Recent content by ve7lyd

Say the local oscillator is always on and you are just switching the routing between tx and rx mixers. Will the spectrum analysis look the same as a AM transmitter modulated at 100% with a square wave? I would think its different since you never switch off the AM carrier, you only add...

Say a relay which switches the PTT lines of a radio. The relay coil is hooked to the square wave generator. For the sake of argument say the relay was perfect and is able to switch at the exact same rate as the relay coil. The square wave would be 0 to + voltage.

chroot's right its not the resistance in the wire, its the capacitance and inductance, which is the root cause for a velocity factor of less than 1 and greater attenuation at higher frequencies.

The only way I can think that something can charge "wirelessly" would be to inductively couple it, but that's nothing new... just maybe to cell phones. To use RF in a house would be quite dangerous, the power levels necessary to charge anything will give you an RF burn if you got too close to...

The south american thing sounds like a myth. The voltage present in the air due to RF is in the microvolts. To get any usable voltage from this, expecially to power appliances isn't possible.

I can't see why this technically can't be done. Soldering irons run at 700 degrees all day, although they will burn tips out eventually if this is done. Now to make one is another story. I figure that a regular car lighter would burn out quickly if left hot all the time. I have a feeling...

I can't see how this is possible, at least with RF.

Don't know if its too late to answer this but here it goes. 1st convert everything to dB, adding and subtracting is way easier then multiplying and dividing. So 100000 Watts EIRP = 80 dBm. Free space loss of 4 GHz at 35,800 Km is 196.2 db. So 80 - 196.2 = -116.2 dbm. Your receiver needs -75...

Hello, have a question... A friend and I have been discussing the difference between an AM signal modulated at 100% and a CW key. The AM transmitter would be modulated with a square wave, and the CW key would be turned on and off at the same rate. The debate is if the spectrum will look the...