Looking for materials about using 1GHz antenna which is buried in the ground
Do you know any good papers on this subject?
Do you have any recommendation on what kind of antenna is the best for this appication?
Thank you for your help.
- Sai Kwok
I did a long study once. Burried under 4" of dirt is not much of a problem for short range communications (30 feet or so). The problem is more in the composition of the soil. If it is going to get wet, it is going to be more of a problem. Also, there are problems with the antenna. You can use something like a standard quarterwave antenna, but you need to enclose it in something to keep the dirt/moisture away, as they will detune the antenna's resonant frequency and cause real trouble.
As you might expect, lower frequencies would work much better. Using an ISM frequency, like 13.56 MHz, would penetrate much better.
There is some recent work on "magnetic" communications that would do better underground, you might want to look into it.
Rich
Rich:
Thank you for your response.
Soil moisture and salinity is a problem for high frequency.
You mentioned about magnetic communication, could you please provide references on this topic?
Regards,
For everyone's education and amusement, in years gone by when atomic bombs falling were a reasonable assumption, many nation's military had HF and lower frequency antennas buried underground so that they would not be damaged by the blast. They found that there were two ray paths. One through the earth and one up bounced against the ionosphere. These had drastically different time delays which formed multipath interference which, using the valve technology of the time, could only be overcome with very low data rates and FSK or OOK modulation.
As far as the magnetic loops, these are decades old technology. One first use that I know of was at hospitals where there was one loop around the whole building. It was used to signal to receivers carried by critical medical people that they were needed immediately in a certain room because the patient was very near death and needed help.
http://www.sara.com/ISR/low_frequenc...unication.html
http://publications.drdo.gov.in/gsdl...dc.dir/doc.pdf