot easier to just throw in some relays to change among fixed 
> networks, I suspect.
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