Antenna match--how bad is ok?
时间：04-10
整理：3721RD
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I have been investigating small antennas for 315 MHz operation, and am basically astounded at how poorly these thing operate out of the box!
I tried one "short" helical that, if you breathed on it, changed resonant frequency by 100 MHz. I have tried another surface mount type whose impedance appears to be 5 -j30 ohms at the "matched" input.
Is it common for commercially available, cheap, board mount style of antennas to be a joke as far as impedance goes. I could probably just snip off a piece of coat hanger, length unmeasured, and jam it onto my board and get better performance.
Am I missing something here?
I tried one "short" helical that, if you breathed on it, changed resonant frequency by 100 MHz. I have tried another surface mount type whose impedance appears to be 5 -j30 ohms at the "matched" input.
Is it common for commercially available, cheap, board mount style of antennas to be a joke as far as impedance goes. I could probably just snip off a piece of coat hanger, length unmeasured, and jam it onto my board and get better performance.
Am I missing something here?
You are right, and you are not missing anything... Especially in this domain the market stinks with a lot of products that probably worth less than 10% of their value.
So many times I proved that small piece of tuned wires works better than ?smart? innovations as chip or SMD antennas.