Dave simply speaks truth. A lot of antenna limitations and abilities is simple physics that you can't escape.

Antenna size: think about audio amplifier power. Doubling the power gives you only 3 more dB of audio volume. It's reasonable to expect that actually doubling an antenna's size gives you in the best cases 3, no more than 6, dB more signal.

As for antenna styles, the GhostKiller worked wonders when I had to mount on a single-story roof on Ventura Blvd where Mt Wilson is very much in line with many tall buildings and reflections from behind the antenna messed up a lot of the signal. Even with the back signal limited, I had to try a couple of roof locations to get decent VHF reception.

I learned the power of aiming away from a transmitter with an FM antenna in the Hollywood Hills. The client wanted to receive 88.1 FM, KLON, The Jazz Station, some thirty miles south AND on the other side of the hills AND a low power station, to boot. I aimed her antenna at that station and she got it! Other stations came in well, too.

But there was some kind of interference there on 88.1. I spent some time listening to the interference and I realized it was a radio station, so I got another receiver and tuned around until I found it. It was 98.7, a rock station, with a transmitter on the top of the Hollywood Hills about a mile from the client.

Why was 98.7 such a problem? Well, it's 10.6 MHz away from 88.1. 10.6 is close to a REAL familiar number: an FM tuner's IF frequency is 10.7 MHz. Apparently the strong 98.7 signal was powerful enough for some of it to blast past the filtering sections of the tuner's IF section.

That made me grin. All I had to do, I hoped, was to lower the signal coming in from 98.7.  I went up on the roof with my signal meter and rotated the antenna. About 15 degrees away from the best aim toward 88.1, I found the worst aim for 98.7, and the interference totally disappeared.

The excellent nulling ability of the antenna allowed me to kill 98.7. The normal wide hot spot 90 degrees away allowed her to still get plenty of (weak) signal from 88.1. The signal meter made it possible to do it at all. Case closed and it's ten years later.