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I didn't mean to insinuate that high VF and low loss are directly correlated. There may be no engineering reason for the two to be related but there sure seams to be a practical correlation between the two in the cables I've compared. And I wouldn't suggest that RG-213 is a bad choice...

And the lower VF, higher loss cable will further attenuate the signal that's reflected before the SWR meter can measure it. So it's double loss. I'm still puzzling the add a no loss feed line and get a higher swr than at the feed point with no feed line. Lower yes, higher didn't think it...

length? Lots of reports of replacing cable with better quality ,higher VF, cable causing SWR to go higher. Usually the losses of the inferior cable is blamed for hiding the true value. But Marconi wrote Marconi did you adjust the length of the models cable to make them both the same...

Take off angles I liked your original post better robb. I do question the validity of the take off angle myth article when applied to the very narrow bandwidth of CB. The article is persuasive and I'm all for avoiding nulls in the forward pattern but it's author uses frequencies that can and...

The physically staggered in phase yagi does work the model was flawed .Corrected model has .98 axial ratio.

I could be wrong but MIMO doesn't use CP.. CP is not even allowed on 2.4 GHz (Legally). MIMO does use polarization diversity to create multiple "channels " All CP antennas create some cross-polarized component. This is undesirable and degrades the axial ratio. I'm pretty sure "simultaneously"...

Well put Shockwave. :thumbup: You say you've use CP for DX work. Was it a yagi like the PDL II fed out of phase? Did you have it switched to select between right and left handed? I think doc was suggesting that the lack of performance would incite the operator to replace with a different...

does it specify dBi or dBd or even in this case dBic? In most cases you will suffer a loss of 3 dB (unless you are talking to another CP antenna of the same rotation). An average of half the signal is "wasted" on polarization angles that aren't used by the linear polarized antenna. Me to...

Retraction :oops: Ok I went back to alter the model I used for post #112 this thread, and found a remnant from the previous model was partly causing the strange pattern. It was phased for no physical separation. The pattern is flawed but the axial ratio on the corrected model at the bore...

modeling advice Personally I learned a lot by dissecting/altering existing models posted by other people. Even if you want to create a model from scratch it's nice to have a template to refer to. It's much easier to alter an existing model and save as newname.nec The models are just text...

Yes the program is 4nec2, it is free and available at 4nec2 antenna modeler and optimizer The free version is the only version so it's true free-ware not cripple-ware or expire-ware or even nag-ware. IMHO it's the best free modeling program. (and not that hard to learn)

circular polarization Lil'Yeshua Ive seen that page you ordered from before. Not trying to get his design for free but, I doubt he has an antenna that is a new design. I am very curious which designs he includes. When you get the plans could you share (in very general terms) the basic type...

CP yagis and nvis NVIS wont work at 11 meter frequencies. The crossed dipoles will function as planned , but contrary to what is spread all over the net adding a reflector (as in two yagis crossed and staggered or fed 90 degrees out of phase ) doesn't work right.

Same pole as in no higher? So the tip of the smaller antenna was lower than the tip of the 5/8 is that right? How did you determine the reliability of those signal reports?

oh.. all the navys resources are on the sea no land based antennas right? Scientists try to limit the variables they must deal with , the less variables there are the more likely a correlation (and maybe a cause and effect)can be observed. Unless you want any data to only pertain to you then...

Of course NEC can't emulate real life. It was never meant to besides real life emulates real life perfectly Houses ,terrain, coax, relative soldering skills and any other real world interferences are what's irrelevant to simple antenna comparisons. But you haven't lived in all terrain types...

The code I posted can be pasted into a editor (notepad ect.) and either "save as" sigma4.nec or just save as a .txt and change the name to .nec instead of .txt save it in the 4nec2/models directory. Start the 4nec2 program, go to the little folder below "file " this should bring up a browse for...

Thanks for the welcome Marconi. Agree 100% My last step is usually to add a variable," SY AGL=240" and add it to all the Z coordinates Is it the sigma 4 baskets and the "trick" employed to help the model show the basket elements in phase with the main radiator? Does this? Hey! I...

Where are the models? Why does anyone use the demo of ez-nec ? With only 20 segments and no variables. I confess I have not tried the program. I saw little reason to learn a program with those limitations. I don't see any models. I see output reports from models. How can we get collaboration...

The model I was looking at is 2 vertical dipoles separated by 7 ft. I wouldn't call them bidirectional with gain of 6.75 dBi and f/b ratio of ~5 (beam width depends on phase delay). This model doesn't perform well at all co-phased (SWR >3) Had to trim the elements to ~101 inches to get SWR...