Public service radio - aircraft bands - are transmitted with massive amounts of power. Not to mention the fact that the airplanes are in the air when they are mainly transmitting. Not that there is much traffic to listen to anymore, with most things being computerized and digital.

There is no reason to use a 3/4 wave antenna, nor is there any benefit in using a antenna more then 5/8 wave long.

Might I suggest you get a copy of the ARRL antenna book, it will cover it better then I can.

The bottom line is - if all you want to listen to is local traffic, all you need is a 1/4 wave antenna - mounted outside, in as clear of a place as possible.
Some building materials - concrete reinforced steel - being one, is opaque to good radio reception.

All effective communications is line of sight.

The best scanner antenna for the money would be a Diamond Discone type antenna - which would cover anything from 10 meters to 999 MHz - all in one antenna.

Using a good high grade coax and connectors would be key to good reception.

As a example, Cleveland Approach is 120 miles from my location, with my Uniden 890XLT - I can hear Cleveland approach and the air traffic between Cleveland / Pittsburgh and Baltimore MD from my location in Central PA.

Not to mention the local air traffic.

Even a old VHF television antenna would get you some reception...

Copper J Poles are great for experimental purposes, but not real good when it comes to reliable reception - even though you are just going to use it inside of your house.
They do offer some front to back - directivity in one or more directions, but there is no reason to use a piece of copper pipe if all you want to do is receive.

You can acheive practically the same thing with a piece of 300 ohm twin lead - if assembled properly.

I have even seen antenna's that were made out of copper foil that worked for what you want to do.