Total posts : 45366
Ermi wrote: Thus, the receiving monopole gain is 6 dB less than the transmitting monopole gain when groundwaves are received. The many thousands of field strength measurements Rich mentions of monopole antennas generating groundwaves are not relevant to this discussion because the transmitting monopole gain is not in dispute.
By Ermi’s analysis, the receive monopole has 3 dB less groundwave gain than a dipole in free space, not 6 dB. The additional 3 dB claimed in Ermi’s 6 dB value is the result of the proven 3 dB gain of the monopole transmit antenna above that of a dipole in free space. So the gain of the transmit monopole is not irrelevant in my previous posts as stated in Ermi’s quote above, or to this analysis.
Ermi has attributed the net gain/loss of this transmit-receive monopole system compared to dipoles in free space as belonging to the receive monopole antenna, alone.
As Ermi has stated that this gain difference for receive monopoles does not apply to received skywaves, maybe he will post his views on the gain values of the elevation pattern of the receive monopole in the region between zero degrees elevation and the elevation angle where he expects that reciprocity takes affect.
Regarding Ermi’s comments about the effective height of the receive monopole I will repeat my statements from my earlier post.
Quoting from Section 11, paragraph 8 of Radio Engineers’ Handbook, 1st edition, by F. E. Terman:
“…the relative response of the antenna to waves arriving from different directions is exactly the same as the relative radiation in different directions from the same antenna when acting as a radiator. Also like the antenna directivity, the effective height and the impedance of the antenna are the same in reception as in transmission. These reciprocal relations between transmission and reception properties make it possible to deduce the merits of a receiving antenna from transmission tests, and vice versa.”
There is no qualification — this applies to all forms of antennas.
As far as I have discovered, there is no authoritative reference stating and conclusively proving that reciprocity fails for monopole antennas — even for the groundwave.
My regrets for introducing the system performance of two dipoles. The subject here is the reciprocity of a single monopole, and not how two monopoles compare to two free-space dipoles.