GPS antenna with zero and 90 degree feed ports

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HexAndFlex
Posts: 13
Joined: Sat 06 Oct 2018, 09:11

GPS antenna with zero and 90 degree feed ports

Post by HexAndFlex » Fri 13 Nov 2020, 08:16

Hi all,

I need to do some work modelling a GPS antenna(RHCP patch).

Physically, this will be fed by a 90 degree hybrid to achieve the desired circular polarization. To simplify and speed up the simulation, I don't want to try and model and simulate the hybrid.

I would like to excite my antenna via 2 lumped ports with 90degree offset signals. However I can't seem to find a simple way to do this.

Does anyone have any tips on what the best way to achieve this?

HexAndFlex
Posts: 13
Joined: Sat 06 Oct 2018, 09:11

Re: GPS antenna with zero and 90 degree feed ports

Post by HexAndFlex » Mon 16 Nov 2020, 14:08

I think I have it working. The answer was buried in the forum, but needed an extra bit of digging to work out how to add a delay to a lumped port.

The simplest way is to add a Delay as shown below

Code: Select all

start = [feed.pos 0 0];
stop  = [feed.pos 0 substrate.thickness];
[CSX port] = AddLumpedPort(CSX, 5 ,1 ,feed.R, start, stop, [0 0 1], true);

start = [0 feed.pos 0];
stop  = [0 feed.pos substrate.thickness];
delay = (1/GPS_L1)*0.25;  #quarter wave time delay
[CSX port] = AddLumpedPort(CSX, 5 ,2 ,feed.R, start, stop, [0 0 1], true, 'Delay', delay);

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