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I am designing a active antenna (100KHz). Can I use AD 797 (ultra LNA) as the amp instead of JFET. the input output impedance of this opamp are similar to that of JFET (high input imp and low output imp). I have not seen any design implementing opamp in active antenna and was curious if there...

Hi I have got few papers which do not exactly explain the theory but gives an equation for calculating the secondary correction factor " Loran is retarded when travelling over sea water as opposed to through the atmosphere. When transmitted, part of the electromagentic wave is in air and some...

Thanks a lot guys I think a lot more research is needed If I get any solution I will definitely post it.

Hi Yes the ASF tables correspond to variations in conductivity. the time required for a loran groundwave signal to propagate comprises of 3 factors 1) primary factor using c = 3e8 m/s. (distance/speed) 2) secondary phase factor (SF), corrects for signal propagation delays over seawater...

Hi I too was under the impression that adjacent media does not affect the speed of light. But apparently there is a very very small change in speed (Loran needs a heck of a timing accuracy and 1us corressponds to 300m) Brian I think 100 Khz is still a high frequency to propagate through the...

These are some numbers I have come across in a paper and they mention that it is an all sea water path. I have found a paper "Geographic information system Loran C coverage modeling". I think this paper has few equations which may answer the question (I am not sure). these equations discuss...

You are correct. I am doing research in Loran. Hence all the timing problems. I think I will have to dig more into the Loran papers as there is no other good solid source of info.

Thanks for the reply. ofcourse C is the max. But in my application time is very critical. a few hundred miles (390 miles) of sea water path as compared to ground path causes a 1 microsecond timing difference and this is throwing me off in my further calculations. Does anyone know any papers...

Hi Is the propagation of a signal on a sea water path faster than that on a all ground path. I know that conductivity causes this but what is the equation or theory that explains this effect on speed. All literature I have got explains propagation INSIDE the medium (in water, in air). My...

I will read more about active antennas and probably buy one thanks

hi thanks By keeping the antennas outside reception is very good. I am will look more into active antennas now thanks

Hi Thanks for the reply. I cannot understand the effect of wavelength over the reception. Can you please give me a clear explanation. Sorry if this causes you any inconvenience.

Hi Thanks for the reply. I am working at 100 Khz hence i cannot use E field antenna (size issues). Is it possible that I use two H field antennas placed at right angles and get a near omnidirectional radiation pattern. How do I sum the outputs of these two antennas. I am thinking of using a...

Hi Thanks for the reply. The antennas are working now and I am still not sure what was the initial problem. I still have one problem. I am known that H field antenna works good inside the building. But my H field antenna dosent... It works very good outside .. but inside it cannot pick up...

what is a magnetic crossed-loop antenna and how does it work.

Hi I am trying to receive Loran (100 KHz) signal using H field and E field antenna. The E field antenna has o/p impedance 50 ohms and a gain of 20 dB. I pass this signal through a LNA (30 dB gain) and then BPF and I get a very clean loran signal. The H field antenna has o/p impedance 50 ohms...

Hi I am trying to receive Loran (100 KHz) signal using H field and E field antenna. The E field antenna has o/p impedance 50 ohms and a gain of 20 dB. I pass this signal through a LNA (30 dB gain) and then BPF and I get a very clean loran signal. The H field antenna has o/p impedance 50 ohms...