I noticed this antenna park in Heidmoosstrasse, Switzerland. What is it used for?
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3 Answers
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UPDATE: I've started a followup question regarding the leftmost antenna, which I originally took to be a discone. See: What sort of antenna would use a bicone or lozenge-like arrangement of vertical wires? (Thanks @HK1A for noticing my error!)
I see at least four antennas in that picture: one discone mystery antenna on the left, two log-periodic on towers in the middle, and a dipole above the building. All look like they are designed to work best at relatively low frequencies, specifically (and confusingly) within the High Frequency (HF) region.
The discone and the LPDAs [would be] interesting to compare and contrast [even though there's probably not a discone in the picture after all]:
- Opposite: a discone is omni-directional (receives/transmits fairly equally all around), while a LPDA is directional (signals focused to/from one direction).
- Opposite: though the polarization is not terribly critical for HF signals, note that the discone is mounted for the vertical component, while the LPDAs are mounted for horizontal signals.
- But alike: both the discone and the LPDA are "wide-band" antennas, which means they work well through a whole range of frequencies. Most antennas work best only within say ± 1% of a particular frequency and/or some harmonics, whereas these antennas work continuously from their lowest frequency to something 5–10x higher than that.
The dipole here is the one that almost looks like a telegraph wire coming out of the shack on the right and then T-ing out above the fence in the picture's framing. That one works on one or a small handful of "fixed" frequencies. Coupling "broadside", it's not really omni-directional but it's not particularly directional either. I shouldn't make it sound too boring, because dipole antennas are pretty much the fundamental concept within the rest of antenna theory. Just not nearly so versatile, or cool-looking, as the other two :-)
answered Mar 8, 2019 at 22:18
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$\begingroup$ @HK1A Ah, yes… good observation. I should make a QA topic for that since I'm not sure of the implications there. $\endgroup$ Sep 23, 2019 at 17:15
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$\begingroup$ The one on the left looks more like a fat (broadband) vertical. $\endgroup$ Sep 25, 2019 at 9:33
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$\begingroup$ The polarization is critical, just not predictable. Fades of 20 dB can be avoided with polarization diversity. Example: lz1aq.signacor.com/docs/antenna-performance/… $\endgroup$ Sep 25, 2019 at 14:01
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There are several antennas of different types. Near the front looks like a discone antenna and the beam on the tower looks like a Log Periodic antenna.
Such an antenna farm is typical of a government or military installation. In the US, the regional FEMA (Federal Emergency Management Agency) sites have similar antenna farms. These are designed to provide multi-frequency (HF, VHF, UHF) communications in times of emergency.
I am not familiar though with Switzerland but likely it is a government site.
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$\begingroup$ Also, the the low height of the dipole may imply that it is intended for "near vertical incident skywave" (NVIS) propagation to provide local and regional communications on HF (medium wave) bands otherwise used over longer distances. $\endgroup$ Mar 8, 2019 at 23:05
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The antenna in the left foreground is probably a conical monopole, as described by E.W. Pappenfus, WB6LOH, in QST for November 1966. Antennas of the size order shown in the OP are probably for use from 4MHz and higher in the medium-wave band.
