[TowerTalk] Matching network for wire antenna needed

[Herbert Schoenbohm]

Question:

Would it not be easier to just have two extra wires cut for for the low 
end and the other for the high end of each band and feed them from a 
common feed point with minimal matching components such as series fixed 
capacitors to bring each wire to resonance?  This perhaps could broaden 
the response but may not be a perfect match depending on how far the 
wires were separated from each other.  It may be a suitable way to avoid 
buying a lot of expensive components.


Herb Schoenbohm, KV4FZ


On 9/14/2014 7:01 PM, Jim Lux wrote:
> On 9/14/14, 3:36 PM, TexasRF--- via TowerTalk wrote:
>> Conceptually this could be done using 50 ohm coax stub matching.
>>
>> Starting with the R +j of the four band segments, a design for each band
>> series segment can be done. Then starting with the shortest series 
>> section,
>> additional series cables can be added to achieve the proper length 
>> for the
>> remaining three band segments. The junctions of the four series coax
>> sections can be connected with Tee connectors. Then four shunt stubs  
>> could be
>> connected by means of suitable relay on the third leg of the Tee  
>> connectors.
>>
>> I have not done this for the stated application but have used the 
>> concept
>> to switch a 40m beam from cw to phone frequencies with excellent 
>> results. In
>>   this case, only two stubs were switched in/out.
>>
>> When doing the design, there are multiple solutions with stub matching.
>> Some solutions require a shorted stub, others require an open stub. 
>> One can
>> visit the various solutions and choose one that minimizes the amount 
>> of coax
>> needed.
>>
>> As usual, I am only the concept guy; you have to do the work. 
>> Transmission
>> line software will make the job easier.
>>
>
> Or lumped LCs.. in general, with N lumped LCs you can get a perfect 
> match at N frequencies.
>
>
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