Martlet 3 Radio Antennas
Thought/Research Dump
We need
A low profile antenna that doesn't get in the airflow
A radiation pattern that ideally has telem going to the ground and GPS to the horizon and up
Resonant on about 868MHz for telem and 1.6GHz for GPS
Problems include
Rocket bodies all conductive so can't easily put an antenna inside
Nosecones an option on boosters only, and even then they separate so not ideal
Some easily discarded designs/ideas
Possible options
Probably the cylindrical patch is the best option. Some details…
Dielectric permittivity sets the size of the patch, so higher would be better
But higher dielectrics give lower bandwidths and efficiencies
Also the dielectric gap has a small effect on the size, and a big effect on the bandwidth and efficiency
We'd like a very small gap but that would give a very small bandwidth
Radiation pattern is broadside from the rocket which is not ideal
Various options for feeding - inset feed with a probe might match to 50R but is hard to do with multiple feedpoints. End feeding gives 200R impedance but we can use a microstrip feed network to match and distribute. This seems the most common approach