VSWR Terminator

BNC connectors are rather indecent going up to three giggles; use H, HN, or GR.

I'd like to see the 1 MHz antenna next to the 3 Gig unit! That sort of testing sounds a bit weird. A quick & dirty way is just using a Bird antenna analyser, a bit pricey but they get results fast. ( nothing up to 3 gig though)

Oops , guess they DO have one..to 6 gig

OK, these are for a ship, so yes all the antenna's will be closely placed on a mast, however great thought by minds sharper than mine have devoted themselves to a layout that utilizes harmonics, dead zones, shadowing and ground planes to prevent interference.

The antenna's are fed by heliac and most of the connectors are 'N' which would eliminate the need for adaptors. There are some H and HG connectors as well, but using adaptors for testing these is acceptable to the customer. Most of the adaptors we have are to or from 'N' style, so that is the preferred style of connector in our lab.

Again, this customer is a 400lb gorilla. They have decided already how they want the antenna's tested. There is no altering what they want. I cannot use an SWR meter. Period. I wish I could. I already have several and it would make my life so much easier.

Don't get me wrong: Thank you for your time in responding, however it does not meet what I need.

RK

The carbonbased lifeform rjkfsm inspired sci.electronics.equipment with:

With the setup you describe the return loss is directly read from the SA when you attach the antennae, no need for an extra calibration. All you need to care about is the directivity of the coupler, which needs to better than the return loss you expect.

Nop, sorry.

Theo

Am I missing something here? Is your 400lb gorilla expecting his antennas to exhibit a lower VSWR than a precision termination?

I'd be more worried about finding directional coupler(s) with sufficient isolation over that frequency range than finding precision terminations, which are fairly plentiful.

Dunno how long your cables are, but their attenuation will mask out small mismatches, anyway, especially at the top end.

rjkfsm

How about using some known attenuators with either shorts or opens on the far end to generate a precision reference R and therby a known VSWR, assuming Heliax, connectors and all are OK. Errors in this value along with directivity of the dual directional coupler reduce margin but it's unlikely that they are bad compared to antennas in the environment you describe.

If you don't want to do the math, you should be able to measure the input resistance of a decent attenuator terminated in a short or open (keep it the same for all measurements) and safely assume that the R is constant with frequency and the the parallel Z is very high.

If you don't mind doing the math, you can validate your method for the gorilla too.

Glenn