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

[jimlux]

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.