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Bends on a TEM line do not create other modes but cause reflections. To reduce reflections, various manuals recommend to increase bend radius or modify characteristic impedance .
What theory? The input voltage is defined by the output voltage from a signal source having a source impedance say R. Then when the signal voltage exceeds Vcc (plus junction voltage, typically 0.7 V), the R with the diode forward resistance forms a voltage divider. Diode forward resistance is...
The two-diode clamping circuit will not allow voltages exceeding the positive or negative lead to get to protected device input.
What is missing is the signal-source resistance which will define a maximum input current for a voltage exceeding the above indicated limits. For such current the...
One problem is that you did not mention if your anechoic chamber is specified for your frequeny of interest. Locating antennas so close as less than 10 wavelengths does introduce large errors due to coupling, ground proximity, etc.
The best solution is to use an open range for such...
+13 dBm looks not enough for Class C operation. Simply make a one-stage amplifier with output tuned to the
3rd harmonic, and adjust the operation point by base current for a max output. At 100/300 MHz, even audio transistors can work. I would try a popular 2N2222 transistor, with 12 VDC and 10...
Good luck! For 100 to 300 MHz I would use a transistor multiplier, it is easy to build and run, has a gain instead of loss, and its input impedance is 50 Ohms.
I would disagree. The I-V nonlinearity of a SRD generates a wide frequency spectrum like a spark gap, and if you filter only the third harmonic, the efficiency will be quite poor. This is why Manley-Rowe equations apply for non-linear variable capacitance elements.
This is why I would recommend...
If you use a standard VNA, it generates a low power for which a SRD multiplier would need an external DC bias to operate. Parametric SRD multipliers usually run at +17 dBm or more, and rectify their DC bias on an adjusted resistor for the optimum perfomance.
If I may, I would add some practical notes.
The PIN or SRD diode multipiers operate as parametric devices. I saw some attempts to calculate input impedance but it never worked. The truth is that you need a wide-range input impedance matching device, like a series-parallel variable capacitors...
The "DC channel sensing", if it means that along with a RF signal you also send a DC voltage like +12 V, can be done using a "bias tee". This is a device with a capacitor in the RF line (between RF connectors), while the third port (usually not a RF connector) is connected with one of the RF...
First to start: Yes, you will damage the spectrum analyzer by applying 12 V DC to its RF input. Inside there is a precision RF attenuator with 50 Ohms nominal impedance. DC input will burn the first resistor and repairs are costly.
To understand the spectrum analyzer use, please find Agilent...
Depends on what point is desired. If you need to detect antenna connection to a device like a transmitter, use a SWR indicator or a reflectometer. A matched antenna will generate a low SWR response, a disconnected antenna a high SWR output.
Another problem is to detect antenna presence in a...
I am n o antenna expert but if you need a fan beam, you can use either prime-focus or Cassegrain or Gregory optics with an offset feed. This avoids any problems you mentioned.
I do not agree. Please look in any choke flange of a waveguide, to see a shorted stub.
If you leave a structure to radiate, it does not make a better short to ground.
I have never heard about a fragile junction with holes. My noise dipole with eb diode of a SMD transistor I made 20 years ago was adjusted for 8 mA to make a strong noise at 11 GHz, and I use it to calibrate and check my radio telescopes. No change was observed except I have to replace the 9V...
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