In a recent article I discussed how InsertionLoss implies InsertionVSWR in lossless devices.
This article looks at measurements of a few antenna switches at hand.
Daiwa CS-201G II
It is difficult to find comprehensive data on the very popular Daiwa CS-201 series switches.
Above is the data from the packet of one of these switches, a CS-201G II. The specifications are pretty loose, and one must depend on one’s own measurements.
Above, the CS-201G II, a basic CS-201 series switch with N connectors, advertised as useful to 2000MHz where InsertionLoss is given as 1.2dB (or better?). If there were no TransmissionLoss in the switch, that would imply InsertionVSWR=3.6, but there is probably some significant TransmissionLoss and InsertionVSWR would be somewhat less. Nevertheless, IMHO InsertionLoss=1.2dB indicates it as unsuitable such frequencies.
Above, a scan of InsertionVSWR 1-500MHz suggests the switch is quite good to 500MHz where maximum InsertionVSWR=1.15.
In some applications, isolation is very important. Isolation=-S21, and above is a scan of S21 shows isolation to be quite good as switches go. The scan does not go to 2000MHz, but the trend is that isolation will be considerably poorer than the specified 45dB at 2000MHz.
But, all in all, a fairly good switch for use up to 500MHz.
The D-5200 was sold by Dick Smith, and is widely available under a range of model names. It appears to be a Japanese clone of the Daiwa CS-201A, but the mounting lugs are located differently. Internally, it is similar and they weight within 1% of each other.
These are often rated as suitable to 600MHz (as is the Daiwa CS-201A… if you are going to steal the design, then steal the specs).
Experience says that you cannot get good performance to 600MHz with UHF series connectors, so lets see how it measures up.
Above is a scan of insertion VSWR to 500MHz. Maximum VSWR is 1.3, it really isn’t suited to use above 150MHz.
Above, the VSWR scan to 150MHz shows maximum InsertionVSWR=1.2, usable but quite usable for most non-instrumenation purposes to 60MHz.
Above is the isolation plot to 150MHz, again usable to 150MHz and quite good to 60MHz.
The following describes a home made switch where the emphasis was on low InsertionVSWR (at the expense of isolation) to 60MHz.
The switch was built into one end of a small die cast aluminium box.
Above is an inside view that shows the ground bonding applied over the top of the wiring.
Above is a tilted view that reveals a little of the internals. The centre conductor is wired using flat brass strip which roughly follows the brass ground plane to achieve less disruption of Zo.
Above is the InsertionVSWR plot to 150MHz, showing Insertion VSWR quite good for HF, and acceptable for most purposes to 60MHz.
Specifications for ham grade coax switches is usually sparse and hardly informative, especially considering advances in instrumentation.