Antenna manufacturers are dishonest and misleading !!
The real problem I see for the most part is your need to receive VHF & UHF channels using one antenna. Unfortunately there are not many choices available in a small package the would be practical for an apartment balcony (Except for my design, which is not really available currently due to patent issues). It really aggravates me to see all of these brand name antenna manufacturers that take advantage of consumers with clever marketing and misleading packaging that makes DTV reception seem so simple.
The consumer gets the poorly designed antenna home expecting great results, only to be disappointed with the results, leaving them feeling that they got ripped off, which they did. Simple physics states that there is no antenna that will receive a signal that is not there. You have to have a reasonable amount of energy reaching the antenna, but this is where the consumer who does not understand the physics themselves gets blindsided by the antenna manufacturer by all of their hype and misleading promises, which then leads to discontent with potential DTV viewers who then spread the rumor that DTV is not worth trying.
Virtually all TV antennas are a compromise due to the TV band frequencies themselves.
VHF Low Band - VHF Ch. 2 - 6 59 - 88 MHz requires an approximate 1/4 wave length of 6 feet
High Band - VHF Ch. 7 - 13 175 - 216 MHz requires an approximate 1/4 wave length of 2.5 up to 3 feet
UHF Band - UHF Ch 14- 51 470 to 698 MHz requires requires an approximate 1/4 wave length of 6 to 6.5 inches
This chart clearly shows the reason conventional antennas are designed the way they are, and the need for the enormous sizes required for the low VHF channels, which leads to many compromises when designing an antenna. The original proposal was for all DTV to be in the UHF band, which would have made it much easier for antenna designers to build small practical antennas, but a lot of the VHF broadcasters who where misinformed about DTV signals, thought that since VHF was the best band for analog signals, the same would automatically apply to DTV, which is not true.
Many former VHF stations got a UHF assignment, and were unhappy due to lots of misconceptions and misinformation, so they lobbied the FCC to allow them to go back to VHF after the transition was complete, and many of them regret that decision to this day, especially those who went back to the low VHF band, which is the worst possible band for DTV broadcasting.
In my opinion, there are no reliable indoor antennas that will perform up to the marketing hype they all seem to be subject to. I wish my antenna was available for sale, for I know it would solve a lot of situations like yours. I just finished my indoor design that measures 16 X 9 not including the stand itself. I can be hung on a wall, or mounted on a stand that would sit on a bookcase or small shelf. It too is a compromise, as are all antennas, but I would grantee its performance against ANY indoor antenna currently on the market with a money back grantee.
I know this does not answer any of your questions, or present any solutions, but the antenna manufacturers are only concerned with sales, and care not about the reputation of DTV reception, or the consumers who purchase their inferior products, and I am not afraid to point out this fact. The dimensions for the indoor version of my antenna are given below, and it does receive UHF and VHF low and VHF high band signals as well, when these signals are actually present at the antennas location. !Remember that no antenna will receive a signal that is not present at the antenna itself !!
My Indoor Antenna Dimensions