I have done an experiment to demonstrate the negative effect of high SWR. Details & pictures/graphs are given below.
Note: I have used RRD Tool /Collectd to plot the performance graphs. Thanks to Oliver Jowett (@obj) for adding the functionality in dump1090-mutability, and to @Xforce30164 for providing auto-install script with very useful tweaks.
I made a Spider and a Franklin-Spider. Simulations gave following results:
Gain: Spider = 1.7dBi, Franklin-Spider = 3.5 dBi
SWR: Spider = 1.4, Franklin-Spider = 2.0
When put on trial run, in spite of Spider having much lower gain than Franklin-Spider, it out performed Franklin-Spider. The reason was not obvious till I added an impedance matching network to Franklin-Spider, bringing it’s SWR down, and then Franklin-Spider out performed the Spider. Please see simulations & photos below.
Image 1 of 6 - COMPARISON GRAPH
Image 2 of 6 - SPIDER
Image 3 of 6 - FRANKLIN-SPIDER
Image 4 of 6 - FRANKLIN-SPIDER (WITH IMPEDANCE MATCHING NETWORK)
Image 5 of 6 - SIMULATION OF SPIDER
Image 6 of 6 - SIMULATION OF FRANKLIN-SPIDER