[MOVED] UWB Transciever Design

Hello all,
Its Ali here. I am a Electrical (Telecom) Engineering student and my Final Year Project (FYP) is Portable GPR in which I am designing UWB transceiver. Currently I am working on the transmitter part.

Here are a few specs of the design:
-Simulation Software: NI Multisim 12.0.1
-Its an Impulse Radar with Bandwidth of 1 GHz centered at 500 MHz (currently)
-I used the logic of NORing a clock with its inverted delayed version, giving an approximate Gaussian Pulse of duration 1 ns. Clock decides Pulse Repetition Frequency (PRF). Its frequency is set to 100 MHz currently. (Idea from the Paper I am following)
-I generated the ref using AD 8009-ARZ, a high speed Op-Amp and generated the inverted version of it using the same op-amp.
-I made the NOR gate by generic transistors (FETs). (Please guide about practical transistors I should use)
-I haven't designed the pulse amplifier yet (current output voltage)

First of all, please comment on the approach I am using i.e., is it okay to generate clock using Op-amps? Is there

any other better way? etc.

The problem(s) are as follows:

-Antenna Design (Vivaldi etc.) on frequency of 0-1 GHz yields an impractical design. I thought of designing an active modulator to ease off the antenna design but have no idea on how to do it. Please help me in this matter.
-Choice of transistors for NOR gate.

What, in your opinion is the best approach to tackle this project?

If anything I wrote above isn't clear, please say so that I can elaborate it/provide visual aid.

P.S: Please don't quote number of results of google by just typing 'frequency multipliers' or anything else like that. I have done my homework on this.

Also, the more you elaborate, the more I can understand as I am quite an amateur in this matter. :)

Thank you in advance.