Hiya! (sorry, I could not address you personally, you did not sign with your name!)
OK, first things first, what is the antenna analyser that you have? Is it one of the MFJ ones, or maybe Palstar, Kuranishi?
Antenna analysers will only show you the SWR and/or impedance of an antenna/feeder combination, they cannot show if your antenna is radiating anything at all.
If you want to see if your antenna is radiating any RF energy you would be better to use an absorption wavemeter or field strength meter to give you a relative indication of radiated energy.
What you antenna analyser can do is help you to tune your antenna to resonance, help you to work out what the SWR bandwidth is, and so on.
Quite obviously then you would expect to find low SWR at the frequency you are intending to transmit on. Since most loaded antennas have a fairly narrow SWR bandwidth, the tuning can very often be quite critical. So set up your antennas tuning carefully.
Very often operators rely on the auto ATU in their transceivers to do all of the work, the 'logic' being that as long as the ATU can match the antenna array to give an impedance suitable for the rigs PA then all will be well. However, loaded antennas generally perform really poorly if operated away from the frequency that they are resonant at. The greater the loading used to bring the antenna to resonance, the narrower the SWR bandwidth, so the poorer the antenna will perform away from its resonant frequency.
Loaded antennas such as the Buddipole tend to only be around 3-7% efficient at best anyway (on the lower bands where the antenna length represents only a small fraction of the 'true' size), and if you try to feed a loaded dipole at a point on the band away from its resonant frequency then the efficiency may well be less that one percent!
The deficiencies of an antenna on receive are very often masked by the transceivers ability to cope with wide ranges of signal levels. Each S-point (according to convention) represents a 6dB change (that's four times) change in signal level. So a signal that is say three S-points down (which doesn't sound too much) is in reality 18dB weaker (thats about one sixty-fourth) than the original level.
So if we use the same antenna for transmit, and remembering the law of reciprocy (what an antenna performs like on receive it will most likely do the same on transmit!), then our transmitted signal will also most likely be 18dB down on what it might otherwise be, so straight away a 100 Watt signal will seem like a 1.56 Watt signal, and couple that with the fact that loaded antennas are fairly inefficient even when they are operated at resonance, then it is a wonder anyone hears us at all!
So IF your brother is using a full size antenna, operated at its resonant frequency, at the optimum height, and IF you are using a loaded antenna, low down, and relying on the ATU in your transceiver to match the antenna, then we have found the answer to your question as to why you can hear him but he cannot hear you (all of this excludes other possible factors such as noise levels, polarisation, other losses etc.)
Hope the above makes sense!
73, Mark.
