Coax Cable for the Microwaves
Ron J. Whitsel W3RJW
Jumpers and short pieces of coax are often needed when setting up a microwave station. Be very careful with the coax cable you use. Never, never use RG-214 at any frequency much above 3 Ghz unless you have need for a dummy load. LMR-400, both the standard and the ultra flex, are usable all the way up to 10 Ghz when some loss can be tolerated. Below are measurements taken on new pieces of RG-214 and LMR-400 Ultra flex. This data can serve as a guide in making coax use decisions.
Loss in 6 Feet of Cable
1.227 Ghz - 0.61 dB - 0.45 dB
2.032 - 0.77 - 0.59
3.502 - 1.20 - 0.91
5.690 - 2.50 - 1.50
10.100 - 50.1*
- 1.80
* There may be a 'waveguide beyond cutoff' effect in this measurement, but loss is loss.