Topband: Nested Loops with one feedline results

[Herb Schoenbohm]

Thanks Rick,  I presume a true quad loop would bring different results 
with a common feed.  I have heard of a single feedline working well with 
a 5 band quad so I presume that a triangular "Delta Loop" has a 
completely different relationship?

Herb, KV4FZ




On 9/2/2013 6:34 PM, Richard (Rick) Karlquist wrote:
> The 18/24 is not a good analogy, because those bands
> are not octave spaced.  My modelling indicated that
> you need to open up the lower frequency antenna at
> two places, 180 degrees opposed, in order for it not
> to affect the higher frequency antenna.  Also, the
> openings should be such that the remaining wires
> are cross polarized to the higher frequency antenna.
>
> Rick N6RK
>
> On 9/2/2013 3:09 PM, Herb Schoenbohm wrote:
>> Several replies to my inquiry on having a closed 80 meter inverted delta
>> loop inside a 160 meter delta loop brought me some nice replies.  So I
>> decided to build one for 18Mhz and 24Mhz with the feed going to the
>> outside Delta loop hoping this would properly allow dual band operation
>> with a single feed.  The inside 24 Mhz delta was closed and hung 
>> inside a
>> the fed 18 Mhz antenna.  The results showed that it had no impact on the
>> 18 Mhz antenna but the VSWR on 24.9 was unusable.  Then I decided to
>> open the 24 Mhz Delta and connect the two wires to the 18 Mhz feed and
>> now have both bands working with a VSRW below 1:2 to 1 on either band.
>> The feed-line for the antenna is RG-213 with a 1/4 wave piece of RG-11
>> cut for 18 Mhz.  I am surprised that the 1/4 wave matching piece did not
>> seem to impact the antenna on 24.9 at all.
>>
>> I will now proceed to build an 80 meter full wave delta inside my 160
>> meter one and rely on the simulation on 18/24 Mhz to get a good match. I
>> trust it will work although the ground proximity might have some impact
>> on everything.
>>
>>
>> Thanks for the replies on this.
>>
>>
>> Herb Schoenbohm, KV4FZ
>> _________________
>> Topband Reflector
>>
>>
> _________________
> Topband Reflector