My first post. I am trying to figure out why the readings I and 2 others are getting that are fairly off the targets real address. We know the general area he is located. Since I am a Ham radio operator the antenna SWR is always important. If I use the 3D antenna arms to measure the antenna length to the frequency UHF range the SWR is over 10. I am using a Rig Expert Antenna analyzer. If I lower the antenna considerably then I get 1:4:1 swr. Does anyone have a different method to measure the antenna lenghts for the given frequency ?
The readings I get are off from a known test transmitter. I started looking at the antenna height settings.The 3D array has measurements for the frequency desired. However when I checked the SWR was 10+ I understand your statement. I have found a tuned antenna “hears” better at a lower SWR than one that is 3+ and up. Its just something I am trying and asked if anyone else has antenna height measurment methods. I also recently discovered the paper array is quite different than the 3D printed arms. I am looking in the 467mhz range
Usually SWR is important for transmission. If you want to adjust the antenna by SWR, then this is only true here and now. You need to install the antenna, lay the feeder and connect a vector analyzer like NANO VNA. Then adjust the length of the antenna. And even in this case, it will be a relative adjustment. Correct antenna adjustment requires knowledge, devices and experience. Good luck.
Thank you, I have the equipment and knowledge. I have set them all the same height. Just the first section out gives me a 1.4 SWR at the end of the cables that connect to the Kraken. I am looking for confirmation or a documented method to adjust for a given frequency. We have the placement worked out the height seems to be a moving target. Just looking to see if anyone else has come up with a method they know works.
By height, do you mean antenna length, or mounting height over vehicle roof?
In either case, the rapid phase shift near resonance should be avoided. This would have the effect of distorting the distance from center of the antenna, and it would be hard to get them all tuned exactly the same. I’ve not seen the antenna length make much difference in real world performance with the Kraken, at least not as much as you seem to be expecting. I’d use different antenna lengths for 2m and 440.
The spacing from center is not intended to tune the antenna to resonance, rather to maximize the phase difference between antennas without exceeding the max shift, where the direction finding ability would be seriously impaired.
As Vadim said, you might want to use a VNA to adjust the antennas, but be aware that they also interact with each other. Don’t be surprised if the antennas don’t read the same after you adjusted one to your desired point. They are rather close to each other.
Also, pull up a calculator for impedance mismatch loss, and decide if the fraction of a dB difference is really worth the pain.
In regards to height. I am asking how far to pull the telescopic antenna sections for any given frequesncy rang. I have a VNA and a RigExpert antenna analyzer. I have just the first section pulled out and all 5 antenas have a good reading. I am looking for any know methods to adjust the antennas. I am not trying to tweak every db out of the array. I am just trying to get it to at least get me closer to where the transmitter is and not a mile off target once you get there. Again thank you.