Other sites  
  - My older page on the subject
- Green Bay Professional Packet Radio (pretty much everything)
 Design Considerations  
  - The FCC code section 15 which covers interference
- Presentation on how the cellphone network functions
- Technical requirements for cell jamming
 VCO design 
  - Maxim's VCO design guide
- Minicircuits' VCO concept
- Alpha Inc's (now SkyWorks) excellent Wideband VCO design, Differential Wideband VCO and Low-phase VCO for PC
 RF parts  
  - Mini-Circuits (RF/uWave designers)
- Micronetics (VCOs and other)
- Analog Devices (Nicely designed parts)
 RF resources  
   Sites:
    
  
  - Philips' RF design guide covers RF design basics
- RF Avenue, for almost everything you could possibly want to know
- AVX has an amazing capacitor specification system that generates datagraphs on the fly based on their spice models
Books:
- The ARRL UHF/Microwave Experimenters Manual - recommended to me but I didn't get much out of it.
- RF Circuit Design by Christopher Bowick - good basic stuff if you've never done RF
 Antenna design  
  
  