PDL II questions

[Marconi]

Hopefully the link below will work to get you to the old CB Tricks Index, and there you can select "Antennas and Manuals," then click on the "A" section, and then select "Avanti" at the bottom.

Select and Click on PDL 2 from the list of Avanti antennas. This will get you to the Manual, and it is a book.

CB Tricks - Home Page

The US Patent is below in the PDF file.

 

[Handy Andy]

Thank you

Reading it as you work on your project...​

 

[Marconi]

@Marconi - Then for my own curiosity - the PLD-2 - using a boom "gamma" (those front elements like you have in the pictured)...does that design offer similar response compared to the (Gamma again - but circular) as the "II" type of curved arms to offer some form of compaction (compact design?) - how do these two designs differ?

I mean if you have to write a book, well, I'd certainly would read it.

But to help the rest of the user base still here, help them to understand the subtle - profound - differences between the two different constructions.

Andy, back in my days the PDL2 was very popular, and likely due in part to the way it looked - small - and that when setup right...it worked very well.

I never owned one, but I was around to see them work. IMO hardly anybody wanted the conventional 2 element yagi, even when Maco came out with the 1/2 Yagi 1/2 Quad two element beam. I saw very few of those around.

Avanti hides matching ideas and makes other details difficult to impossible to find dimensions for, and the PDL 2 is gloriously unique in its complexity. If you read somewhere in the links above, I think you will read the word "Balance" and I think that was one of the buzz words in that group, and i also agree.

I would have loved to try and model it and still do, but I know it would be near to impossible to get the accurate and necessary dimensions and then being able to duplicate all the dimensional relationships...that would also be near impossible.

I would just get frustrated trying and missing some of the finer points in the matching design and never getting it done. So, I just dream a little instead.

I just finished modeling, what I consider a reasonable effort, of Jay's I-10K ground plane, and that took me, in bits and pieces, several years of trying to get all the little dimensions and the peculiar and spatial relationships figured out.

That antenna does not deserve to be modeled like an ordinary 5/8 wave, even though I'm sure some would strongly question my antenna model and say "...why go to all the trouble, a 5/8 wave is a 5/8 wave, etc.," I think it is unique. I just never used it much, because it was so big and heavy. so I had little to compare at the end of my comparing days and trying to understand antennas and modeling and a little about how they work.

I have not studied the PDL 2 idea either, but I think it does something a little different. I remember my best radio friend that had one, repeatedly saying how quiet it was in operations.

 

[Handy Andy]

@Marconi - per your advice, and being curious, the cautionary tale of the antenna thru the description of it's patent, shows - or tells me, there are two aspects the antenna the PDL2 and it's subsequent brethren the PDL-II - although similar in view, I can see where the transmission construction is different between the two.

Both use the concept of Loop antenna - the Summary in the first of the pages helps with understand the basic theory,

​

Per the patents' description, it's a loop antenna...

It just depends on where you hook up the driven elements - does the polarization effect occur - by the location of the DRIVEN element in the loop.

In their description, FIG 7a and FIG 7b - show the antenna working as a Horizontally polarized loop antenna.

They state the same can occur when the VERTICAL element is driven - you get a Vertically polarized loop antenna.

So to me, both the PDL2 and the PDL-II (Roman numeral 2) - function the same, but the matching scheme is different.

So thank you! For that tour!

To add:

How I came across this antenna was thru using the CB during one of my earlier fun days of learning and developing a system both myself and my family could live with. Mine was/evolved as simple Ground plane, onto a JB-1 Big Stick with my Archer Crossbow in there as a short term failure of an antenna I learned more about than I care to.

So the PDL design being a bean came into play as one from a neighbor that used theirs for the purposes of getting in touch with a relative - only being that the beam allowed them to communicate the longer distance that would otherwise had to be done thru a telephone and it's usage charges for long distance. The Tolls charged can easily surpass a typical blue collar works pay for two weeks - in just one call of a length of time they would otherwise spend using the CB as this means to chat.

Where I came into this was to help them develop a network of stations that can offer assistance - which then would help act as a relay - when conditions or locals not wanting them to talk - tended to interfere, the network allowed the conversation to continue as a relay - run particularly useful as a "net" more than a simple chat on the two-way.

So to push this into a box and put a bow on it. The PDL II i learned about thru conversations on the air thru all of this, they needed help with making a stronger back door to help in signal capture and rejection - make the beam tighter - per-se. So they needed help and advice to install an extra wire loop, at the aluminum brace joints to offer better support and functionality - they simply put on a smaller diameter loop using the aluminum to fiberglass joint part way up the cross element boom of the rear reflection.

It seemed to help their efforts will little impact on the weight or wind loading which in our area being on the upslope of a hill in the prevailing winds - they would blow down a TV aerial mounted on a 5 foot mast on a 3-foot tripod on a typical home in the area when the airport reported 35 MPH gusts on their equipment - we'd normally see much higher gusts due to the terrain we lived in.