On 06/27/18 20:35 PM, Jim Miller wrote:
Could you layout the typical matrix of connectors from the cell
antenna down to what remains of the shed at the bottom.?
2G (GSM & TDM) used mostly simple N connector based transmission lines
with top and bottom N jumpers. Concept of PIM was largely unknown.
3G (CDMA & UMTS) sites typically have diplexers and/or triplexers, top
and bottom, with Bias T's to power TMA's etc., to maximize usage of
limited feedline counts. Lots of connectors (almost always 7-16 DIN),
lots of potential for PIM issues. Fortunately 3G was not as fussy about
PIM as 4G turned out to be.
I heard somewhere that there was a general move afoot to eliminate
the fire hoses running up the towers in favor of fiber and put the transmitter
and receiver electronics at the top.
4G (LTE) started out using the traditional 3G model (ground mounted RF
gear), but it quickly became clear that moving the RF to the tower top
was the way to go. So we're running power & fiber up towers, and
gradually retiring the big hardlines. In fact there was a brief period
when we were installing antennas with the radios built in. But that has
fallen out of favor already, for various reasons.
If true that would seem to put 7-16 on the way out along with all the
big hard lines.
On cell sites the 7-16 connector is a fine connector for the short
jumpers between the radio and antenna. The only problem is the size -
because some antennas and some radios are now coming with 8-12 RF ports
each. It's hard to weatherproof connectors that are only nanometers
apart. But...the cell industry is not the only market for high
performance connectors. I'm pretty sure that 7-16 DIN, 4.3-10 DIN, N,
and UHF will all be available for a long time.
-Steve K8LX
I haven't looked, but I'm guessing that neither of the *mini* DIN
series have much to choose from as far as connectors for 3/8"
braided coax (RG213, LMR400, etc). They were developed to be the
next generation connector for the Remote Radio Head to Antenna
jumper interface, which is 1/2" corrugated hardline 99% of the
time. The availability scenario will improve as time goes on, but
I'd bet on the 4.3-10 to be the survivor.
Whereas 7-16 DIN has gained enough market share to be available
for almost all cables, and will be for the foreseeable future.
The 4.1-9.5 has been around for 15 years at least, and is the
one properly called mini-DIN. The 4.3-10 is much more recent, and
was developed specifically with ultra low PIM in mind, plus high
density jack fields. The 4.3-10 is what all new cell equipment is
and will be using, especially as we move into 5G.
Either series though is a big upgrade to the N in mechanical
robustness.
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