Rat Race phase shifter // or Hybrid junction for phase shift
Rat Race phase shifter // or Hybrid junction for phase shift
(OP)
I'm looking to design a sysetm that will let me feed four patch antennas out of phase. First one, 0 degress, then 90 degrees, 180 and 270 degrees. Question is where can i find a design for a rat-race type hybrid, OR is there a way i can use a number of hybrids to accompolish this? Power is 20 watts, frequ is 200-400 MHz.
RE: Rat Race phase shifter // or Hybrid junction for phase shift
Start with mincircuits or use werlatone if you have the money.
kch
RE: Rat Race phase shifter // or Hybrid junction for phase shift
Frank
RE: Rat Race phase shifter // or Hybrid junction for phase shift
Patches aren't 2:1 bandwidth (not even if you say please), they're typically 1% to 20%.
Do you really mean patch antennas?
If yes, then you're probably operating within the 200-400 MHz band and only need a small percentage (like 390 MHz +/- 10 MHz), or you thought patches were wideband.
kch
RE: Rat Race phase shifter // or Hybrid junction for phase shift
again thanks,
f
RE: Rat Race phase shifter // or Hybrid junction for phase shift
If you're forced to retreat to a narrower bandwidth, then you could use cable lengths to set the relative phases. For example, when making circular polarization with crossed dipoles, it's common to use cable length to set the 90-degree phase delta.
RE: Rat Race phase shifter // or Hybrid junction for phase shift
Tough to do at your frequencies, you'd need a patch at 400 MHz that's 6" tall and 14" long. Twice that at 200 MHz. Do you have the room? Your array will be 30" square x 6" tall for a four element array at 400 Mhz and 60" square and one foot tall at 200 Mhz, roughly +/- 15%.
We did some thick and double tuned patch designs last year. See Pozars book on thick patches. He says 20% vswr bandwidth with a thick patch.
kch
RE: Rat Race phase shifter // or Hybrid junction for phase shift
The ViaSat QDC-100 combines four antennas for enhanced reception of UHF MilSatCom around 300MHz. It also controls a 1-of-4 switch for the transmit path. There's info on the 'net.