A network analyzer is ideal to test your first two circuits. The network analyzer applies a swept-frequency RF stimulus to one port of your circuit and measures the response at the same or a different port. A scalar network analyzer only measures the response magnitude and a vector network analyzer measures both magnitude and phase.
The key to obtaining accurate measurements from a network analyzer is calibration. Essentially this means testing known standard devices to determine the performance of the network analyzer, then using this knowledge to correct the measurements you do later on your device under test (DUT). More and more complex types of network analyzer allow testing more standard devices to obtain more and more accurate final measurements. Your network analyzer will come with detailed instructions on how to do the different calibrations that it supports.
So for a butterworth filter, you calibrate your network analyzer, then connect your DUT, measure the response, and check whether it matches the ideal response of a butterworth filter. If you also have specs on return loss, you could check those at the same time.
For a power amplifier, you would measure the response and see if the gain is what is required.
If you want to test your PA for harmonic distortion you will rather have a synthesizer and a spectrum analyzer. You apply an input at different frequencies and power levels using the synthesizer, and use the spectrum analyzer to measure the power in the output fundamental and harmonics.
For an RF detector, you would apply a stimulus using a synthesizer and measure the output using a multimeter.
For the comparator, you will probably need to set up something more complex -- your set up will probably involve an osilloscope. What you test will depend on what are your critical specs and how your final system will work.
The standard link loss equation is: -
Link loss (dB) = 32.4 dB + 20log(MHz) + 20log(kilometres)
If your RF sensitivity is -121dBm (about right for 1 kbps) and you can transmit at +20 dBm then it could theoretically (in outer space with very little interference and without earth getting in the way) work with a link loss of 141 dB (20 dBm - (-121 dBm))
So, we now have 141 dB = 32.4 dB + 59.2 dB = 20log(km)
Therefore 20log(km) = 49.4 dB which means distance = 295 km = 183 miles.
All sounds great until you factor in real-world problems such as fade margin - this is a kind of rule of thumb that suggests that link loss (at any given distance) is usually degraded by at least 20 dB. I'm not going to justify this BTW.
This now means distance is 29.5 km = 18.3 miles.
By the way, 0 dBi antennas usually imply isotropic antennas (a theoretical device) but straight wires usually imply a quarter wave dipole and these have a small gain of about 1.7 dB.
If you were transmitting at 28 kbps, your receiver sensitivity will be decreased to: -
154 dBm - 10log(data rate) = 109 dBm - this reduces your range to about 7.5 km = 4.6 miles.
If you are in a built-up area with buildings and other forms of interference you might lose another 10 to 20 dB so be aware of this.
Here is a very approachable document that largely covers what I've said in my answer.
Best Answer
Here is an extract from the LT5534's data sheet. Note the part enclosed in a red box: -
What that line is saying is that the input power range is -63dBm to -2dBm i.e. a range of 61dB as indicated in the line below.
If you are still confused then 0(zero)dBm is 1 milli watt and if the circuit impedance is 50 ohm this means: -
\$\sqrt{P R}\$ volts or \$\sqrt{1\times 10^{-3}\times 50}\$ volts = 223.6mV RMS.
If you are still confused -63dBm is a power level of 501.2 pico watts and -2dBm is a power of 631 micro watts. I think you should be able to convert these to voltages by now.