Wrap your head around this stuff

Good article. I wouldn't get too hung up on the physics of how an antenna works. To me the phase angle comes into play with the coax length due to velocity factor. This causes a problem, because 12 to 14 feet (depending on VF of the coax), is probably too short for most mobile installations. Or it can be way too long if you cut it to the next 1/2 wavelength. I don't think I've ever seen a manufacturer say to install their antennas a certain distance from a metal object. Like the 1 inch that was recommended in the article. Of course that wouldn't apply to the 11 meter HF band. Unfortunately the biggest problem with 1/4 wavelength antennas, is the location on the vehicle. I've always summed up mobile antennas in one word.... compromise. You just have to do whatever it takes to make it work. If every vehicle's ground plane was like a big suburban or van, the antenna system would be so much better. Mobile antennas are a constant learning experience as you have mentioned a time or two. Thank goodness for the antenna analyzer. It sure does help.

 

Ya, I hear what your saying. You just made a great reason for not tilting a cb antenna forward. Sure it may show a lower swr reading, but low swr reading doesn't necessarily mean the antenna is resanant. From what I understand, a 1/4 wave mobile antenna's impeadance is around 25 to 36 ohms. So if an antenna mounted on a mirror is 36 ohms. Then according to the math.... a 50 ohm radio/coax divided by 36 ohm antenna equals around 1.4 for swr. 50/36=1.39, or about 1.4 for swr. I wish I had my rig expert analyzer when I was still driving that old Pete. Since I had a 2 foot coax jumper cable, I used the vna calibration kit to calibrate the analyzer with the jumper cable attached. This would have made it real easy to attach the analyzer to the antenna mount, and verified what was the impeadance of that hustler antenna I was using. Then compared that reading according to what the math says the antenna should be, without the radio and coax hooked up. I believe that would be the ideal way to adjust the antenna. That's another good reason to have an analyzer too.

 

Lol... Ya that's easy to do. Sometimes I can't think of a word either when I'm trying to explain something. Anyway, I just bought a simple open/short test kit off of fleebay. Something like this kit.

SMA-Type 50Ohm NanoVNA Vector Network Analyzer Calibration Kit Load&Short&Open | eBay

You can make these kits if you have the time. But it seemed that after you buy all the parts, it didn't cost much more than to just buy the kit that's already made.

 

A few weeks later after I bought my sma kit. I discovered that mfj makes a calibration kit too.

MFJ-252U, ANALYZER CAL LOADS SET,UHF, HAS OPEN/SHORT/50 OHM

The nice thing about their kit, is that they use uhf connectors instead of the sma. That saves you from having to buy an adapter.

 

If you are referring to the mfj kit, they look like female uhf connectors. You will still need the male to male pl259 adapter. I think I paid $11 for the sma o/s/l kit. I bought the female uhf to sma adapter for $6. I already had the male to male pl259 adapter. That's a good video about making your own calibration kit. Here's a picture of what I have.